LAUSR

Background: Probiotics have attracted a great attention aiming to develop natural non-toxic antioxidants, because of their role in decreasing the risk of reactive oxygen species [ROS] accumulation. Objectives: The purpose of this study was to assess the antioxidant activity of a probiotic Streptococcus salivarius ssp thermophillus [St.sa] and to evaluate its protective effect against the oxidative stress induced by a toxic dose of paracetamol in Wistar rats. Materials and Methods: Several assays were used to investigate the in vitro antioxidant capacity of the strain. To evaluate the protective effect against oxidative stress induced by paracetamol in liver, hepatic marker enzymes, the antioxidant enzyme activities, malondialdehyde [MDA] and glutathione [GSH] content in liver tissues were investigated. Results: The strain has shown a considerable ability to scavenge DPPH free radical [89.43%],a good resistance to hydroxyl radicals [47%], a considerable ability to chelate iron ions [33.21%] and a good inhibitory effect against plasma lipid peroxidation [54.36%]. Significant changes in liver function tests, antioxidant enzyme activities, MDA and GSH levels in paracetamol treated group were obtained compared to control group. Pretreatment with probiotic removed significantly the inhibition of antioxidant enzymes and suppressed MDA increase and GSH depletion. The analysis of the level of mRNA expression of antioxidant enzymes showed no significant differences in the expression of the enzymes in treated or non-treated groups. Conclusion: This finding emphasizes the protective role of probiotics against ROS generated during the treatment with paracetamol