Discovery of simplified sampangine derivatives as novel fungal biofilm inhibitors.

Lack of novel antifungal agents and severe drug resistance have led to high incidence and associated mortality of invasive fungal infections. To tackle the challenges, novel antifungal agents with new chemotype, fungicidal activity and anti-resistant potency are highly desirable. On the basis of our previously identified simplified analogue of antifungal natural product sampangine, systemic structure-activity relationships were clarified and two novel derivatives showed promising features as novel antifungal lead compounds. Compounds 22b and 22c showed good fungicidal activity against both fluconazole-sensitive and fluconazole-resistant Candida albicans strains. Moreover, they were proven to be potent inhibitors of Candida albicans biofilm formation and yeast-to-hypha morphological transition by down-regulating biofilm-associated genes. In a rat vaginal Candida albicans infection model, compounds 22b and 22c showed excellent therapeutic effects with low toxicity. The results highlighted the potential of sampangine derivatives to overcome fluconazole-related and biofilm-related drug resistance.