Enzyme Assisted Extraction, Purification and Structure Analysis of the Polysaccharides from Naked Pumpkin Seeds

Enzyme assisted extraction was used to extract the polysaccharides from pumpkin seeds (PSP) and the extraction parameters were optimized by response surface methodology (RSM). Under the optimum experimental parameters: Extraction temperature of 60 degrees C, extraction time of 43 min, enzyme concentration of 2.5%, and pH of 6.0, the yield of PSP was 3.22 +/- 0.04%, which was in close agreement with the predicted value (3.24%). After further purification on anion exchange column and gelfiltration column, a novel purified polysaccharide (PSPE) with molecular weight of 16,700 g/mol was obtained. PSPE was mainly composed of mannose, galactose and glucose in the molar ratio of 1.00:3.84:1.62. NMR spectra analysis showed that the major backbone of PSPE consisted of -> 4)-alpha-D-Glcp-(1 ->, -> 4)-beta-D-Manp-(1 ->, -> 3,6)-beta-D-Glap-(1 ->, and beta-D-galactose.