Effect of flavonoids on androgen and glucocorticoid receptors based on in vitro reporter gene assay.

The effect of 32 flavonoids on androgen (AR) and glucocorticoid receptors (GR) was investigated using an MDA-kb2 human breast cancer cell line to predict potential AR and GR activities. Among them, 5-hydroxyflavone (7) had the highest AR antagonistic activity with an IC(50) value of 0.3 microM, whereas 6-methoxyflavone (11) had the highest induced luciferase activity with an EC(150) value of 0.7 microM. Genistein (2) and daizein (1) showed a sufficient increase of luciferase activities as their concentrations increased with EC(150) values of 4.4 and 10.1 microM, respectively. These findings provide evidence of a fundamental property of their structure-activity relationship with AR and/or GR.

Comparison of antiandrogenic activities of vinclozolin and D,L-camphorquinone in androgen receptor gene transcription assay in vitro and mouse in utero exposure assay in vivo.

A chemical substance used as a photoinitiator for light-cure resin compositions, D,L-camphorquinone (CQN) was found to be weakly antiandrogenic in vitro. It competitively antagonized dihydrotestosterone (DHT)-induced transcriptional activity on the yeast-based androgen receptor gene transcription assay (YAA). Antiandrogenic activity of CQN was shown at higher concentration than 10(-4) M while the well-known antiandrogen, vinclozolin (VCZ) showed the activity at concentrations of 10(-6) M and above in YAA. The antiandrogenic activity of CQN was reconfirmed in the human cell line-based androgen receptor gene transcription assay (HCAA). To determine whether CQN affect male reproductive development, CQN or VCZ was administered to pregnant mice daily from gestational days 10 to 18 by gavage. In utero exposure to VCZ at 100 mg/kg/day caused a significant decrease in anogenital distance (AGD) of F1 neonates and reduced spermatogenesis in F1 males at 42 days of age. In contrast, maternal doses (100 and 300 mg/kg/day) of CQN had no affect on these endpoints in F1 offspring. Further, VCZ or CQN had no adverse affect on F1 male fertility. From these observations, CQN is potentially antagonistic to androgen receptor (AR) in vitro, but is estimated to be less antiandrogenic in vivo when it is administered to pregnant mice by gavage. Furthermore, these findings are the first to demonstrate that VCZ exerts significant antiandrogenic effects on reproductive tract development during gestation in mice.

The effect of calcium ion on the biodegradation of octylphenol polyethoxylates, and the antiandrogenic activity of their biodegradates.

Because limes have been used as important fertilizers to neutralize acidified farmland in Japan, our interest in this study was focused on the effect of calcium ion on the biodegradation of octylphenol polyethoxylates (OPEOn) by a pure culture of Pseudomonas putida S5 isolated from a rice paddy field in Japan. In the presence of calcium ion, P. putida S5 accelerated the formation of octylphenol oligoethoxy carboxylates (OPECn) rather than that of octylphenol oligoethoxylates under an aerobic condition, indicating that more soluble biodegradates with terminal carboxyl group may liquate out easily to surface and ground water rather than more hydrophobic biodegradates with shorter ethylene oxide residues. Therefore, the androgen receptor (AR) activity of their degradation products was characterized using an in vitro reporter gene assay. As ethylene oxide chain length decreased, the biodegradates, OPEOn (n < 3), increased their AR antagonist activity. However, OPECn (n < 3) were unable to determine their AR activity because of their cytotoxicity in our reporter gene assay system.

Structural basis for androgen receptor agonists and antagonists: interaction of SPEED 98-listed chemicals and related compounds with the androgen receptor based on an in vitro reporter gene assay and 3D-QSAR.

The androgen receptor (AR) activity of listed chemicals, so called SPEED 98, by the Ministry of the Environment, Japan, and structurally related chemicals was characterized using MDA-kb2 human breast cancer cells stably expressing an androgen-responsive luciferase reporter gene, MMTV-luc. Since our results suggested that chemicals with diverse chemical structures were capable of disrupting the endocrine systems mediated by AR, a comparative molecular field analysis (CoMFA) model was developed to analyze the structural requirements necessary to disrupt AR function. A significant CoMFA model with r(2)=0.825 and q(2)=0.332 was developed for AR antagonist activity of 35 pure antagonists excluding procymidone. On the other hand, a good CoMFA model with r(2)=0.983 and q(2)=0.555 was obtained for antagonist activity of 13 chemicals with both agonist and antagonist activities. The steric and electrostatic properties were sufficient to describe the structural requirements for AR antagonist activity. In addition, the structural difference of AR agonists and antagonists was explained based on CoMFA results and the AR-LBD crystal structure. As several ERalpha agonists such as diethylstilbestrol (DES) acted as AR antagonists, the surface area of the AR ligand-binding domain (LBD) was compared with that of the ERalpha-LBD based on their reported crystal structures to analyze how those ligands interact with LBDs. The surface area of AR-LBD was shown to be smaller than that of ERalpha-LBD and therefore compounds with both estrogenic and antiandrogenic activities can fit well into the ERalpha-LBD but may protrude from the AR-LBD. It is likely that this subtle difference of the surface areas of the LBDs determines whether an ERalpha agonist acts as an AR antagonist or an agonist.