Study of Antibacterial Components of Endophytic Streptomyces S009 from Dracaena Cochinchinensis

OBJECTIVE To investigate the antibacterial components of endophytic Streptomyces S009 from Dracaena cochinchinensis.METHODS The fermentation extracts of S009 were isolated and purified by Sephadex LH-20, reversed phase column chromatography, silica gel column chromatography and semi-preparative HPLC. The chemical structures were identified by MS and NMR spectral analysis.RESULTS Four macrotetrolide components, including nonactin(1), monactin(2), dinactin(3) and trinactin(4), were isolated and identified from S009. The bioactivity results showed that compounds 3 and 4 possessed strong antibacterial activity against various G⁺ bacteria, G^– bacteria and Candida albicans. In addition, compounds 2–4 also had strong anti-methicillin-resistant Staphylococcus aureus(MRSA) activity, and the minimum inhibitory concentration(MIC) values of them against a variety of tested MRSA strains were less than or equal to that of positive drug, vancomycin(MIC: 1–4 μg·mL^-1). Especially, compound 3 had the most significant activity (MIC≤0.125 μg·mL^-1).CONCLUSION The results of this study can not only provide lead compounds for developing new anti-MRSA drugs, but also has important meaning for the effective utilization and protection of the rare and endangered Dracaena cochinchinensis.