Phenolic compounds from endophytic Pseudofusicoccum sp. Isolated from Annona muricata

Abstract

Endophytic fungal populations of Nigerian medicinal plants have been shown to possess enormous potentials as sources of biologically active compounds of pharmaceutical and industrial importance. Our study was carried out to investigate the secondary metabolites of an endophytic fungus Pseudofusicoccum sp. isolated from the leaves of Annona muricata growing in Ifite Dunu, Anambra State, South-East Nigeria. Isolation of the endophyte, identification by DNA amplification and sequencing of the internal transcribed spacer (ITS) region were carried out using standard methods. Solid state fermentation of the endophyte was carried out in rice medium and the metabolites were extracted with ethyl acetate. The crude ethyl acetate extract was subjected to antioxidant and antimicrobial assays. Fractionation of the fungal extract, and the isolation and characterization of compounds were carried out using various chromatographic and spectroscopic methods. The fungal crude extract showed mild antimicrobial activity against B. subtilis, S. typhi and C. albicans, with inhibition zone diameters (IZDs) of 2, 3, and 2 mm respectively. The extract showed good antioxidant activity with an inhibition of 96%. Chromatographic purification of the fungal extract afforded three known phenolic compounds (1-3) that are known for their antioxidant properties. This study shows that A. muricata harbor endophytes that could be excellent sources of pharmacologically active compounds.