Glucose consumption and alpha-glucosidase inhibitory activities of aqueous root extract of Helicteres angustifolia

X.-S. Hu, D.-L. Cheng, K.-J. Li, L.-B. Wang, X. Yang, S. Sun, Y.-P. Wang, S.-H. Li, Z.-F. Lei, Z.-Y. Zhang

Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan. zhang.zhenya.fu@u.tsukuba.ac.jp

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• Pharmacology

OBJECTIVE: The root of Helicteres angustifolia L. (Sterculiaceae) has been used as tea to treat diabetics effectively by local people in Laos. However, no scientific evidence is available for this ethnomedicinal usage. This study was undertaken to explore the hypoglycemic effect of aqueous extract from Helicteres angustifolia root.

PATIENTS AND METHODS: The effect of aqueous extract from Helicteres angustifolia root on glucose consumption in C2C12 myotubes was investigated at a dose of 25, 50 and 100 µg/mL, respectively. The alpha-glucosidase inhibitory activity of the extract was evaluated using rat intestinal maltase and sucrose. Moreover, oral sucrose tolerance test (OSTT) in normal and streptozotocin induced diabetic rats was performed. Finally, their cytotoxicity in C2C12 cells and acute oral toxicity in rats was analyzed.

RESULTS: Aqueous root extract of Helicteres angustifolia significantly enhanced glucose consumption in C2C12 myotubes. The extract also significantly inhibited rat intestinal maltase (IC50 = 1.44 ± 0.24 mg/mL) and sucrase activity (IC50 = 0.54 ± 0.12 mg/mL), respectively. The OSTT results showed that the extract significantly suppressed the increase of blood glucose levels in normal and diabetic rats. The extract was also proven to have low acute toxicity (LD50 > 5 g/kg) and low cytotoxicity in C2C12 cells (IC50 > 0.4 mg/mL).

CONCLUSIONS: The findings from this study indicate that aqueous root extract of Helicteres angustifolia possesses significant alpha-glucosidase inhibitory activity and moderate enhanced glucose consumption activity, while with low cytotoxic and acute toxicity.

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