Polysaccharides in Laminaria japonica (LP): Extraction, physicochemical properties and their hypolipidemic activities in diet-induced mouse model of atherosclerosis

The crude polysaccharides of Laminaria japonica (LP) were extracted with the optimal conditions as follows: raw materials to water 1:50 (w/v), extraction temperature 60 °C and extraction time 60 min. Trypsinase (6 U/ml) in combination with sevag reagent was beneficial to the removal of proteins from crude LP. Three fractions of LP1, LP2 and LP3 were obtained from the crude LP by using a final concentration of 40%, 60% and 80% ethanol to precipitate in turn. The three fractions showed obvious differences in monosaccharide compositions, molecular weight distribution, viscosity, IR spectroscopy and glycosyl linkages. In comparison with the control group, crude LP at a dose of 400 mg/kg/day caused a reduction in total serum cholesterol, triglycerides, high density lipoprotein-cholesterol and low density lipoprotein-cholesterol in serum by 80.6%, 63.4%, 43.8% and 79.8%, respectively. Moreover, crude LP exhibited good potential of enhancing antioxidant enzyme activities in serum of atherosclerosis mice.