In vitro inhibition of type 2 diabetes key enzymes; effect of extracts and solvent-solvent fractions of Daniellia oliveri (Rolfe) Hutch. & Dalziel

Abstract

Daniellia oliveri is a tree species belonging to the subfamily Caesalpinioideae (Leguminosae), whose young leaves are used locally to manage type 2 diabetes in Nigeria. This study aims at evaluating the inhibitory potentials of its crude ethanolic extract (Do-C) and solvent-solvent fractions (n-hexane (Do-H), diethyl ether (Do-D), and ethyl acetate (Do-E)) obtained from Do-C on α-amylase, α-glucosidase activities in-vitro and 1,1-diphenyl-2-picraylhydrazine (DPPH) radical scavenging activity using standard protocols. Our findings showed that the Do-C and its fractions had significant TFC and TPC composition. All fractions inhibited DPPH free radicals effectively, with Do-E having excellent inhibition when compared with BHT. In this study, Do-C and its solvent-solvent fractions (Do-D, Do-E, and Do-H) inhibited α-amylase and α-glucosidase in a dose-dependent pattern. However, compared to acarbose, the Do-E exhibited similar inhibitory activity against α-amylase (P≤ 0.05). Nevertheless, the Do-E (IC50 35.02 ± 1.22 μg/ml) and Do-H (IC50 31.28 ± 1.23 μg/ml) had the best inhibitory activity against α-glucosidase comparatively after acarbose (25.97 ± 0.96 μg/ml). The inhibitory potential of Do-E could be linked to its TFC and TPC. Therefore, ethyl acetate fraction obtained from the crude ethanolic extract of D. oliveri could effectively inhibit key enzymes linked to type 2 diabetes (α-amylase and α-glucosidase). Further studies recommended to isolate antidiabetic compounds present.