パラオキシ安息香酸エステル類のヒトエストロゲン受容体αとβ結合作用

抄録

Alkyl p-hydroxybenzoates such as isobutyl p-hydroxybenzoate (PHBA-iBu), butyl p-hydroxybenzoate (PHBA-nBu), isopropyl p-hydroxybenzoate (PHBA-iPr), propyl p-hydroxybenzoate (PHBA-nPr), ethyl p-hydroxybenzoate (PHBA-Et), and methyl p-hydroxybenzoate (PHBA-Me) are widely used as preservatives, stabilizers and antiseptics for medical supplies, cosmetics, foodstuffs etc. We determined the binding affinity of alkyl p-hydroxybenzoates to human estrogen receptor α (ERα) and β (ERβ) by non-RI receptor binding assays. PHBA-iBu had a high binding affinity for ERα (IC₅₀ : 6.0×10^-6M, the relative binding affinity (RBA) : 0.267) and ERβ (IC₅₀ : 5.0×10^-6M, RBA : 0.340). These IC₅₀ values and RBA were almost the same as those of bisphenol A. The ranking of the estrogenic potency of alkyl p-hydroxybenzoates for both ERs is different; that is, PHBA-iBu>PHBA-nBu≒PHBA-iPr≒PHBA-nPr>PHBA-Et»PHBA-Me. Alkyl p-hydroxybenzoates bound with equal relative affinity to both ERα and β proteins. Alkyl p-hydroxybenzoate having a long alkyl side-chain showed a high affinity for ERα and β. These findings suggest that p-hydroxybenzoates may be endocrine disruptors.