Antioxidant property of Eucalyptus globulus Labill. Extracts and inhibitory activities on carbohydrate metabolizing enzymes related to type-2 diabetes

Abstract This research evaluated the antioxidant property and carbohydrate metabolizing enzyme inhibitory activity of Eucalyptus globulus Labill leaf extracts. Ethanol extracts of the prior hexane-defatted (DEE) and the non-defatted (NEE) leaf samples of the plant were prepared and screened for constituent phytochemicals by HPLC-DAD. The extracts were tested for antioxidant activity, α-amylase and α-glucosidase inhibitory activities and molecular docking with selected protein targets were carried out. The two extracts showed notable antioxidant property. Lipid peroxidation inhibitory activities of DEE, NEE and ascorbic acid were 28.4 ± 1.1 μg/ml, 33.3 ± 1.1 μg/ml, and 34.5 ± 1.2 μg/ml, respectively, in terms of IC50. The extracts also demonstrated appreciable inhibition of the carbohydrate metabolizing enzymes when compared to acarbose. IC50 values for α-amylase inhibition were 23.6 ± 1.2 μg/ml, 14.8 ± 1.2 μg/ml and 5.2 ± 1.3 μg/ml for DEE, NEE and acarbose, respectively (p