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The syntheses and characterization of bisphenol A mono- and di-beta-D-glucopyranosides were undertaken to confirm that these compounds are major plant metabolities of bisphenol A (BPA) and to allow an assessment of their estrogenicity. Synthesis involved the glucosidation of unprotected BPA with glucose penta-acetate with phosphorus oxychloride as catalyst. The estrogenic activity of BPA and its mono- and di-beta-D-glucopyranosides were measured with an enzyme-linked immunosorbent assay (ELISA)-based estrogen receptor competitive binding assay and with a yeast two-hybrid assay adapted to a chemiluminescent reporter gene (for beta-galactosidase). Both methods showed that the estrogenicity of BPA was eliminated by formation of the di-glucoside, but whereas the ELISA-based method indicated that reduced activity remained in the monoglucoside, the yeast two-hybrid method showed the monoglucoside to be inactive. Presumably these results reflect the more complex interactions of test compound and cellular components required to demonstrate estrogenicity in the yeast two-hybrid assay. As these processes parallel those in mammalian cells, the yeast two-hybrid method is likely to be the more realistic assay. The uptake and metabolism of BPA by plants offers the possibility of phytoremediation of contaminated water, but also provides an additional route for the compound to enter the human food chain.

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ABSTRACT. Isobutyl-paraben (IBP), a widely used preservative in a variety of foods, shows high comparative binding affinity to estrogen receptors. Here, we examined the effects of maternal exposure of rats to IBP on plasma hormone concentrations and organ weights in dams, ratio of male pups, anogenital distance, organ weights and plasma hormone concentrations in offspring, puberty, estrous cycle and response of organ weight and plasma hormone concentrations to estrogen in adult female offspring, and reproductive and adrenal function in adult male offspring, all of which are under developmental estrogen regulation, to clarify the estrogenic effects of IBP during gestation and lactation on the endocrine systems of dams and offspring. While maternal exposure of IBP decreased the plasma corticosterone concentration and increased the uterus weight in dams and increased uterine sensitivity to estrogen in adult female offspring, the other indices examined were largely unaffected by the present treatment. Even though these results indicate little sign of endocrine disrupting effects for IBP, the existence of activity may be a matter of concern due to the possible impact on the health of future generations.KEY WORDS: corticosterone, estrogen, isobutyl-paraben, maternal, rat.J. Vet. Med. Sci. 71(8): 1027-1033, 2009 Parabens have been the most widely used preservatives for more than 50 years in a variety of food, cosmetic and pharmaceutical products [2,4,23] due to their broad spectrum of activity, inertness, low cost and long history of safe use. They have been detected in human urine collected from a demographically diverse group of male and female adults with no known exposure to parabens, suggesting that the majority of people have already been exposed to them [32]. Several studies indicate that exposure to parabens modulates the endocrine system and thus may have harmful consequences on animal and human health [4,7,13,22,28] because of the estrogenic activities of these compounds in vitro and in vivo [7,24], and anti-estrogenic activity in human skin has been shown [22]. In addition, exposure to parabens during adult periods has been implicated in reduction of the male reproductive system in rodents [7,19,20,21], whereas a recent study could not confirm these effects [10]. On the other hand, investigation of the effects of exposure to parabens during gestation to lactation is important because exposure to estrogenic chemicals during development could be a contributory factor in the rising incidence of endocrine dysfunction of offspring later in life [3,5,14,16,26]. But, the effects of early exposure to parabens are not consistent in previous reports [6,13,27,28]. Furthermore, the effects of early exposure to parabens on the endocrine system in adult female offspring, except for vaginal opening and intact uterus weight [13], are unclear. Therefore, we examined the effects of maternal exposure to parabens on several aspects of the endocrine system in male and female offspring, especially the effects on plasma hormone co...