Abstract: Objectives: To screen for lactobacilli with high antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals in vitro and to evaluate their tolerance to simulated gastrointestinal environment and their protective effect against oxidative injury induced by acrylamide in intestinal epithelial cells. Methods: Lactobacillus GBE17 and GBE29, which were found to have strong antioxidant potential, were identified by were identified by 16S rDNA sequencing. The protective effect of the viable cells and cell-free culture supernatant of either strain on acrylamide-induced oxidative injury in Caco-2 cells was assessed by morphological observation and measurement of antioxidant compounds contents and enzyme activities in the cell culture supernatants and lysates. Changes in the viable cell count after 1–4 h of exposure to different pHs (3.0 and 2.5) and different bile salt concentrations (0.05% and 0.1%) were monitored. Results: The scavenging percentages of DPPH radical by the culture supernatants of L. plantarum GBE17 and L. salivarius GBE29 were 89.44% and 79.24%, respectively. Both treatment and prevention with GBE17 as well as prevention with GBE29 could increase cell viability by decreasing lactate dehydrogenase activity and increasing the activities of superoxide dismutase and catalase in Caco-2 cells. For both strains, the number of cells surviving pH 3.0 and 0.1% bile salt environments for 4 h was higher than 7.0 (lg(CFU/mL)). Conclusion: L. plantarum GBE17 and L. salivarius GBE29 have stress tolerance and show a protective effect against acrylamide-induced oxidative damage in Caco-2 cells by increasing intracellular antioxidant enzymes activities.

Key words: Lactobacillus, oxidative damage, acrylamide, resistance, Caco-2 cells