Enzymatic synthesis and chemical inversion provide both enantiomers of bioactive epoxydocosapentaenoic acids

Abstract

Epoxy PUFAs are endogenous cytochrome P450 (P450) metabolites of dietary PUFAs. Although these metabolites exert numerous biological effects, attempts to study their complex biology have been hampered by difficulty in obtaining the epoxides as pure regioisomers and enantiomers. To remedy this, we synthesized 19,20- and 16,17-epoxydocosapentaenoic acids (EDPs) (the two most abundant EDPs in vivo) by epoxidation of DHA with WT and the mutant (F87V) P450 enzyme BM3 from WT epoxidation yielded a 4:1 mixture of 19,20:16,17-EDP exclusively as (,) enantiomers. Epoxidation with the mutant (F87V) yielded a 1.6:1 mixture of 19,20:16,17-EDP; the 19,20-EDP fraction was ∼9:1 (,):(,), but the 16,17-EDP was exclusively the (,) enantiomer. To access the (,) enantiomers of these EDPs, we used a short (four-step) chemical inversion sequence, which utilizes 2-(phenylthio)ethanol as the epoxide-opening nucleophile, followed by mesylation of the resulting alcohol, oxidation of the thioether moiety, and base-catalyzed elimination. This short synthesis cleanly converts the (,)-epoxide to the (,)-epoxide without loss of enantiopurity. This method, also applicable to eicosapentaenoic acid and arachidonic acid, provides a simple, cost-effective procedure for accessing larger amounts of these metabolites.

Regioselective and Stereoselective Epoxidation of n-3 and n-6 Fatty Acids by Fungal Peroxygenases

“…The regioselectivities observed in the Aae UPO reactions are the highest reported to date for these compounds. In different publications, P450 BM3 and its F87V variant have demonstrated to be capable of yielding mono-epoxides at the last double bond from 4 and 7, but with lower regioselectivities [ 11 , 45 , 46 ].…”

A Synthetic Epoxydocosapentaenoic Acid Analogue Ameliorates Cardiac Ischemia/Reperfusion Injury: The Involvement of the Sirtuin 3–NLRP3 Pathway

“…For instance, the peak plasma concentration of these metabolites occurred 1 min post intraperitoneal injection, indicating a relatively short half-life for these metabolites [67,68]. Moreover, EDPs may slowly darken and polymerize upon exposure to light, heat or oxygen because of the presence of their multiple double bonds [44]. Considerable interest has arisen in developing methods or surrogates to enhance the bioavailability of EDPs, particularly 16,17-EDP and 19,20-EDP, the two most abundant and potent regioisomers [69,70].…”

“…However, EDPs are rapidly converted to the corresponding and less biologically active vicinal diol by soluble epoxide hydrolase (sEH) or can be metabolized by other pathways including β-oxidation, chain shortening and chain elongation [42,43]. Accordingly, there is interest in developing methods to enhance their bioavailability [44]. In the current study, we synthesize and investigate the cardioprotective properties of the 19,20-EDP analogue AS-II-75-27 (AS-27) as well as the 16,17-EDP analogues AA-XII-52-4 (AA-4) and SA-II-109-26 (SA-26) against IR injury.…”

Cytochrome P450 Metabolism of Polyunsaturated Fatty Acids and Neurodegeneration

“…While enzymatic epoxidation seems to be an effective way to generate single enantiomers, using a chemical inversion process is inevitable to access the corresponding enantiomers. Besides, this method is non-diversifiable and cannot be utilized in synthesize the corresponding analogs [ 116 , 117 ]. Progress in synthetic routes to achieve large quantities of specific regio-/stereoisomers with high purity is the key to improve our understanding of these isomers and the mechanisms of their functions.…”