Abstract
Feeding of ellagic acid, one of the naturally occurring plant phenols, at varying dose levels through drinking water for eight weeks resulted in a dose-dependent significant increase in the hepatic glutathione-S-transferase activity as well as in the hepatic and pulmonary reduced glutathione levels. However, the pulmonary glutathione-S-transferase activity was not affected. Glutathione-S-transferase inhibition curve, obtained at different concentrations of ellagic acid in the 10, 000×g hepatic supernatant using 1-chloro-2, 4-dinitrobenzene as substrate, suggests two types of isoenzymes of glutathione-S-transferase, ellagic acid-binding (isoenzymes to which ellagic acid is prone to bind) and ellagic acid-non binding (isoenzymes to which ellagic acid does not bind). I50 for ellagic acid-binding isoenzymes was found to be 35μM. Kinetic studies revealed that ellagic acid inhibited glutathione-S-transferase activity non-competitively with respect to 1-chloro-2, 4-dinitro-benzene as a substrate, with a Ki of 450μM and Ks of 322μM.
