Secondary Metabolite and Antioxidant Activity of Endophytic Fungi Isolated from Syzygium aqueum Leaves Stalk

Abstract

Medicinal plants are a promising host for endophytic fungi to produce secondary metabolites relevant for food and health. In this study, we evaluate antioxidant activity to determine the species of endophytic fungi isolated from Syzygium aqueum. Endophytic fungi were isolated from leaf stalks through surface sterilization. The fungi’s isolate was identified with morphology and molecular analysis (ITS-rDNA). The pure fungi strain was cultivated on PDB media for 4 weeks, and metabolites were extracted using ethyl acetate. The crude extract of endophytic fungi was examined for its antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH). The pure compound was isolated using the chromatography method, and its structure was determined using spectroscopy analysis involving NMR 1D and 2D. In total, four obtained endophytic fungi were isolated from leaf stalks. The fungi with good antioxidant activity (IC50 59.2 µg/mL) were identified as Beltrania rhombica. The characteristics of the pure compound are white-yellowish powder with IC50 44.2 µg/mL. Based on spectroscopy analysis, the pure compound was identified as 3-(hydroxyl(3,4,5-trihydroxylphenyl)methyl)-3,4-dihydro-2H-pyran-4,5,6-triol.