Polysaccharide from Rubus chingii Hu affords protection against palmitic acid-induced lipotoxicity in human hepatocytes

Palmitic acid (PA) is known to induce lipotoxicity, a metabolic syndrome as a result of lipid accumulation in multiple cell lines. Bioactive phytochemicals derived from vegetables and fruits have gained increasing attention owing to their potential on suppressing the detrimental effect of excessive PA accumulation. However, the protective effect of natural phytochemicals derived from Rubus chingii Hu, a kind of fruit widely grown in China, against PA-induced lipotoxicity is still uncleared. In the present study, we therefore extracted the polysaccharide from Rubus chingii Hu, and identified its chemical structure. Structural characterization by HPLC, HPGPC, IR spectroscopy and GC indicated that the polysaccharide mainly consists of galacturonic acid and arabinose with copious 1 → 2 glycosidic linkages in its backbone. In addition, our results showed the cytoprotective effect of the polysaccharide against PA-induced lipotoxicity in normal human hepatocyte cell line L02. Further study indicated that the polysaccharide mitigated oxidative stress through impeding cellular reactive oxygen species (ROS) accumulation, alleviating mitochondrial membrane potential (MMP) collapse and attenuating glutathione (GSH) reduction. Overall, this study revealed that Rubus chingii Hu polysaccharide was capable of effectively alleviating palmitic acid-induced lipotoxicity, which provided a novel perspective of the health-promoting potential of isolated polysaccharide.