Hypolipidemic Effects of Mesona chinensis Benth Polysaccharides with Different Structures and Molecular Weights

Four novel Mesona chinensis Benth polysaccharides were isolated using aqueous alcohol precipitation. Their molecular weights were determined using high-performance gel permeation chromatography: MA1 (2.3 kDa), MA2 (80.5 kDa), MA3 (180.9 kDa), and MA4 (635.2 kDa), and their compositions were analyzed using GC-MS. The polysaccharides were mainly D-glucose, D-galactose, L-Rhamnose, D-arabinose, D-xylose, and D-mannose. The structural characteristics were further analyzed using infrared spectrophotometry and were identified as a type of pyrrhic sugar. An insulin-induced insulin resistance model of HepG2 cells and oleic acid-induced fat accumulation model of insulin were established to evaluate the hypolipidemic effects. Three Bacteroides spp. [Bacteroides thetaiotaomicron (BT), B. ovatus (BO), and B. cellulosilyticus (BC)] that were negatively correlated with lipid-lowering activity were used to evaluate the lipid-lowering activity of polysaccharides. The Bacteroides metabolites of MA1 and MA2 exhibited hypolipidemic effects and antioxidant activities and could potentially be used as lipid-lowering supplements.