Efficacy of two novel antifungal lipopeptides, <scp>AF₄</scp> and <scp>AF₅</scp> of bacillomycin D family in murine models of invasive candidiasis, cryptococcosis, and aspergillosis

Invasive fungal diseases are an important public health concern due to an increase in the at-risk population and high mortality associated with these infections. Managing invasive fungal infections poses a significant challenge given the limited antifungal options and the emergence of resistance in key fungal pathogens. Through a comprehensive approach, we evaluated the in vitro antifungal activity and the in vivo efficacy of two novel lipopeptides, AF₄ and AF₅ in murine models of disseminated candidiasis, cryptococcosis, and aspergillosis. Flow cytometry analysis with propidium iodide showed a dose-dependent increase in the permeability and disruption of fungal cell membranes, underscoring the membrane perturbing effects of AF₄ and AF₅. These observations were further substantiated by SEM analyses that showed yeast cell and hyphal deformation and leakage of cellular contents. Our in vivo investigations utilizing two doses (5 and 10 mg/kg bodyweight) of each lipopeptide and its comparison with standard antifungal therapies showed lipopeptides significantly improved the odds of mice survival in invasive candidiasis and cryptococcosis models, with a reduction in organ fungal burden by 2 to 3-log₁₀ order. Additionally, in the disseminated aspergillosis model, treatment with 10 mg/kg of AF₄ significantly improved median survival from 4 to 10 days while achieving a notable 1-log10 order reduction in organ fungal burden. Overall, our study underscores the potent and broad-spectrum antifungal activity of lipopeptides in mouse infection models, hinting at their promising therapeutic potential in invasive fungal disease.