Synthesis and biological evaluation of biguanide and dihydrotriazine derivatives as potential inhibitors of dihydrofolate reductase of opportunistic microorganisms.

ABSTRACT

Twenty-one biguanide and dihydrotriazine derivatives were synthesized and evaluated as inhibitors of dihydrofolate reductase (DHFR) from opportunistic microorganisms Pneumocystis carinii (pc), Toxoplasma gondii (tg), Mycobacterium avium (ma), and rat liver (rl). The most potent compound in the series was B2-07 with 12 nM activity against tgDHFR. The most striking observation was that B2-07 showed similar potency to trimetrexate, approximately 233-fold improved potency over trimethoprim and approximately 7-fold increased selectivity as compared to trimetrexate against tgDHFR. Molecular docking studies in the developed homology model of tgDHFR rationalized the observed potency of B2-07. This molecule can act as a good lead for further design of molecules with better selectivity and improved potency.