Human cytochrome P450 liability studies of trans-dihydronarciclasine: a readily available, potent, and selective cancer cell growth inhibitor.

The cytochrome P45O activities of the naturally occurring Amaryllidaceae alkaloid narciclasine (3), isolated from Narcissus pseudonarcissus, and synthetic derivative trans-dihydronarciclasine (5) are reported. While narciclasine was found to possess potent inhibitory activity to human CYP3A4, its dihydro analogue was inactive. This study revealed that the C1-C10b double bond is required for inhibition of this crucial metabolizing enzyme. Compound 5 also demonstrated no inhibition of the related human cytochromes CYP19 and CYP1A1. This study elevates the status of trans-dihydronarciclasine (5) as a highly privileged, readily available molecule, with potent and selective anticancer activity.