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Abstract

The alkaloid rutaecarpine exhibits antithrombotic and vasorelaxant effects. To characterize mouse cytochrome P450 (P450, CYP)-catalyzed rutaecarpine hydroxylations, the induction, inhibition, and kinetic properties of rutaecarpine hydroxylations were determined using liver microsomes of C57BL/6J mice. In untreated mice, rutaecarpine 10-, ll-, 12, and 3-hydroxylation had Km and Vmax values ranging, respectively, between 11.6-16.7 μM and 62-97 pmol/min/mg protein. The formation rates of the four hydroxylated metabolites were inhibited by α-naphthoflavone and orphenadrine, but not by either sulfaphenazole or ketoconazole. 3-Methylcholanthrene-treatment increased rutaecarpine ll-, 12-, and 3-hydroxylation activities. Phenobarbital-treatment increased rutaecarpine 10-, ll-, 12-, and 3-hydroxylation activities. Dexamethasone had no effect on these hydroxylation reactions in mice. These results indicated that CYP1A and CYP2B, but not CYP3A, play major roles in rutaecarpine hydroxylations in mice.

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