Introduction: In Iraq, medicinal plants have not received much attention in terms of quantifying their antioxidant and other biological/pharmacological activities so the objective of the present study was to assess the antioxidant activity of selected medicinal plants grown in Iraq and relate it to their total phenolic contents and their inhibitory effect on carbohydrate-hydrolyzing enzymes. Methods: Antioxidant activity was assessed by ferric reducing antioxidant power (FRAP) and oxygen reactive absorbance capacity (ORAC) methods. The possible inhibitory effect on carbohydrate-hydrolyzing enzymes was also investigated. Results: In almost all the parameters used, the aqueous extracts from Mentha piperita showed significantly higher (P < 0.0001) activities than other plants. Antioxidant activity was significantly correlated (P < 0.0001) with TPC among all the plants studied. In addition, the plant extracts showed strong inhibition against pancreatic α-amylase and yeast α-glucosidase. Only Cyperus rotundus and Prosopis farcta have been used traditionally for the treatment of diabetes in Iraq. Conclusions:In conclusion, to the best of our knowledge, the remaining four plants and herbs (Glycyrrhiza glabra, H. Sabdariffa, Matricaria chamomilla, and M. piperita) have no records in the literature for their antidiabetic effects. Consequently, this study identifies these four medicinal plants as novel inhibitors of key enzymes (α-glucosidase and α-amylase) relevant for type 2 diabetes that showed even higher activity than the currently being used for the treatment of diabetes by the Iraqi herbalists.

Water-soluble