α-Glucosidase and α-Amylase Inhibitory Activities of Nine Sri Lankan Antidiabetic Plants

Aims: α-Amylase and α-glucosidase have been recognized as therapeutic targets for reduction of postprandial hyperglycaemia in diabetes mellitus. Objective of the study was to assess the α-amylase and α-glucosidase inhibitory potential of nine Sri Lankan antidiabetic plants.

Study Design: In vitro enzyme inhibitory assays.

Place and Duration of Study: Department of Biochemistry, Faculty of Medicine, University of Peradeniya, Sri Lanka, from October 2013 to December 2014.

Methodology: Methanol extracts of nine plant parts were used. Pterocarpus marsupium latex was used without extraction. Enzyme inhibition assays were conducted in the presence and absence of plant extracts using porcine pancreatic α-amylase and α-glucosidase from Saccharomyces cerevisiae. Acarbose was used as the standard inhibitor. Percentage inhibition of the two enzymes and the IC50 values were determined.

Results: The IC50 values of Ficus racemosa stem bark and Pterocarpus marsupium latex were significantly lower (p< 0.05) than the IC50 value of Acarbose for porcine pancreatic amylase. Lowest IC50 for amylase was observed with P. marsupium. The IC50 values of Phyllanthus emblica fruit, Phyllanthus debilis whole plant, P. marsupium and F. racemosa were significantly lower (p<0.05) than Acarbose for yeast glucosidase. Musa paradisiaca yam and Tinospora cordifolia leaves showed considerable inhibitory effects on glucosidase activity. Coccinia grandis, Gymnema lactiferum, Gymnema sylvestre and Strychnos potatorum seeds did not show considerable inhibitory effects on α-amylase and α-glucosidase.

Conclusion: A significantly high (p< 0.05) in vitro α-amylase and α-glucosidase inhibitory activities were observed with the methanol extracts of F. racemosa, P. emblica, P. debilis and P. marsupium.