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摘要
This study aimed to isolate and characterize antibacterial metabolites from Pharbitis nil seeds and investigate their antibacterial activity against various plant pathogenic bacteria. The methanol extract of P. nil seeds showed the strongest activity against Xanthomonas arboricola pv. pruni (Xap) with a minimum inhibition concentration (MIC) value of 250 mu g/ml. Among the three solvent layers obtained from the methanol extract of P. nil seeds, only the butanol layer displayed the activity with an MIC value of 125 mu g/ml against Xap. An antibacterial fraction was obtained from P. nil seeds by repeated column chromatography and identified as pharbitin, a crude resin glycoside, by instrumental analysis. The antibacterial activity of pharbitin was tested in vitro against 14 phytopathogenic bacteria, and it was found to inhibit Ralstonia solanacearum and four Xanthomonas species. The minimum inhibitory concentration values against the five bacteria were 125-500 mu g/ml for the n-butanol layer and 31.25-125 mu g/ml for pharbitin. In a detached peach leaf assay, it effectively suppressed the development of bacterial leaf spot, with a control value of 87.5% at 500 mu g/ml. In addition, pharbitin strongly reduced the development of bacterial wilt on tomato seedlings by 97.4% at 250 mu g/ml, 7 days after inoculation. These findings suggest that the crude extract of P. nil seeds can be used as an alternative biopesticide for the control of plant diseases caused by R. solanacearum and Xanthomonas spp. This is the first report on the antibacterial activity of pharbitin against phytopathogenic bacteria.
- 出版日期2017-10
