Linoleic acid metabolism in the red algaLithothamnion corallioides: Biosynthesis of 11(R)-hydroxy-9(Z),12(Z)-octadecadienoic acid |
| |
Authors: | Mats Hámberg William H Gerwick Per Arvid Åsen |
| |
Affiliation: | (1) College of Pharmacy, Oregon State University, 97331 Corvallis, Oregon;(2) Department of Botany, Kristiansand Museum, N-4602 Kristiansand, Norway;(3) Department of Physiological Chemistry, Karolinska Institutet, Box 60400, S-104 01 Stockholm, Sweden |
| |
Abstract: | Incubation of 1-14C]linoleic acid with an enzyme preparation obtained from the red algaLithothamnion corallioides
Crouan resulted in the formation of 11-hydroxy-9(Z),12(Z)-octadecadienoic acid as well as smaller amounts of 9-hydroxy-10(E),12(Z)-octadecadienoic acid, 13-hydroxy-9(Z),11(E)-octadecadienoic acid and 11-keto-9(Z),12(Z)-octadecadienoic acid. Steric analysis showed that the 11-hydroxyoctadecadienoic acid had the (R) configuration. The 9- and 13-hydroxyoctadecadienoic acids were not optically pure, but were due to mixtures of 75% (R) and 25% (S) enantiomers (9-hydroxyoctadecadienoate), and 24% (R) and 76% (S) enantiomers (13-hydroxy-octadecadienoate). 11-Hydroxyoctadecadienoic acid was unstable at acidic pH. In acidified water,
equal parts of 9(R,S)-hydroxy-10(E),12(Z)-octadecadienoate and 13(R,S)-hydroxy-9(Z),11(E)-octadecadienoate, plus smaller amounts of the corresponding (E),(E) isomers were produced. In aprotic solvents, acid treatment resulted in dehydration and in the formation of equal amounts
of 8,10,12- and 9,11,13-octadecatrienoates. The enzymatic conversion of linoleic acid into the hydroxyoctadecadienoic acids
and the ketooctadecadienoic acid was oxygen-dependent; however, inhibitor experiments indicated that neither lipoxygenase
nor cytochrome P-450 were involved in the conversion. This conclusion was supported by experiments with18O2 and H2
18O, which demonstrated that the hydroxyl oxygen of the hydroxy-octadecadienoic acids and the keto oxygen of the 11-ketooctadecadienoic
acid were derived from water and not from molecular oxygen.
The term “oxylipin” was introduced recently (ref. 1) as an encompassing term for oxygenated compounds which are formed from
fatty acids by reaction(s) involving at least one step of mono- or dixoygenase-catalyzed oxygenation. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|