Inhibitory and in silico molecular docking of Xeroderris stuhlmannii (Taub.) Mendonca & EP Sousa phytochemical compounds on human α-glucosidases

Ethnopharmacological relevance: Herbal 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 (alpha-glucosidases) that are linked to high blood sugar in humans. Aim of the study: This work aims to investigate whether bioactive phytochemicals of crude X. stuhlmannii (Taub.) can scavenge free radicals and inhibit alpha-glucosidases in order to reduce blood sugar in humans. Materials and methods: Here we examined the free radical scavenging potential of crude aqueous, ethyl acetate and methanolic extracts of X. stuhlmannii (Taub.) using the diphenyl-2-picrylhydrazyl assay in vitro. Furthermore, we carried out in vitro inhibition of alpha-glucosidases (alpha-amylase and alpha-glucosidase) by the crude extracts using chromogenic 3,5-dinitrosalicylic acid and p-nitrophenyl-alpha-D-glucopyranoside substrates. We also used molecular docking approaches (Autodock Vina) to screen for bioactive phytochemical compounds targeting the digestive enzymes. Results: Our results showed that phytochemicals in X. stuhlmannii (Taub.) aqueous, ethyl acetate and methanolic extracts scavenged free radicals with IC50 values ranging from 0.002 to 0.013 mu g/mL. Furthermore, crude aqueous, ethyl acetate and methanolic extracts significantly inhibited alpha-amylase and alpha-glucosidase with IC50 values of 10.5-29.5 mu g/mL (versus 54.1 +/- 0.7 mu g/mL for acarbose) and 8.8-49.5 mu g/mL (versus 161.4 +/- 1.8 mu g/ mL for acarbose), respectively. In silico molecular docking findings and pharmacokinetic predictions showed that myricetin is likely a novel plant-derived alpha-glucosidase inhibitor. Conclusion: Collectively, our findings suggest pharmacological targeting of digestive enzymes by X. stuhlmannii (Taub.) crude extracts may reduce blood sugar in humans with T2DM via inhibition of alpha-glucosidases.

Automated summary

This study aimed to investigate the ability of bioactive phytochemicals from X. stuhlmannii (Taub.) to scavenge free radicals and inhibit alpha-glucosidases in order to reduce blood sugar. The results showed that the extracts of X. stuhlmannii (Taub.) had the potential to scavenge free radicals and inhibit alpha-glucosidases, suggesting their use as a potential treatment for type 2 diabetes.