Simple spectrophotometric method for the assessment of aspirin esterase activity

Aspirin, either in combination or alone, is possibly one of the most prescribed medications worldwide. Aspirin hydrolysis is based on enzyme systems found in the liver, intestine, and serum. This work explained and demonstrated the repeatability, accuracy, and precision of a simple spectrophotometric method for assessing aspirin esterase (ASE) activity. In the present assay, ASE activity was determined by incubating enzyme samples with Tris buffer (pH 7.6) containing appropriate quantities of acetylsalicylic acid. At the end of the incubation time, the enzymatic reaction was stopped using zinc sulfate. Finally, the supernatant of the enzymatic reaction was treated with ferric ammonium sulfate (NH 4 Fe [SO 4 ] 2 ·12H 2 O). The linkage of the generated salicylic acid to ferric ions yielded a violet-colored ferrisalicylate complex with a wavelength of 540 nm. The Box–Behnken design was utilized to optimize the formation of the violet-colored ferrisalicylate complex. The method’s accuracy was determined using response surface methodology. Bland–Altman plots for ASE activity in matched biological samples were used to validate the new fluorescence protocol. The method proposed in this work does not require hazardous materials, such as mercuric chloride, or high concentrations of strong acids to terminate the ASE reaction. The correlation coefficient between the present and previous procedures was 0.99. This result suggested that the new procedure is very accurate and comparable with previous procedures. Graphical abstract