Alpha-amylase and alpha-glucosidase inhibitory property and antioxidant potential of Polyalthia longifolia bark extracts
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Date
2012
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Abstract
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia and it is one of the free
radical mediated ailments. Among the various anti-diabetic therapeutic approaches one major strategy is
reducing gastrointestinal absorption of glucose by inhibition of carbohydrate metabolizing enzymes
alpha-amylase and alpha-glucosidase In the present study the aqueous extracts of Polyalthia longifolia
bark has been assessed for the inhibition of alpha-amylase and alpha-glucosidase and total antioxidant
potential (FRAP assay). In vitro antioxidant activity of the ethanol extract (polar solvent) and hexane
extract (non-polar solvent) has been assessed using various antioxidant model systems, viz DPPH, ABTS,
NO, OH, SO and inhibition of in vitro lipid peroxidation. The aqueous extract of the bark exhibits highest
alpha-amylase and alpha-glucosidase inhibition. Ethanol extract of Polyalthia longifolia is found to
possess highest DPPH, ABTS, nitric oxide, hydroxyl, superoxide scavenging activity at lower concentration
compared to the hexane extract. Also the ethanolic extract of Polyalthia longifolia is found to be good
inhibitor of in vitro lipid peroxidation. Saturation in the enzyme inhibition and free radical scavenging
activity has been attained in a concentration dependent manner. This study indicates significant alphaamylase
and alpha-glucosidase inhibition, free radical scavenging potential and lipid peroxidation
inhibition of Polyalthia longifolia bark which can be exploited for the treatment of various free radical
mediated diseases like diabetes mellitus. Studies are being done on the various solvent extracts of the
bark for enzyme inhibition to isolate the active compounds with potent inhibition for alpha-amylase,
alpha-glucosidase and antioxidant potential.