Effects of different deproteinization methods on the hepatoprotective activity of Smilax china L. polysaccharides against CCl4-induced acute liver injury in mice.

Acute liver injury (ALI) is typically caused by chemical toxicants and can progress to severe liver disease. Smilax china L. polysaccharides (SCPs) show significant hepatoprotective activity, but the proteins in SCPs might impact their effectiveness. This study aimed to evaluate whether different deproteinization methods affect the structure of SCPs and the hepatoprotective effects. Three deproteinized Smilax china L. polysaccharides (D-SCPs), namely SCP-R, SCP-S, and SCP-T, were prepared using repeated freeze-thawing (RFT), Sevag, and trichloroacetic acid (TCA) methods, respectively. Structural analysis revealed that D-SCPs shared similar core features, but SCP-R had higher molar ratios of rhamnose, arabinose, and galacturonic acid. In mice with carbon tetrachloride (CCl4)-induced ALI, D-SCPs alleviated liver injury, with SCP-R exhibiting superior protective efficacy. SCP-R significantly reduced serum levels of ALT, AST, and LDH, enhanced antioxidant enzyme activities, suppressed pro-inflammatory cytokines, modulated dysregulated liver amino acid and lipid metabolism, and effectively ameliorated gut dysbiosis. These findings indicate that the hepatoprotective effects of SCP-R are mediated through activation of the Nrf2-dependent antioxidant pathway and inhibition of the NF-κB signaling pathway, thereby strengthening antioxidant and anti-inflammatory responses and restoring gut microbiota homeostasis. SCP-R demonstrates promising potential as a therapeutic candidate for liver protection, while the RFT deproteinization method represents an eco-friendly approach with potential for further development.