Novel Small Molecule with Potent Antifungal Activity for Fungal Infections

Methods: Initially, library of 50,000 small molecules were examined for yeast-to-hypha transition inhibitors (Y-Hi) of Candida albicans by 384-well format high throughput assays. Y-Hi were further examined under strong hyphal inducing conditions using C. albicans ATCC and clinical isolates. Next, antifungal activity of identified Y-Hi was examined using CLSI standards for various Candida species and Cryptococcus neoformans, and further validated by dose-dependent and time-dependent studies. Next, anti-biofilm activity of molecules was evaluated using standard XTT reduction assay. Small molecule SM21 which showed potent antifungal activity against fungal biofilms was extensively tested for its safety using cytotoxicity assays in primary cell cultures and animal models.

Results: Initially, 20 Y-Hi of C. albicans was indentified. Eight small molecules showed strong Y-Hi activity under all hyphal inducing conditions. Four small molecules exhibited potent antifungal activity against wide range of fungal species including C. albicans, C. glabrata. C. krusei, C. tropicalis, C. parapsilosis and C. neoformans in their planktonic mode of growth. One small molecule (SM21) showed anti-biofilm activity against Candida biofilms. SM21 was more effective than amphotericin B and caspofungin. Activity of SM21 was fungal specific and effective against resistant fungal isolates for existing antifungals. Safety of SM21 was confirmed by both in vitro and in vivo assays.

Conclusion: We have discovered a novel small molecule with strong antifungal activity which could be developed as a novel antifungal agent for treating fungal infections (HKU Seed funding for CJS & LPS).