Fatty acids hydroperoxides formation

Hamberg, M. and B. Gotthammar. 1973. A new reaction of unsaturated fatty acid hydroperoxides formation of 11-hydroxy-12,13-epoxy-9-octadecenoic acid from... 

An example of an experiment in which LDL has been treated with 15-lipoxygenase and the oxidation monitored by the formation of conjugated diene is shown in Fig. 2.2. In the absence of transition metal, a rapid increase in absorbance occurs, with no lag phase, which ceases after a period of about 90 min under these conditions. If copper is added to promote LDL oxidation at this point, LDL treated with lipoxygenase oxidizes at a faster rate with a short lag phase when compared to the control. During this procedure there is only a minimal loss of a-tocopherol and so we may ascribe the shortened lag phase to the increase in lipid peroxides brought about by lipoxygenase treatment. A similar result was found when LDL was supplemented with preformed fatty acid hydroperoxides (O Leary eta/., 1992). 

Support for this conclusion is provided by the hydroperoxide specificity of BP oxidation. The scheme presented in Figure 6 requires that the same oxidizing agent is generated by reaction of h2°2/ peroxy acids, or alkyl hydroperoxides with the peroxidase. Oxidation of any compound by the iron-oxo intermediates should be supported by any hydroperoxide that is reduced by the peroxidase. This is clearly not the case for oxidation of BP by ram seminal vesicle microsomes as the data in Figure 7 illustrate. Quinone formation is supported by fatty acid hydroperoxides but very poorly or not at all by simple alkyl hydroperoxides or H2C>2. The fact that... 

Unsaturated fatty acids in foods are very susceptible to oxidation by oxygen in the air during processing and storage. The oxidation results initially in the formation of fatty acid hydroperoxides by a free radical chain mechanism. The hydroperoxides are subject to several further reactions forming secondary products such as aldehydes, ketones, and other volatile compounds, many of which are odorous and cause rancid flavor in the food. This development of rancid flavor limits the storage stability of a large number of food products. 

Oil-acrylate hybrid-emulsions were formed using the fatty-acid hydroperoxides as initiator system for the miniemulsion polymerization of acrylate. The initiation took place at the droplet interface and resulted in the formation of triglycide modified polyacrylate molecules which act as compatibili-... 

The formation of Cg aldehyde and alcohols in plant tissues is related to cell destruction. Disruption of intact cells during crushing and milling results in the release of lipid-degrading en2ymes, lipoxygenases and fatty acid hydroperoxide lyase, which cleave the fatty acid moiety to Cg... 

Fatty acid hydroperoxide lyase is one of the enzymes responsible for volatile Cft- and C9-aldehyde formation from linoleic and linolenic acid. This enzyme cleaves 9- and/or 13-hydroperoxides derived from linoleic and linolenic acid. The enzyme is distributed in a wide range of plant species in membrane bound forms both chloroplastic and non-chloroplastic. Three types of hydroperoxide lyases have been reported 9-hydroperoxide-specific, 13-hydroperoxide-specific and nonspecific. Other properties of the hydroperoxide lyase including substrate specificity and reaction mechanism are discussed in this review. 

Four principal reactions of the peroxyl radical are important for the outcome of lipid peroxidation formation of a fatty acid hydroperoxide, p-fragmentation, addition to a double bond, and formation of peroxide bridges. 

The formation and decomposition of fatty acid hydroperoxides in aqueous solution under physiological conditions furnishes a range of poly- nctional short-chain compounds such as 4-hydroperoxynon-2-enal and 4-hydroxyoct-2-enal. The latter displays a number of significant physiological effects based on its reaction with thiol groups, including those which are active sites of enzymes. 

Scheme 3 Product formation in the lipoxygenase-catalysed free radical reaction with unsaturated fatty acids and fatty acid hydroperoxides ...

IMMOBILIZATION OF LIPOXYGENASE IN AN ALGINATE-SILICATE SOLGEL MATRIX FORMATION OF FATTY ACID HYDROPEROXIDES... 

Immobilization of Lipoxygenase in Alginate-Silicate Sol-Gel Matrix Formation of Fatty Acid Hydroperoxides. 

Ketoses may also enter into the reaction, and then the formation of glycosylamine is followed by Heyns rearrangement (Section 4.7.5.1). The reaction could also include not only carbonyl compounds derived from the degradation of sugars, but also Strecker aldehydes arising from amino acids and reactive aldehydes and other compounds produced as secondary decomposition products of fatty acid hydroperoxides in hpid peroxidation. 

Oxylipins are commonly found metabolites in higher plants and most of them originate from polyunsaturated fatty acid hydroperoxides by enzymatic transformations which have been extensively studied (for recent reviews, see 1,2). Two well characterized enzymes a lyase and an allene oxide synthase were shown to degrade hydroperoxides into compounds of physiological importance since they can ultimately yield fragrances or plant hormones such as jasmonic acid. We have recently reported a new fate for fatty acid hydroperoxides the peroxygenase pathway. It involves two enzyme activities i.e. a peroxygenase and an epoxide hydrolase which lead to the formation of epoxidized fatty acids and their derived dihydrodiols which are relevant to plant defense mechanisms. 

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