Inhibitory andin silicomolecular docking ofXeroderris stuhlmannii(Taub.) Mendonca & E.P. Sousa phytochemical compounds on human α-glucosidases

Abstract

ABSTRACTEthnopharmacological relevanceHerbal traditional medicine is used by millions of people in Africa for treatment of ailments such as diabetes mellitus, stomach disorders and respiratory diseases.Xeroderris stuhlmannii (Taub.) Mendonca & E.P. Sousa (X. stuhlmannii(Taub.)) is a medicinal plant used traditionally in Zimbabwe to treat type 2 diabetes mellitus (T2DM) and its complications. However, there is no scientific evidence to support its inhibitory effect against digestive enzymes (α-glucosidases) that are linked to high blood sugar in humans.Aim of the study: This work aims to investigate whether bioactive phytochemicals of crudeX. stuhlmannii(Taub.) can scavenge free radicals and inhibit α-glucosidases in order to reduce blood sugar in humans.Materials and methodsHere we examined the free radical scavenging potential of crude aqueous, ethyl acetate and methanolic extracts ofX. stuhlmannii(Taub.) using the diphenyl-2-picrylhydrazyl assayin vitro. Furthermore, we carried outin vitroinhibition of α-glucosidases (α-amylase and α-glucosidase) by the crude extracts using chromogenic 3,5-dinitrosalicylic acid and p-nitrophenyl-α-D-glucopyranoside substrates. We also used molecular docking approaches (Autodock Vina) to screen for bioactive phytochemical compounds targeting the digestive enzymes.ResultsOur results showed that phytochemicals inX. stuhlmannii(Taub.) aqueous, ethyl acetate and methanolic extracts scavenged free radicals with IC50values ranging from 0.002-0.013 μg/mL. Furthermore, crude aqueous, ethyl acetate and methanolic extracts significantly inhibited α-amylase and α-glucosidase with IC50values of 10.5-29.5 μg/mL (versus 54.1±0.7 μg/mL for acarbose) and 8.8-49.5 μg/mL (versus 161.4±1.8 μg/mL for acarbose), respectively.In silicomolecular docking findings and pharmacokinetic predictions showed that myricetin is likely a novel plant-derived α-glucosidase inhibitor.ConclusionCollectively, our findings suggest pharmacological targeting of digestive enzymes byX. stuhlmannii(Taub.) crude extracts may reduce blood sugar in humans with T2DM via inhibition of α-glucosidases.