Design, synthesis and biological evaluation of bis(hydroxyphenyl) azoles as potent and selective non-steroidal inhibitors of 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) for the treatment of estrogen-dependent diseases

The 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) catalyses the reduction of the weakly active estrone (E1) into the most potent estrogen, 17beta-estradiol (E2). E2 stimulates the growth of hormone-dependent diseases via activation of the estrogen receptors (ERs). 17beta-HSD1 is often over-expressed in breast cancer cells. Thus, it is an attractive target for the treatment of mammary tumours. The combination of a ligand- and a structure-based drug design approach led to the identification of bis(hydroxyphenyl) azoles as potential inhibitors of 17beta-HSD1. Different azoles and hydroxy substitution patterns were investigated. The compounds were evaluated for activity and selectivity with regard to 17beta-HSD2, ERalpha and ERbeta. The most potent compound is 3-[5-(4-hydroxyphenyl)-1,3-oxazol-2-yl]phenol (18, IC(50)=0.31 microM), showing very good selectivity, high cell permeability and medium CaCo-2 permeability.