Oxazines and their derivatives are an uncommon natural heterocyclic compounds, which contain oxygen and nitrogen atoms and possess various bioactivities. A novel 1,4-oxazine-xanthone derivative, fusarioxazin (4) and three known sterols (1-3) were separated from Fusarium oxysporum EtOAc extract associated with Vicia faba L. (broad bean, Fabaceae) roots. Their structural assignment was accomplished using various spectroscopic tools and comparing with literature data. The cytotoxic and antimicrobial potentials of the novel metabolite (4) were evaluated. It possessed a significant antibacterial activity towards S. aureus (IZD 14.8 mm and MIC 5.3 µg/mL) and B. cereus (IZD 18.9 mm and MIC 3.7 µg/mL), in comparison to ciprofloxacin (IZDs 16.9 and 20.5 mm; MICs 3.9 and 2.3 µg/mL, respectively). Furthermore, it displayed a promising cytotoxic effect toward HCT-116 (IC50 2.1 µM), MCF-7 (IC50 1.8 µM), and A549 (IC50 3.2 µM) comparable to doxorubicin (IC50s 0.68, 0.54, and 0.39 µM, respectively).
Keywords: Fusarium oxysporum; Vicia faba; antimicrobial; cytotoxic; endophytes.