-Glucosidase and -amylase inhibitory effect and antioxidant activity of ten plant extracts traditionally used in Iran for diabetes

Abstract

In the present study various extracts of ten medicinal plants, collected in Iran, were examined for α-glucosidase and α-amylase inhibition using an in vitro model. Also total phenol content and antioxidant activity of the extracts were investigated. Various extracts of the plants (Cinnamomum zeylanicum, Crataegus oxyacantha, Hibiscus sabdariffa, Morus alba, Portulaca oleracea, Rubus fruticosus, Syzygium aromaticum, Teucrium polium,Trigonella foenum-graecum, and Vaccinium arctostaphylos) were prepared using n-hexane, dichloromethane, chloroform, ethyl acetate and methanol. Methanol, dichloromethane and n-hexane extracts of S. aromaticum exerted high in vitro inhibitory potential against α-glucosidase and α-amylase with IC50 ranging from 0.3 to 1.1 and 36.2 to 41.9 µg/ml, respectively. The mentioned extracts possessed the highest total phenolic contents (139.8, 119.6 and 136.1 mg GAE/g of extract). The antioxidant activities of the extracts, measured in terms of IC50 values were 2.2, 3.9 and 0.7 µg/ml, respectively. C. zeylanicum was another traditionally used medicinal plant, which its extracts exhibited high hypoglycaemic effect by inhibition of α-glucosidase and α-amylase (IC50 ranged from 0.5 to 8.7 and 37.1 to 52.5 µg/ml, respectively). The obtained results support the traditionally use of a number of the analyzed species.   Key words: α-Glucosidase, α-amylase, enzyme inhibition, diabetes, antioxidant activity.