Purification, composition and antioxidant activity of polysaccharides from wolfberry, cherry, kiwi and cranberry fruits

Water-soluble polysaccharides from wolfberry (Lycium barbarum L.), sweet cherry (Prunus avium L.), kiwi (Actinidia chinensis L.) and cranberry fruits (Vaccinium macrocarpon Aiton) were extracted with boiling water, fractionated using ion exchange column chromatography, and characterized for molecular weight by high performance size exclusion chromatography (HPSEC). Monomer sugar composition was determined by gas chromatography (GC), and antioxidant activity was assayed by oxygen radical absorbance capacity (ORAC) and Trolox equivalent antioxidant capacity (TEAC). All four types of fruit investigated had four separate polysaccharide fractions; however, the polysaccharides from sweet cherries had higher molecular weight fractions. All the fruits contained rhamnose, fucose, arabinose, xylose, mannose, galactose, and glucose, but the polysaccharides from different fruits, and from cherries of different cultivars and maturity levels, had different ratios of simple sugars. TEAC and ORAC assays revealed that raw and purified polysaccharides from cherries, cranberries, kiwi, and wolfberries have antioxidant activity, and sweet cherry polysaccharides have the highest antioxidant activity