In order to explore the possible role of sulfation in the inactivation of environmental estrogens at gastrointestinal sites and their subsequent removal, we investigated the effects of phenolic environmental estrogens on sulfotransferase (ST) activity. The mouse intestine and a human colon carcinoma cell line, Caco-2, were studied. ST enzymes were found to have a high affinity for diethylstilbestrol (DES) and bisphenol A (BPA), whereas phenol ST (PST) activity was strongly inhibited by nonylphenol and genistein in both mice and humans. Kinetic analysis showed that this inhibition was competitive. These observations suggest that nonylphenol and genistein compounds might inhibit PST activity in the human intestine and that they might escape detoxification by sulfation.
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