Evaluation of Antioxidant Potentials and α-Amylase Inhibition of Different Fractions of Labiatae Plants Extracts: As a Model of Antidiabetic Compounds Properties

In an attempt to identify herbal drugs which may become useful in the prevention of diabetes, antioxidant potentials and α-amylase inhibition by the ethanol extracts of two plants belonging to Lamiaceae family, Otostegia persica and Zataria multiflora, and their different fractions were studied. Also, inhibition of α-amylase by Salvia mirzayanii and its fractions was evaluated. All of the samples exhibited antioxidant activities, among which ethyl acetate fraction of Zataria multiflora (17.21 ± 0.17 mg GAE/g) was found to contain the highest amounts of phenols and the ethyl acetate fraction of Zataria multiflora (218 ± 2.76 mg QUE/g) had the most values of flavonoids. Ethyl acetate fraction of Zataria multiflora (IC(50) = 3.05 ± 0.51 μg/ml) was shown to have the most reducing power and the ethyl acetate fraction of Zataria multiflora (IC(50) = 32.17 ± 1.82 μg/ml) exhibited the highest DPPH radical scavenging. The ethyl acetate fraction of Otostegia persica (99.39 ± 0.94%) showed the highest α-amylase inhibitory activity which was similar to acarbose used as a standard. Mode of α-amylase inhibition of the most samples was uncompetitive except for ZMC, OPP, OPC, and SMP which presented competitive inhibition. The present findings showed that studied samples may have some compounds with antioxidant and antidiabetic effects.