A 5 + 1 polyene scaffold that selectively recognizes ergosterol’s conjugated diene uncouples antifungal potency from host toxicity

Abstract

Amphotericin B remains the gold-standard therapy for invasive fungal infections, but its clinical utility is limited by toxicity arising from poor selectivity for fungal ergosterol over mammalian cholesterol, a challenge that decades of medicinal chemistry have failed to fully overcome. Here, we report mandimycin M16, a polyene macrolide engineered from a unique 5 + 1 polyene scaffold that uncouples antifungal potency from host toxicity. Mandimycin M16 exhibited potent, broad-spectrum activity against 11 tested World Health Organization (WHO) priority fungal pathogens. Unlike amphotericin B, which binds cholesterol, M16 exhibited no detectable cholesterol binding and showed no detectable hemolysis, cytotoxicity, or nephrotoxicity at concentrations up to 128 micrograms per milliliter in vitro and after up to seven daily intravenous doses in mice. Mechanistic studies revealed that mandimycin M16 exerted rapid fungicidal activity through selective recognition of the conjugated C5–C8 diene system present in ergosterol but absent in cholesterol, a mode of sterol discrimination fundamentally different from classical polyenes. In multiple disseminated murine infection models, M16 outperformed liposomal amphotericin B at equivalent doses, achieving up to 3.4 log reduction in fungal burden and 100% survival without detectable renal injury by biomarkers or histopathology. These findings establish that the 5 + 1 polyene architecture enables complete sterol selectivity and molecularly uncouples antifungal potency from host toxicity, providing a next-generation antifungal candidate for the treatment of invasive fungal infections.