Screening for anti-diabetic activity of medicinal plant extracts from the Canadian Boreal Forest

Among the Cree of Northern Quebec, there is a disproportionately high rate of diabetic complications due to the cultural inadequacy of modern type II diabetes therapies. In order to establish culturally adapted anti-diabetic treatments, our team identified several candidate plant species used by the Cree to treat symptoms of diabetes. An initial study focused on 8 species and revealed that most possess significant in vitro anti-diabetic activity. The purpose of the present study was to assess a further 9 species identified through the ethnobotanical survey. Crude plant extracts were screened for: 1) potentiation of basal and insulin-stimulated glucose uptake by skeletal muscle cells (C2C12) and adipocytes (3T3-L1); 2) potentiation of glucose-stimulated insulin secretion by pancreatic β-cells (βTC); 3) potentiation of adipogenesis in 3T3-L1 cells; 4) protection against glucose toxicity and deprivation in PC12-AC neuronal precursor cells; and 5) diphenylpicrylhydrazyl (DPPH) oxygen free-radical scavenging. Four species potentiated basal glucose uptake in C2C12s or 3T3-L1s, one being as potent as metformin. Adipogenesis was accelerated by four species with a potency roughly half that of rosiglitazone. Five species protected PC12-AC cells against glucose toxicity and 4 protected against glucose deprivation. Five species exhibited anti-oxidant activity comparable to ascorbic acid. However, no species increased insulin secretion. The present study revealed that several plants exhibit a promising profile of anti-diabetic potential. Such profiles are varied and can be used to inform the rational choice of plants for more in depth evaluation. Such profiles also confirm the validity of our novel ethnobotanical approach.

Acknowledgement: Funded by the CHIR