Antioxidant and Anti-Inflammatory Effects of Live and Heat-Killed Limosilactobacillus fermentum isolated from Baekkimchi

This study aimed to evaluate the probiotic properties of Limosilactobacillus fermentum SMF680 and Limosilactobacillus fermentum SMF709, which were isolated from Baekkimchi, and to assess the antioxidant and anti-inflammatory activities of live and heat-killed cells. The selected SMF680 and SMF709 strains showed similar acid resistance, bile resistance, and intestinal cell adhesion compared to Lacticaseibacillus rhamnosus GG (LGG), a commercial probiotic strain. The live and heat-killed cells of SMF680 and SMF709 did not show toxicity at a concentration of 1 mg/mL against intestinal cells (HT-29) and macrophages (RAW 264.7). The heat-killed cells of SMF680 and SMF709 showed significantly higher DPPH and ABTS radical scavenging activities as well as β-carotene bleaching inhibitory activity than those of LGG (p<0.05). Moreover, the heat-killed cells of SMF680 and SMF709 showed significantly higher ABTS radical scavenging and β-carotene bleaching inhibition activities compared to the live cells (p<0.05). The treatment of live or heat-killed cells of SMF680 and SMF709 significantly suppressed the expression of TNF-α, IL-6, iNOS and COX-2 in LPS-stimulated RAW 264.7 macrophages (p<0.05). The live and heat-killed cells of SMF680 and SMF709 exhibited superior inhibitory activities on the expression of TNF-α, IL-6, iNOS and COX-2 compared to those of LGG. In particular, the heat-killed cells of SMF709 showed the most potent anti-inflammatory effect by inhibiting IL-6, iNOS and COX-2 expression by 73.86%, 81.93%, and 65.75%, respectively. Therefore, the results of this study suggest that the heat-killed cells of L. fermentum SMF680 and L. fermentum SMF709 strains could be utilized as natural antioxidant and anti-inflammatory agents in the food, pharmaceutical, and cosmetic industries.