Antiprotozoal and antimicrobial activities of O-alkylated and formylated acylphloroglucinols Original Research Article

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 IC50s 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 IC50 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 IC50s of 2.0 and 2.5 μg/mL, respectively, and was fungicidal toward Candida albicans.