Metabolism of bisphenol A in the rat syncytiotrophoblast cell line, TR-TBT 18d-1

TR-TBT 18d-1 is a syncytiotrophoblast cell line established from placenta of the transgenic rat harboring temperature-sensitive simian virus 40 large T-antigen (Tg-rat). Previously we have reported high level expressions of drug metabolizing enzymes in the TR-TBT cells. To elucidate the ability of metabolizing xenobiotics in the TR-TBT cells, we measured the metabolism of bisphenol A (BPA) as a model compound in the TR-TBT 18d-1 cells. It was found that BPA was metabolized and secreted as a monoglucuronide conjugate in a manner proportional to the incubation time and the BPA concentration. To elucidate the possible effect of green tea consumption on the placental metabolism, we investigated the effect of green tea on the metabolism of BPA in the TR-TBT cells. Green tea inhibited the conjugation reaction of BPA at the low concentration (IC₅₀=5%), however, epigallocathechin gallate (EGCG) showed only weak inhibition, suggesting another active component existence. These results suggest that TR-TBT cells are useful for the model system of rat syncytiotrophoblasts which act as a barrier to protect fetus from harmful xenobiotics.