Involvement of oxidative stress in protocatechuic acid-mediated bacterial lethality.

The involvement of oxidative stress in protocatechuic acid-mediated bacterial lethality was investigated. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) of protocatechuic acid against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus are 600 and 700 µg/ml, 600 and 800 µg/ml, and 600 and 800 µg/ml, respectively. The optical densities and colony-forming units of protocatechuic acid-treated bacteria decreased in time-dependent manner. Protocatechuic acid (4× MIC) significantly increased the superoxide anion content of E. coli, P. aeruginosa, and S. aureus compared to dimethyl sulfoxide (DMSO). Superoxide dismutase, catalase, and NAD+ /NADH in protocatechuic acid-treated E. coli, P. aeruginosa, and S. aureus increased significantly when compared to DMSO. Conversely, level of reduced glutathione decreased in protocatechuic acid-treated E. coli, P. aeruginosa, and S. aureus, while glutathione disulfide increased when compared to DMSO. Furthermore, malondialdehyde and fragmented DNA increased significantly following exposure to protocatechuic acid. Protocatechuic acid inhibited the activity of complexes I and II. From the above findings, protocatechuic acid 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 in lipid peroxidation and DNA fragmentation and consequentially bacterial cell death.

A fermented sorghum/millet-based beverage, Obiolor, extenuates high-fat diet-induced dyslipidaemia and redox imbalance in the livers of rats.

BACKGROUND: Obiolor, a non-alcoholic beverage produced from fermented sorghum and millet malts, is widely consumed on a daily basis by the Igala tribe in Nigeria and is closely associated with good health. The effect of Obiolor on dyslipidaemia, protein oxidation, lipid peroxidation and DNA fragmentation in the liver of rats fed a high-fat diet was investigated. RESULTS: High-fat diet-mediated alterations in liver and serum total cholesterol, triacylglycerol, high-density lipoprotein cholesterol, low-density cholesterol and very low-density lipoprotein cholesterol were significantly (P < 0.05) reversed by Obiolor. The beverage increased the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose 6-phosphate dehydrogenase in the liver of rats. These increases significantly (P < 0.05) attenuated the high-fat diet-mediated decrease in antioxidant enzymes. High-fat diet-mediated elevations in the levels of conjugated dienes, lipid hydroperoxides, malondialdehyde, protein carbonyl and DNA fragmentation in the livers of rats were lowered by the beverage. CONCLUSION: This study showed that Obiolor extenuated high-fat diet-mediated dyslipidaemia, protein oxidation, lipid peroxidation and DNA fragmentation in rats.