Iturin A disrupts Cryptococcus neoformans membrane integrity, attenuates virulence, and synergizes with amphotericin B

Cryptococcus neoformans is a major fungal pathogen with severely limited therapeutic options. We evaluated the antifungal activity of the lipopeptide iturin A against eight clinical isolates of C. neoformans . Iturin A exhibited robust anti-cryptococcal activity, with minimum inhibitory concentrations ranging from 12.5 to 25 μg/mL, and demonstrated minimal toxicity in A549 lung epithelial cells and HepG2/C3A liver cells. Combination treatment with amphotericin B was synergistic (fractional inhibitory concentration index, 0.37). Mechanistic analyses showed that iturin A disrupts cryptococcal membrane integrity and induces intracellular reactive oxygen species accumulation, leading to fungal cell death. Iturin A also reduced biofilm formation and impaired capsule production. In the Caenorhabditis elegans infection model, treatment with iturin A alone or in combination with amphotericin B prolonged host survival and reduced fungal burden. Although iturin A decreased cryptococcal phagocytosis by J774 macrophage- and NR-9460 microglia-like cells, it enhanced intracellular killing by these phagocytes. Collectively, these findings demonstrate that iturin A exhibits multifaceted activity against C. neoformans through membrane disruption, oxidative stress induction, and interference with virulence determinants, supporting its potential as a novel anti-cryptococcal therapeutic agent.