Protective mechanisms of intra- and extracellular polysaccharides from Schizophyllum commune on H₂O₂-induced oxidative damage of human skin fibroblasts

Schizophyllum commune is a fungus with applications both in medicine and foods, which produces IPS and EPS. However, there is no comparative study on the activity comparison of IPS and EPS and its mechanism of antioxidant effect. In this study, the antioxidant activities of the two polysaccharides were measured in biochemical, cellular and molecular levels, and H2O2 induced oxidative damage model of HSFs was established to explore the protective effects of EPS and IPS. We found IPS and EPS both achieved a good antioxidant effect. They can also improve the cellular levels of SOD and reduce MDA. Insights regarding the molecular mechanism were studied, we found that both EPS and IPS could increase the expression of Nrf2 in Keap1-Nrf2/ARE signaling pathway. At the same time, they could inhibit the expression of the negative feedback gene Keap1 and promote the expression of downstream gene GCLC, Gstt-1, Nqo1 and Ho-1.