Epoxides as obligatory intermediates in the metabolism of olefins to glycols.

In the presence of rat liver microsomes and NADPH n-loctene, n-4-octene and 3-ethyl-2-pentene were converted to the glycols with no trace of epoxides. Increased substitution of ethylenic hydxogen atoms by alkyl groups was found to retard. the rate of biological oxid.ation but to enhance that of epoxidation by perbenzoic acid. in chloroform. Microsomes without cofactors hydrolyzed the monosubstituted ethylene oxide more rapidly than the dior trisubstituted derivatives. The relative rates were in the opposite order of those predicted for acid-catalyzed hydrolysis. The epoxides were found capable of inhibiting epoxide hydrolase. Incubation of microsomes and NADPH with 1 mM n-1-octene in the presence of 20 m&r 4,5-epoxy-n-octane yielded both 1,2epoxy-n-octane and n-octane-l ,2-diol. However, in the presence of 20 mM 1,2-epoxy-n-octane, 1 mM n-4-octene yielded 4,5-epoxy-n-octane but no n-octane-4,5-diol. The complete replacement of n-octane-4,5-diol by 4,5-epoxy-noctane in the presence of the inhibitor indicates that the epoxide is an obligatory intermediate in the conversion of n-4-octene to the glycol.