Linolenic acid, components formed

Biosynthesis of triene pheromone components with a triene double bond system that is n-3 (3,6,9-) are probably produced from linolenic acid [49]. Moths in the families Geometridae, Arctiidae, and Noctuidae apparently utilize linoleic and linolenic acid as precursors for their pheromones that must be obtained in the diet,since moths can not synthesize these fatty acids [50]. Most of the Type II pheromones are produced by chain elongation and decarboxylation to form hydrocarbons [51]. Oxygen is added to one of the double bonds in the polyunsaturated hydrocarbon to produce an epoxide [49]. 

The stability of canola oil is limited mostly by the presence of linolenic acid, chlorophyll, and its decomposition products and other minor components with high chemical reactivity, such as trace amounts of fatty acids with more than three double bonds. These highly unsaturated fatty acids can possibly be formed during refining and bleaching (52). The presence of 7% to 11% of linolenic acid in the acylglyce-rols of canola oil places it in a similar category with soybean oil with respect to flavor and oxidative stability. The deterioration of flavor as the result of auto -and photo-oxidation of unsaturated fatty acids in oils and fats is referred to as oxidative rancidity. 

Tressl et al. (16, 17) had shown that linolenic acid (C 18 3) could also be enzymically converted to volatile C8-compounds. However, 1,5-octadien-3-ol and 2,5-octadien-l-ol would be two major C8-compounds formed. No significant amount of 1,5-octadien-3-ol and 2,5-octadien-l-ol could be detected in the volatile components of Shiitake mushrooms blended with sunflower oil hydrolysate (Table I). Instead, significant amount of 1,5-octadien-3-ol or 2,5-octa-dien-l-ol was observed in the sample to which soybean oil hydrolysate was added (20). This is in good agreement with the linolenic acid content in sunflower oil (trace) and soybean oil (ca. 7%). ... 

Aside from essential amino acids, the n-3 and n-6 fatty acids constitute the largest chemical component of the cerebral cortex and retina that can be obtained only from the diet. The body cannot synthesize either the n-3 or the n-6 structure. Once the basic n-3 structure is consumed in the form of linolenic acid (18 3), the body can synthesize the longer-chained and highly polyunsaturated fatty acid docosahexaenoic acid (22 6), which is the n-3 fatty acid so predominant in the nervous system. Similarly, in the n-6 series, linoleic acid (18 2) is converted to arachidonic acid (20 4), the predominant n-6 fatty acid... 

Figure 1 shows Cg-, Cg-, Cs-, C- o snd C- 2 components which are formed from linolenic acid in certain plants, fruits, vegetables, and mushrooms. There are normally four enzymes involved which seem to be membrane bonded and located in the chloroplasts. In 1970 we tried to Isolate and characterize these enzymes and could demonstrate that lipoxygenase (Ei), an... 

Figure 1. Various components formed from linolenic acid in certain plants, fruits,...

The results of the analogous experiments with linolenate are summarized in Table II. Major products formed by 02-oxidation caprylic acid, 2,4-heptenals, 2,4,7-decatrienals, 9-oxononanoic acid. Major components indicating 102-reactions 2-butenal, 2,4-hepta-dienal, and 10-oxo-(E)-8-decenoate. 2-Hexenal, 3-hexe-nal, 2,6- and 3,6-nonadienals - known as enzymic degradation products from linolenic acids in fruits and vegetables - were detected as minor components. 

Linolenic acid is better metabolized than linoleic acid (6 % 15 %). (Z,Z)-3,6-Nonadienal is transformed into (E,Z)-2,6-nonadienal and pentenylfuran, which has been characterized for the first time. In all experiments 9-oxononanoic acid was formed as a major component as shown recently (22). Green bananas posses a similar enzyme system producing strictly Cg-compo-nents. 

The enzymic formation of Cs- and Cg-components in vegetables is determined by the cleaving-system E2. Tomatoes possess a lipoxygenase-system which forms 9-LOOH and 13-LOOH in a ratio of 95 5 (23). According to Matthew et al. (2 ) only the 13-LOOH is decomposed into Cg- and C-j2 components by the lyase-system E2 This is consistent with the results of Kazeniac et Hall (2 ) who demonstrated the formation of ( ) -2-hexenal, ( )-3-hexenal and ( )-3-hexen-1-ol from linolenic acid in tomato homogenates. 

Figure 10 summarizes some results of the lipid-oxidation system in basldlomycetes, leaves, fruits, vegetables, and cereals. It can be seen that there is a development with evolution and differentiation. The enzyme system is highly substrate specific to a (Z,Z)-1,4-pentadiene system converting linoleic- and linolenic acids into carbonyls and oxoacids which may undergo further isomerization (E3) and/or reduction (E4). Some of the components formed are very potent aromatics, pheromones, and wound hormones. Basidio-mycetes and Fungi produce (-)-1-octen-3-ol as their sensorial principle. 9-Oxodecanoic acid is known as queen substance and is the sex pheromone of honey bees. 

Gamma-linolenic acid (GLA), one of the primary constituents of borage seed oil, is a compound naturally formed in the human body and is a component of human breast milk (Carter 1988). 

There are few data on the types of CFAM from oils used under real frying conditions. The studies, cited above, of saturated monocyclic (7) and bicyclic acids (23) formed in sunflower oils are examples. In another study (25), the CFAM from peanut and soybean oils, used in the flying of frozen prefried french flies, were analyzed after hydrogenation. The types of CFAM were essentially similar between the two oils, with differences only in the relative proportions of components. This observation may seem surprising because the fatty acid compositions of the two oils differ (only soybean oil contains significant amounts of a-linolenic acid) this may be explained in part by the derivation of the same hydrogenated CFAM from different intact CFAM. However, the detection of an acid with a eyelopentyl ring between C-11 and... 

C18H30O2 M 278.434 (Z,Z,Z) form [506-26-3] y-Linolenic acid. Gamolenic acid, ban, usan Isol. from evening primrose seed oil. A minor component of many animal lipids. Antihypercholesterolemic drug. Hexabromide Mp 196 dec. 

Odor-Active Monocarbonyl Compounds. Model expriments showed that the volatile fractions formed during the autoxidation of oleic, linoleic and linolenic acid contain mainly aldehydes and ketones (Table 3.31). Linoleic acid, a component of all lipids sensitive to autoxidation, is a precursor of hexanal that is predominant in... 

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