Oxidation of linoleic acid

Marcuse, R. (1962). The effect of some amino acids on the oxidation of linoleic acid and its methyl ester. Journal of the American Oil Chemists Society, Vol. 39, No.2 (February 1962) pp. 97-103, ISSN 0003-021X. 

The origin of many of the components of black tea aroma has been studied. Aldehydes are produced by catechin quinone oxidation of amino acids. Enzymic oxidation of carotenoids during manufacture generates ionones and their secondary oxidation products such as theaspirone and dihydroactinidolide. Oxidation of linoleic acid is responsible for the formation of trans-2-hexenal.82... 

Lopez-Nicolas JM, Bru R and Garcia-Carmona F. 1997. Enzymatic oxidation of linoleic acid by lipoxygenase forming inclusion complexes with cyclodextrins as starch model molecules. J Agric Food Chem 45 1144-1148. 

Inhibition and stimulation of LOX activity occurs as a rule by a free radical mechanism. Riendeau et al. [8] showed that hydroperoxide activation of 5-LOX is product-specific and can be stimulated by 5-HPETE and hydrogen peroxide. NADPH, FAD, Fe2+ ions, and Fe3+(EDTA) complex markedly increased the formation of oxidized products while NADH and 5-HETE were inhibitory. Jones et al. [9] also demonstrated that another hydroperoxide 13(5)-hydroperoxy-9,ll( , Z)-octadecadienoic acid (13-HPOD) (formed by the oxidation of linoleic acid by soybean LOX) activated the inactive ferrous form of the enzyme. These authors suggested that 13-HPOD attached to LOX and affected its activation through the formation of a protein radical. Werz et al. [10] showed that reactive oxygen species produced by xanthine oxidase, granulocytes, or mitochondria activated 5-LOX in the Epstein Barr virus-transformed B-lymphocytes. 

In the case of ubiquinones we have already considered the ability of quinones to react with superoxide and other free radicals. Naphthoquinones, vitamin K and its derivatives, especially menadione, are the well known producers of superoxide through redox cycling with dioxygen. However, in 1985, Canfield et al. [254] have shown that vitamin K quinone reduced the oxidation of linoleic acid while vitamin K hydroquinone stimulated lipid peroxidation. Surprisingly, later on, conflicting results were reported by Vervoort et al. [255] who found that only hydroquinones of vitamin K and its analogs inhibited microsomal lipid peroxidation. 

CLA as An Antioxidant. The complete mechanism of anticarcinogenic activity of CLA is not known. Some of the CLA effect is believed due to its antioxidant properties. For example, use of a water/ethanol system that is incubated at 40"C under air for 14 days, showed CLA reduced the oxidation of linoleic acid by 86% (8), Under the same conditions a-tocopherol reduced oxidation by only 63% and butylated hydroxytoluene (BHT) reduced oxidation by 92%. Dose-response studies were conducted, and it was found that the optimal ratio for CLA to protect linoleic acid from oxidation is 1 1000 (CLAilinoleic acid). 

Furimsky E, Howard JA, Selwyn J (1980) Absolute rate constants for hydrocarbon autoxidation. 28. A low temperature kinetic electron spin resonance study of the self- reactions of isopropylperoxy and related secondary alkylperoxy radicals in solution. Can J Chem 58 677-680 Gebicki JM, Allen AO (1969) Relationship between critical micelle concentration and rate of radiolysis of aqueous sodium linolenate. J Phys Chem 73 2443-2445 Gebicki JM, Bielski BHJ (1981) Comparison of the capacities of the perhydroxyl and the superoxide radicals to initiate chain oxidation of linoleic acid. J Am Chem Soc 103 7020-7022 Gilbert BC, Holmes RGG, Laue HAH, Norman ROC (1976) Electron spin resonance studies, part L. Reactions of alkoxyl radicals generated from alkylhydroperoxidesand titanium(lll) ion in aqueous solution. J Chem Soc Perkin Trans 2 1047-1052... 

Oxidation of linoleic acid Linolenic acid ABAP Spectrophotometric (assay of conjugated dienes) L14... 

What is the sequence of events in the complete oxidation of linoleic acid ... 

After one further -oxidation cycle, a 4-cis-enoyl CoA intermediate is formed. It is acted upon by enoyl-CoA dehydrogenase to give 2-trans, 4-cis-dienoyl CoA. Further metabolism of this intermediate proceeds through one cycle of /3-oxidation and requires a second auxiliary enzyme, 2,4-dienoyl-CoA reductase which has high activity in mitochondria. Thus, nine molecules of acetyl-CoA are produced from the oxidation of linoleic acid. 

Esterbauer, H., and Schauenstein, E. 1977. Isomeric trihydroxy-octadecenoic acids formed upon enzymic oxidation of linoleic acid by barley flour. Monatshefte fiir Chemie, 108, 963-972. 

Ogoshi and coworkers reported regio- and stereospecific oxidation of linoleic acid by singlet oxygen, which was generated by CDx-sandwiched porphyrin sensitization [125] (Scheme 21). 

Figure 7. Reaction scheme for positional isomerization of double bonds and formation of trans-, trans-hydroperoxides during oxidation of linoleic acid via reversible p-scission of oxygen. Adapted from (246, 248, 250).

That lipid alkoxyl radicals recombine (Reaction 71) at diffusion controlled rates (k= 10 M s ) (198, 305) probably accounts for the presence of low levels of peroxides even under mild conditions and low levels of oxidation. In one study, oxidation of linoleic acid at 30°C gave —C—O—O—C— dimers. Reactions 71-73 were found in linolenic acid oxidized under mild conditions to PV 585 this increased to > 50% at PV 4000 and to > 75% after heating to 40°C (276). Alkoxyl radicals from hydroperoxyepidioxides heated at 40°C generated > 90% dimers (276). 

Afrormosin, 243, calycosin, 245, and odoratin, 252, have been found to be the antioxidative components of the methanolic extract of A. membranaceus by using the evaluation method on the air oxidation of linoleic acid [243]. Some isoflavonoids have also been determined in root cultures of A. membranaceus by reverse phase HPLC [324]. 

Chiral y-lactones are important compounds of many fruits and give strawberries, peaches, apricots and many other fruits their characteristic and distinctive notes [74]. Albrecht and Tressl [75] investigated the biogenetic sequence of y-decalactone. These results indicate that (E)-3,4-epoxydecanoic acid, formed from (E)-3-decenoyl-CoA, an intermediate of the P-oxidation of linoleic acid, is the genuine precursor in the biosynthesis of y-decalactone. 

The labeling pattern of the (3 lactone moiety could be easily explained by Claisen condensation of octanoyl-CoA (33) with 3-hydroxy-5,8-tetradecanoyl-CoA (32) obtained by (3 oxidation of linoleic acid, as opposed to polyketide-type biosynthesis from low-molecular-weight fragments64... 

These results from Reference 68 were determined from inhibited oxidation of linoleic acid in cyclohexane. 

It has been established that in many edible mushrooms such as Agaricus campestris and Agaricus bisporus, the C8-compounds are formed enzymically during the oxidation of linoleic acid (16-20). In the present study, the identification of l-octen-3-ol and 2-octen-l-ol as major C8-compounds in macerated fresh Shiitake mushrooms suggested a similar biosynthetic origin. The amount of C8-compounds (primarily l-octen-3-ol and 2-octen-l-ol) in the blanched (97°C, 8 min) or the hot-air dried (commercial process)... 

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