Structure-In Vitro Activity Relationships of Pentamidine Analogues and Dication-Substituted Bis-Benzimidazoles as New Antifungal Agents

Abstract

ABSTRACT Twenty analogues of pentamidine, 7 primary metabolites of pentamidine, and 30 dicationic substituted bis-benzimidazoles were screened for their inhibitory and fungicidal activities against Candida albicans and Cryptococcus neoformans . A majority of the compounds had MICs at which 80% of the strains were inhibited (MIC 80 s) comparable to those of amphotericin B and fluconazole. Unlike fluconazole, many of these compounds were found to have potent fungicidal activity. The most potent compound against C. albicans had an MIC 80 of ≤0.09 μg/ml, and the most potent compound against C. neoformans had an MIC 80 of 0.19 μg/ml. Selected compounds were also found to be active against Aspergillus fumigatus , Fusarium solani , Candida species other than C. albicans , and fluconazole-resistant strains of C. albicans and C. neoformans . It is clear from the data presented here that further studies on the structure-activity relationships, mechanisms of action and toxicities, and in vivo efficacies of these compounds are warranted to determine their clinical potential.