Fatty-acid derived substances number

PG [Prostaglandin] A group of hormone-like substances found in virtually all tissues and organs that are derived from unsaturated fatty acids. These substances mediate a wide range of physiological functions, the most common of which are muscular constriction and the mediation of inflammation. Letters after PG in the abbreviation symbolize different substitutions made to the hydrocarbon backbone, whereas subscript numbers indicate tlae degree of unsaturation (i.e., the number of double bonds). 

The major fatty acids present in plant-derived fatty substances are oleic acid (9-octadecenoic, C18 l), linoleic acid (9,12-octadecadienoic, C18 2) and the conjugated isomers thereof and linolenic acid (9,12,15-octadecatrienoic, C18 3) (Scheme 31.1). Their rates of oxygen absorption are 100 40 1, respectively, hence partial hydrogenation with consequent lowering of the iodine number would lead to a significant increase in oxidative stabihty, particularly when C18 3 is reduced. 

Extractives in native feedstocks comprise an extraordinary large number of diverse substances, mainly with low molecular masses and their amount and composition vary widely from species to species. The most important compounds are volatile and nonvolatile terpenes and their oxygen-containing derivatives (terpenoids) as well as various esters of fatty acids. During softwood kraft pulping, the volatile turpentine (mainly mono- and sesquiterpenes) components are chemically stable, but the fatty acid esters are removed and almost completely hydrolyzed in the early stage of the cook. ° In case of hardwood pulping, more neutral (i.e., chemically unsaponifiable or difficult to saponify) extractives are present and their efficient removal is sometimes... 

In addition to the commonly encountered silicone compounds listed above, a number of other specialized silicone derivatives may be found in personal care formulations. These substances include siliconized natural waxes, fragrances, sunscreens, pigments, amino acids, minerals, vitamins, botanical extracts, essential oils, fatty acids, fatty alcohols, and the like. The various types of compounds that have been covalently bonded onto silicone polymers are quite extensive and will not be discussed in further detail in this chapter. 

It is mainly the lower carboxylic acids and some aromatic carboxylic acids that are active as odour- or taste-active compounds. Taste-active substances are predominantly polyhydric carboxylic acids and some aliphatic carboxylic acids such as acetic and lactic acids, which are major carriers of the sour taste in food raw materials and foods. Short chain fatty acids also have some importance as flavour-active substances (C and Cg) and medium chain fatty acids (Cg-Ci2). A number of carboxylic acids can become precursors of important flavour-active derivatives, such as, for example, esters and lactones. 

By far the greatest number of lichen substances are derived by condensation of a starter unit, usually acetyl-SCoA( ),t and -malonyl-SCoAunits with concomitant decarboxylation. The putative poly-/S-ketothioesterthus formed undergoes modification to give the observed metabolites, also known as polyketides (Collie, 1907), a name best restricted to non-fatty-acid compounds. 

Fluoroacetic acid (pK, = 2.7 0.2) and certain of its derivatives are toxic substances capable of inhibiting the oxidation of fatty acids and pyruvate. The group of compounds known as fluoroacetates may be denoted by the general formula F (CH2) n-iCOOH. The w-fluoroacetates are toxic when n is an even number, i.e., when they contain an even number of carbons they are essentially nontoxic when n is odd. 

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