Purification, characterization and bioactivity determination of a novel polysaccharide from pumpkin (Cucurbita moschata) seeds

摘要

The crude polysaccharides from pumpkin seeds were obtained with hot water extraction and ethanol precipitation. After purification by Q-Sepharose FF column and Sephadex G-100 gelfiltration, a protein bound polysaccharide (PSP-I) was obtained and characterized. PSP-I was composed of mannose, glucose and galactose in a molar ratio of 1.0:12.9:5.3 with molecular weight of 21,100 g/mol. H-1 NMR and C-13 NMR spectra revealed that the backbone of PSP-I consisted of (1 -> 4)-linked 13-D-glucopyranosyl, (1 -> 2)-linked alpha-D-galactose and (1 -> 6)-linked alpha-D-mannopyranosyl. PSP-I contained 17 general amino acids and was rich in glutamic acid, alanine and glycine. The alkali sensitive O-glycoprotein was identified by beta-elimination reaction. The antioxidative assays in vitro indicated that PSP-I showed the moderate scavenging activities on DPPH radical and hydroxyl radical. Moreover, PSP-I displayed the obvious inhibitory activity against alpha-amylase and strong antibacterial activity. (C) 2016 Elsevier Ltd. All rights reserved.