Hypolipidaemic and antioxidant capacities of polysaccharides obtained from Laminaria japonica by different extraction media in diet‐induced mouse model

This study shows the industrial feasibility of using aqueous methods to produce antioxidative and hypolipidaemic polysaccharides from Laminaria japonica (LJP). Comparison was firstly made among the polysaccharides prepared using different extraction media, that is water alone (LJPW) and citric acid (LJPC), sulphuric acid, hydrochloric acid and phosphoric acid. LJPC enabled the highest extract yield (~11% dry weight), bile salt adsorption rate (~59% dry weight), ABTS radical scavenging activity (IC₅₀ value 1.06 mg mL^?1) and ORAC antioxidant activity (341.87 μmol Trolox g^?1). In animal trial using diet‐induced high‐fat mice, oral administration of LJP produced with citric acid (LJPC) at a high dose (200 mg kg^?1 body mass per day) enabled significantly higher serum HDL‐C, lower LDL‐C/HDL‐C and unaltered LDL‐C, whilst a medium dose (100 mg kg^?1 body mass per day) significantly decreased LDL‐C. Administration of LJP produced with water (200 mg kg^?1 body mass per day) significantly lowered serum LDL‐C. Therefore, LJP may provide dose‐dependent pharmacological and therapeutic effects to combat atherosclerosis through their hyperlipidaemic and antioxidant properties.