Inhibition of alpha-amylase and alpha-glucosidase by Acanthus montanus Leaf Extracts

Aim: The aim of this study was to determine the in-vitro anti-diabetic potentials of Acanthus montanus. This was done by assessing the inhibitory effect of both methanol and ethylacetate extracts of the plant on the activities of alpha-amylase and alpha-glucosidase. Study Design: The design included extraction of A. montanus leaves with methanol and ethanol and subsequent evaluation of the extracts for possible hypoglycemic effect. Place and Duration of Study: The leaves of A. montanus were obtained from Badagry Area of Lagos, Nigeria in December 2012. The plant was identified and authenticated by Dr. S. O. Shosanya of the Forestry Research Institute of Nigeria (FRIN), Ibadan, Nigeria. Methodology: The powdered leaves were extracted with ethylacetate and methanol separately for 24 h. The resulting infusions were decanted, filtered and evaporated in a rotary evaporator. Dried extracts were weighed and dissolved in dimethylsulphoxide (DMSO) to yield a stock solution from which lower concentrations were prepared. The inhibitory actions of both extracts against a amylase and a-glucosidase were determined established procedures. Results: The results showed that of the two extracts, methanol showed more inhibitory action than ethanol against both alpha-amylase and alpha-glucosidase. Lineweaver-Burk plot also depicted that the methanol extract inhibited both alpha-amylase and a-glucosidase in a non-competitive and competitive manner respectively. Conclusion: It can be concluded that the hypoglycemic effect of extracts of A. montanus may be as a result of the inhibition of these enzymes (a -amylase and a-glucosidase). This observation may be elicited by the presence of some phytochemicals present in the extracts.