Photoreactivity of some light-sensitive estrogen derivatives. Use of an exchange assay to determine their photointeraction with the rat uterine estrogen binding protein.

Abstract

The photoreactivity of 20 estrogen derivatives (4 azides 4 diazos 4 triarylethylenes and 8 miscellaneous) was analyzed by a rat uterus cytosol exchange assay. The photosensitive derivative was incubated with rat uterus supernatant fraction with or without estradiol for 1-2 hours at 4 degrees C. then irradiated with 254 nm or 315 nm light at 2 degrees C. while samples were removed for assay of tritiated estrogen-binding sites. The reaction efficiency or percent of estrogen-binding capacity consumed by photolysis was computed. The reaction efficiency of azides and diazos ranged from 0%-21% and of triarylethylenes 20%-51%. Benzil o-iodophenol o-nitrophenol alpha-oximo ketone stilbene and styrene chromophores were unreactive. The kinetics of reaction was usually biphasic with a rapid initial rate due to photolysis of the photosensitive moiety and a slower rate interpreted as direct photolytic degradation of the estrogen-binding protein. 6-oxoestradiol had a first order reaction.