| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1253530 | Chemistry and Physics of Lipids | 2013 | 12 Pages |
We characterize the allylic epoxyalcohols and their trihydroxy hydrolysis products generated from 9R- and 9S-hydroperoxy-octadecenoic acid (HPODE) under non-enzymatic conditions, reaction with hematin and subsequent acid hydrolysis, and enzymatic conditions, incubation with Beta vulgaris containing a hydroperoxide isomerase and epoxide hydrolase. The products were resolved by HPLC and the regio and stereo-chemistry of the transformations were determined through a combination of 1H NMR and GC–MS analysis of dimethoxypropane derivatives. Four trihydroxy isomers were identified upon mild acid hydrolysis of 9S,10S-trans-epoxy-11E-13S-hydroxyoctadecenoate: 9S,10R,13S, 9S,12R,13S, 9S,10S,13S and 9S,12S,13S-trihydroxy-octadecenoic acids, in the ratio 40:26:22:12. We also identified a prominent δ-ketol rearrangement product from the hydrolysis as mainly the 9-hydroxy-10E-13-oxo isomer. Short incubation (5 min) of 9R- and 9S-HPODE with B. vulgaris extract yielded the 9R- and 9S-hydroxy-10E-12R,13S-cis-epoxy products respectively. Longer incubation (60 min) gave one specific hydrolysis product via epoxide hydrolase, the 9R/S,12S,13S-trihydroxyoctadecenoate. These studies provide a practical approach for the isolation and characterization of allylic epoxy alcohol and trihydroxy products using a combination of HPLC, GC–MS and 1H NMR.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Allylic epoxy alcohols were isolated from 9-HPODE reaction with hematin. ► HPLC analysis of trihydroxy hydrolysis products, assignment by GC–MS, CD, and 1 H NMR. ► 9R- and 9S-HPODE metabolism by epoxyalcohol synthase and epoxide hydrolase. ► Identification of a δ-ketol rearrangement product of 9,10-trans-epoxy alcohol.
