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Characterization of polysaccharide fractions in mulberry fruit and assessment of their antioxidant and hypoglycemic activities in vitro

Chen, Chun, You, Li-Jun, Abbasi, Arshad Mehmood, Fu, Xiong, Liu, Rui Hai, Li, Chao
Food & function 2016 v.7 no.1 pp. 530-539
alpha-amylase, alpha-glucosidase, antioxidant activity, antioxidants, arabinose, galactose, gel chromatography, glucose, glycemic effect, hypoglycemic agents, mannose, molecular weight, mulberries, polysaccharides, scanning electron microscopy, sodium chloride, solvents, xylose
The present study aimed to characterize and investigate the polysaccharide fractions of mulberry fruit, and their antioxidant and hypoglycemic activities. Mulberry fruit polysaccharides (MFP) were extracted by using hot water as the solvent and fractioned by using a DEAE-Sepharose fast-flow column. In total four eluents of water (MFP-1), 0.1 M NaCl (MFP-2), 0.2 M NaCl (MFP-3) and 0.3 M NaCl (MFP-4) were fractionated. Arabinose, galactose, glucose, xylose and mannose were the main components present in MFP-1, while MFP-2 and MFP-3 were composed of arabinose and galactose, and MFP-4 of arabinose, galactose and glucose. High-performance gel permeation chromatography (HP-GPC) analysis indicated a narrower molecular weight distribution in the MFP-1 fraction. Scanning electron microscopy (SEM) exhibited a smooth surface for MFP-1 and MFP-3 fractions, whereas MFP-2 and MFP-4 have pore openings and flocculent fibers on a smooth surface. Tertiary structure analyses indicated that none of the fractions had a triple-helical conformation. On the whole, MFP-3 and MFP-4 showed better antioxidant activity and inhibitory effects on α-amylase and α-glucosidase compared to MFP-1 and MFP-2. These results show significant potential for the antioxidant and hypoglycemic activities of MFP-3 and MFP-4 indicating the need for their further exploration as potential antidiabetic agents.