title: Structure-activity relationships of 3-deoxy androgens as aromatase inhibitors. Synthesis and biochemical studies of 4-substituted 4-ene and 5-ene steroids.
abstract: As part of our investigation into the structure-activity relationship of a novel class of aromatase inhibitors, two series of 3-deoxy androgens, androst-5-en-17-ones with a non-polar alkoxy (5 and 6), alkyl (20-22), or phenylalkyl (23 and 24) group at C-4beta and 4-acyloxyandrost-4-en-17-ones (29-32, and 34) were synthesized and evaluated. The 4beta-alkyl and 4beta-phenylalkyl compounds were obtained through reaction of 4alpha,5alpha-epoxy steroid (8) with RMgBr (R: alkyl and phenylalkyl) followed by dehydration of the 4beta-substituted 5alpha-hydroxy products (15-19) with SOCl(2) as key reactions. Acylation of 4alpha,5alpha-diol (25) with (RCO)(2)O in pyridine and subsequent dehydration with SOCl(2) gave the 4-acyloxy steroids. All of the steroids studied, except for 4-acetoxy-19-ol (34) that was a non-competitive inhibitor of human placental aromatase, blocked aromatase activity in a competitive manner. 4-Benzoyloxy- and 4-acetoxy steroids (31) and (32) were the most powerful inhibitors of aromatase (K(i)=70 and 60nM, respectively). Elongation of an acetoxy group in a series of 4-acyloxy steroids or a methyl group in a series of 4beta-alkyl steroids decreased affinity for aromatase principally in relation to carbon number of the acyl or alkyl function. The present findings are potentially useful for understanding the spatial and electronic nature of the binding site of aromatase as well as for developing effective aromatase inhibitors.
authors.affiliation: Tohoku Pharmaceutical University, 4-1 Komatsushima-4-chome, Aobaku, 981-8558, Sendai, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Nagaoka
authors.forename: Yoko
authors.initials: Y
authors.lastname: Watari
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yajima
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tsukioka
authors.forename: Yasuyo
authors.initials: Y
authors.lastname: Muroi
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamada
authors.forename: Mitsuteru
authors.initials: M
authors.lastname: Numazawa
mesh_terms: D047072:Aromatase Inhibitors; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D005260:Female; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D010920:Placenta / Q000201:enzymology; D013057:Spectrum Analysis; D013256:Steroids / Q000138:chemical synthesis / Q000494:pharmacology; D013329:Structure-Activity Relationship; D045165:Testosterone Congeners / Q000138:chemical synthesis* / Q000494:pharmacology*
chemical_list: D047072:Aromatase Inhibitors; D013256:Steroids; D045165:Testosterone Congeners; D003687:Dehydroepiandrosterone; C097404:androst-5-en-17-one