Hypolipidemic effect of polysaccharide from Sargassum fusiforme and its ultrasonic degraded polysaccharide on zebrafish fed high-fat diet

Sargassum fusiforme is a brown seaweed that grows abundantly along the rocky coastlines of Asian countries. The polysaccharides derived from Sargassum fusiforme (SFPS) have received much interest due to their various bioactivities, such as hypolipidemic, hypoglycemic, and antioxidant activities. In this study, we extracted and purified SFPS, and obtained the ultrasonic degradation product (SFPSUD). The lipid regulatory effects of SFPS and SFPSUD were investigated in a zebrafish model fed a high-fat diet. The results showed that SFPS significantly decreased the levels of total cholesterol (TC) and triglycerides (TG), and increased the activities of lipoprotein lipase (LPL) and hepatic lipase (HL). SFPSUD was more effective than the SFPS in reducing the TC and TG levels in zebrafish, as well as increasing the LPL and HL activities. Histopathological observations of zebrafish livers showed that SFPSUD significantly improved lipid metabolism disorder in the hepatocytes. The possible lipid-lowering mechanism in zebrafish associated with SFPS and SFPSUD may involve acceleration of the lipid metabolism rate by increasing the activities of LPL and HL. Thus, SFPSUD could be tested as a highly effective hypolipidemic drug. Our results suggest that SFPS and SFPSUD have potential uses as functional foods for the prevention and treatment of hyperlipidemia. Ultrasound can be effectively applied to degrade SFPS to improve its physicochemical properties and bioactivities.