Abstract: Purpose: To investigate the hypoglycemic and hepatoprotective effects of Angelica dahurica polysaccharide (ADP). Methods: The contents of neutral sugar, total glyoxylate and total protein, molecular mass and monosaccharide composition of ADP were determined by the phenol-sulfuric acid method, the sulfuric acid-carbazole method, the Coomassie brilliant blue method, high performance gel permeation chromatography (HPGPC) and high performance liquid chromatography (HPLC), respectively. Type 2 diabetes mellitus (T2DM) was induced in rats by high-fat and high-sucrose diet feeding combined with injection of streptozotocin (STZ). Five groups of rats were set up: blank control, model, low-dose ADP (200 mg/kg mb), high-dose ADP (400 mg/kg mb), and positive control (200 mg/kg mb metformin). The rats in the blank control and model groups were gavaged with distilled water. After four weeks of administration, body mass, fasting blood sugar (FBG), oral glucose tolerance test (OGTT), fasting insulin (FINS), homeostatic model assessment for insulin resistance (HOMA-IR) and glycogen levels were measured, hematoxylin-eosin (HE) staining was used to observe hepatic histopathological changes, and commercial kits were used to determine lipid metabolism, oxidative stress and liver function indexes. Results: ADP had the following composition: (83.26 ± 0.67)% neutral sugar, (8.32 ± 1.25)% glyoxylate, and (0.64 ± 0.07)% protein, and its molecular mass was 10.28 × 103 Da. Monosaccharide composition analysis showed that ADP consisted of rhamnose, arabinose, galactose, glucose, mannose, glucuronide acid and galacturonic acid with a molar ratio of 0.09:0.45:0.43:1.00:0.05:0.53:0.08. ADP significantly increased body mass, blood glucose, FINS and glycogen levels of T2DM rats (P < 0.01), significantly decreased FBG and HOMA-IR (P < 0.01), improved liver histopathology, and significantly improved lipid metabolism, oxidative stress and liver function indexes (P < 0.01). Conclusion: ADP has hypoglycemic and hepatoprotective effects, probably through regulating abnormal lipid metabolism and oxidative stress.

Key words: Angelica dahurica polysaccharide; type 2 diabetes; liver; lipid metabolism; oxidative stress