Synthesis of Classical, Four-Carbon Bridged 5-Substituted Furo[2,3-<i>d</i>]pyrimidine and 6-Substituted Pyrrolo[2,3-<i>d</i>]pyrimidine Analogues as Antifolates
作者:Aleem Gangjee、Yibin Zeng、John J. McGuire、Roy L. Kisliuk
DOI:10.1021/jm058213s
日期:2005.8.1
We report, for the first time, the biological activities of four-carbon-atom bridged classical antifolates on dihydrofolate reductase (DHFR), thymidylate synthase (TS), and folylpolyglutamate synthetase (FPGS) as well as antitumor activity. Extension of the bridge homologation studies of classical two-carbon bridged antifolates, a 5-substituted 2,4-diaminofuro[2,3d]pyrimidine (1) and a 6-subsituted 2-amino-4-oxopyrrolo[2,3-d]pyrimidine (2), afforded two four-carbon bridged antifolates, analogues 5 and 6, with enhanced FPGS substrate activity and inhibitory activity against tumor cells in culture (EC50 <= 10(-7) M) compared with the two-carbon bridged analogues. These results support our original hypothesis that the distance and orientation of the side chain p-aminobenzoyl-L-glutamate moiety with respect to the pyrimidine ring are a crucial determinant of biological activity. In addition, this study demonstrates that, for classical antifolates that are substrates for FPGS, poor inhibitory activity against isolated target enzymes is not necessarily a predictor of a lack of antitumor activity.