Antibacterial activity of Syzygium aromaticum seed: studies on oxidative stress biomarkers and membrane permeability

Abstract

The involvement of reactive oxygen species and oxidative stress in 2-(2-nitrovinyl) furan mediated bacterial cell death was investigated in Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Time kill assay resulted in significant decrease in the optical density and colony-forming unit (CFU) of E. coli, P. aeruginosa and S. aureus. The level of superoxide anion radical and nitric oxide increased significantly in concentration dependent when compared with dimethyl sulfoxide (DMSO) treated bacteria. Similar concentration dependent increase in the activity of superoxide dismutase and catalase were recorded. The non-enzymatic antioxidant glutathione decreased significantly with a concomitant increase in glutathione disulfide. The level of malondialdehyde and fragmented DNA increased significantly in the bacterial cells treated with 2-(2-nitrovinyl) furan when compared with DMSO treated cells. The CFU of E. coli, P. aeruginosa and S. aureus following exposure to 2-(2-nitrovinyl) furan increased significantly (p < 0.05) in the presence of 2,20 bipyridyl, an Fe chelator, significantly when compared with only 2-(2-nitrovinyl) furan suggesting the involvement of hydroxyl radical in the cell death. The available data from this study showed that 2-(2-nitrovinyl) furan induced oxidative stress in E. coli, P. aeruginosa and S. aureus as evident from elevated levels of superoxide anion radical nitric oxides and antioxidant enzymes.