title: Plant phenols as in vitro inhibitors of glutathione S-transferase(s).
abstract: Ellagic acid, a commonly occurring plant phenol, was shown to be a potent in vitro inhibitor of GSH-transferase(s) activity. Other plant phenols such as ferrulic acid, caffeic acid and chlorogenic acid also showed a concentration dependent inhibition of GSH-transferase(s) activity. The I50 values of ellagic acid, caffeic acid, chlorogenic acid and ferrulic acid were 8.3 X 10(-5)M, 14.0 X 10(-5)M, 20.0 X 10(-5)M and 22.0 X 10(-5)M respectively, suggesting that ellagic acid is the most potent inhibitor of all the four studied plant phenols. At 55 microM concentration of ellagic acid, a significant inhibition (35-47%) was observed on GSH-transferase activity towards CDNB, p-nitrobenzyl chloride and 1,2-epoxy-3-(p-nitrophenoxy)propane as substrates. Ellagic acid inhibited GSH-transferase(s) activity in a non-competitive manner with respect to CDNB while with respect to GSH it inhibited the enzyme activity in a competitive manner. Other phenolic compounds purpurogallin , quercetin, alizarin and monolactone also showed a concentration dependent inhibition of the enzyme activity with a I50 of 0.8 X 10(-5)M, 1.0 X 10(-5)M, 8.0 X 10(-5)M and 16.0 X 10(-5)M respectively. These inhibitors of GSH-transferase(s) activity should be useful in studying the in vitro enzyme mediated reactions of exogenous and endogenous compounds.
mesh_terms: D000818:Animals; D002109:Caffeic Acids / Q000494:pharmacology; D002264:Carboxylic Acids / Q000494:pharmacology*; D002726:Chlorogenic Acid / Q000494:pharmacology; D003373:Coumaric Acids / Q000494:pharmacology; D004137:Dinitrochlorobenzene / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004610:Ellagic Acid / Q000494:pharmacology; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors*; D008099:Liver / Q000201:enzymology*; D010944:Plants / Q000032:analysis*; D051381:Rats
chemical_list: D002109:Caffeic Acids; D002264:Carboxylic Acids; D003373:Coumaric Acids; D004137:Dinitrochlorobenzene; D004610:Ellagic Acid; D002726:Chlorogenic Acid; C004999:ferulic acid; D005982:Glutathione Transferase; C040048:caffeic acid