All (S) stereoconfiguration of 7,10-dihydroxy-8(E)-octadecenoic acid from bioconversion of oleic acid by Pseudomonas aeruginosa

A previously established method was utilized to determine the stereoconfiguration of 7,10-dihydroxy-8(E)-octadecenoic acid (DHOE) from bioconversion of oleic acid by Pseudomonas aeruginosa NRRL strain B-18602 (PR3). The method involved formation of the (-)-menthoxycarbonyl (MCO) derivative of the two hydroxyls, oxidative cleavage of the double bond, and gas chromatography (CC) analysis of the two methyl-esterified diastereomeric fragments, methyl 2-MCO-decanoate and dimethyl 2-MCO-octanedioate. As described by previous workers, the 2(S)-MCO derivatives elute at earlier times by GC than the 2(R)-MCO derivatives. By comparing the GC analysis of the 2-MCO derivatives obtained from DHOE with that obtained from a partially racemized sample, DHOE was determined to be 7(S),10(S)-dihydroxy-8(E)-octadecenoic acid.