Cytochrome P-450-dependent oxygenation of arachidonic acid to hydroxyicosatetraenoic acids.

Abstract

Arachidonic acid is oxidized by a NADPH-dependent oxygenase of rat liver microsomes to a number of O2-containing products, which can be resolved by high pressure liquid chromatography. Several of these products were purified and characterized. They exhibit an absorbance in the UV region of the spectrum that has a maximum at 235 nm, indicative of the presence of a conjugated diene function. Mass spectral analysis of the trimethylsilyl ether derivatives of the methyl esters of the hydrogenated and nonhydrogenated metabolites shows that they are the 9-, 11-, 12- and 15-monohydroxy derivatives of arachidonic acid, the hydroxyicosatetraenoic acids (HETE). Their UV absorbance and chromatographic properties suggest that these products possess cis, trans-diene geometry characteristic of HETE isolated from other mammalian sources. The isolation of these isomeric HETE suggests that cytochrome P-450 may play a role in the oxidative metabolism of arachidonic acid to physiologically and pharmacologically important hydroxylated unsaturated fatty acids.