Physicochemical characterization and bile acid-binding capacity of water-extract polysaccharides fractionated by stepwise ethanol precipitation from Caulerpa lentillifera

Abstract

Herein, water-extracted Caulerpa lentillifera polysaccharides were structurally characterized and their bile acid-binding capacities were investigated. WCLP-25, WCLP-40, WCLP-55, WCLP-70, and WCLP-85 were obtained by graded ethanol precipitation with ethanol concentrations of 25%, 40%, 55%, 70%, and 85%. The total carbohydrate, protein, uronic acid and sulfate contents as well as the monosaccharide composition, molecular weight, and rheological properties were determined. Their infrared spectra, thermogravimetric curves, and scanning electron microscopy (SEM) images were acquired. The hypolipidaemic effects of the WCLPs were assessed with in vitro simulated bile acid-binding capacity experiments. The WCLPs are high-molecular-weight sulfated heteropolysaccharides, and the ethanol concentration significantly influenced the physicochemical properties of the extract. The bile acid-binding capacities of WCLP-55 and WCLP-70 were significantly higher than those of the other tested WCLP samples, which may be due to their higher neutral sugar, uronic acid and sulfate contents or due to their higher viscosities and a larger sheet structure based on SEM. This study will broaden the sources of raw materials for functional foods and provide a reference for the scientific use of C. lentillifera.