Oxidation of Naringenin, Apigenin, and Genistein by Human Family 1 Cytochrome P450 Enzymes and Comparison of Interaction of Apigenin with Human P450 1B1.1 and Scutellaria P450 82D.1.

Naringenin, an initial synthesized flavanone in various plant species, is further utilized for production of many biologically active flavonoids, e.g., apigenin, eriodictyol, and genistein, by various plant enzymes including cytochrome P450s (P450s or CYPs). We examined how these flavonoids are oxidized by human P450 family 1 and 2A enzymes. Naringenin was principally oxidized at the 3'-position to form eriodictyol by CYP1 enzymes more efficiently than by CYP2A enzymes, and the resulting eriodictyol was further oxidized to two penta-hydroxylated products. In contrast to plant P450 enzymes, these human P450s did not mediate the desaturation of naringenin and eriodictyol to give apigenin and luteolin, respectively. Apigenin was oxidized at the C3' and C6 positions to form luteolin and scutellarein by these P450s. CYP1B1.1 and 1B1.3 had high activities in apigenin 6-hydroxylation with a homotropic cooperative manner, as has been observed previously in chrysin 6-hydroxylation (Nagayoshi et al.,