In this research, the crude polysaccharides were extracted from Chinese traditional medicine Huidouba and then isolated and purified by DEAE-52 cellulose and Sephadex G-100 chromatographic columns. The hypoglycemic activities of two fractions were determined by α-glucosidase inhibitory activity in vitro. The fraction HDBP-3A showed the best α-glucosidase inhibitory activity with an IC50 of 0.0075 mg/mL, which was lower than the acarbose positive control (IC50 of 0.092 mg/mL). The structural features of HDBP-3A was investigated by the high-performance gel permeation chromatography (HPGPC), gas chromatography(GC), UV spectroscopy, FT-IR, periodate oxidation and Smith degradation. The results demonstrated that the HDBP-3A with a molecular weight of 86,749 Da mainly composed of l-rhamnose, d-fucose, l-arabinose, d-xylose, d-mannose, d-glucose and d-galactose with the molar ratio of 2.33:1.58:1.00:1.37:4.86:4.00:7.30. The branches of HDBP-3A were composed of (1 → 4)-linked, (1 → 6)-linked, (1 → 2)-linked or (1 → 3)-linked. The IR spectrum implied that β-pyranoside linkage and α-configurations existed in HDBP-3A simultaneously.
Keywords: Huidouba; Periodate oxidation and Smith degradation; α-Glucosidase inhibitory.
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