Structural Characterization of Polysaccharides from Partridge Tea and Their Effects on Improving FFA-Induced Lipid Accumulation in L02 Cells

This study characterized the basic structure of partridge tea leaves polysaccharides and comparatively analyzed the in vitro lipid-lowering activity of total partridge tea polysaccharide (PTPS) and its two purified homogeneous fractions, namely PTPS-I (13,560 Da) and PTPS-III (30,935 Da). In terms of structural composition, PTPS-I and PTPS-III share identical monosaccharide types but differ significantly in monosaccharide proportions, glycosidic linkages and backbone structures. In vitro experiments demonstrated that PTPS, PTPS-I, and PTPS-III could effectively reduce intracellular lipid levels and oxidative stress in free fatty acids (FFA)-injured L02 cells and alleviate the decline of mitochondrial membrane potential in damaged hepatocytes. At the high concentration of 400 μg/mL, PTPS-III showed a superior effect in reducing triglyceride (TG) content compared with the other two samples, with the value reaching 0.31 ± 0.024 mmol/mg prot. Additionally, 400 μg/mL PTPS markedly decreased total cholesterol (TCHO) content and enhanced superoxide dismutase (SOD) activity, which were 0.55 ± 0.039 mmol/mg prot and 29.92 ± 0.22 μmol/mg prot, respectively. PTPS-I of 400 μg/mL significantly reduced malondialdehyde (MDA) content to 1.31 ± 0.288 μmol/mg prot and inhibited the decline of mitochondrial membrane potential (MMP) by 9.67%. The three polysaccharide fractions could elevate the mRNA expression of Nrf2, NQO1 and HO-1 in the Nrf2/HO-1 signaling pathway and the gene expression of PPARα, CPT-1 and ACOX1 in the lipid metabolism pathway, and ultimately regulate lipid accumulation in L02 cells. This study validated the in vitro antilipid activities of partridge tea leaves polysaccharide and provided fundamental data for research on its bioactivity and functional components. Further in vivo assays and mechanism exploration will be conducted to evaluate its potential application in fatty liver intervention product development.