7,10,12-trihydroxy-8 -octadecenoic

Another dihydroxy fatty acid, 10,12-dihydroxy-8( )-octadecenoic acid (DHOD), was produced as an intermediate in the conversion of ricinoleic acid to 7,10,12-trihydroxy-8( )-octadecenoic acid (TOD) by PR3 (Fig. 31.2) (Kim... 

Masui, H., Kondo, T., and Kojima, M. 1989. An antifungal compound, 9,12,13-trihydroxy-( )-octadecenoic acid, from Colocasia antiquorum inoculated with Ceratocytis fimbriata. Phytochem., 28, 2613-2615. 

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... 

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. 

Autoxidation of linoleic acid gives rise to three isomers of trihydroxy-octadecenoic acid. The concentrations found in beer (Table 22.7) are higher than those found for linoleic acid itself [47]. All three acids are potential precursors of 2-trans-nonmdX which is an important component of the cardboard or paper flavour of stale beer. 

Graveland has shown that in the enzymic oxidation of linoleic acid in doughs and in flour-water suspensions the products include two isomeric hydroperoxy-acids, two isomeric hydroxy-acids, two isomeric hydroxy-epoxy-octadecenoic acids, and some trihydroxy-octadecenoic acids. 

It was reported earlier that strain ALA2 converted a-linolenic acid to 13,16-dihydroxy-12,15-epoxy-9(Z)-octadecenoic acid, and 7,13,16-trihydroxy-12,15-epoxy-9(Z)-octadecenoic acid (Hosokawa et aL, 2003b). From product structures obtained from the co-3 PUFAs EPA and DHA, it seems that strain ALA2 places hydroxyl groups at similar positions from the omega (co)-terminal end of the substrates and cyclizes them to related THF ring structures, despite their increased total carbon chain lengths (by 2 and 4 carbons, respectively) and numbers of double bonds (by 1 and 2 respectively). 

Strain ALA2 showed the highest relative in vivo activity for the bioconversion linoleic acid to trihydroxy-9(Z)-octadecenoic acid per Table 16.1 (Hosokawa et al., 2003c). The relative activities for a- and y-linolenic acids toward trihydroxy products were lower than that of linoleic acid, though still relatively... 

Hou, C. T. 1996. A novel compound, 12,13,17-trihydroxy-9(Z)-octadecenoic acid, from linoleic acid by a new microbial isolate Clavibacter sp ALA2. J. Am. Oil Chem. Soc., 73,1359-1362. 

Ricinoleic acid (i -12-hydroxy-9-cw-octadecenoic acid) (Fig. 6) accounts for 80-90% of fatty acids in castor oil (from Ricinus communis). It is found in other plant species and in the sclerotia of the ergot fungus Claviceps purpurea). Lesquerolic acid (i -14-hydroxy-ll-cw-eicosenoic acid), which is a C20 homolog of ricinoleic acid, occurs in Lesquerella species (up to 70% of total fatty acids). Isoricinoleic acid (i -9-hydroxy-12-cw-octadecenoic acid, or 9-OH 18 2 12c) is a major acid in the Wrightia species. In plants, several C16 and C18 mono, di, and trihydroxy fatty acids are stmctural components of cutin (a polyester constituent of plant cuticle). 

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-... 

Identification of 12,13,16-Trihydroxy-9(Z)-Octadecenoic Acid. For the biosynthetic pathway of linoleic acid to THFA, it appears that we missed an intermediate between 12,13-DHOA and THFA. Previously, we found this missing intermediate in the reaction mixture and determined its structure by GC/MS as 12,13,16-THOA (10). Now, we were able to separate this product and study its structure by proton and NMR analyses. The NMR signals at 73.0,... 

The hydroxy group at the C-7 position was confirmed by C NMR chemical shift at 70.9 ppm and H NMR signals at 3.60 ppm (Table 2). Other C NMR chemical shifts and H NMR resonance patterns were very similar to those of 13,16-THFA. From these data, the structure of the product with GC Rt of 26 min was shown to be 7,13,16-trihydroxy-12, 15-epoxy-9-(Z)-octadecenoic acid (7,13,16-trihydroxy-THFA). 

A chemo-enzymatic enantiospecific synthesis of (S)-coriolic acid, (13S)-hy-droxy-18 2(9Z,ll ), mediated via immobilized alcohol dehydrogenase of baker s yeast has been described (31). 15,16-Didehydrocoriolic acid, 13-hydroxy-18 3(9Z, 11E, 15Z), was stereoselectively synthesized starting from pent-2-en-4-yn-1 -ol (32). Four stereoisomers of 9,10,13-trihydroxy-18 l(ll ) were derived from methyl 9,10-epoxy-12-octadecenoate. The latter was obtained by partial epoxidation of methyl linoleate. These trihydroxy C j g fatty acids are potential antirice blast fungal substances (33). (115)-Hydroxy-(125,13S)-epoxy-18 2(9Z,15Z) was synthesized from D-mannose (34). 

Trihydroxy-10( )-octadecenoic acid was also isolated from Colocasia antiquorum inoculated with Cemtocystis fimbriata and showed activity against black rot fungus (48). 

Masui, H., T. Kondo, and M. Kojima, An Antifungal Compound, 9,12,13-Trihydroxy-( )-10-octadecenoic Acid, from Colocasia antiquorum Inocidated with Ceratocystisfim-briata, Phytochemistry 28 2613-2615 (1989). 

Farnesol, F-00003 Farnesylic acid, see T-00205 Ferulic acid, see H-00304 Filfiline, in D-00199 Floionolic acid, in T-OOl96 16-Fluorohexadecanoic acid, F-00004 18-Fluorooctadecanoic acid, F-(KX)05 18-Fluoro-9-octadecenoic acid, F-00006 16-Fluoropalmitic acid, see F-00004 12-Fluoro-PGF2a, in F-00007 18-Fluorostearic acid, see F-00005 12-Fluoro-9,11,15-trihydroxy-5,13-prostadienoic acid, F-00007 )-cis-erythro (orm, in D-00145... 

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