Inhibitory effects of the Food Azo Dyes on Pig Liver Carboxylesterase Activity

The paper reports the inhibition kinetics of pig liver carboxylesterase (CE) by two food azo dyes, tartrazine (E 102) and green dye (E102-E132), using ethyl butyrate as substrate. Optimum pH and temperature for pig liver CE were found to be 8.0 and 45°C. The kinetics of CE-catalyzed hydrolysis of ethyl butyrate followed the Haldane model with an optimum substrate concentration of 30 mM. Km and Vmax values were found to be 9.44 mM and 504.62 μM/min, respectively. Pig liver CE was significantly inhibited by tartrazine and green dye with IC50 values of 0.68 mM and 1.37 mM, respectively. The kinetic analyses showed that the inhibition of CE activity by the tartrazine and green dye was uncompetitive type with KI values of 0.46 mM and 0.62 mM, respectively. From the experimental results, it was found that tartrazine is a more effective inhibitor due to lower KI and IC50 values.