Purification and Characterization of Polysaccharides from Sweet Cherries, Raspberries, and Ginseng: Chemical Composition and Bioactivity.
Ross, K.A., Godfrey, D.V., and Fukumoto, L.R. (2015). "Purification and Characterization of Polysaccharides from Sweet Cherries, Raspberries, and Ginseng: Chemical Composition and Bioactivity.", Research in Health and Nutrition (RHN), 3, pp. 1-13.
Water soluble polysaccharides were isolated from three varieties of sweet cherries, raspberries, and ginseng berry pulp using a hot water extraction regime followed by ethanolic precipitation and resolubilization in water and centrifugation to ensure water solubility of the polysaccharides at conditions relevant for chemical characterization and bioactivity tests. The water soluble polysaccharides were purified into water eluted/neutral and NaCl eluted/acidic fractions using anion exchange chromatography. The water soluble polysaccharides and purified fractions were evaluated for their chemical composition and molecular weight. In terms of chemical in vitro bioactivity tests, the antioxidant activity (FRAP and ABTS assays) and potential of the polysaccharides to serve as α-amylase and α-glucosidase inhibitors were determined. All of the polysaccharides contained protein and phenolics and in most cases the NaCl eluted/acidic fractions contained higher levels of these compounds compared with water soluble polysaccharides and water eluted/neutral fractions. The sugar monomer and uronic acid content of the purified polysaccharides was influenced by both fruit type and fraction. The water eluted/neutral polysaccharide fractions from the cherry and raspberry samples were of higher molecular weights compared to their respective NaCl eluted/acidic fractions while the opposite was seen for the ginseng berry pulp polysaccharides. All of the polysaccharides possessed antioxidant activity. Of the fractions, only the NaCl eluted/acidic cherry polysaccharides demonstrated α-glucosidase inhibition with values exceeding those of the acarbose control. This work provides information necessary to aid in defining the relationship between chemical characteristics of polysaccharide and bioactivity. Results from this study support the concept that polysaccharides may act as health promoting compounds in fruits and serves as an impetus for increased work in this area.