Antioxidant Acitivity <em>in vitro</em> and <em>in vivo</em> of Polysaccharide Isolated from Pumpkin

A water-soluble polysaccharide named as PP-e was obtained from pumpkin by the water and ethanol extract, deproteinization, alcohol grading, gel chromatography. The average molecular weight of PP-e was 4.63 kDa determined by HPGPC. PP-e was a heteropolysaccharide by the analysis of GC and consisted of L-rhamnose L-arabinose, D-glucose and D-galactose in a molar ratio of 1.12:5.19:1.00:3.91. The antioxidant activity of PP-e in vitro and in vivo was also evaluated. In vitro antioxidant assay, PP-e showed strong inhibition of superoxide radical, hydroxyl radical and DPPH radical. For antioxidant testing in vivo, PP-e was administrated by intraperitoneal injection with the dosage of 150 mg/kg in alloxan-induced mice model. As results, PP-e could significantly inhibit the formation of malondialdehyde and nitric oxide in mice livers and raised the activities of antioxidant enzymes in mice livers and serums. The results suggest that the polysaccharide from pumpkin has direct and potent antioxidant activities.