Structural characterization and hypoglycemic activity of Trichosanthes peel polysaccharide

• A novel polysaccharide from Trichosanthes peel was isolated for the first time.
• The molecular weight of TPP-1 was 1.2 × 105 Da.
• The backbone of TPP-1 was composed of 1,4,6-Galp, 1,4-Galp, 1,3,6-Manp and 1,4-Manp.
• The branches of TPP-1 consisted of 1,3-Araf, 1-Araf and 1-Glcp.
• TPP-1 possessed significant hypoglycemic activities.

Trichosanthes peel polysaccharide (TPP) was obtained from the aqueous extract of Trichosanthes peel by alcohol precipitation, deproteinization and decoloration. TPP was then separated and purified by Sephadex G-100 column to obtain the homogeneous component TPP-1 (1.2 × 105 Da). The compositions in monosaccharides were d-arabinose (Ara), d-mannose (Man), d-glucose (Glc) and d-galactose (Gal) with a molar ratio of 1.00:3.27:4.26:6.01. Its backbone was composed of 1,4,6-Galp, 1,4-Galp, 1,3,6-Manp and 1,4-Manp, while the branches comprised of 1,3-Araf, 1-Araf and 1-Glcp. Diabetic mice experiments showed that the blood glucose levels in hyperglycemia mice reduced by 22.47%, 15.38% and 12.72% after administration of high, medium and low doses of TPP-1, respectively. Compared with the negative control group, the contents of insulin and total superoxide dismutase of the hyperglycemia mice in groups treated with different doses of TPP-1 were increased significantly, while the contents of biochemical indexes including malondialdehyde, creatinine, triglyceride, total cholesterol low density lipoprotein cholesterin and blood urea nitrogen were decreased in different degrees. These results suggested that TPP-1 possessed strong hypoglycemic activity on streptozotocin-induced model mice.