Steric analysis of epoxyalcohol and trihydroxy derivatives of 9-hydroperoxy-linoleic acid from hematin and enzymatic synthesis.
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 (1)H 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 (1)H NMR.
Department of Pharmacology, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN 37232-6602, USA.
Christopher P
CP
Thomas
William E
WE
Boeglin
Yoel
Y
Garcia-Diaz
Valerie B
VB
O'Donnell
Alan R
AR
Brash
D027461:Beta vulgaris / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004851:Epoxide Hydrolases / Q000378:metabolism; D004852:Epoxy Compounds / Q000737:chemistry* / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006427:Hemin / Q000031:analogs & derivatives* / Q000378:metabolism; D006868:Hydrolysis; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D007536:Isomerism; D019787:Linoleic Acid / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D009829:Oleic Acids / Q000737:chemistry* / Q000378:metabolism; D020005:Propanols / Q000737:chemistry* / Q000378:metabolism; D013237:Stereoisomerism
C107326:10-hydroperoxy-8-octadecenoic acid; D004852:Epoxy Compounds; D009829:Oleic Acids; D020005:Propanols; C006463:allyl alcohol; D006427:Hemin; D019787:Linoleic Acid; D004851:Epoxide Hydrolases; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase