Background and aim: The aim of this study was to find endophytic fungi with potential antifungal activities against some pathogenic fungi. Materials and methods: Antifungal activities of 24 endophytic fungal strains, including Fusarium, Aspergillus, Cylindrocladium, Penicillium, Chaetomium, Alternaria, Cladosporium, Nigrospora, Aureobasidium, Bipolaris, and sterile mycelia, were tested against Candida albicans using a visual agar plate assay method. Endophytic fungus F-12-BSU, with the highest antifungal activities, was identified using ITS1/4 sequencing and cultured on potato dextrose broth medium for 21 days at 26°C. The culture filtrate was extracted using methanol, ethanol, and ethyl acetate, water and concentrated by a rotary evaporator. Antifungal susceptibility testing against C. albicans, C. tropicalis, C. glabrata, Cryptococcus neoformans, Aspergillus fumigatus, A. flavus, Trichophyton rubrum, and T. mentagrophytes was performed by CLSI microbroth dilution method (M-27-A3, M38-A2).Results: The results of ITS sequencing led to the identification of A. aculeatus as an endophytic fungus (F-12-BSU). Regarding the minimum inhibitory concentration (MIC), methanolic extract showed the MIC50 and MIC90 values of 0.32 and 0.64 μg/ml against C. albicans, respectively. Meanwhile, fluconazole had the MIC50 value of 2 μg/ml against this Candida species. Furthermore, C. tropicalis, C. glabrata, and C. krusei had the MIC50 values of 0.01, 0.04, and 0.032 μg/ml, respectively, compared to fluconazole with the MIC50 values of 4, 16, and 16 μg/ml. Filamentous fungi of A. fumigatus and A. flavus had the MIC50 values of 0.32 and 0.08 μg/ml, respectively, while fluconazole had the MIC50 values of 128 and 64 μg/ml, respectively, against these species. Additionally, Cryptococcus neoformans, T. rubrum, and T. mentagrophytes with the MIC50 value of more than 5 μg/ml had the highest MICs against the crude extract of endophytic fungus, compared to fluconazole with the MIC50 values of 8, 4, and 8 μg/ml, respectively. Conclusion: Based on the findings of the present study, the methanolic extract of A. aculeatus as an endophytic fungus can be a suitable substitute for antifungal drugs, which can be used against the pathogenic fungi after standardization and purification.
