Identification of Plant Extracts with Potential Antidiabetic Properties: Effect on Human Peroxisome Proliferator-activated Receptor (PPAR), Adipocyte Differentiation and Insulin-stimulated Glucose Uptake

Thiazolidinediones (TZDs) are insulin sensitizing drugs used to treat type 2 diabetes. The primary target of the TZDs is the peroxisome proliferator-activated receptor (PPAR) gamma, a key regulator of adipogenesis and glucose homeostasis. Currently prescribed TZDs are full PPAR gamma agonists, and their use is associated with several side effects. Partial PPAR gamma agonists appear to be associated with fewer side effects but may still confer the desired insulin sensitizing action. Extracts from common medicinal/food plants were tested in a screening platform comprising a series of bioassays, including tests for PPAR gamma, alpha and delta transactivation, adipocyte differentiation and insulin-stimulated glucose uptake, allowing identification of plants containing potentially interesting PPAR agonists. Twenty-two plant extracts out of 133 were found to increase insulin-stimulated, glucose uptake and 18 extracts were found to activate PPAR gamma, 3 to activate PPAR alpha and gamma, 6 to activate PPAR delta and gamma, and 9 to activate PPAR gamma, alpha and delta. Among the 24 different plant species tested in the platform, 50% were shown to contain compounds capable of activating PPAR gamma and stimulating insulin-dependent glucose uptake with no or little effect on adipocyte differentiation warranting further studies and characterization. Copyright (c) 2009 John Wiley & Sons, Ltd.