Laboratory for Redox Regulation, Tohoku University Graduate School of Dentistry , 4-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan.
J Agric Food Chem. 2012 Oct 10;60(40):10048-54. doi: 10.1021/jf303177p. Epub 2012 Oct 1.
It is known that gallic acid shows antimicrobial activity. In the present study, photoirradiation induced reactive oxygen species formation was investigated for augmentation of the antimicrobial activity of gallic acid. Staphylococcus aureus suspended in 4 mmol/L gallic acid was exposed to blue light of a LED at 400 nm. This treatment killed the bacteria, and a >5-log reduction of the viable counts was observed within 15 min. By contrast, neither the LED treatment alone nor the treatment with gallic acid alone showed substantial bactericidal effect. When hydroxyl radical scavengers were added to the suspension, the bactericidal effect of photoirradiated gallic acid was attenuated. Furthermore, electron spin resonance analysis demonstrated that hydroxyl radicals were generated by the photoirradiation of gallic acid. Thus, the present study suggests that the photo-oxidation can enhance the antimicrobial activity of gallic acid via hydroxyl radical formation.
已知没食子酸具有抗菌活性。本研究探讨了光诱导活性氧形成来增强没食子酸的抗菌活性。将悬浮于 4mmol/L 没食子酸中的金黄色葡萄球菌用 400nm 的 LED 蓝光照射。该处理能杀灭细菌，在 15 分钟内观察到活菌数减少超过 5 个对数级。相比之下，单独的 LED 处理或单独使用没食子酸处理均没有显著的杀菌效果。当向悬浮液中加入羟基自由基清除剂时，光辐照没食子酸的杀菌效果减弱。此外，电子自旋共振分析表明，羟基自由基是通过没食子酸的光氧化产生的。因此，本研究表明，光氧化可以通过形成羟基自由基来增强没食子酸的抗菌活性。
