Anti-hyperglycemic effects and mechanism of traditional Chinese medicine Huanglian Wan in streptozocin-induced diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Huanglian Wan (HLW) is a prescription of traditional Chinese medicine (TCM), which has been used to treat diabetes mellitus for thousands of years in China. In this study we provide experimental evidence for the clinical use of HLW in the treatment of diabetes mellitus.

MATERIALS AND METHODS: HLW extract was prepared and the main components (namely berberine and catalpol) contained in the extract were assayed with high performance liquid chromatography (HPLC), and diabetic model rats were induced by intraperitoneal injection of streptozotocin (STZ). After grouped randomly, diabetic rats were administered low or high dose of HLW extract, acarbose and vehicle for 33 days, respectively. Body weight, food intake, urine volume, urine sugars, fasting plasma glucose and fasting plasma insulin were monitored to evaluate its antidiabetic effects in diabetic rats. Intestinal mucosa homogenate was prepared and the activities of intestinal disaccharidases were assayed. Moreover, oral sucrose tolerance test (OSTT) was performed and the inhibitory effect of HLW extract on the maltase and sucrase in vitro was evaluated.

RESULTS: After the treatment of HLW extract, the body weight and the fasting plasma insulin level were found to be increased while food intake, urine volume, urine sugars and fasting plasma were decreased. OSTT showed that HLW extract could lower the postprandial plasma glucose level of diabetic rats. Furthermore, HLW extract could inhibit the activities of sucrase and maltase in vitro.

CONCLUSIONS: According to our present findings, the TCM prescription HLW possessed potent anti-hyperglycemic effect on STZ-induced diabetic rats. And HLW extract exerted anti-hyperglycemic effect partly via inhibiting the increased activities of intestinal disaccharidases and elevating the level of plasma insulin in diabetic rats induced by streptozotocin.