Abstract
Biochanin A (BCA) is a dietary isoflavone present in red clover (Trifoliumn pretense) and many herbal products. BCA has been reported to have chemopreventive actions against various cancers including prostate, breast, colon cancer, and so on. Sulfotransferases are a family of phase II drug‐metabolizing enzymes, which are important for xenobiotic detoxification and regulation of biological signaling molecule biological activities. Sulfotransferase gene expressions are regulated by different hormones and xenobiotics. Improper regulation of sulfotransferases leads to improper functions of biological signaling molecules, which in turn can cause cancer or other diseases. BCA inhibits the enzyme activities of the phase I drug‐metabolizing enzymes CYP1A1 and CYP1B1 in Chinese hamster ovary cells and induces the phase II drug‐metabolizing enzymes UDP‐glucuronosyltransferases in human prostate cancer cells. BCA induction of sulfotransferases has not been studied. This investigation evaluates the in vivo regulation of sulfotransferases at protein and mRNA levels in the liver and intestine of Sprague‐Dawley rats treated with BCA (0, 2, 10, and 50 mg/kg/day) for 7 days. Our experimental results demonstrate for the first time that chronic BCA treatment can significantly induce the expression of rat sulfotransferase 1A1 (rSULT1A1, AST‐IV), sulfotransferase 2A1 (rSULT2A1, STa), and rat estrogen sulfotransferase (rSULT1E1, EST) in rat liver and intestine. Our Western blot results are in good agreement with real‐time RT‐PCR data, suggesting that BCA induction of sulfotransferases occurs at the transcriptional level. © 2010 Wiley Periodicals, Inc. J Biochem Mol Toxicol 24:102–114, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20318