Antioxidant Activity and Antidiabetic Activities of Northern Thai Indigenous Edible Plant Extracts and Their Phytochemical Constituents

Abstract

Diabetes is a disease affecting health and economic system. The diabetic drugs are often reported to have side effects. So, antidiabetic activities such as alpha-amylase inhibition and alpha-glycosidase inhibition, total phenolic content (TP), total flavonoid content (TF), antioxidant activity and some phytochemical constituents of twenty-eight indigenous edible plants obtained from northern Thailand, were investigated to evaluate the potential of preventing diabetes. It was found that Caesalpinia mimosoides Lam., Azadirachta indica A . var. indica, Glochidion hirsutum, Glochidion wallichianum, Polygonum odoratum showed high amount of total phenolic content, total flavonoid content, and antioxidant activity. Those indigenous species also showed low IC50 for alpha-glucosidase inhibitory and alpha-amylase inhibitory which are lowered than that of acarbose standard. The IC50 for alpha-glucosidase inhibition negatively correlated well with TF content, TP content, and antioxidant activity. Thus, these five indigenous plants might be natural antidiabetics suitable for use as functional foods in the future.