Structural characterization of a polysaccharide isolated from Lady Godiva pumpkins (Cucurbita pepo lady godiva)

In this study, a crude water-soluble heteropolysaccharide was isolated from Lady Godiva pumpkins (Cucurbita pepo Lady Godiva). After protein removal and purification, polysaccharides of the pumpkin fruit termed LGPP2-1 were subjected to structural identification. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that LGPP2-1 mainly comprised L-fucose, D-galactose, D-glucose, and D-mannose. The glycosidic linkages were determined by methylation analysis and GC/MS. The results showed that LGPP2-1 consisted of 1,2,6-trisubstitued-galactopyranosyl, 1,6-disubstitued-galactopyranosyl, 1,4,6-trisubstitued-glucopyranosyl, 1,3-disubstituedglucopyranosyl, terminal-glucopyranosyl, and terminal-fucopyranosyl, with a molar proportion of 1:4:2:2:2:1. The Nuclear magnetic resonance (NMR) spectroscopy further confirmed that the configuration of L-fucose and D-galactose were in the alpha-form, while D-glucose was in the beta-form. The molecular weight of LGPP2-1 measured using high-performance gel-permeation chromatography (HPGPC) was 1.01x10(4) Da.