[Effect of polar and non-polar Aloe vera L. leaf extracts on alpha-amylase and alpha-glucosidases inhibitory activity in vitro]

ABSTRACT

Intestinal alpha-glucosidase and alpha-amylase are two carbohydrate-hydrolysing enzymes that play a key role in conversion of disaccharide to glucose. Inhibition of these two enzymes provides a therapeutic option for treatment of postprandial hyperglycemia in diabetic patients. The aim of the current study was to evaluate the inhibitory effects of different Aloe vera L. extracts against alpha -amylase and alpha -glucosidase in vitro. Aloevera L. leaf was collected from the Institute of Medicinal Plants farm and several extracts were prepared by n-hexane, chloroform, ethyl acetate and methanol solvents. The inhibitory effects of the extracts were tested on alpha -amylase and alpha -glucosidase enzyme separately. In this experiment, the minimum concentration of the extract required for 50% inhibition of enzyme activity [IC[50]], was obtained and compared with acarbose as a positive control. The results showed that total methanol extract of Aloe vera L. leaf had significantly [p<0.001] higher alpha-amylase inhibitory [28.2 +/- 1.3 microg/ml] effect than other solvent fractions but lower than acarbose [25.4 +/- 1.9 microg/ml]. Furthermore total methanol extract and solvent fractions of methanol and ethyl acetate of Aloe vera L. leaf had significantly [p<0.001] higher inhibitory effect on alpha -glucosidase enzyme activity [2.3 +/- 0.1 microg/ml, 2.7 +/- 0.1 microg/ml, 3.4 +/- 0.1 microg/ml, respectively] than other solvent fractions as well as compared with acarbose [5.8 +/- 0.6 microg/ml]. Total methanol extracts of Aloe vera L leaf has strong alpha -amylase and alpha -glucosidase inhibitory activity than chloroform, n-hexane, chloroform, ethyl acetate and methanol solvent fraction