College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
Lett Appl Microbiol. 2010 Feb;50(2):223-9. doi: 10.1111/j.1472-765X.2009.02783.x. Epub 2009 Nov 30.
To evaluate the effect of subinhibitory concentrations of licochalcone A (LicA) on alpha-toxin secretion in Staphylococcus aureus.
A haemolysin assay was used to investigate the haemolytic activities in culture supernatants of both methicillin-sensitive and methicillin-resistant Staph. aureus isolates cultured with graded subinhibitory concentrations of LicA. Alpha-toxin secretion was detected by immunoblot analysis. Moreover, quantitative RT-PCR was performed to assess the influence of LicA on the transcription of hla (the gene encoding alpha-toxin) and agr (accessory gene regulator). Growth in the presence of LicA markedly inhibited the mRNA levels of hla and agr in Staph. aureus, resulting in a reduction of alpha-toxin secretion and, thus, haemolytic activities.
The secretion of alpha-toxin in Staph. aureus is decreased by LicA; this effect may be partially dependent upon inhibition of the Agr two-component system.
The findings in our study may support the use of LicA as a lead compound in the design of more potent antibacterial agents that are based on the chalcone template.
评估低浓度白藜芦醇 A（LicA）对金黄色葡萄球菌α-毒素分泌的影响。
采用溶血试验检测不同浓度 LicA 作用下，耐甲氧西林和甲氧西林敏感金黄色葡萄球菌分离株培养上清液中的溶血活性。免疫印迹分析检测α-毒素的分泌。此外，采用实时定量 RT-PCR 评估 LicA 对 hla（编码α-毒素的基因）和 agr（辅助基因调节因子）转录的影响。LicA 存在时的生长显著抑制金黄色葡萄球菌中 hla 和 agr 的 mRNA 水平，导致α-毒素分泌减少，从而降低溶血活性。
LicA 可减少金黄色葡萄球菌α-毒素的分泌；这种作用可能部分依赖于 Agr 双组分系统的抑制。
我们的研究结果可能支持将 LicA 用作基于查尔酮模板的更有效的抗菌药物设计的先导化合物。
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