In Vitro α-Amylase and α-Glucosidase Inhibitory and Antioxidant Activities of the Crude Extract and Solvent Fractions of Hagenia abyssinica Leaves

BACKGROUND: The leaves of Hagenia abyssinica have been used in the management of diabetes mellitus in Ethiopian folk medicine. Thus, this study is aimed at investigating the in vitro α-amylase and α-glucosidase inhibitory and antioxidant activities of the crude extract and solvent fractions of H. abyssinica leaves. METHODS: The in vitro α-amylase and α-glucosidase inhibitory and antioxidant activities of the plant extract were assessed using 3,5-dinitrosalicylic acid (DNSA), p-nitro-phenyl-a-D glucopyranoside (p-NPG), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays, respectively. Each value of percent inhibition of α-amylase, α-glucosidase, and DPPH scavenging effect was presented as means ± SEM (n = 3). RESULTS: The α-amylase inhibitory activity of the crude extract and solvent fractions was found to be concentration-dependent. The strongest activity was exhibited by the crude extract at the highest concentration with a percentage inhibition of 74.52% (IC(50), 14.52 μg/ml) followed by water fraction 68.24% (IC(50), 16.31 μg/ml), ethyl acetate fraction 61.57% (IC(50), 18.73 μg/ml), and chloroform fraction 56.87% (IC(50), 21.57 μg/ml) of H. abyssinica leaves. In the α-glucosidase inhibition assay, the maximum activity was exhibited by the aqueous fraction 62.54% (IC(50), 11.67 μg/ml) followed by ethyl acetate fraction 54.97% (IC(50), 15.89 μg/ml), crude extract 46.79% (IC(50), >16.5 μg/ml), and chloroform fraction 36.44% (IC(50), >16.5 μg/ml). In the antioxidant assay, the crude extract exhibited the highest antioxidant activity 86.36% (IC(50), 10.25 μg/ml) followed by water fraction 78.59% (IC(50), 13.86 μg/ml), ethyl acetate fraction 71.58% (IC(50), 16.34 μg/ml), and chloroform fraction 63.65% (IC(50), 18.83 μg/ml). CONCLUSION: This study has revealed that H. abyssinica leaves possess noticeable in vitro α-amylase and α-glucosidase inhibitory and antioxidant activities.