Antiandrogenic properties of parabens and other phenolic containing small molecules in personal care products

Abstract

To identify the androgenic potency of commonly used antimicrobials, an in vitro androgen receptor-mediated transcriptional activity assay was employed to evaluate the androgenic/antiandrogenic activity of parabens and selected other antimicrobials containing a phenolic moiety. This cell-based assay utilizes a stably transfected cell line that lacks critical steroid metabolizing enzymes and is formatted in a 96-well format. At a concentration of 10 microM, methyl-, propyl- and butyl-4-hydroxybenzoate (parabens) inhibited testosterone (T)-induced transcriptional activity by 40%, 33% and 19%, respectively (P<0.05), while 4-hydroxybenzoic acid, the major metabolite of parabens, had no effect on T-induced transcriptional activity. Triclosan inhibited transcriptional activity induced by T by more than 92% at a concentration of 10 microM, and 38.8% at a concentration of 1.0 microM (P<0.05). Thirty-four percent of T-induced transcriptional activity was inhibited by thymol at 10 microM (P<0.05). Cell proliferation and/or cytotoxicity were not observed in any of the treatments. None of the compounds appeared to be androgenic when tested individually without T. The data presented in this report demonstrate that some widely used antimicrobial compounds have antiandrogenic properties and warrant further investigation to fully understand their potential impact on human reproductive health.

Figure 1

Cell proliferation and cytotoxicity evaluation in MTT assay. No significant cytotoxicity or cell proliferation was observed for parabens, triclosan or thymol either tested alone or in combination with T. There was no significant cell proliferation or cytotoxicity observed in the T treated cells when compared to the vehicle control. 1: control with and without T; 2: p-hydroxybenzoic acid; 3: butyl-4-hydroxybenzoate; 4: methyl-4-hydroxybenzoate; 5: propyl-4-hydroxybenzoate; 6: triclosan and 7: thymol.

Figure 2

The effect of strong antiandrogens on AR-mediated transcriptional activity induced by 1.0 nM T. Open circle: vinclozolin alone; closed circle: vinclozolin in the presence of 1.0 nM T. Open square: flutamide alone; solid square: flutamide in the presence of 1.0 nM T.

Figure 3

The effect of parabens on AR-mediated transcriptional activity induced by 0.125 nM T. Open square: p-hydroxybenzoic acid alone; closed square: p-hydroxybenzoic acid in the presence of 0.125 nM T. Open diamond: butyl-4-hydroxybezoate alone; closed diamond: butyl-4-hydroxybenzoate in the presence of 0.125 nM T. Open triangle: propyl-4-hydroxybenzoate; closed triangle: propyl-4-hydroxybenzoate in the presence of 0.125 nM T. Open circle: methyl-4-hydroxybenzoate alone; closed circle: methyl-4-hydroxybenzoate in the presence of 0.125 nM T. *: significant decrease of T induced transcriptional activity by butyl, methyl and propyl-4-hydroxybenzoate at 10 μM; **: significant decrease of T induced transcriptional activity by methyl and propyl-4-hydroxybenzoate at 1.0 μM.

Figure 4

The effect of thymol and triclosan on AR-mediated transcriptional activity induced by 0.125 nM T. Open circle: thymol alone; closed circle: thymol in the presence of 0.125 nM T. Open square: triclosan alone; solid square: triclosan in the presence of 0.125 nM T. *: significant decrease of T induced transcriptional activity by thymol and triclosan at concentrations of 1.0 μM and 10 μM.