Comparative study of alpha amylase inhibitory activity of flavonoids of Vitex negundo Linn. and Andrographis paniculata Nees

Abstract

Background: One important therapeutic approach for the treatment of Type 2 Diabetes Mellitus is by decreasing the postprandial increase of glucose. This is possible by inhibiting certain carbohydrate hydrolyzing enzymes like alpha‑amylase. Aim: The objective of the present study was to evaluate the alpha amylase inhibitory activity of flavonoids extracts of different parts of Vitex negundo Linn and Andrographis paniculata Nees. Materials and Methods: In the present study, the percentage inhibitory effect of flavonoids isolated from different parts of Vitex negundo and Andrographis paniculata were studied with salivary alpha amylase and starch as
substrate using chromogenic DNSA method and starch iodine method for qualitative estimation. Statistical Analysis: All experiments were performed in 3 different sets with each set in triplicates. The data are expressed as mean ± SEM (standard error of the mean). Statistical difference and linear regression analysis were performed using Graph pad prism 5 statistical software. Statistical analysis was performed for ANOVA (analysis of variance) using Statistical Package for Social Sciences (SPSS) version 11.5. Values of P which were ≤0.05 were considered as significant. Results and Conclusion: The results clearly indicated that highest inhibition (62.22%) was obtained at the concentration of 1.5 mg/ml of flavonoids extracted from the leaves of A. paniculata, with an IC50 value of 0.004 mg/ml.
Except Vitex leaf flavonoids extract, all other tested flavonoids of different parts of both the plants have shown more than 50% inhibition of alpha amylase activity. Thus the results are clearly indicating that the flavonoids of V. negundo and A. paniculata might be effective in lowering post prandial hyperglycemia.
Key words: Alpha amylase inhibition, Andrographis paniculata, flavonoids, post‑prandial hyperglycemia, Vitex negundo