Antioxidants, Redox Biology and Toxicology Research Laboratory, Department of Biological Sciences, Al-Hikmah University, Ilorin, Nigeria.
Antioxidants, Redox Biology and Toxicology Research Laboratory, Department of Biological Sciences, Al-Hikmah University, Ilorin, Nigeria.
Chem Biol Interact. 2016 Oct 25;258:276-87. doi: 10.1016/j.cbi.2016.09.010. Epub 2016 Sep 12.
The contribution of reactive oxygen species to (+)-catechin-mediated bacterial lethality was investigated. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) of (+)-catechin against E. coli, P. aeruginosa and S. aureus were investigated using 96-well microtitre plate. MIC and MBC of (+)-catechin against E. coli, P. aeruginosa and S. aureus are 600 and 700; 600 and 800; 600 and 800 μg/mL respectively. The optical densities and colony forming units of (+)-catechin-treated bacteria decreased. (+)-Catechin (4× MIC) significantly increased the superoxide anion content of E. coli, P. aeruginosa and S. aureus compared to DMSO. Superoxide dismutase and catalase in (+)-catechin treated E. coli, P. aeruginosa and S. aureus increased significantly. Conversely, level of reduced glutathione in (+)-catechin-treated E. coli, P. aeruginosa and S. aureus decreased significantly while glutathione disulfide increased significantly. Furthermore, malondialdehyde and fragmented DNA increased significantly following exposure to (+)-catechin. From the above findings, (+)-catechin enhanced the generation of reactive oxygen species (superoxide anion radical and hydroxyl radical) in E. coli, P. aeruginosa and S. aureus, possibly by autoxidation, Fenton chemistry and inhibiting electron transport chain resulting into lipid peroxidation and DNA fragmentation and consequentially bacterial cell death.
本研究旨在探讨活性氧（ROS）在（+）-儿茶素介导的细菌杀伤中的作用。采用 96 孔微量滴定板法测定（+）-儿茶素对大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。（+）-儿茶素对大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌的 MIC 和 MBC 分别为 600 和 700μg/mL、600 和 800μg/mL、600 和 800μg/mL。（+）-儿茶素处理后的细菌的光密度和菌落形成单位减少。与 DMSO 相比，（+）-儿茶素（4×MIC）显著增加了大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌中超氧阴离子的含量。（+）-儿茶素处理的大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌中的超氧化物歧化酶和过氧化氢酶显著增加。相反，（+）-儿茶素处理的大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌中的还原型谷胱甘肽水平显著降低，而谷胱甘肽二硫化物水平显著升高。此外，暴露于（+）-儿茶素后，丙二醛和断裂的 DNA 显著增加。从上述发现可以看出，（+）-儿茶素可能通过自动氧化、芬顿化学和抑制电子传递链，增强了大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌中活性氧（超氧阴离子自由基和羟自由基）的产生，导致脂质过氧化和 DNA 断裂，从而导致细菌细胞死亡。
