Sulfated modification of the polysaccharides from Crassostrea gigas and their antioxidant and hepatoprotective activities through metabolomics analysis

Sulfated polysaccharides from Crassostrea gigas (SCGP) were successfully prepared using chlorosulfonic acid-pyridine method. The structure of SCGP was determined by high performance liquid chromatography (HPLC), Fourier transform infrared spectrometry (FT-IR) and nuclear magnetic resonance (NMR). The results of spectra indicated the substitution by the sulfate group primarily appeared at C-6. Further, the antioxidant activities of CGP and SCGP were contrasted, and SCGP exhibited the higher DPPH, hydroxyl and ABTS radical scavenging activities. The study was further evaluated the hepatoprotective effect of SCGP in alcoholic liver injury mice and determined total cholesterol (T-CHO), low density lipoprotein cholesterol (LDL-C), total bilirubin (TBIL), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels of serum in mice. The results demonstrated that SCGP improved blood biochemical levels and had a hepatoprotective effect. Additionally, metabolite analysis of serum was performed by UHPLC-Q-TOF-MS to assess the hepatoprotection effect of SCGP in alcoholic liver injury mice. A total of twenty-one metabolites were identified as potential biomarkers. The result suggested that SCGP altered the metabolic pathways including amino acid metabolism, oxidative stress and immune response. These data provided reference of the SCGP of treating alcoholic liver injury.