Plant phenols as in vitro inhibitors of glutathione S-transferase(s) |
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Authors: | M Das D R Bickers H Mukhtar |
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Affiliation: | 1. Department of Dermatology, Case Western Reserve University Cleveland, Ohio 44106 USA;2. Veterans Administration Medical Center Cleveland, Ohio 44106 USA |
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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. |
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Keywords: | GSH glutathione CDNB 1-chloro-2,4-dinitrobenzene GSH-transferase glutathione S-transferase PAH polycyclic aromatic hydrocarbons |
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