Hydroperoxidation by cytochrome P-450 oxygenase: metabolism of 9-methylfluorene.
9-Methylfluorene was metabolized by rat liver microsomes to 9-hydroperoxy-9-methylfluorene and 9-hydroxy-9-methylfluorene. The results were confirmed by using a reconstituted cytochrome P-450 oxygenase system purified from phenobarbital-induced rat liver which established its involvement. SKF-525A strongly inhibited the formation of both oxygenation products. Cytochrome P-450 alone brought about the conversion of the hydroperoxide to its alcohol. NADPH augmented the peroxidative reaction, but the presence of NADPH-cytochrome P-450 reductase was without effect. Certain microsomal preparations and reconstituted enzyme yielded little or no detectable amounts of hydroperoxide. This was due to a too rapid conversion of the hydroperoxide to its alcohol. The addition of metyrapone, a compound that inhibited such conversion, resulted in accumulation of 9-hydroperoxy-9-methylfluorene for positive identification. Incubation of 9-methylfluorene with microsomes and NADPH resulted in covalent binding of its metabolite to microsomal proteins. Incubation of 14C-labeled 9-hydroperoxy-9-methylfluorene caused covalent binding of label to proteins, RNA, and DNA.
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System; D005449:Fluorenes / Q000378:metabolism*; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000201:enzymology*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000378:metabolism*; D051381:Rats
D005449:Fluorenes; D046911:Macromolecular Substances; C044948:9-hydroperoxy-9-methylfluorene; D009249:NADP; C044947:9-hydroxy-9-methylfluorene; D003577:Cytochrome P-450 Enzyme System; C030636:9-methylfluorene; D010105:Oxygenases