Studies on the Novel Anticancer Agents Metabolically Formed form 17- Beta-Estradiol

摘要

This is the final report for my Predoctoral Traineeship Award (No. DAMD17-02-1-0566). The studies described in the original grant proposal have been completed. Our major findings included the following: (1) We demonstrated, for the first time, that a novel class of nonpolar estradiol (E2) metabolites Were formed by human liver microsomes and also by certain human cytochrome P450 (CYP) enzymes using NADPH as a cofactor,. (2), Among a total of some 20 nonpolar E2 metabolite peaks detected, M15 and M16 were only selectively formed with a few of the human CYP isoforms (namely CYP3A4, CYP3A5, CYP1A1, CYP2C8, and CYP2C9). The formation of these two representative nonpolar estrogen metabolites by human CYP isoforms did not correlate with their overall catalytic activity for the oxidative metabolism of E2. (3) The structures of the metabolically formed M15 and M16 were unequivocally identified to be the dimers of E2, linked together through a diaryl ether bond between a phenolic oxygen atom of one E2 molecule and the 2- or 4-position aromatic carbon of another E2. (4) M15 and M16 were chemically synthesized by using estradiol as the starting material.