OA02.11. Alpha–amylase inhibitory property and antioxidant potential of Saraca indica and Polyalthia longifolia bark extracts

PURPOSE: The present study was designed to study the alphaamylase inhibitory property and antioxidant potential of the various solvent extracts of the bark of two medicinal plants Saraca indica and Polyalthia longifolia. METHOD: The yield percentage of aqueous, ethanol, ethyl acetate, hexane and chloroform extracts of Saraca indica and Polyalthia longifolia bark were assessed by extracting 5 g of the dried plant material in 25 ml of the respective solvent in a shaker at 40 degree celsius for 48 hours. Filtered and evaporated the solvents at room temperature. Aqueous extract was subjected to lyophilization. The residues were weighed to calculate the yield. Total antioxidant potential of the extracts were assessed by FRAP assay and compared with standard ascorbic acid. Inhibition of in vitro lipid peroxidation of the potent extract was studied using linolenic acid micelles as model system. Alphaamylase inhibitory property of the extracts was studied by the method given by Bernfield (1995) and compared with that of the standard inhibitor acarbose. Also the type of inhibition of the potent extracts was studied by Dixon plot. RESULT: The results revealed that the yield percentage was highest for ethanolic extracts of Saraca indica and Polyalthia longifolia bark. Among all the tested extracts the ethanolic extract of both the barks found to possess highest antioxidant potential and alpha amylase inhibitory activity followed by the aqueous and ethylacetate extracts. Hexane and chloroform extracts possessed lowest antioxidant and amylase inhibition potential. The ethanolic extracts presented good inhibition of in vitro lipid peroxidation. The type of inhibition of amylase showed by the ethanolic extracts was found to be competitive. CONCLUSION: To conclude, the ethanolic extracts of Saraca indica and Polyalthia longifolia bark were found to possess good antioxidant potential and also showed efficient inhibition of the enzyme alphaamylase.