Evaluation of α-Glucosidase Inhibitory Assay using Different Sub-classes of Flavonoids

Main Article Content

Natnicha Promyos
Piya Temviriyanukul
Uthaiwan Suttisansanee*


Diabetes mellitus is one of the metabolic disorders that cause high blood glucose levels with deficiency of released insulin from β cells in pancreas. Alternative medicinal treatment is to control blood glucose level through inhibition of α-glucosidase, leading to delayed starch degradation and slower rate of raising blood glucose level. However, the methods for α-glucosidase inhibitory assay were varied, leading to confusion on reliability to evaluate α-glucosidase inhibition of particular bioactive compounds. Interestingly, pervious researchers had reported anti-diabetic potential of flavonoids, which provided great inhibitory activities among phenolics. Therefore, the aim of this research was to evaluate different methodologies of α-glucosidase inhibitory assays using five selected flavonoids (epigallocathchin gallate (EGCG), genistein, myricetin, luteolin and naringenin) as the models. The results indicated that enzyme kinetic assay exhibited the advantages over other fundamental assay methods, including higher range of measurement and reliability of the enzyme reaction. All investigated flavonoids exhibited the half maximal inhibitory concentration (IC50) in the range of 1-81 µM, which were corresponded to the previous literature. EGCG was the strongest inhibitor against α-glucosidase, while naringenin was the weakest. The outcome of our study might be useful for drug design and functional cure of diabetic patients in the future.

Keywords: diabetes, α-glucosidase, flavonoids, enzyme inhibition

*Corresponding author: Tel.: 0-2800-2380 ext. 422; Fax: 0-2441-9344

 E-mail: uthaiwan.sut@mahidol.ac.th


Download data is not yet available.

Article Details

Research Articles


[1] Telagari, M. and Hullatti K., 2015. In-vitro α-amylase and α-glucosidase inhibitory activity of Adiantum caudatum Linn. and Celosia argentea Linn. extracts and fractions. Indian Journal of Pharmacology, 47(4), 425-429.
[2] Kim, J.S., Kwon, C.S. and Son, K.H., 2000. Inhibition of alpha-glucosidase and amylase by luteolin, a flavonoid. Bioscience, Biotechnology, and Biochemistry, 64(11), 2458-2461.
[3] Yin, Z., Zhang, W., Feng, F., Zhang, Y. and Kang W., 2014. α-Glucosidase inhibitors isolated from medicinal plants. Food Science and Human Wellness, 3(3-4), 136-174.
[4] Perez, G.R.M., Zavala, S.M.A., Perez, G.S. and Perez, G.C., 1998. Antidiabetic effect of compounds isolated from plants. Phytomedicine, 5(1), 55-75.
[5] Taylor, R.N., Fulford, K.M. and Huong, A.Y., 1978. Comparison of kinetic and end-point diffusion methods for quantitating human serum immunoglobulins. Journal of Clinical Microbiology, 8(1), 23-27.
[6] Srisawasdi, P., Kroll, M.H. and Lolekha, P.H., 2007. Advantages and disadvantages of serum cholesterol determination by the kinetic vs the end point method. American Journal of Clinical Pathology, 127(6), 906-918.
[7] Wu, L. and Zhang, Z.Y., 1996. Probing the function of Asp128 in the low molecular weight protein,-tyrosine phosphatase-catalyzed reaction. A pre-steady-state and steady-state kinetic investigation. Biochemistry, 35(17), 5426-5434.
[8] Bisswanger, H., 2014. Enzyme assays. Perspectives in Science, 1(1–6), 41-55.
[9] Vicario, L.R., Gómez Casati, D.F. and Iglesias, A.A., 1997. A simple laboratory experiment for the teaching of the assay and kinetic characterization of enzymes. Biochemical Education, 25(2), 106-109.
[10] Hadrich, F., Bouallagui, Z., Junkyu, H. and Sayadi, S., 2015. The α-glucosidase and α-amylase enzyme inhibitory of hydroxytyrosol and oleuropein. Journal of Oleo Science, 64(8), 835-843.
[11] Rubilar, M., Jara, C., Poo, Y., Acevedo, F., Gutierrez, C., Sineiro, J. and Shene, C., 2011. Extracts of Maqui (Aristotelia chilensis) and Murta (Ugni molinae Turcz.): Sources of antioxidant compounds and α-glucosidase/α-amylase inhibitors. Journal of Agricultural and Food Chemistry, 59(5), 1630-1637.
[12] Son, H.U. and Lee, S.H., 2013. Comparison of α-glucosidase inhibition by Cudrania tricuspidata according to harvesting time. Biomedical Reports, 1(4), 624-628.
[13] Tierno, M.B., Johnston, P.A., Foster, C., Skoko, J.J, Shinde, S.N. and Shun, T.Y., 2007. Development and optimization of high-throughput in vitro protein phosphatase screening assays. Nat Protocols, 2(5), 1134-1144.
[14] Patras, A., Brunton, N.P., O'Donnell, C. and Tiwari, BK., 2010. Effect of thermal processing on anthocyanin stability in foods; mechanisms and kinetics of degradation. Trends in Food Science & Technology, 21(1), 3-11.
[15] Fossen, T., Cabrita, L. and Andersen, O.M., 1998. Colour and stability of pure anthocyanins influenced by pH including the alkaline region. Food Chemistry, 63(4), 435-440.
[16] Tadera, K., Minami, Y., Takamatsu, K. and Matsuoka, T., 2006. Inhibition of alpha-glucosidase and alpha-amylase by flavonoids. Journal of Nutritional Science and Vitaminology, 52(2), 149-153.
[17] Xiao, J., Kai, G., Yamamoto, K. and Chen, X., 2013. Advance in dietary polyphenols as α-glucosidases inhibitors: A review on structure-activity relationship aspect. Critical Reviews in Food Science and Nutrition, 53(8), 818-836.
[18] Gao, J., Xu, P., Wang, Y. and Wang, Y., 2013. Combined effects of green tea extracts, green tea polyphenols or epigallocatechin gallate with acarbose on inhibition against α-amylase and α-glucosidase in Vitro. Molecule, 18(9), 11614-11623.
[19] Yilmazer-Musa, M., Griffith, A.M., Michels, A.J., Schneider, E. and Frei, B., 2012. Grape seed and tea extracts and catechin 3-gallates are potent inhibitors of α-amylase and α-glucosidase activity. Journal of Agricultural and Food Chemistry, 60(36), 8924-8929.
[20] Yilmazer-Musa, M., Griffith, A.M., Mic els, A.J., Schneider, E. and Frei, B., 2012. Inhibition of α-amylase and α-glucosidase activity by tea and grape seed extracts and their constituent catechins. Journal of Agricultural and Food Chemistry, 60(36), 8924-8929.
[21] Liu, C.Y., Huang, C.J., Huang, L.H., Chen, I.J., Chiu, J.P. and Hsu, C.H., 2014. Effects of green tea extract on insulin resistance and glucagon-like peptide 1 in patients with type 2 diabetes and lipid abnormalities: A randomized, double-blinded, and placebo-controlled trial. PLoS ONE, 9(3), e91163.
[22] Liu, K., Zhou, R., Wang, B., Chen, K., Shi, L.Y. and Zhu, J.D., 2013. Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials. The American Journal of Clinical Nutrition, 98(2), 340-348.
[23] Alam, M.A., Subhan, N., Rahman, M.M., Uddin, S.J., Reza, H.M. and Sarker, S.D., 2014. Effect of citrus flavonoids, naringin and naringenin, on metabolic syndrome and their mechanisms of action. Advances in Nutrition, 5(4), 404-417.
[24] Garza, A.L., Etxeberria, U., San Román, B., Barrenetxe, J. and Martínez, J.A., 2013. Helichrysump and Grapefruit Extracts Inhibit Carbohydrate Digestion and Absorption, Improving Postprandial glucose levels and hyperinsulinemia in rats. Journal of Agricultural and Food Chemistry, 61(49), 12012-12019.
[25] Zygmunt, K., Faubert, B., MacNeil, J. and Tsiani, E., 2010. Naringenin, a citrus flavonoid, increases muscle cell glucose uptake via AMPK. Biochemical and Biophysical Research Communications, 398(2), 178-183.