Focus on Alternative and Complementary Therapies
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Focus Alternat Complement Ther©2005 Pharmaceutical Press
Focus Altern Complement Ther 2004; 9: 13–4
The Canadian blueberry Vaccinium angustifolium was identified as the most recommended plant for treating symptoms of type 2 diabetes mellitus in a survey of Quebec naturopaths and herbalists (Haddad et al., J. Herbs, Spices, and Medicinal Plants, 2003). Despite its widespread use, little is known about its biological activity.
To analyse insulin-sensitising and insulinotropic activities of V. angustifolium using cell-based bioassays.
Fruits, leaves, stems and roots were extracted in ethanol. The effect of each extract on glucose uptake was analysed by 3H-deoxyglucose transport assays in C2C12 myotubes and 3T3-L1 adipocytes following a 20-h incubation. Effects on signalling pathways downstream of the insulin receptor were analysed by immunoblots of C2C12, 3T3 and HTC hepatoma homogenates. Insulinotropic effects were analysed in INS 832/13 insulin-secreting cells.
A non-toxic dose of 12.5 μg/ml was used for all experiments. Activation of effector pathways of insulin was increased by leaf, root and stem extracts in both the absence and presence of submaximal doses of insulin. Glucose transport was significantly increased by 16–26% in myotubes at 0, 1 and 100 nm insulin, comparable to the effects of 400 μm metformin. In adipocytes, only stem and root stimulated uptake, whereas leaf extract had an inhibitory effect. Leaf extract also stimulated insulin secretion in the presence of 11 mm glucose in INS 832/13 cells.
Extracts of V. angustifolium enhance insulin-related cellular activities in insulin-sensitive cell lines. These effects support the ethnopharmacological use of this plant for the management of diabetes.
Funded by the Canadian Diabetes Association.
