Antiprotozoal and antimicrobial activities of O-alkylated and formylated acylphloroglucinols

Abstract

In the present article, we examined the antileishmanial, antimalarial, antibacterial, and antifungal activities of several newly synthesized O-alkylated phloroglucinol compounds ( 11– 19) which are analogues of the naturally occurring antimalarial compound 1. Analogues 12 and 16 exhibited antileishmanial activity against, Leishmania donovani promastigotes with IC 50s of 5.3 and 4.2 μg/mL, respectively. Naturally occurring monomeric formylated acylphloroglucinol compounds, grandinol ( 2), jensenone ( 3), and their analogues ( 29– 37), were also synthesized and evaluated for antileishmanial, antimalarial, antibacterial, and antifungal activities. Amongst these, both grandinol and jensenone showed mild to moderate antibacterial, antifungal, and antileishmanial activities. Jensenone ( 3) was effective against Candida albicans with an IC 50 of 5.5 μg/mL but was ineffective against Cryptococcus neoformans and methicillin-resistant Staphylococcus aureus. Among the analogues, 34 was the most active against C. albicans and C. neoformans with IC 50s of 2.0 and 2.5 μg/mL, respectively, and was fungicidal toward Candida albicans.