Antidiabetic Activity of Extracts from Needle, Bark, and Cone of Picea glauca: Organ-Specific Protection from Glucose Toxicity and Glucose Deprivation

摘要

The incidence of type 2 diabetes mellitus has reached epidemic proportions worldwide. Canadian aboriginal communities, particularly the Cree Nation of Eeyou Istchee, have been identified as a high-risk population. Culturally acceptable treatment options are limited notably for diabetic complications resulting in peripheral neuropathy. Here, we describe results of an ongoing collaborative research project with Cree of Eeyou Istchee to identify botanicals capable of protecting peripheral neuronal precursors from glucose toxicity and glucose deprivation in vitro. Polar fractions of three plant organs (needles, cone, and bark) collected from Picea glauca (Moench) Voss (Pinaceae), were tested for toxicity under normoglucose, glucotoxicity, and glucose deprivation conditions. The profile of phenolic metabolites in each extract was first characterized by high-performance liquid chromatography-diode array detection-atmospheric pressure chemical ionisation mass spectrometry (HPLC-DAD-APCI/MS). We report here that these fractions are well-tolerated by PC 12 neuronal precursors under normoglucose conditions. LD_(50) concentrations of needle extracts exceeded 100mug/mL, whereas the LD_(50) of bark and cone extracts was 40 and 36.4 mug/mL, respectively. We further show that the cytopro-tective properties of minhikw after glucose challenge are concentration-dependent and organ-specific. Needle extracts protected PC 12 cells from both glucotoxicity and glucose deprivation. Bark extracts had negligible activity. Cone extracts further impaired PC 12 cell glucose tolerance. This study provides the first validation of antidiabetic activity of minhikw organs at the cellular level relevant to the management of diabetic peripheral neuropathy.