Abstract:To explore the protective effect of exopolysaccharides (EPS) of Lactiplantibacillus plantarum IMAU30043 on oxidative damage in RAW264.7 macrophages, the author assessed the in vitro antioxidant activity of EPS using reducing ability, superoxide anion free radical inhibition ability, and DPPH free radical scavenging ability. The composition of IMAU30043 EPS was analyzed by ion chromatography, and an oxidative damage model in RAW264.7 macrophages was established by stimulating the cells with lipopolysaccharide (LPS). The changes in superoxide dismutase (SOD) enzyme activity, malondialdehyde (MDA) and NO molality, and inflammatory factor expression levels were determined. In addition, the mechanism by which EPS protect cells from oxidative damage and inhibit inflammatory responses were further investigated by analyzing the expression levels of key genes in the Nrf2/HO-1/NF-κB signaling pathway. The results showed that IMAU30043 EPS exhibited strong in vitro antioxidant activity and were composed of fucose, rhamnose, galactose, glucose, xylose, mannose, glucuronic acid, and mannuronic acid, with a molar ratio of 4.50∶51.49∶256.73∶95.96∶3.64∶5.35∶111.10∶16.93. Additionally, EPS significantly increased SOD enzyme activity and reduced the MDA and NO molality following LPS-induced oxidative damage in RAW264.7 macrophages. At the gene level, EPS significantly down-regulated the expression of iNOS, TNF-α, IL-1β, and IL-6, while up-regulating IL-10 expression. Moreover, EPS enhanced the mRNA expression of Nrf2 and HO-1 gene and inhibited NF-κB activation in the model cells. This study found that the EPS from Lactiplantibacillus plantarum IMAU30043 can effectively protect macrophages from oxidative damage, with this protective effect being associated with the Nrf2/HO-1/NF-κB signaling pathway.
