The increasing occurrence of systemic fungal infections, particularly among AIDS patients, has stimulated the search for better antifungal agents. l In a program aimed at identifylng novel antifungal agents, we focused on developing compounds that would selectively inhibit the enzyme dihydrofolate reductase (DHFR) from fungal species. Inhibition of DHFR is a well-established mechanism of drug action. 2 DHFR catalyzes the reduction of ...