Department of Biochemistry, University of Ilorin, Ilorin, Nigeria.
Antioxidants, Redox Biology and Toxicology Research Group, Department of Medical Biochemistry, College of Health Sciences, Nile University of Nigeria, FCT-Abuja, Nigeria.
Microb Pathog. 2017 Oct;111:338-344. doi: 10.1016/j.micpath.2017.08.012. Epub 2017 Aug 12.
Contribution of reactive oxygen species and oxidative stress in the antibacterial activities of betulin, betulinic acid and ursolic acid against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was investigated. The minimum inhibitory concentrations of betulin, betulinic acid and ursolic acid against E. coli, P. aeruginosa and S. aureus are 1024-, 256- and 1024-μg/mL; 512-, 256- and 256 μg/mL; 256-, 256- and 64 μg/mL respectively. Cell viability of betulin-, betulinic acid- and ursolic acid-treated bacteria decrease in time dependent manner. Treatment of bacteria in the presence of 2,2'-bipyrydyl increased cell viability. Superoxide anion radical production increased significantly (p < 0.05) in bacterial cells-treated with betulin, betulinic acid and ursolic acid. Furthermore, NAD/NADH ratio increased significantly (p < 0.05) in betulin-, betulinic acid- and ursolic acid-treated bacteria. Similarly, level of reduced glutathione in E. coli, P. aeruginosa and S. aureus decreased significantly with corresponding increase in glutathione disulphide, malondialdehyde and fragmented DNA following betulin, betulinic acid and ursolic acid treatments. It is evident from the above findings that betulin, betulinic acid and ursolic acid enhanced electron transport chain activity in E. coli, P. aeruginosa and S. aureus leading to increased ROS generation, Fenton reaction, lipid peroxidation, fragmented DNA and consequentially bacterial death.
研究了活性氧物种和氧化应激在白桦脂醇、白桦脂酸和熊果酸对大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌的抗菌活性中的作用。白桦脂醇、白桦脂酸和熊果酸对大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌的最小抑菌浓度分别为 1024、256 和 1024μg/mL；512、256 和 256μg/mL；256、256 和 64μg/mL。白桦脂醇、白桦脂酸和熊果酸处理的细菌的细胞活力随时间呈下降趋势。在 2,2'-联吡啶存在的情况下处理细菌会增加细胞活力。超氧阴离子自由基的产生在白桦脂醇、白桦脂酸和熊果酸处理的细菌中显著增加（p<0.05）。此外，白桦脂醇、白桦脂酸和熊果酸处理的细菌中 NAD/NADH 比值显著增加（p<0.05）。同样，白桦脂醇、白桦脂酸和熊果酸处理后大肠杆菌、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下降，相应的谷胱甘肽二硫化物、丙二醛和断裂的 DNA 水平增加。从上述发现可以明显看出，白桦脂醇、白桦脂酸和熊果酸增强了大肠杆菌、铜绿假单胞菌和金黄色葡萄球菌中的电子传递链活性，导致 ROS 生成、芬顿反应、脂质过氧化、断裂的 DNA 增加，从而导致细菌死亡。
