Carbon-centered free radical intermediates in the hematin- and ram seminal vesicle-catalyzed decomposition of fatty acid hydroperoxides.

Heme-catalyzed decomposition of unsaturated hydroperoxy fatty acids has been proposed to proceed via carbon-centered free radicals (delocalized at positions C11, C12, and C13 for 15-hydroperoxy-eicosatetraenoic acid (15-HPETE). The stable products are usually epoxy fatty acids and epoxy alcohols. Hydroperoxides from arachidonic acid can decompose via this mechanism to form leukotrienes of potential biological significance and can catalyze the epoxidation of proximal carcinogens to ultimate carcinogenic metabolites. We have used electron spin resonance spin-trapping techniques to detect carbon-centered radicals formed by heme- or ram seminal vesicle-catalyzed decomposition of 15-HPETE. For both systems we detect both a short- and a long-lived radical adduct. We proposed that these radical adducts are derived from C11 and C13 carbon-centered free radicals generated in the decomposition of 15-HPETE.