title: Regioselective reaction of thiols with catechol estrogens and estrogen-O-quinones.
abstract: Incubations of [3H]estradiol and [3H]2-hydroxyestradiol (2-OHE2) with rat liver microsomes and mushroom tyrosinase were carried out in the presence of glutathione and 2-mercaptoethanol. A ratio of about 3.5:1 for the C-4 and C-1 thioether conjugates of 2-OHE2 was observed. Chemical reaction of estradiol-2, 3-O-quinone with various thiols showed that alkyl and phenyl thiols gave about a 1:1 ratio of C-4 to C-1 thioethers. However, reaction of the O-quinone with 4-nitrothiophenol gave a C-4/C-1 ratio of 0.25 while 4-bromothiophenol gave a C-4/C-1 ratio of 4.0. These studies suggest that the regioselectivity of the reaction of thiols with estrogen catechols and O-quinones may be dependent on the nature of the thiol compounds and less on steric hindrance.
mesh_terms: D000818:Animals; D004958:Estradiol / Q000031:analogs & derivatives* / Q000378:metabolism; D002393:Estrogens, Catechol / Q000378:metabolism*; D066298:In Vitro Techniques; D008862:Microsomes, Liver / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000494:pharmacology; D051381:Rats; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D002393:Estrogens, Catechol; D013438:Sulfhydryl Compounds; C049872:estradiol-2,3-O-quinone; D004958:Estradiol; C001390:2-hydroxyestradiol; D014442:Monophenol Monooxygenase