Bioassay-guided fractionation of the crude extract of fermentation broth of one symbiotic strain Fusarium oxysporum ZZP-R1 derived from coastal plant Rumex madaio Makino, one traditional Chinese medicine used as a treatment of inflammation and toxication, yielded two novel compounds, fusariumins C (1) and D (2). Chemical structures of 1 and 2 were respectively determined as one meroterpene with cyclohexanone moiety and a sesquiterpene ester with a conjugated triene and an unusual oxetene ring by a combination of spectroscopic methods, including 1D and 2D NMR, mass spectrometry, and optical rotation analysis, as well as by comparison with literature data. Bioassay results indicated that compound 1 displayed potent activity against Staphyloccocus aureus with an MIC value of 6.25 μM, and compound 2 had a moderate inhibitory effect on S. aureus with an MIC value of 25.0 μM. It was the first report that phytochemical investigation of Fusarium strain from R. madaio Makino led to isolation of new antimicrobial agents.
Keywords: Bioactivity; Fusarium oxysporum; Fusariumin; Rumex madaio Makino; Symbiosis.
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