1.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
2.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses
3.
European Chemicals Agency
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ECHA is the driving force among regulatory authorities in implementing the EUs chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and it is located in Helsinki, Finland. The Agency, headed by Executive Director Geert Dancet, started working on 1 June 2007, the REACH Regulation requires companies to provide information on the hazards, risks and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most commonly used substances have been registered, the information is technical but gives detail on the impact of each chemical on people and the environment. This also gives European consumers the right to ask whether the goods they buy contain dangerous substances. The Classification, Labelling and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU. This worldwide system makes it easier for workers and consumers to know the effects of chemicals, companies need to notify ECHA of the classification and labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100000 substances, the information is freely available on their website. Consumers can check chemicals in the products they use, Biocidal products include, for example, insect repellents and disinfectants used in hospitals. The Biocidal Products Regulation ensures that there is information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation, the law on Prior Informed Consent sets guidelines for the export and import of hazardous chemicals. Through this mechanism, countries due to hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have effects on human health and the environment are identified as Substances of Very High Concern 1. These are mainly substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment, other substances considered as SVHCs include, for example, endocrine disrupting chemicals. Companies manufacturing or importing articles containing these substances in a concentration above 0 and they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy, once a substance has been officially identified in the EU as being of very high concern, it will be added to a list. This list is available on ECHA’s website and shows consumers and industry which chemicals are identified as SVHCs, Substances placed on the Candidate List can then move to another list
4.
PubChem
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PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds, more than 80 database vendors contribute to the growing PubChem database. PubChem consists of three dynamically growing primary databases, as of 28 January 2016, Compounds,82.6 million entries, contains pure and characterized chemical compounds. Substances,198 million entries, contains also mixtures, extracts, complexes, bioAssay, bioactivity results from 1.1 million high-throughput screening programs with several million values. PubChem contains its own online molecule editor with SMILES/SMARTS and InChI support that allows the import and export of all common chemical file formats to search for structures and fragments. In the text search form the database fields can be searched by adding the name in square brackets to the search term. A numeric range is represented by two separated by a colon. The search terms and field names are case-insensitive, parentheses and the logical operators AND, OR, and NOT can be used. AND is assumed if no operator is used, example,0,5000,50,10 -5,5 PubChem was released in 2004. The American Chemical Society has raised concerns about the publicly supported PubChem database and they have a strong interest in the issue since the Chemical Abstracts Service generates a large percentage of the societys revenue. To advocate their position against the PubChem database, ACS has actively lobbied the US Congress, soon after PubChems creation, the American Chemical Society lobbied U. S. Congress to restrict the operation of PubChem, which they asserted competes with their Chemical Abstracts Service
5.
International Chemical Identifier
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Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure
6.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES
7.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
8.
Density
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity, osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume. As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
9.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
10.
Boiling point
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The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the environmental pressure. A liquid in a vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a boiling point than when that liquid is at atmospheric pressure. For a given pressure, different liquids boil at different temperatures, for example, water boils at 100 °C at sea level, but at 93.4 °C at 2,000 metres altitude. The normal boiling point of a liquid is the case in which the vapor pressure of the liquid equals the defined atmospheric pressure at sea level,1 atmosphere. At that temperature, the pressure of the liquid becomes sufficient to overcome atmospheric pressure. The standard boiling point has been defined by IUPAC since 1982 as the temperature at which boiling occurs under a pressure of 1 bar, the heat of vaporization is the energy required to transform a given quantity of a substance from a liquid into a gas at a given pressure. Liquids may change to a vapor at temperatures below their boiling points through the process of evaporation, evaporation is a surface phenomenon in which molecules located near the liquids edge, not contained by enough liquid pressure on that side, escape into the surroundings as vapor. On the other hand, boiling is a process in which molecules anywhere in the liquid escape, a saturated liquid contains as much thermal energy as it can without boiling. The saturation temperature is the temperature for a corresponding saturation pressure at which a liquid boils into its vapor phase, the liquid can be said to be saturated with thermal energy. Any addition of energy results in a phase transition. If the pressure in a system remains constant, a vapor at saturation temperature will begin to condense into its liquid phase as thermal energy is removed, similarly, a liquid at saturation temperature and pressure will boil into its vapor phase as additional thermal energy is applied. The boiling point corresponds to the temperature at which the pressure of the liquid equals the surrounding environmental pressure. Thus, the point is dependent on the pressure. Boiling points may be published with respect to the NIST, USA standard pressure of 101.325 kPa, at higher elevations, where the atmospheric pressure is much lower, the boiling point is also lower. The boiling point increases with increased pressure up to the critical point, the boiling point cannot be increased beyond the critical point. Likewise, the point decreases with decreasing pressure until the triple point is reached
11.
Solubility
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Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent. The solubility of a substance depends on the physical and chemical properties of the solute and solvent as well as on temperature, pressure. The solubility of a substance is a different property from the rate of solution. Most often, the solvent is a liquid, which can be a substance or a mixture. One may also speak of solid solution, but rarely of solution in a gas, the extent of solubility ranges widely, from infinitely soluble such as ethanol in water, to poorly soluble, such as silver chloride in water. The term insoluble is often applied to poorly or very poorly soluble compounds, a common threshold to describe something as insoluble is less than 0.1 g per 100 mL of solvent. Under certain conditions, the solubility can be exceeded to give a so-called supersaturated solution. Metastability of crystals can also lead to apparent differences in the amount of a chemical that dissolves depending on its form or particle size. A supersaturated solution generally crystallises when seed crystals are introduced and rapid equilibration occurs, phenylsalicylate is one such simple observable substance when fully melted and then cooled below its fusion point. Solubility is not to be confused with the ability to dissolve a substance, for example, zinc dissolves in hydrochloric acid as a result of a chemical reaction releasing hydrogen gas in a displacement reaction. The zinc ions are soluble in the acid, the smaller a particle is, the faster it dissolves although there are many factors to add to this generalization. Crucially solubility applies to all areas of chemistry, geochemistry, inorganic, physical, organic, in all cases it will depend on the physical conditions and the enthalpy and entropy directly relating to the solvents and solutes concerned. By far the most common solvent in chemistry is water which is a solvent for most ionic compounds as well as a range of organic substances. This is a factor in acidity/alkalinity and much environmental and geochemical work. According to the IUPAC definition, solubility is the composition of a saturated solution expressed as a proportion of a designated solute in a designated solvent. Solubility may be stated in units of concentration such as molarity, molality, mole fraction, mole ratio, mass per volume. Solubility occurs under dynamic equilibrium, which means that solubility results from the simultaneous and opposing processes of dissolution, the solubility equilibrium occurs when the two processes proceed at a constant rate. The term solubility is used in some fields where the solute is altered by solvolysis
12.
Flash point
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The flash point is the lowest temperature at which vapours of a volatile material will ignite, when given an ignition source. The flash point may sometimes be confused with the autoignition temperature, the fire point is the lowest temperature at which the vapor will keep burning after being ignited and the ignition source removed. The fire point is higher than the point, because at the flash point the vapor may be reliably expected to cease burning when the ignition source is removed. The flash point is a characteristic that is used to distinguish between flammable liquids, such as petrol, and combustible liquids, such as diesel. It is also used to characterize the fire hazards of liquids, all liquids have a specific vapor pressure, which is a function of that liquids temperature and is subject to Boyles Law. As temperature increases, vapor pressure increases, as vapor pressure increases, the concentration of vapor of a flammable or combustible liquid in the air increases. Hence, temperature determines the concentration of vapor of the liquid in the air. The flash point is the lowest temperature at which there will be enough flammable vapor to induce ignition when a source is applied. There are two types of flash point measurement, open cup and closed cup. In open cup devices, the sample is contained in a cup which is heated and, at intervals. The measured flash point will vary with the height of the flame above the liquid surface and, at sufficient height. The best-known example is the Cleveland open cup, in both these types, the cups are sealed with a lid through which the ignition source can be introduced. Closed cup testers normally give lower values for the point than open cup and are a better approximation to the temperature at which the vapour pressure reaches the lower flammable limit. The flash point is an empirical measurement rather than a physical parameter. The measured value will vary with equipment and test protocol variations, including temperature ramp rate, time allowed for the sample to equilibrate, sample volume, methods for determining the flash point of a liquid are specified in many standards. For example, testing by the Pensky-Martens closed cup method is detailed in ASTM D93, IP34, ISO2719, DIN51758, JIS K2265 and AFNOR M07-019. Determination of flash point by the Small Scale closed cup method is detailed in ASTM D3828 and D3278, EN ISO3679 and 3680, cEN/TR15138 Guide to Flash Point Testing and ISO TR29662 Guidance for Flash Point Testing cover the key aspects of flash point testing. Gasoline is a used in a spark-ignition engine
13.
Standard enthalpy of formation
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Its symbol is ΔHo f or ΔfHo. The superscript Plimsoll on this symbol indicates that the process has occurred under standard conditions at the specified temperature. One exception is phosphorus, for which the most stable form at 1 atm is black phosphorus and this is true for all enthalpies of formation. In physics the energy per particle is expressed in electronvolts. All elements in their states have a standard enthalpy of formation of zero. The formation reaction is a constant pressure and constant temperature process, since the pressure of the standard formation reaction is fixed at 1 atm, the standard formation enthalpy or reaction heat is a function of temperature. For tabulation purposes, standard formation enthalpies are all given at a temperature,298 K. The standard enthalpy of formation is equivalent to the sum of separate processes included in the Born–Haber cycle of synthesis reactions. This is because enthalpy is a state function, in the example above the standard enthalpy change of formation for sodium chloride is equal to the sum of the standard enthalpy change of formation for each of the steps involved in the process. This is especially useful for very long reactions with many intermediate steps, chemists may use standard enthalpies of formation for a reaction that is hypothetical. That it is shows that the reaction, if it were to proceed, would be exothermic. It is possible to heat of formations for simple unstrained organic compounds with the Heat of formation group additivity method. Standard enthalpies of formation are used in thermochemistry to find the enthalpy change of any reaction. This implies that the reaction is exothermic, the converse is also true, the standard enthalpy of reaction will be positive for an endothermic reaction. When a reaction is reversed, the magnitude of ΔH stays the same, when the balanced equation for a reaction is multiplied by an integer, the corresponding value of ΔH must be multiplied by that integer as well. Allotropes of an element other than the state generally have non-zero standard enthalpies of formation. Standard enthalpy of sublimation, or heat of sublimation, is defined as the required to sublime one mole of the substance under standard conditions. Standard enthalpy of solution is the change associated with the dissolution of a substance in a solvent at constant pressure under standard conditions
14.
Gibbs free energy
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Just as in mechanics, where the decrease in potential energy is defined as maximum useful work that can be performed, similarly different potentials have different meanings. The Gibbs energy is also the potential that is minimized when a system reaches chemical equilibrium at constant pressure and temperature. Its derivative with respect to the coordinate of the system vanishes at the equilibrium point. As such, a reduction in G is a condition for the spontaneity of processes at constant pressure and temperature. The Gibbs free energy, originally called available energy, was developed in the 1870s by the American scientist Josiah Willard Gibbs. The initial state of the body, according to Gibbs, is supposed to be such that the body can be made to pass from it to states of dissipated energy by reversible processes. In his 1876 magnum opus On the Equilibrium of Heterogeneous Substances, according to the second law of thermodynamics, for systems reacting at STP, there is a general natural tendency to achieve a minimum of the Gibbs free energy. A quantitative measure of the favorability of a reaction at constant temperature and pressure is the change ΔG in Gibbs free energy that is caused by the reaction. As a necessary condition for the reaction to occur at constant temperature and pressure, ΔG must be smaller than the non-PV work, ΔG equals the maximum amount of non-PV work that can be performed as a result of the chemical reaction for the case of reversible process. The equation can be seen from the perspective of the system taken together with its surroundings. First assume that the reaction at constant temperature and pressure is the only one that is occurring. Then the entropy released or absorbed by the system equals the entropy that the environment must absorb or release, the reaction will only be allowed if the total entropy change of the universe is zero or positive. This is reflected in a negative ΔG, and the reaction is called exergonic, if we couple reactions, then an otherwise endergonic chemical reaction can be made to happen. In traditional use, the term free was included in Gibbs free energy to mean available in the form of useful work, the characterization becomes more precise if we add the qualification that it is the energy available for non-volume work. However, a number of books and journal articles do not include the attachment free. This is the result of a 1988 IUPAC meeting to set unified terminologies for the scientific community. This standard, however, has not yet been universally adopted. Further, Gibbs stated, In this description, as used by Gibbs, ε refers to the energy of the body, η refers to the entropy of the body
15.
Triglyceride
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A triglyceride is an ester derived from glycerol and three fatty acids. Triglycerides are the constituents of body fat in humans and other animals. They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver, there are many different types of triglyceride, with the main division between saturated and unsaturated types. Saturated fats are saturated with hydrogen – all available places where hydrogen atoms could be bonded to carbon atoms are occupied and these have a higher melting point and are more likely to be solid at room temperature. Unsaturated fats have double bonds between some of the atoms, reducing the number of places where hydrogen atoms can bond to carbon atoms. These have a melting point and are more likely to be liquid at room temperature. Triglycerides are chemically tri esters of fatty acids and glycerol. Triglycerides are formed by combining glycerol with three fatty acid molecules, organic acids have a carboxyl group. Alcohols and organic acids join to form esters, the glycerol molecule has three hydroxyl groups. Each fatty acid has a carboxyl group, the chain lengths of the fatty acids in naturally occurring triglycerides vary, but most contain 16,18, or 20 carbon atoms. Bacteria, however, possess the ability to synthesise odd- and branched-chain fatty acids, as a result, ruminant animal fat contains odd-numbered fatty acids, such as 15, due to the action of bacteria in the rumen. Many fatty acids are unsaturated, some are polyunsaturated, most natural fats contain a complex mixture of individual triglycerides. Because of this, they melt over a range of temperatures. Cocoa butter is unusual in that it is composed of only a few triglycerides, derived from palmitic, oleic, and stearic acids in the 1-, 2-, the simplest triglycerides are those where the three fatty acids are identical. Their names indicate the fatty acid, stearin derived from acid, palmitin derived from palmitic acid. These compounds can be obtained as three forms or polymorphs, α, β, and β′ and these forms differ in terms of their melting points. If the first and third chain R and R″ are different, then the carbon atom is a chiral centre. The pancreatic lipase acts at the bond, hydrolysing the bond. In triglyceride form, lipids cannot be absorbed by the duodenum, fatty acids, monoglycerides, and some diglycerides are absorbed by the duodenum, once the triglycerides have been broken down
16.
Fatty acid
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In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms. Fatty acids are derived from triglycerides or phospholipids. Fatty acids are important dietary sources of fuel for animals because, many cell types can use either glucose or fatty acids for this purpose. Fatty acids that have double bonds are known as unsaturated. Fatty acids without double bonds are known as saturated and they differ in length as well. Fatty acid chains differ by length, often categorized as short to very long, short-chain fatty acids are fatty acids with aliphatic tails of five or fewer carbons. Medium-chain fatty acids are fatty acids with aliphatic tails of 6–12 carbons, long-chain fatty acids are fatty acids with aliphatic tails of 13 to 21 carbons. Very long chain fatty acids are fatty acids with aliphatic tails of 22 or more carbons, unsaturated fatty acids have one or more double bonds between carbon atoms. The two carbon atoms in the chain that are next to either side of the double bond can occur in a cis or trans configuration. Cis A cis configuration means that the two atoms adjacent to the double bond stick out on the same side of the chain. The rigidity of the double bond freezes its conformation and, in the case of the cis isomer, causes the chain to bend, the more double bonds the chain has in the cis configuration, the less flexibility it has. When a chain has many cis bonds, it becomes quite curved in its most accessible conformations, for example, oleic acid, with one double bond, has a kink in it, whereas linoleic acid, with two double bonds, has a more pronounced bend. α-Linolenic acid, with three bonds, favors a hooked shape. Trans A trans configuration, by contrast, means that the adjacent two hydrogen atoms lie on opposite sides of the chain, as a result, they do not cause the chain to bend much, and their shape is similar to straight saturated fatty acids. In most naturally occurring unsaturated fatty acids, each bond has three n carbon atoms after it, for some n, and all are cis bonds. Most fatty acids in the configuration are not found in nature and are the result of human processing. Fatty acids that are required by the body but cannot be made in sufficient quantity from other substrates
17.
Oleic acid
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Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish, in chemical terms, oleic acid is classified as a monounsaturated omega-9 fatty acid, abbreviated with a lipid number of 18,1 cis-9. The term oleic means related to, or derived from, olive oil which is composed of oleic acid. The corresponding stereoisomer trans-9-Octadecenoic acid is called Elaidic acid and these isomers have distinct physical properties and biochemical properties. Elaidic acid, the most abundant trans fatty acid in diet, fatty acids do not often occur as such in biological systems. Instead fatty acids oleic acid occur as their esters, commonly triglycerides. Fatty acids can be obtained via the process of saponification, triglycerides of oleic acid compose the majority of olive oil, although there may be less than 2. 0% as free acid in virgin olive oil, with higher concentrations making the olive oil inedible. It is abundantly present in animal fats, constituting 37 to 56% of chicken. Oleic acid is the most abundant fatty acid in adipose tissue. Oleic acid is emitted by the corpses of a number of insects, including bees and Pogonomyrmex ants. If a live bee or ant is daubed with oleic acid, the oleic acid smell also may indicate danger to living insects, prompting them to avoid others who have succumbed to disease or places where predators lurk. The biosynthesis of oleic acid involves the action of the enzyme stearoyl-CoA 9-desaturase acting on stearoyl-CoA, in effect, stearic acid is dehydrogenated to give the monounsaturated derivative oleic acid. Oleic acid undergoes the reactions of acids and alkenes. It is soluble in aqueous base to give soaps called oleates, iodine adds across the double bond. Hydrogenation of the double bond yields the saturated derivative stearic acid, oxidation at the double bond occurs slowly in air, and is known as rancidification in foodstuffs or drying in coatings. Reduction of the acid group yields oleyl alcohol. Ozonolysis of oleic acid is an important route to azelaic acid, the coproduct is nonanoic acid, H17C8CH=CHC7H14CO2H + 4O → H17C8CO2H + HO2CC7H14CO2H Esters of azelaic acid find applications in lubrication and plasticizers. The trans isomer of oleic acid is called elaidic acid, a naturally occurring isomer of oleic acid is petroselinic acid
18.
Olive oil
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Olive oil is a liquid fat obtained from olives, a traditional tree crop of the Mediterranean Basin. The oil is produced by pressing whole olives and it is commonly used in cooking, whether for frying or as a salad dressing. It is also used in cosmetics, pharmaceuticals, and soaps, and as a fuel for oil lamps. It is associated with the Mediterranean diet for its health benefits. The olive is one of three core food plants in Mediterranean cuisine, the two are wheat and grapes. Olive trees have grown around the Mediterranean since the 8th millennium BC. Spain is the largest producer of oil, followed by Italy. However, per capita consumption is highest in Greece, followed by Spain, Italy, consumption in North America and northern Europe is far less, but rising steadily. The composition of oil varies with the cultivar, altitude, time of harvest. It consists mainly of acid, with smaller amounts of other fatty acids including linoleic acid. The olive tree is native to the Mediterranean basin, wild olives were collected by Neolithic peoples as early as the 8th millennium BC, the wild olive tree originated in Asia Minor or in ancient Greece. It is not clear when and where trees were first domesticated, in Asia Minor, in the Levant. Archeological evidence shows that olives were turned into oil by 6000 BC and 4500 BC in present-day Palestine. Until 1500 BC, eastern areas of the Mediterranean were most heavily cultivated. Evidence also suggests that olives were being grown in Crete as long ago as 2,500 BC, the cultivation of olive trees in Crete became particularly intense in the post-palatial period and played an important role in the islands economy, as it did across the Mediterranean. Recent genetic studies suggest that species used by modern cultivators descend from multiple wild populations, Olive trees and oil production in the Eastern Mediterranean can be traced to archives of the ancient city-state Ebla, which were located on the outskirts of the Syrian city Aleppo. Here some dozen documents dated 2400 BC describe lands of the king and these belonged to a library of clay tablets perfectly preserved by having been baked in the fire that destroyed the palace. A later source is the frequent mentions of oil in the Tanakh, dynastic Egyptians before 2000 BC imported olive oil from Crete, Syria and Canaan and oil was an important item of commerce and wealth
19.
Lorenzo's oil
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Lorenzo’s oil is 4 parts of glyceryl trioleate and 1 part glyceryl trierucate, which are the triacylglycerol forms of oleic acid and erucic acid and are prepared from olive oil and rapeseed oil. It is used in the treatment of asymptomatic patients with adrenoleukodystrophy. Suddaby and his colleague, Keith Coupland, received U. S, patent No.5,331,009 for the oil. The royalties received by Augusto were paid to the Myelin Project which he and Michaela founded to further treatments for ALD. The Odones and their invention obtained widespread publicity in 1992 because of the film Lorenzo’s Oil, Lorenzo Odone died on May 30,2008, at the age of 30, after suffering from aspiration pneumonia, caused by food getting stuck in his lungs. Lorenzos oil costs approximately US $440 for a months treatment, in the U. S. Lorenzos oil is currently available to only the patients taking part in a clinical trial under the direction of the Kennedy Krieger Institute. Thus, Lorenzos oil can be obtained only through prescription by Kennedy Krieger Institute-authorized physicians, a 500-ml bottle costs approximately $56.00. Some insurance companies provide coverage for the oil, but others do not because it is still considered an experimental drug by the Food. The mixture of fatty acids reduces the levels of very long chain fatty acids. It does so by inhibiting the enzyme that forms VLCFAs. Lorenzos oil, in combination with a low in VLCFA, has been investigated for its possible effects on the progression of ALD. Clinical results have been mixed and the use of Lorenzos oil has been due to uncertainties regarding its clinical efficacy. Hugo Moser played a prominent role in both the treatment of Lorenzo Odone and the evaluation of Lorenzos oil. Moser appraised Lorenzos oil again in a 2007 report, mosers findings, that Lorenzos oil did not help symptomatic ALD patients, are consistent with prior studies published in 2003 and 1999. A study by Poulos published in 1994 found that Lorenzos oil is of limited value in correcting the accumulation of saturated VLCFAs in the brain of patients with ALD, comparative autopsies showed that treatment enriched erucic acid in plasma and tissues, but not in the brain. The oil has been shown to cause a lowered platelet count, there are no reports of toxicity from dietary consumption of erucic acid. Dietary manipulation using Lorenzos oil has been shown to lower levels of very-long-chain fatty acids. However, studies by Dr. Hugo Moser have found evidence that use of the oil by asymptomatic patients may slightly delay the onset of symptoms, the Myelin Project Lorenzo and His Parents
20.
Respiratory quotient
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The respiratory quotient, is a dimensionless number used in calculations of basal metabolic rate when estimated from carbon dioxide production. Such measurements, like measurements of oxygen uptake, are forms of indirect calorimetry and it is measured using a respirometer. It can be used in the alveolar gas equation, the respiratory quotient is the ratio, RQ = CO2 eliminated / O2 consumed where the term eliminated refers to carbon dioxide removed from the body. In this calculation, the CO2 and O2 must be given in the same units, acceptable inputs would be either moles, or else volumes of gas at standard temperature and pressure. Many metabolized substances are compounds containing only the carbon, hydrogen. Examples include fatty acids, glycerol, carbohydrates, deamination products, for complete oxidation of such compounds, the chemical equation is CxHyOz + O2 → x CO2 + H2O and thus metabolism of this compound gives an RQ of x/. The range of respiratory coefficients for organisms in metabolic balance usually ranges from 1.0 to ~0.7, in general, molecules that are more oxidized require less oxygen to be fully metabolized and, therefore, have higher respiratory quotients. Conversely, molecules that are less oxidized require more oxygen for their metabolism and have lower respiratory quotients. See BMR for a discussion of how numbers are derived. A mixed diet of fat and carbohydrate results in a value between these numbers. An RQ may rise above 1.0 for an organism burning carbohydrate to produce or lay down fat, RQ value corresponds to a caloric value for each liter of CO2 produced. If O2 consumption numbers are available, they are used directly, since they are more direct. RQ as measured includes a contribution from the produced from protein. By increasing the proportion of fats in the diet, the quotient is driven down. This reduces the burden to eliminate CO2, thereby reducing the amount of energy spent on respirations. Reference Respiratory Exchange Ratio 516948028 at GPnotebook
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International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
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International Standard Serial Number
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An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication. The ISSN is especially helpful in distinguishing between serials with the same title, ISSN are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an International Organization for Standardization international standard in 1971, ISO subcommittee TC 46/SC9 is responsible for maintaining the standard. When a serial with the content is published in more than one media type. For example, many serials are published both in print and electronic media, the ISSN system refers to these types as print ISSN and electronic ISSN, respectively. The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers, as an integer number, it can be represented by the first seven digits. The last code digit, which may be 0-9 or an X, is a check digit. Formally, the form of the ISSN code can be expressed as follows, NNNN-NNNC where N is in the set, a digit character. The ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, for calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, the modulus 11 of the sum must be 0. There is an online ISSN checker that can validate an ISSN, ISSN codes are assigned by a network of ISSN National Centres, usually located at national libraries and coordinated by the ISSN International Centre based in Paris. The International Centre is an organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, at the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept, where ISBNs are assigned to individual books, an ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an identifier associated with a serial title. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change, separate ISSNs are needed for serials in different media. Thus, the print and electronic versions of a serial need separate ISSNs. Also, a CD-ROM version and a web version of a serial require different ISSNs since two different media are involved, however, the same ISSN can be used for different file formats of the same online serial
23.
Lipid
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In biology, lipids comprise a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main biological functions of lipids include storing energy, signaling, lipids have applications in the cosmetic and food industries as well as in nanotechnology. Biological lipids originate entirely or in part from two types of biochemical subunits or building-blocks, ketoacyl and isoprene groups. Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides, lipids also encompass molecules such as fatty acids and their derivatives, as well as other sterol-containing metabolites such as cholesterol. Although humans and other mammals use various biosynthetic pathways both to break down and to synthesize lipids, some essential lipids cannot be made this way, the word lipid stems etymologically from the Greek lipos. The fatty acid structure is one of the most fundamental categories of biological lipids, the carbon chain, typically between four and 24 carbons long, may be saturated or unsaturated, and may be attached to functional groups containing oxygen, halogens, nitrogen, and sulfur. If a fatty acid contains a double bond, there is the possibility of either a cis or trans geometric isomerism, cis-double bonds cause the fatty acid chain to bend, an effect that is compounded with more double bonds in the chain. This in turn plays an important role in the structure and function of cell membranes, most naturally occurring fatty acids are of the cis configuration, although the trans form does exist in some natural and partially hydrogenated fats and oils. Examples of biologically important fatty acids include the eicosanoids, derived primarily from arachidonic acid and eicosapentaenoic acid, that include prostaglandins, leukotrienes, docosahexaenoic acid is also important in biological systems, particularly with respect to sight. Other major lipid classes in the fatty acid category are the fatty esters, fatty esters include important biochemical intermediates such as wax esters, fatty acid thioester coenzyme A derivatives, fatty acid thioester ACP derivatives and fatty acid carnitines. The fatty amides include N-acyl ethanolamines, such as the cannabinoid neurotransmitter anandamide, glycerolipids are composed of mono-, di-, and tri-substituted glycerols, the best-known being the fatty acid triesters of glycerol, called triglycerides. The word triacylglycerol is sometimes used synonymously with triglyceride, in these compounds, the three hydroxyl groups of glycerol are each esterified, typically by different fatty acids. Because they function as a store, these lipids comprise the bulk of storage fat in animal tissues. The hydrolysis of the bonds of triglycerides and the release of glycerol. Additional subclasses of glycerolipids are represented by glycosylglycerols, which are characterized by the presence of one or more sugar residues attached to glycerol via a glycosidic linkage, examples of structures in this category are the digalactosyldiacylglycerols found in plant membranes and seminolipid from mammalian sperm cells. Glycerophospholipids, usually referred to as phospholipids, are ubiquitous in nature and are key components of the bilayer of cells, as well as being involved in metabolism. Neural tissue contains high amounts of glycerophospholipids, and alterations in their composition has been implicated in various neurological disorders. Examples of glycerophospholipids found in biological membranes are phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine, the major sphingoid base of mammals is commonly referred to as sphingosine
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Saturated fat
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A saturated fat is a type of fat in which the fatty acids all have single bonds. A fat is made of two kinds of molecules, monoglyceride and fatty acids. Fats are made of chains of carbon atoms. Some carbon atoms are linked by bonds and others are linked by double bonds. Double bonds can react with hydrogen to form single bonds and they are called saturated, because the second bond is broken up and each half of the bond is attached to a hydrogen atom. The fats of plants and fish are generally unsaturated, various fats contain different proportions of saturated and unsaturated fat. Certain vegetable products have high saturated fat content, such as coconut oil, many prepared foods are high in saturated fat content, such as pizza, dairy desserts, and sausage. The effect of saturated fat on risk of disease is controversial, many reviews recommend a diet low in saturated fat and argue it will lower risks of cardiovascular diseases, diabetes, or death. However, other reviews have rejected those arguments or advocated for examining the proportion of saturated to unsaturated fat in the diet, while nutrition labels regularly combine them, the saturated fatty acids appear in different proportions among food groups. Lauric and myristic acids are most commonly found in tropical oils, the saturated fat in meat, eggs, cacao, and nuts is primarily the triglycerides of palmitic and stearic acids. Sources of lower saturated fat but higher proportions of unsaturated fatty acids include olive oil, peanut oil, canola oil, avocados, safflower, corn, sunflower, soy, the effect of saturated fat on cardiovascular disease is controversial. Until the picture becomes clearer, experts recommend people stick to the current guidelines on fat consumption, the consumption of saturated fat is generally considered a risk factor for dyslipidemia, which in turn is a risk factor for some types of cardiovascular disease. There are strong, consistent, and graded relationships between saturated fat intake, blood levels, and the mass occurrence of cardiovascular disease. The relationships are accepted as causal, meta-analyses have found a significant relationship between saturated fat and serum cholesterol levels. High total cholesterol levels, which may be caused by many factors, are associated with a risk of cardiovascular disease. However, other indicators measuring cholesterol such as high total/HDL cholesterol ratio are more predictive than total serum cholesterol, in a study of myocardial infarction in 52 countries, the ApoB/ApoA1 ratio was the strongest predictor of CVD among all risk factors. Different saturated fatty acids have differing effects on various lipid levels, a meta-analysis published in 2003 found a significant positive relationship in both control and cohort studies between saturated fat and breast cancer. However two subsequent reviews have found weak or insignificant associations of saturated fat intake and breast cancer risk, one review found limited evidence for a positive relationship between consuming animal fat and incidence of colorectal cancer
25.
Unsaturated fat
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An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is monounsaturated if it contains one double bond, where double bonds are formed, hydrogen atoms are subtracted from the carbon chain. Thus, a saturated fat has no double bonds, has the number of hydrogens bonded to the carbons. In cellular metabolism, unsaturated fat molecules contain less energy than an equivalent amount of saturated fat. The greater the degree of unsaturation in a fatty acid the more vulnerable it is to lipid peroxidation, antioxidants can protect unsaturated fat from lipid peroxidation. Double bonds may be in either a cis or a trans isomer, in the cis isomer, hydrogen atoms are on the same side of the double bond, whereas in the trans isomer, they are on opposite sides of the double bond. Saturated fats are useful in processed foods because saturated fats are less vulnerable to rancidity, unsaturated chains have a lower melting point, hence these molecules increase the fluidity of cell membranes. Although both monounsaturated and polyunsaturated fats can replace saturated fat in the diet, trans unsaturated fats should not, replacing saturated fats with unsaturated fats helps to lower levels of total cholesterol and LDL cholesterol in the blood. Trans unsaturated fats are an exception because the double bond stereochemistry predisposes the carbon chains to assume a linear conformation, the geometry of the cis double bond induces a bend in the molecule, thereby precluding rigid formations. Natural sources of fatty acids are rich in the cis isomer and this probably is an indication of the greater vulnerability of polyunsaturated fats to lipid peroxidation, against which vitamin E has been shown to be protective. Examples of unsaturated fatty acids are palmitoleic acid, oleic acid, myristoleic acid, linoleic acid, foods containing unsaturated fats include avocado, nuts, and vegetable oils such as canola and olive oils. Meat products contain both saturated and unsaturated fats, most foods contain both unsaturated and saturated fats. Marketers advertise only one or the other, depending on which one makes up the majority, thus, various unsaturated fat vegetable oils, such as olive oils, also contain saturated fat. In chemical analysis, fatty acids are separated by gas chromatography of methyl esters, additionally, incidence of Insulin resistance is lowered with diets higher in monounsaturated fats, while the opposite is true for diets high in polyunsaturated fats as well as saturated fats. These ratios can be indexed in the phospholipids of human skeletal muscle, but this is contrary to the suggestion of more recent studies, in which polyunsaturated fats are shown as protective against insulin resistance. This fatty acid results in a more fluid cell membrane but also one that is permeable to various ions. This maintenance cost has been argued to be one of the key causes for the metabolic rates and concomitant warm-bloodedness of mammals. However polyunsaturation of cell membranes may also occur in response to cold temperatures as well
26.
Monounsaturated fat
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In biochemistry and nutrition, monounsaturated fatty acids are fatty acids that have one double bond in the fatty acid chain with all of the remainder carbon atoms being single-bonded. By contrast, polyunsaturated fatty acids have more than one double bond, Fatty acids are long-chained molecules having an alkyl group at one end and a carboxylic acid group at the other end. Monounsaturated fatty acids are liquids at room temperature and semisolid or solid when refrigerated, common monounsaturated fatty acids are palmitoleic acid, cis-vaccenic acid and oleic acid. Palmitoleic acid has 16 carbon atoms with the first double bond occurring 7 carbon atoms away from the methyl group and it can be lengthened to the 18-carbon cis-vaccenic acid. Oleic acid has 18 carbon atoms with the first double bond occurring 9 carbon atoms away from the acid group. The illustrations below show a molecule of acid in Lewis formula. Polyunsaturated fats protect against cardiovascular disease by providing more membrane fluidity than monounsaturated fats, the large scale KANWU study found that increasing monounsaturated fat and decreasing saturated fat intake could improve insulin sensitivity, but only when the overall fat intake of the diet was low. However, some monounsaturated fatty acids may promote resistance, whereas polyunsaturated fatty acids may be protective against insulin resistance. Studies have shown that substituting dietary monounsaturated fat for saturated fat is associated with increased physical activity. More physical activity was associated with a higher-oleic acid diet than one of a palmitic acid diet, from the study, it is shown that more monounsaturated fats lead to less anger and irritability. Foods containing monounsaturated fats reduce low-density lipoprotein cholesterol, while possibly increasing high-density lipoprotein cholesterol, however, their true ability to raise HDL is still in debate. Levels of oleic along with other monounsaturated fatty acids in red cell membranes were positively associated with breast cancer risk. The saturation index of the same membranes was inversely associated with breast cancer risk, monounsaturated fats and low SI in erythrocyte membranes are predictors of postmenopausal breast cancer. Both of these depend on the activity of the enzyme delta-9 desaturase. In children, consumption of monounsaturated oils is associated with healthier serum lipid profiles, the Mediterranean Diet is one heavily influenced by monounsaturated fats. The diet in Crete is fairly high in total fat yet affords a protection from coronary heart disease. Monounsaturated fats are found in foods such as red meat, whole milk products, nuts and high fat fruits such as olives. Olive oil is about 75% monounsaturated fat, the high oleic variety sunflower oil contains as much as 85% monounsaturated fat
27.
Polyunsaturated fat
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Polyunsaturated fats are lipids in which the constituent hydrocarbon chain possesses two or more carbon–carbon double bonds. Polyunsaturated fat can be mostly in nuts, seeds, fish, algae, leafy greens. Unsaturated refers to the fact that the molecules contain less than the amount of hydrogen. These materials exist as cis or trans isomers depending on the geometry of the double bond, saturated fats have hydrocarbon chains which can be most readily aligned. The hydrocarbon chains in trans fats align more readily than those in cis fats and this means that, in general, the melting points of fats increase from cis to trans unsaturated and then to saturated. See the section on chemical structure of fats for more information, the position of the carbon-carbon double bonds in carboxylic acid chains in fats is designated by Greek letters. The carbon atom closest to the group is the alpha carbon. In fatty acids the carbon atom of the group at the end of the hydrocarbon chain is called the omega carbon because omega is the last letter of the Greek alphabet. Omega-3 fatty acids have a double bond three carbons away from the carbon, whereas omega-6 fatty acids have a double bond six carbons away from the methyl carbon. The illustration below shows the omega-6 fatty acid, linoleic acid, while it is the nutritional aspects of polyunsaturated fats that are generally of greatest interest, these materials do also have non-food applications. Drying oils, which polymerize on exposure to oxygen to form films, are polyunsaturated fats. The most common ones are linseed oil, tung oil, poppy seed oil, perilla oil and these oils are used to make paints and varnishes. In preliminary research, omega-3 fatty acids in algal oil, fish oil, fish, ongoing research indicates that omega-6 fatty acids in sunflower oil and safflower oil may also reduce the risk of cardiovascular disease. Among n-3 fatty acids, neither long-chain nor short-chain forms were associated with breast cancer risk. High levels of acid, however, the most abundant n-3 PUFA in erythrocyte membranes, were associated with a reduced risk of breast cancer. The DHA obtained through the consumption of polyunsaturated fatty acids is associated with cognitive. In addition DHA is vital for the grey matter structure of the human brain, dietary intake of polyunsaturated fatty acids has been shown in preliminary studies to decrease the risk of developing amyotrophic lateral sclerosis. The importance of the ratio of essential fatty acids as established by comparative studies shows an Omega-6
28.
Essential fatty acid
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Those not essential are non-essential fatty acids. The term essential fatty acid refers to fatty acids required for biological processes but does not include the fats that only act as fuel, Essential fatty acids should not be confused with essential oils, which are essential in the sense of being a concentrated essence. Only two fatty acids are known to be essential for humans, alpha-linolenic acid and linoleic acid. When the two EFAs were discovered in 1923, they were designated vitamin F, but in 1929, the biological effects of the ω-3 and ω-6 fatty acids are mediated by their mutual interactions, see Essential fatty acid interactions for detail. In the body, essential fatty acids serve multiple functions, in each of these, the balance between dietary ω-3 and ω-6 strongly affects function. The carbon next to the carboxylate is known as α, the next carbon β, since biological fatty acids can be of different lengths, the last position is labelled as a ω, the last letter in the Greek alphabet. The physiological properties of unsaturated fatty acids largely depend on the position of the first unsaturation relative to the end position, for example, the term ω-3 signifies that the first double bond exists as the third carbon-carbon bond from the terminal CH3 end of the carbon chain. The number of carbons and the number of bonds are also listed. ω-318,4 or 18,4 ω-3 or 18,4 n−3 indicates an 18-carbon chain with 4 double bonds, double bonds are cis and separated by a single methylene group unless otherwise noted. So in free fatty acid form, the structure of stearidonic acid is, For complete tables of ω-3 and ω-6 essential fatty acids. In humans, arachidonic acid can be synthesized from LA by alternative desaturation and this is illustrated by studies in vegans and vegetarians. If there is relatively more LA than ALA in the diet it favors the formation of acid from LA rather than docosahexaenoic acid from ALA. This effect can be altered by changing the ratio of LA, ALA. However, the capacity to convert LA to AA and ALA to DHA in the infant is limited. Both AA and DHA are present in breastmilk and contribute along with the parent fatty acids LA and ALA to meeting the requirements of the newborn infant, many infant formulas have AA and DHA added to them with an aim to make them more equivalent to human milk. Essential nutrients are defined as those that cannot be synthesized de novo in sufficient quantities for normal physiological function and this definition is met for LA and ALA but not the longer chain derivatives in adults. The longer chain derivatives particularly, however, have properties that can modulate disease processes. Between 1930 and 1950, arachidonic acid and linolenic acid were termed essential because each was more or less able to meet the requirements of rats given fat-free diets
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Fat
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Fat is one of the three main macronutrients, along with carbohydrate and protein. Fats, also known as triglycerides, are esters of three fatty acid chains and the alcohol glycerol, the terms oil, fat, and lipid are often confused. Oil normally refers to a fat with short or unsaturated fatty acid chains that is liquid at room temperature, lipid is the general term, as a lipid is not necessarily a triglyceride. Fats, like lipids, are generally hydrophobic, and are soluble in organic solvents. Fat is an important foodstuff for many forms of life, and they are a necessary part of the diet of most heterotrophs. Some fatty acids that are set free by the digestion of fats are called essential because they cannot be synthesized in the body from simpler constituents, there are two essential fatty acids in human nutrition, alpha-linolenic acid and linoleic acid. Other lipids needed by the body can be synthesized from these, fats and other lipids are broken down in the body by enzymes called lipases produced in the pancreas. Fats and oils are categorized according to the number and bonding of the atoms in the aliphatic chain. Fats that are saturated fats have no double bonds between the carbons in the chain, unsaturated fats have one or more double bonded carbons in the chain. The nomenclature is based on the end of the chain. This end is called the end or the n-end. Thus alpha-linolenic acid is called an omega-3 fatty acid because the 3rd carbon from that end is the first double bonded carbon in the counting from that end. Some oils and fats have double bonds and are therefore called polyunsaturated fats. Unsaturated fats can be divided into cis fats, which are the most common in nature, and trans fats. Unsaturated fats can be altered by reaction with hydrogen effected by a catalyst and this action, called hydrogenation, tends to break all the double bonds and makes a fully saturated fat. However, trans fats are generated during hydrogenation as contaminants created by a side reaction on the catalyst during partial hydrogenation. Saturated fats can stack themselves in a closely packed arrangement, so they can easily and are typically solid at room temperature. For example, animal fats tallow and lard are high in saturated fatty acid content and are solids, olive and linseed oils on the other hand are unsaturated and liquid
30.
Oil
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An oil is any neutral, nonpolar chemical substance that is a viscous liquid at ambient temperatures and is both hydrophobic and lipophilic. Oils have a carbon and hydrogen content and are usually flammable. The general definition of oil includes classes of compounds that may be otherwise unrelated in structure, properties. Oils may be animal, vegetable, or petrochemical in origin and they are used for food, fuel, medical purposes, lubrication, and the manufacture of many types of paints, plastics, and other materials. Specially prepared oils are used in religious ceremonies and rituals as purifying agents. First attested in English 1176, the oil comes from Old French oile, from Latin oleum, which in turn comes from the Greek ἔλαιον, olive oil, oil. The earliest attested forms of the word are the Mycenaean Greek
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Trans fat
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Trans fat has been shown to consistently be associated, in an intake-dependent way, with increased risk of coronary heart disease, a leading cause of death in Western nations. Fats contain long chains, which can either be unsaturated, i. e. have double bonds, or saturated. In nature, unsaturated fatty acids generally have cis as opposed to trans configurations, Trans fats also occur naturally in a limited number of cases. Vaccenyl and conjugated linoleyl containing trans fats occur naturally in trace amounts in meat, most artificial trans fats are chemically different from natural trans fats. A study by the US Department of Agriculture showed that vaccenic acid raises both HDL and LDL cholesterol, whereas industrial trans fats only raise LDL without any effect on HDL. In 2003 the World Health Organisation recommended that trans fats make up no more than 1% of a persons diet. On 16 June 2015, the FDA finalized its determination that trans fats are not generally recognized as safe, in other countries, there are legal limits to trans fat content. Trans fats levels can be reduced or eliminated using saturated fats such as lard, palm oil or fully hydrogenated fats, other alternative formulations can also allow unsaturated fats to be used to replace saturated or partially hydrogenated fats. Hydrogenated oil is not a synonym for trans fat, complete hydrogenation removes all unsaturated fats, nobel laureate Paul Sabatier worked in the late 1890s to develop the chemistry of hydrogenation, which enabled the margarine, oil hydrogenation, and synthetic methanol industries. Whereas Sabatier considered hydrogenation of only vapors, the German chemist Wilhelm Normann showed in 1901 that liquid oils could be hydrogenated, during the years 1905–1910, Normann built a fat-hardening facility in the Herford company. At the same time, the invention was extended to a plant in Warrington, England, at Joseph Crosfield & Sons. It took only two years until the fat could be successfully produced in the plant in Warrington, commencing production in the autumn of 1909. The initial years production totalled nearly 3,000 tonnes, in 1909, Procter & Gamble acquired the US rights to the Normann patent, in 1911, they began marketing the first hydrogenated shortening, Crisco. Further success came from the technique of giving away free cookbooks in which every recipe called for Crisco. Normanns hydrogenation process made it possible to stabilize affordable whale oil or fish oil for human consumption, prior to 1910, dietary fats consisted primarily of butterfat, beef tallow, and lard. During Napoleons reign in France in the early 19th century, a type of margarine was invented to feed the troops using tallow and buttermilk, it did not gain acceptance in the U. S. In the early 20th century, soybeans began to be imported into the U. S. as a source of protein, what to do with that oil became an issue. At the same time, there was not enough available for consumers
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Omega-3 fatty acid
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Omega-3 fatty acids—also called ω-3 fatty acids or n-3 fatty acids—are polyunsaturated fatty acids with a double bond at the third carbon atom from the end of the carbon chain. One way in which a fatty acid is named is determined by the location of the first double bond, counted from the end, that is. However, the chemical nomenclature system starts from the carbonyl end. The three types of fatty acids involved in human physiology are α-linolenic acid, eicosapentaenoic acid. Marine algae and phytoplankton are primary sources of fatty acids. Dietary supplementation with omega-3 fatty acids does not appear to affect the risk of death, furthermore, fish oil supplement studies have failed to support claims of preventing heart attacks or strokes. Omega-3 fatty acids are important for normal metabolism, the ability to make the longer-chain omega-3 fatty acids from ALA may be impaired in aging. In foods exposed to air, unsaturated fatty acids are vulnerable to oxidation, supplementation does not appear to be associated with a lower risk of all-cause mortality. The evidence linking the consumption of fish to the risk of cancer is poor, supplementation with omega-3 fatty acids does not appear to affect this either. A2006 review concluded there was no link between omega-3 fatty acids consumption and cancer. In those with advanced cancer and cachexia, omega-3 fatty acids supplements may be of benefit, improving appetite, weight, there is tentative evidence that marine omega-3 polyunsaturated fatty acids reduce the risk of breast cancer but this is not conclusive. The effect of consumption on cancer is not conclusive. There is a risk with higher blood levels of DPA. Evidence, in the population generally, does not support a role for omega-3 fatty acid supplementation in preventing cardiovascular disease or stroke. No protective effect against the development of stroke or all-cause mortality was seen in this population, eating a diet high in fish that contain long chain omega-3 fatty acids does appear to decrease the risk of stroke. Fish oil supplementation has not been shown to benefit revascularization or abnormal heart rhythms and has no effect on heart failure hospital admission rates, furthermore, fish oil supplement studies have failed to support claims of preventing heart attacks or strokes. Evidence suggests that omega-3 fatty acids modestly lower blood pressure in people with hypertension, Omega-3 fatty acids reduce blood triglyceride levels but do not significantly change the level of LDL cholesterol or HDL cholesterol in the blood. ALA does not confer the cardiovascular benefits of EPA and DHAs
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Omega-6 fatty acid
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Linoleic acid, the shortest-chained omega-6 fatty acid, is one of many essential fatty acids and is categorized as an essential fatty acid because the human body cannot synthesize it. Mammalian cells lack the enzyme omega-3 desaturase and therefore cannot convert omega-6 fatty acids to omega-3 fatty acids, closely related omega-3 and omega-6 fatty acids act as competing substrates for the same enzymes. This outlines the importance of the proportion of omega-3 to omega-6 fatty acids in a diet, Omega-6 fatty acids are precursors to endocannabinoids, lipoxins, and specific eicosanoids. Medical research on humans found a correlation between the intake of omega-6 fatty acids from vegetable oils and disease in humans. Competitive interactions with the fatty acids affect the relative storage, mobilization, conversion and action of the omega-3. Some medical research suggests that levels of omega-6 fatty acids from seed oils relative to certain omega-3 fatty acids may increase the probability of a number of diseases. Modern Western diets typically have ratios of omega-6 to omega-3 in excess of 10 to 1, some as high as 30 to 1, the average ratio of omega-6 to omega-3 in the Western diet is 15, 1–16.7,1. Humans are thought to have evolved with a diet of a 1-to-1 ratio of omega-6 to omega-3, a ratio of 2–3,1 omega 6 to omega 3 helped reduce inflammation in patients with rheumatoid arthritis. A ratio of 5,1 had an effect on patients with asthma. A ratio of 2.5,1 reduced rectal cell proliferation in patients with colorectal cancer, Excess omega-6 fatty acids from vegetable oils interfere with the health benefits of omega-3 fats, in part because they compete for the same rate-limiting enzymes. A high proportion of omega-6 to omega-3 fat in the diet shifts the state in the tissues toward the pathogenesis of many diseases, prothrombotic, proinflammatory. Chronic excessive production of omega-6 eicosanoids is correlated with arthritis, inflammation, many of the medications used to treat and manage these conditions work by blocking the effects of the COX-2 enzyme. The COX-1 and COX-2 inhibitor medications, used to treat inflammation and pain, the LOX inhibitor medications often used to treat asthma work by preventing the LOX enzyme from converting arachidonic acid into the leukotrienes. Many of the medications used to treat bipolar disorder work by targeting the arachidonic acid cascade in the brain. A high consumption of oxidized polyunsaturated fatty acids, which are found in most types of vegetable oil, similar effect was observed on prostate cancer, but the study was performed on mice. Another analysis suggested an association between total polyunsaturated fatty acids and breast cancer risk, but individual polyunsaturated fatty acids behaved differently. A20,2 derivative of linoleic acid was inversely associated with the risk of breast cancer, Omega-6 and omega-3 are essential fatty acids that are metabolized by some of the same enzymes, and therefore an imbalanced ratio can affect how the other is metabolized. In a study performed by Ponnampalam, it was noticed that feeding systems had an effect on nutrient content on the meat sold to consumers
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Eicosanoid
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In performing these tasks, eicosanoids most often act as autocrine signaling agents to impact their cells of origin or as paracrine signaling agents to impact cells near to their cells of origin. However, they can act as endocrine agents to control the function of distant cells. Mammals, including humans, are unable to convert ω-6 into ω-3 PUFA, in consequence, tissue levels of the ω-6 and ω-3 PUFAs and their corresponding eicosanoid metabolites link directly to the amount of dietary ω-6 versus ω-3 PUFAs consumed. Eicosanoid is the term for straight-chain polyunsaturated fatty acids of 20 carbon units in length that have been metabolized or otherwise converted to oxygen-containing products. Adrenic acid,7,10,13, 16-docosatetraenoic acid, is an ω-6 fatty acid with four cis double bounds, each located between carbons 7-8, 10-11, 13-14, and 17-18. 5Z, 8Z, 11Z, 14Z, 17Z-eicosapentaenoic acid is an ω-3 fatty acid with five cis double bonds, each located between carbons 5-8, 8-9,11, -12, 14-15, and 17-18. Dihomo-gamma-linolenic acid, 8Z, 11Z, 14Z-eicosatrienoic acid is an ω-6 fatty acid with three cis double bonds, each located between carbons 8-9,11, -12, and 14-15. Mead acid, i. e. 5Z, 8Z, 11Z-eicosatrienoic acid, is an ω-9 fatty acid containing three cis double bonds, each located between carbons 5-6, 8-9, and 11, -12. Examples are, The EPA-derived prostanoids have three double bonds while leukotrienes derived from EPA have five double bonds, the AA-derived prostanoids have two double bonds while their AA-derived leukotrienes have four double bonds. Hydroperoxy-, hydroxyl-, and oxo-eicosanoids possess a hydroperoxy, hydroxy and their trivial names indicate the substituent as, Hp or HP for a hydroperoxy residue, H for a hydroxy residue, and oxo- for an oxo residue. g. ALOX12B forms R chirality products, i. e. 12R-HpETE and 12R-HETE, similarly, ALOXE3 metabolizes arachidonic acid to 12R-HpETE and 12R-HETE, however these are minor products that this enzyme forms only under a limited set of conditions. ALOXE3 preferentially metabolizes arachidonic acid to hepoxilins, all of these epoxides are converted, sometimes rapidly, to their dihydroxy metabolites, by various cells and tissues. PGH2 has a 5-carbon ring bridged by molecular oxygen, the 5-carbon ring of prostacyclin is conjoined to a second ring consisting of 4 carbon and one oxygen atom. See Leukotriene#Biosynthesis, Hydroxyeicosatetraenoic acid, and Eoxin#Human biosynthesis, alternately, ALOX5 uses its LTA synthase activity to act convert 5-HPETE to leukotriene A4. LTA4 is then metabolized either to LTB4 by Leukotriene A4 hydrolase or Leukotriene C4 by either LTC4 synthase or microsomal glutathione S-transferase 2, either of the latter two enzymes act to attach the sulfur of cysteines thio- group in the tripeptide glutamate-cysteine-glycine to carbon 6 of LTA4 thereby forming LTC4. After release from its parent cell, the glutamate and glycine residues of LTC4 are removed step-wise by gamma-glutamyltransferase, the decision to form LTB4 versus LTC4 depends on the relative content of LTA4 hydrolase versus LTC4 synthase class of eicosanoids, possess anti-inflammatory and inflammation resolving activity. RvE1 is also in development studies for the treatment of neurodegenerative diseases. They are proposed to reduce the actions of their aracidonate-derived analogs by replacing their production with weaker analogs, eicosapentaenoic acid-derived counterparts of the Eoxins have not been described
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Prostaglandin
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The prostaglandins are a group of physiologically active lipid compounds having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals and they are derived enzymatically from fatty acids. Every prostaglandin contains 20 carbon atoms, including a 5-carbon ring and they are a subclass of eicosanoids and of the prostanoid class of fatty acid derivatives. The structural differences between prostaglandins account for their different biological activities, a given prostaglandin may have different and even opposite effects in different tissues in some cases. The ability of the same prostaglandin to stimulate a reaction in one tissue and they act as autocrine or paracrine factors with their target cells present in the immediate vicinity of the site of their secretion. Prostaglandins differ from endocrine hormones in that they are not produced at a specific site, prostaglandins are powerful locally acting vasodilators and inhibit the aggregation of blood platelets. Through their role in vasodilation, prostaglandins are also involved in inflammation and they are synthesized in the walls of blood vessels and serve the physiological function of preventing needless clot formation, as well as regulating the contraction of smooth muscle tissue. Conversely, thromboxanes are vasoconstrictors and facilitate platelet aggregation and their name comes from their role in clot formation. Specific prostaglandins are named with a letter followed by a number, for example, prostaglandin E1 is abbreviated PGE1 or PGE1, and prostaglandin I2 is abbreviated PGI2 or PGI2. The name prostaglandin derives from the prostate gland, when prostaglandin was first isolated from seminal fluid in 1935 by the Swedish physiologist Ulf von Euler, and independently by M. W. Goldblatt, it was believed to be part of the prostatic secretions, in fact, prostaglandins are produced by the seminal vesicles. It was later shown that many other tissues secrete prostaglandins for various functions, the first total syntheses of prostaglandin F2α and prostaglandin E2 were reported by E. J. Corey in 1969, an achievement for which he was awarded the Japan Prize in 1989. In 1971, it was determined that aspirin-like drugs could inhibit the synthesis of prostaglandins, the biochemists Sune K. Bergström, Bengt I. Samuelsson and John R. Vane jointly received the 1982 Nobel Prize in Physiology or Medicine for their research on prostaglandins, prostaglandins are found in most tissues and organs. They are produced by almost all nucleated cells and they are autocrine and paracrine lipid mediators that act upon platelets, endothelium, uterine and mast cells. They are synthesized in the cell from the fatty acids. An intermediate arachidonic acid is created from diacylglycerol via phospholipase-A2, then brought to either the cyclooxygenase pathway or the lipoxygenase pathway, prostaglandins were originally believed to leave the cells via passive diffusion because of their high lipophilicity. The release of prostaglandin has now also shown to be mediated by a specific transporter, namely the multidrug resistance protein 4
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Prostacyclin
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Prostacyclin is a prostaglandin member of the eicosanoid family of lipid molecules. It inhibits platelet activation and is also an effective vasodilator, when used as a drug, it is also known as epoprostenol. The terms are used interchangeably. During the 1960s, a U. K. research team, headed by Professor John Vane, began to explore the role of prostaglandins in anaphylaxis and respiratory diseases. Working with a team from the Royal College of Surgeons, Sir John discovered that aspirin and this critical finding opened the door to a broader understanding of the role of prostaglandins in the body. Sir John and a team from the Wellcome Foundation, had identified a lipid mediator they called “PG-X, pG-X, which later would become known as prostacyclin, is 30 times more potent than any other then-known anti-aggregatory agent. By 1976, John Vane and fellow researchers Salvador Moncada, Ryszard Gryglewski, the collaboration produced a synthesized molecule, which was given the name epoprostenol. But, as with native prostacyclin, the structure of the epoprostenol molecule proved to be unstable in solution and this presented a challenge for both in vitro experiments and clinical applications. To overcome this challenge, the team that discovered prostacyclin was determined to continue the research in an attempt to build upon the success they had seen with the prototype molecule. The research team synthesized nearly 1,000 analogues, prostacyclin is produced in endothelial cells, which line the walls of arteries and veins, from prostaglandin H2 by the action of the enzyme prostacyclin synthase. Although prostacyclin is considered an independent mediator, it is called PGI2 in eicosanoid nomenclature, the series-3 prostaglandin PGH3 also follows the prostacyclin synthase pathway, yielding another prostacyclin, PGI3. The unqualified term prostacyclin usually refers to PGI2, PGI2 is derived from the ω-6 arachidonic acid. PGI3 is derived from the ω-3 EPA, prostacyclin chiefly prevents formation of the platelet plug involved in primary hemostasis. It does this by inhibiting platelet activation and it is also an effective vasodilator. Prostacyclins interactions in contrast to thromboxane, another eicosanoid, strongly suggest a mechanism of cardiovascular homeostasis between the two hormones in relation to vascular damage, prostacyclin, which has a half-life of 42 seconds, is broken down into 6-keto-PGF1, which is a much weaker vasodilator. The platelet Gs protein-coupled receptor is activated when it binds to PGI2 and this activation, in turn, signals adenylyl cyclase to produce cAMP. CAMP goes on to any undue platelet activation and also counteracts any increase in cytosolic calcium levels that would result from thromboxane A2 binding. PGI2 also binds to endothelial prostacyclin receptors and in the same manner raise cAMP levels in the cytosol and it can be noted that PGI2 and TXA2 work as physiological antagonists
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Thromboxane
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Thromboxane is a member of the family of lipids known as eicosanoids. The two major thromboxanes are thromboxane A2 and thromboxane B2, the distinguishing feature of thromboxanes is a 6-membered ether-containing ring. Thromboxane is named for its role in clot formation, thromboxane-A synthase, an enzyme found in platelets, converts the arachidonic acid derivative prostaglandin H2 to thromboxane. Thromboxane acts by binding to any of the receptors, G-protein-coupled receptors coupled to the G protein Gq. Thromboxane is a vasoconstrictor and a potent hypertensive agent, and it facilitates platelet aggregation and it is in homeostatic balance in the circulatory system with prostacyclin, a related compound. The mechanism of secretion of thromboxanes from platelets is still unclear and they act in the formation of blood clots and reduce blood flow to the site of a clot. If the cap of a vulnerable plaque erodes or ruptures, as in MI, platelets stick to the lining of the vessel and to each other within seconds. These Sticky platelets secrete several chemicals, including thromboxane A2 that stimulate vasoconstriction, thromboxane A2, produced by activated platelets, has prothrombotic properties, stimulating activation of new platelets as well as increasing platelet aggregation. Platelet aggregation is achieved by mediating expression of the glycoprotein complex GP IIb/IIIa in the membrane of platelets. Circulating fibrinogen binds these receptors on adjacent platelets, further strengthening the clot and it is believed that the vasoconstriction caused by thromboxanes plays a role in Prinzmetals angina. It is believed that this shift in balance lowers the incidence of myocardial infarction, hepatic inflammatory processes, acute hepatotoxicity etc. TxB2, a degradation product of TxA2, plays a role in acute hepatoxicity induced by acetaminophen. Thromboxane inhibitors are classified as either those that inhibit the synthesis of thromboxane. Low-dose, long-term aspirin use irreversibly blocks the formation of thromboxane A2 in platelets and this anticoagulant property makes aspirin useful for reducing the incidence of heart attacks. Thromboxane synthase inhibitors inhibit the enzyme in the synthesis of thromboxane. Ifetroban is a potent and selective thromboxane receptor antagonist, dipyridamole antagonizes this receptor too, but has various other mechanisms of antiplatelet activity as well. The inhibitors of the effects of thromboxane are the thromboxane receptor antagonist. Picotamide has activity both as a thromboxane synthase inhibitor and as a receptor antagonist
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Leukotriene
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Leukotrienes use lipid signaling to convey information to either the cell producing them or neighboring cells in order to regulate immune responses. Leukotriene production is accompanied by the production of histamine and prostaglandins. One of their roles is to trigger contractions in the smooth muscles lining the bronchioles, their overproduction is a cause of inflammation in asthma. Leukotriene antagonists are used to treat these disorders by inhibiting the production or activity of leukotrienes, the name leukotriene, introduced by Swedish biochemist Bengt Samuelsson in 1979, comes from the words leukocyte and triene. What would be later named leukotriene C, slow reaction smooth muscle-stimulating substance was originally described between 1938 and 1940 by Feldberg and Kellaway, the researchers isolated SRS from lung tissue after a prolonged period following exposure to snake venom and histamine. Leukotrienes are commercially available to the research community, LTC4, LTD4, LTE4 and LTF4 are often called cysteinyl leukotrienes due to the presence of the amino acid cysteine in their structure. The cysteinyl leukotrienes make up the substance of anaphylaxis. LTF4, like LTD4, is a metabolite of LTC4, but, unlike LTD4, LTB4 is synthesized in vivo from LTA4 by the enzyme LTA4 hydrolase. Its primary function is to recruit neutrophils to areas of tissue damage, drugs that block the actions of LTB4 have shown some efficacy in slowing the progression of neutrophil-mediated diseases. There has also postulated the existence of LTG4, a metabolite of LTE4 in which the cysteinyl moiety has been oxidized to an alpha-keto-acid. Very little is known about this putative leukotriene, leukotrienes originating from the omega-3 class eicosapentanoic acid have diminished inflammatory effects. Leukotrienes are synthesized in the cell from arachidonic acid by arachidonate 5-lipoxygenase, the catalytic mechanism involves the insertion of an oxygen moiety at a specific position in the arachidonic acid backbone. The lipoxygenase pathway is active in leukocytes and other immunocompetent cells, including mast cells, eosinophils, neutrophils, monocytes, when such cells are activated, arachidonic acid is liberated from cell membrane phospholipids by phospholipase A2, and donated by the 5-lipoxygenase-activating protein to 5-lipoxygenase. 5-Lipoxygenase uses FLAP to convert arachidonic acid into 5-hydroperoxyeicosatetraenoic acid, which reduces to 5-hydroxyeicosatetraenoic acid. The enzyme 5-LO acts again on 5-HETE to convert it into leukotriene A4, in cells that express LTC4 synthase, such as mast cells and eosinophils, LTA4 is conjugated with the tripeptide glutathione to form the first of the cysteinyl-leukotrienes, LTC4. Outside the cell, LTC4 can be converted by enzymes to form successively LTD4 and LTE4. Both LTB4 and the cysteinyl-leukotrienes are partly degraded in local tissues, leukotrienes act principally on a subfamily of G protein-coupled receptors. They may also act upon peroxisome proliferator-activated receptors, leukotrienes are involved in asthmatic and allergic reactions and act to sustain inflammatory reactions
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Caprylic acid
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Caprylic acid is the common name for the eight-carbon saturated fatty acid known by the systematic name octanoic acid. Its compounds are naturally in the milk of various mammals. It is a liquid that is minimally soluble in water with a slightly unpleasant rancid-like smell. Two other acids are named after goats via the Latin word capra, caproic acid, along with caprylic acid these total 15% in goat milk fat. Caprylic acid is used commercially in the production of esters used in perfumery, in addition, caprylic acid is used as an algaecide, bactericide, and fungicide in nurseries, greenhouses, garden centers, and interiorscapes on ornamentals. Products containing caprylic acid are formulated as soluble concentrate/liquids and ready-to-use liquids, for ghrelin to have a hunger-stimulating action on a hypothalamus, caprylic acid must be linked to a serine residue at the 3-position of ghrelin. To cause hunger, it must acylate an -OH group, other fatty acids in the same position have similar effects on hunger. The acid chloride of caprylic acid is used in the synthesis of perfluorooctanoic acid, caprylic acid is taken as a dietary supplement. There has also been interest in MCTs from endurance athletes and the bodybuilding community, but MCTs are not beneficial to improved exercise performance
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