Structure analysis of an acidic polysaccharide isolated from Epimedium koreanum Nakai and its improvement on liver oxidative stress injury in STZ-induced diabetic rats via NRF2/HO-1 pathways.

Epimedium koreanum Nakai (E. koreanum), a traditional Chinese herbal medicine, has been widely used to improve liver function. The acidic polysaccharides from certain plants are known to exhibit liver-protective effects. The structural features and pharmacological efficacy of acid polysaccharide derived from E. koreanum in mitigating liver injury remain unclear. Here, we isolated an acidic polysaccharide (designated EKPA) with a molecular weight of 125.8 kDa from E. koreanum. Structural analysis revealed that EKPA has a backbone consisting of 1,4-α-Glcp, 1,4-α-GlcAp and 1,3,6-β-Galp residues, with branching substitutions at the C-6 of 1,3, 6-β-Galp. The branches are terminated by t-α-Araf and t-β-Manp, exhibiting a degree of branching of 24.9 %. EKPA dose-dependently decreased the blood sugar and blood lipids levels, improved insulin resistance, antioxidative and hepatic functions in T2DM rats. Furthermore, EKPA upregulated the protein expression of NRF2 and HO-1, downregulated Keap1 in the liver of T2DM rats. These results demonstrated EKPA alleviates T2DM-induced hepatic injury via activation of the NRF2/HO-1 pathway. Therefore, EKPA may be used as a promising natural agent for protection of liver injury.