Antiprotozoal and antimicrobial activities of O-alkylated and formylated acylphloroglucinols

Antiprotozoal and antimicrobial activities of several new O-alkylated and formylated acylphloroglucinols have been evaluated. Some of the O-alkylated and formylated acylphloroglucinols showed antileishmanial activity while only formylated acylphloroglucinols exhibited antibacterial and antifungal activities. 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.