Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan.
FEMS Microbiol Lett. 2010 May;306(1):54-60. doi: 10.1111/j.1574-6968.2010.01931.x. Epub 2010 Feb 19.
The use of natural compounds as inhibitory agents for virulence factor production is a new approach to overcome increased antimicrobial resistance in pathogenic bacteria. In this study, we examined whether red chilli (Capsicum annuum) contains any such compound(s) that can repress the cholera toxin (CT) production in Vibrio cholerae. We found that the methanol extract of red chilli could inhibit CT production in recently emerged V. cholerae O1 El Tor variant strains without affecting their viability. Interestingly, capsaicin, a well-studied active component of red chilli, also drastically inhibited CT production in V. cholerae strains belonging to various serogroups including variants. Real-time quantitative reverse transcription-PCR assay revealed that capsaicin effectively repressed the transcription of ctxA, tcpA and toxT genes, but not of toxR and toxS genes. On the contrary, capsaicin significantly enhanced the transcription of the hns gene, the product of which is known to regulate negatively the transcription of ctxAB, tcpA and toxT genes. These results suggest that capsaicin might act as a potent repressor for CT production possibly by enhancing the transcription of hns.
利用天然化合物作为毒力因子产生的抑制剂是克服致病性细菌中抗菌药物耐药性增加的一种新方法。在这项研究中，我们研究了红辣椒（Capsicum annuum）是否含有任何可以抑制霍乱弧菌（Vibrio cholerae）产毒的化合物。我们发现红辣椒的甲醇提取物可以抑制最近出现的霍乱弧菌 O1 El Tor 变异株的 CT 产生，而不影响其活力。有趣的是，辣椒素，一种研究得很好的红辣椒活性成分，也能显著抑制属于各种血清群的霍乱弧菌菌株，包括变异株的 CT 产生。实时定量逆转录-PCR 分析显示，辣椒素能有效地抑制 ctxA、tcpA 和 toxT 基因的转录，但不能抑制 toxR 和 toxS 基因的转录。相反，辣椒素显著增强了 hns 基因的转录，hns 基因的产物已知能负调控 ctxAB、tcpA 和 toxT 基因的转录。这些结果表明，辣椒素可能通过增强 hns 基因的转录而作为 CT 产生的有效抑制剂。
