A new antifungal aminobenzamide derivative from the endophytic fungus Fusarium sp.

Abstract

Background: Endophytic fungi attracted attention as a prolific source of bioactive natural products with a potent pharmaceutical activity and unique structure. Objective: The main goal of the study is to separate and identify the bioactive constituents from the endophytic fungus Fusarium sp. as well as to evaluate the antimicrobial of the new metabolites. Materials and Methods: The fungus was cultured on a rice medium, and then, the cultures were extracted with ethyl acetate (EtOAc). The EtOAc extract was chromatographed utilizing different chromatographic methods to give five metabolites. The structural determination of these metabolites was carried out by the analyses of various spectroscopic data, in addition to comparison with the formerly reported data. The antifungal and antibacterial potentials were evaluated toward various microbial strains using disc diffusion assay. Results: A new aminobenzamide derivative, namely fusaribenzamide A (2), and four known metabolites: (22E,24R)-stigmasta-5,7,22-trien-3-β-ol (1), adenosine (3), p-hydroxyacetophenone (4), and tyrosol (5) were isolated. Fusaribenzamide A (2) possessed significant antifungal activity toward Candida albicans with minimum inhibitory concentration (MIC) value 11.9 μg/disc compared to nystatin (MIC 4.9 μg/disc). Conclusion: The endophytic fungus Fusarium sp. could be considered as a wealthy pool for the isolation of aminobenzamide derivatives. Fusaribenzamide A may be a candidate for the discovery of a promising antifungal agent. Abbreviations Used: CC: Column chromatography; CHCl3: Chloroform; COSY: Correlations spectroscopy; DBE: double bond equivalent; EtOAc: Ethyl acetate; DMSO: Dimethyl sulfoxide; H2SO4: Sulfuric acid; HMBC: Heteronuclear multiple bond correlation experiment; HRMS: High-resolution mass spectrometry; HRESIMS: High-resolution electrospray ionization mass spectrometry; HSQC: Heteronuclear single quantum correlation; IR: Infrared; IZD: Inhibition zone diameter; KBr: Potassium bromide; LTQ: Linear trap quadrupole; MeOH; Methanol; MIC: Minimum inhibitory concentration; NMR: Nuclear magnetic resonance; RP: Reversed phase; SiO2: Silica gel; TLC: Thin-layer chromatography; UV: Ultraviolet; VLC: Vacuum liquid chromatography.