Ka. Hostetler et al., EVALUATION OF THE DISODIUM SALT OF 4,4'-DIAMINO-2,2'-STILBENE DISULFONIC ACID FOR ESTROGENIC ACTIVITY, Journal of toxicology and environmental health, 48(2), 1996, pp. 141-149
4,4'-Diamino-2,2'-stilbene disulfonic acid (DAS), a key intermediate i
n the synthesis oi dyes and fluorescent whitening agents, has been pur
ported to have weak estrogenic properties based on apparent structural
similarity with diethylstilbestrol (DES) and unsubstantiated reports
of male reproductive dysfunction in an industrial setting. In weanling
rats, high doses of DAS (300 mg/kg ip; 1000-3000 mg/kg oral) have bee
n associated with modest increases in the uterus/body weight ratio (Sm
ith & Quinn, 1992). In order to more directly and definitively determi
ne ii DAS possesses estrogenic activity, in vitro studies were conduct
ed to establish its relative binding affinity to the human estrogen re
ceptor (ER) in MCF-7 cells, a well-characterized breast cancer cell li
ne. At concentrations approaching its solubility limit (10(-4) M), DAS
failed to displace [-H-3]-17 beta-estradiol (E(2)) from the ER. In co
ntrast, DES and E(2) demonstrated characteristic competitive binding c
urves (50% displacement of H-3-E(2) at 3.33 x 10(-9) and 1.33 x 10(-8)
M, respectively). Parallel in vivo comparisons of DAS (10 or 30 mg/an
imal) and DES (1 or 3 mu g/animal) were also conducted to assess utero
tropic effects. After three daily subcutaneous injections, DAS did not
induce uterine weight gain. In contrast DES consistently and markedly
increased uterine weight and induced uterine water imbibition, with t
he latter effect being absent in DAS-treated rats. Under these experim
ental conditions, DAS was shown to possess negligible, ii any, estroge
nic activity, despite apparent structural similarity with known estrog
ens.