Ultrasound-assisted Enzymatic Extraction of Polysaccharides from Algal Residue of Caulerpa lentillifera and Analysis of Their Lipid-lowering Effects
The optimal conditions for ultrasound-assisted enzymatic extraction of polysaccharides from the algal residue of Caulerpa lentillifera were determined and the lipid-lowering effects of the extracted polysaccharides were investigated.Single-factor experiments and the response surface methodology were used to optimize the extraction parameters.The in vitro lipid-lowering effects of the extracted polysaccharides were evaluated on the basis of their ability to bind with bile acids.Additionally,mice were fed a high-fat diet to induce hyperlipidemia and then administered the extracted polysaccharides via oral gavage for 4 weeks.The optimal conditions for the ultrasound-assisted enzymatic extraction process were an enzyme mass fraction of 2.5%(neutral protease∶xylanase∶cellulase=1∶1∶1),an extraction temperature of 48 ℃,and an extraction time of 123 min.Under these conditions,the polysaccharide yield was 36.62%and the mass fraction was 87.20%.The binding rates of the extracted polysaccharides with cholic,deoxycholic,taurocholic,and glycocholic acids were 86.56%,89.47%,84.26%,and 64.68%,respectively.Compared with the hyperlipidemic mice,the mice treated with 200 or 400 mg/kg of the extracted polysaccharides exhibited significant decreases in body weight(11.29%and 15.38%,respectively),fat indices(4.07%and 3.18%),serum triglyceride levels(59.87%and 68.42%),total cholesterol(28.24%and 39.08%),and low-density lipoprotein-cholesterol(34.93%and 49.28%),as well as significant increases in high-density lipoprotein-cholesterol levels(52.67%and 99.00%).In conclusion,the optimized conditions for the ultrasound-assisted enzymatic extraction of polysaccharides from algal residue of C.lentillifera were reasonable and reliable,and the extracted polysaccharides showed good bile acid-binding abilities in vitro as well as hyperlipidemia-ameliorating effects in model mice fed a high-fat diet.