ASSESSMENT OF α-AMYLASE INHIBITION ACTIVITY BY AN OPTIMIZED AND VALIDATED IN VITRO MICROSCALE METHOD

Metabolic disorders, including hyperglycemia, characterize type-2 diabetes. One of the treatment methods used for postprandial hyperglycemia includes using potential therapeutic agents to inhibit α-amylase activity. This study utilized fractional design and the simplex method to optimize in vitro microscale assay inhibition conditions using Miller’s reaction. In addition, the effect of substrate concentration on enzyme activity was analyzed. Enzyme concentration of 0.15 U mL-1 and pre- and post-incubation times of 7.2 and 5.5 min, respectively, in water bath (15.6 min) equipment, were set up for optimized condition for the enzyme activity. Analytical validation was performed based on different international guidelines. Km was found to be 0.38 mg mL-1. Linearity was obtained at the acarbose concentration of 1.5 µg mL-1 and 5 µg mL-1. The IC50 for the positive control was found to be 0.6 µg mL-1. The relative standard deviation and Z value were found to be <4% and >0.93, respectively. Additionally, the optimized assay was applied to extracts from five different plants. Two plant extracts (Zanthoxylum fagara and Chrysactinia mexicana) inhibited α-amylase activity. The optimized and validated method was accurate, precise, and linear.