A novel low-molecular-mass pumpkin polysaccharide: Structural characterization, antioxidant activity, and hypoglycemic potential

The novel natural low-molecular-mass polysaccharide (SLWPP-3) from pumpkin (Cucurbia moschata) was separated from the waste supernatant after macromolecular polysaccharide production and purified using a DEAE cellulose-52 column and gel-filtration chromatography. Chemical and instrumental studies revealed that SLWPP-3 with a molecular mass of 3.5 kDa was composed of rhamnose, glucose, arabinose, galactose and uronic acid with a weight ratio of 1: 1: 4: 6: 15, and primarily contained →3,6)-β-d-Galp-(1→, →4)-α-GalpA-(1→(OMe), →4)-α-GalpA-(1→, →2,4)-α-d-Rhap-(1→, →3)-β-d-Galp-(1→, →4)-α-d-Glcp, and →4)-β-d-Galp residues in the backbone. The branch chain passes were connected to the main chain through the O-4 atom of glucose and O-3 atom of arabinose. Physiologically, the ability of SLWPP-3 to inhibit carbohydrate-digesting enzymes and DPPH and ABTS radicals, as well as protect pancreatic β cells from oxidative damage by decreasing MDA levels and increasing SOD activities, was confirmed. The findings elucidated the structural types of pumpkin polysaccharides and revealed a potential adjuvant natural product with hypoglycemic effects.