Hypolipidemic activity and safety evaluation of a rhamnan-type sulfated polysaccharide-chromium (III) complex

Hyperlipidaemia is a chronic disorder characterized by imbalance of energy metabolism and high blood lipid level. The rhamnan-type sulfated polysaccharide is an excellent metal-ion chelating ligands. In this study, hypolipidemic activity and safety evaluation of a rhamnan-type sulfated polysaccharide-chromium (III) complex (RSPC) were studied.Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the structure of RSPC. The effects of the RSPC on lipid metabolism in hyperlipidemic mice were evaluated by lipid contents, histopathological observation, immunofluorescent analysis, and adipocytokine levels. Moreover, sub-acute toxicity evaluation of RSPC was carried out on ICR mice.SEM and AFM further demonstrated formation of the polysaccharide-chromium (III) complex and revealed the intertwined network of RSPC. The RSPC significantly (p < 0.05) regulated lipid levels in the mice. The RSPC inhibited over-growth of adipocytes and reduced inflammatory infiltration induced by hyperlipidemia. The RSPC promoted differentiation of white adipose tissue into beige adipocytes and increased expression of uncoupling protein 1 (UCP1), thereby eliminating fat accumulation. Moreover, RSPC (5 mg/kg for mice; equivalent to 924 µg/d for adults) promoted secretion of adiponectin and suppressed resistin, leptin, and tumor necrosis factor alpha. Sub-acute toxicity evaluation showed that 1500 mg/kg of RSPC exhibited no apparent adverse effects on the mice.These results indicated that RSPC could be safely used to prevent hyperlipidemia and inflammation and may provide a new idea for the prevention of hyperlipidaemia and the related metabolic disorders.