Effect of Polar and Nom-polar Aloe vera L. Leaf Extracts on α-amylase and α-Glucosidases Inhibitory Activity In vitro

Intestinal α-glucosidase and α-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 α-amylase and α-glucosidase in vitro. Aloe vera 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 α-amylase and α-glucosidase enzyme separately. In this experiment، the minimum concentration of the extract required for 50% inhibition of enzyme activity (IC50)، 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 α-amylase inhibitory (28. 2 ± 1. 3 µg/ml) effect than other solvent fractions but lower than acarbose (25. 4 ± 1. 9 µg/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 α-glucosidase enzyme activity (2. 3 ± 0. 1 µg/ml، 2. 7 ± 0. 1 µg/ml، 3. 4 ± 0. 1 µg/ml، respectively) than other solvent fractions as well as compared with acarbose (5. 8 ± 0. 6 µg/ml). Total methanol extracts of Aloe vera L. leaf has strong α-amylase and α-glucosidase inhibitory activity than chloroform، n-hexane، chloroform، ethyl acetate and methanol solvent fraction.