Antifungal activity of extracts from Atacama Desert fungi against Paracoccidioides brasiliensis and identification of Aspergillus felis as a promising source of natural bioactive compounds

Fungi of the genus Paracoccidioides are responsible forparacoccidioidomycosis. The occurrence of drug toxicity and relapse in this diseasejustify the development of new antifungal agents. Compounds extracted from fungalextract have showing antifungal activity. Extracts of 78 fungi isolated from rocks ofthe Atacama Desert were tested in a microdilution assay againstParacoccidioides brasiliensis Pb18. Approximately 18% (5) of theextracts showed minimum inhibitory concentration (MIC) values≤ 125.0µg/mL. Among these, extract from the fungus UFMGCB 8030 demonstrated the bestresults, with an MIC of 15.6 µg/mL. This isolate was identified asAspergillus felis (by macro and micromorphologies, and internaltranscribed spacer, β-tubulin, and ribosomal polymerase II gene analyses) and wasgrown in five different culture media and extracted with various solvents to optimiseits antifungal activity. Potato dextrose agar culture and dichloromethane extractionresulted in an MIC of 1.9 µg/mL against P. brasiliensis and did notshow cytotoxicity at the concentrations tested in normal mammalian cell (Vero). Thisextract was subjected to bioassay-guided fractionation using analyticalC18RP-high-performance liquid chromatography (HPLC) and an antifungal assay usingP. brasiliensis. Analysis of the active fractions by HPLC-highresolution mass spectrometry allowed us to identify the antifungal agents present inthe A. felis extracts cytochalasins. These results reveal thepotential of A. felis as a producer of bioactive compounds withantifungal activity.