Trihydroxy fatty acids production

In plant tissues, various enzymes convert the hydroperoxides produced by LOX to other products, some of which are important as flavor compounds. These enzymes include hydroperoxide lyase, which catalyzes the formation of aldehydes and oxo acids hydroperoxide-dependent peroxygenase and epoxygenase, which catalyze the formation of epoxy and hydroxy fatty acids, and hydroperoxide isomerase, which catalyzes the formation of epoxyhydroxy fatty acids and trihydroxy fatty acids. LOX produces flavor volatiles similar to those produced during autoxidation, although the relative proportions of the products may vary widely, depending on the specificity of the enzyme and the reaction conditions. 

Since Wallen et al. (1962) reported the first bioconversion of oleic acid to 10-hydroxystearic acid by a Pseudomonad, microbial conversions of unsaturated fatty acids from different substrates by various microbial strains have been widely exploited to produce new, value-added products. Among the unsaturated fatty acids used for microbial production of hydroxy fatty acids, three (oleic, linoleic, and linolenic acids) were well studied as substrates to produce mono-, di-, and trihydroxy fatty acids. Recently, a bacterial strain Pseudomonas aeruginosa NRRL B-18602 (PR3) has been studied to produce hydroxy fatty acids from several fatty acid substrates. In this review, we introduce the production of hydroxy fatty acids from their corresponding fatty acid substrates by P. aeruginosa PR3 and their industrially valuable biological activities. 

There are reports about the production of certain 18 carbon-trihydroxy fatty acids from plants (Baur et al., 1977 Dix and Marnett, 1985 Esterbauer and... 

According to the reports describing metabolic pathways involved in the conversion of linoleic acid to trihydroxy fatty acids, several intermediate reaction products, such as trihydroxy-, hydroperoxy-, dihydroxy-, and hydroxyepoxy-octadecenoate, were involved (Kato et al., 1984,1986). Those metabolites of linoleic acid showed distinct biological functions according to their intermediate structures, including mono-, di-, trihydroxy-octadecenoic acid, and hydroperoxy-, epoxy-forms (Kato et al., 1984 Blair, 2001 Gobel et al., 2002 Hou and Forman, 2000). In an effort to understand the overall mechanism involved in the varied biological functions of the complicated reaction metabolites of bio-converted polyunsaturated fatty acids, Kim et al. (2006) studied the oxidative activities on fish oil, of crude extracts produced by PR3 from... 

The epoxy compounds formed via the peroxygenase reaction may then be hydrolysed by epoxide hydrolases that are an integral part of the peroxygenase pathway, forming di- or trihydroxy fatty acids. This pathway is of importance for plant defence as it is hkely to be involved in the biosynthesis of cutin monomers, in the production of antifungal compounds and in detoxification mechanisms [6]. 

This enzyme oxidizes linoleic and linolenic acids rapidly in whole flour or milling products containing wheat germ or bran mixed with water. The initial hydroperoxides formed by lipoxygenases in stored wheat bran are converted to secondary products, mono- and trihydroxy fatty acids. These oxidation products causing bitter and rancid flavors are formed in higher concentrations in hydrated products than in dry raw materials. Rancid flavors develop rapidly on hydration. 

Strain ALA2 converted y-linolenic acid (18 3 all ds-6,9,12) to several products including 12,17 13,17-diepoxy-6,9-octadecadienoic acid 12,13,17-trihydroxy-6(Z),9(Z)-octadecadienoic acid and 12-hydroxy-13,16-epoxy-6(Z),9(Z)-octadecadienoic acid as depicted in the top half of Figure 16.2 (Hosokawa et al, 2003a). Strain ALA2 also converted the substrate arachidonic acid (20 4 all civ-5,8,11,13) to cyclic and trihydroxyl fatty acids as reported previously (Hosokawa et al., 2003a). These reactions resulted in compounds 14,19 15,19-diepoxy-5(Z),8(Z),ll(Z)-eicosatrienoic acid 14-hydroxy-15,18-epoxy-5(Z),... 

The products obtained from the co-6 fatty acids (linoleic acid, y-linolenic acid, and arachidonic acid) by in vivo reactions with strain ALA2 contain diepoxy bicyclic structures, tetrahydrofuranyl rings, and/or trihydroxy groups in their molecules. In contrast to these co-6 PUFAs, substrates classified as co-3 PUFAs (a-linolenic acid, EPA, and DHA) are only converted to hydroxyl THFAs by strain ALA2 with no diepoxy bicyclic or trihydroxy derivatives uncovered to date. Both the hydroxyl groups and cyclic structures derived there from appear to be placed at the same positions on the substrates from the co-carbon termini within each PUFA class, despite differences in carbon chain length and the number of double bonds in the specific PUFA substrates. 

Hou, C. T., Brown, W., Labeda, D. P., Abbott, T. P., and Weisleder, D. 1997. Microbial production of a novel trihydroxy unsaturated fatty acid from linoleic acid. J. Irtd. Microbiol. Biotechnol., 19, 34-38. 

Bioconversion of 12,13,17-THOA and DEOA. For the biosynthesis of diepoxy bicyclic unsaturated fatty acid by strain ALA2, we predicted that linoleic acid is converted to 12,13-dihydroxy-9(Z)-octadecenoic acid (12,13-DHOA) and then is oxidized at C-17 to form 12,13,17-trihydroxy-9( -oc-tadecenoic acid. This compound is possibly cyclized to form diepoxy bicyclic products. To prove this cyclization step, we used purified 12,13,17-THOA as substrate. Figure 1 demon-... 

It should not be assumed that hydroxy fatty acids are biologically inactive. Hydroxy fatty acids are chemotactic and vasoactive. Such fatty acids could perturb phospholipids in membranes. For instance, cardiolipin containing hydroxy-linoleic acid does not support the electron transport coupled to ATP production of the mitochondrion. 5-Hydroxy de-canoic acid is a well-known inhibitor of the K -ATP channel. Isoprostanes, trihydroxy oxidation products of arachi-donic acid, are vasoconstrictors (76). 13-Hydroxy linoleic acid (13-HODE) is a lipoxygenase-derived metabolite that influences the thromboresistant properties of endothelial cells in culture (77). However, there is some doubt about the tme nature of these hydroxy-fatty acids generated by the cells, as there are several GSH- and NADPH-dependent pathways that can immediately reduce hydroperoxy- to hydroxy-fatty acids. Furthermore, the reduction step of the analytical method would have converted the hydroperoxy- to a hydroxy-group. Nevertheless, much work remains to be done to determine the relative contribution of hydroperoxy- and hydroxy- to the biological effects of fried fat, and in particular their role in endothelial dysfunction and activation of factor VII. There have been earlier suggestions that a diet rich in lipid peroxidation products may lead to atherosclerosis and CHD (34,78). 

Other than extraction from plant materials, our discovery is the first report on production of trihydroxy unsaturated fatty acids by microbial transformation. The microorganism that performs fliis unique reaction was isolated from a dry soil sample collected from McCalla, AL. Strain ALA2 is a gram-positive, nonmotile rod (0.5 pm X 2 pm). The strain was identified as Clavibacter sp. ALA2 (49). 

A variety of oxygenated derivatives is formed during the reaction of lipoxygenases with fatty acid substrates. The biosynthesis of the monohydroxy and dihydroxy acids proceeds via the corresponding hydroperoxy acids, as is the case in the plant systems. The immediate product of the lipoxygenase thus is a hydroperoxy acid. This product is reduced to the corresponding hydroxy acid, presumably both enzymatically by peroxidases and through non-enzymatic decomposition. However, the hydroperoxy acid can also be converted to a ketone or to an epoxy-hydroxy acid that can hydrolyze into a trihydroxy acid (see below). 

There is ample evidence for hydroxy fatty acids in other yeasts. Saccharomycopsis malanga (Ascomycota, Saccharomycetales, Saccharomyco-psidaceae) forms 3-hydroxypalmitic acid [31] while trihydroxy acids are formed in Picia sydowiorum (Ascomycota, Saccharomycetales, Saccharomycetaceae) [32] and an unidentified yeast [33]. 2-Hydroxy long-chain fatty acids are found in S. cerevisiae [34]. The production of 2-hydroxyhexadecanoic acid in P. sydowiorum was increased in the presence of the mycotoxin fumonisin B, and a cyt P-450 mechanism of production suggested [32]. In many cases, these compounds are esterified in wall or membrane fractions but they may also occur as free acids. Unfortunately, none of these oxylipins has been linked to a specific regulatory function. 

Hydroperoxides formed enz)unatically in food are usually degraded further. This degradation can also be of a nonenzymatic nature. In nonspecific reactions involving heavy metal ions, heme(in) compounds or proteins, hydroperoxides are transformed into oxo, expoxy, mono-, di- and trihydroxy carboxylic acids (Table 3.35). Unlike hydroperoxides, i.e. the primary products of autoxidation, some of these derivatives are characterized as having a bitter taste (Table 3.35). Such compounds are detected in legumes and cereals. They may play a role in other foods rich in unsaturated fatty acids and proteins, such as fish and fish products. 

Naturally Occurring Substances.— Tall oil, obtained as a by-product of pulping conifer wood chips, contains a mixture of fatty and diterpenoid resin acids and neutral compounds. The latter include" pimara-8(14),15-diene-3/S,18-diol, abieta-8,ll,13-triene-15,18-diol, 19-hydroxy-15,16-bisnorlabda-8(17)-en-13-one, 8,13i8-epoxylabd-14-en-6a-ol (6a-hydroxy-13-epimanoyl oxide), and the 9,10-secoabietatriene (41). The latter was also isolated from the bark of the jack pine (Pinus banksiana) and western white pine (P. monticola). A range of 7-monohydroxy, 1,7- and 1,11-dihydroxy-, and 1,7,11-trihydroxy-sandaraco-pimaradienes and their acetates (42) have been obtained" from Zexmenia (Compositae) species. The l,ll-diacetoxy-7-ketone and 6,7-epoxide were also isolated. 

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