Combination of isobavachalcone and amphotericin B has antifungal effect against Cryptococcus neoformansand protects host tissue damage by inhibiting ferroptosis

Despite advancements in the treatment of cryptococcal infections, the availability of antifungal agents remains limited compared to antibiotics used for bacterial infections. The development of novel therapeutic strategies is imperative, albeit challenging. A promising approach involves the synergistic interaction between existing antifungal agents and supplements to enhance efficacy, reduce dosages, and mitigate resistance. This study aims to investigate the effects of Isobavachalcone (IBC) and Amphotericin B (AmB) in novel in vitro and in vivo models, with a focus on ferroptosis regulation.In a novel Caenorhabditis elegans model of cryptococcal infection, we analyzed ferroptosis-related biomarkers, including glutathione (GSH), malondialdehyde (MDA), ferrous ions, and reactive oxygen species (ROS). The results demonstrated that IBC (4 μg/mL) significantly reduced the minimum inhibitory concentration (MIC) of AmB from 1 μg/mL to 0.25 μg/mL, indicating a fourfold increase in potency. The IBC-AmB combination exhibited detrimental effects on membrane permeability and cell wall integrity in Cryptococcus neoformans.Furthermore, this combination elevated host GSH levels while concurrently decreasing ferrous ions, MDA, and ROS. Mechanistically, the treatment upregulated antioxidant/stress response genes (SKN-1, GST-4, GST-5, GPX-1, DAF-16, CNC-11) and antimicrobial peptides (NLP-29), while downregulating PMK-1. These findings suggest a dual mechanism of action involving direct disruption of fungal membranes and modulation of host ferroptosis.This study underscores the potential of combining natural compounds with existing antifungal agents to address the limitations of the current antifungal drug repertoire.