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Purpose: To investigate the inhibitory effect of S. alata leaf extracts on α-amylase and α-glucosidase, and its potential for reducing postprandial blood glucose level of rats.
Methods: The α-amylase and α-glucosidase inhibitory potentials of acetone, ethylacetate and hexane extracts of S. alata were investigated by reacting different concentrations (0.63 – 10.0 mg/mL) of the extracts with the enzymes and substrates while the mode(s) of inhibition of both enzymes were determined using the Lineweaver-Burk plot. The effect of oral administration of the hexane extract (with lowest IC50 for α-glucosidase) of the plant in sucrose-induced hyperglycemic rats was also determined by evaluating fasting blood glucose levels.
Results: The acetone extract of S. alata displayed the highest inhibitory activity against α-amylase (IC50 = 6.41 mg/mL) while hexane extract exhibited highest inhibitory effect on α-glucosidase (IC50 = 0.85 mg/mL). Both acetone and hexane extracts inhibited α-amylase and α-glucosidase in a competitive and uncompetitive manner respectively. The hexane extract of S. alata also caused significant reduction (p < 0.05) in the postprandial blood glucose level of sucrose-loaded rats within two hours.
Conclusions: It can be suggested that one of the mechanisms of anti-diabetic action of S. alata leaf is the inhibition of intestinal α-glucosidase.
Keywords: Senna alata, Diabetes, Postprandial hyperglycemia, Phytochemicals, α-glucosidase, α- amylase