Isolation, preliminary structural characterization and hypolipidemic effect of polysaccharide fractions from Fortunella margarita (Lour.) Swingle

In order to understand the multiple relationships between the structural characteristics and hypolipidemic effect of polysaccharides from Fortunella margarita (Lour.) Swingle (FMPS), four polysaccharide fractions, FMPS1, FMPS2, FMPS3 and FMPS4, were isolated from FMPS by the column chromatography using DEAE Sepharose CL-6B and Sephadex G-100. The results showed that FMPS1 and FMPS3 were mainly pectic polysaccharides while FMPS2 and FMPS4 were mainly composed of neutral polysaccharides. FMPS1, FMPS2 and FMPS3 linked by alpha- and beta-glycosidic linkages while FMPS4 only linked by beta-glycosidic linkages. According to the size-exclusion chromatography coupled with multi-angle laser light-scattering and refractive index (SEC-MALLS-RI) system, the molecular weight of FMPS1 and FMPS2 was greater compared to FMPS3 and FMPS4. The chain conformation analysis indicated FMPS3 and FMPS4 were highly branched polymers whereas FMPS1 and FMPS2 existed as globular shape and random coil conformation in aqueous, respectively. In addition, among the four polysaccharide fractions, FMPS1 and FMPS3 displayed the stronger inhibitory effect on the pancreatic lipase, FMPS1 and FMPS2 displayed the stronger ability to bind bile acids, and FMPS3 and FMPS4 displayed the greater antioxidant activity. The hypolipidemic activity of polysaccharide fractions was affected by the monosaccharide composition, glycosidic linkage, molecular weight and chain conformation in aqueous. This functional property was a result of a combination of multiple structural factors. (C) 2015 Elsevier Ltd. All rights reserved.