Investigations on the effects of basic side chains on the hormonal profile of (4R,5S)/(4S,5R)-4,5-bis(4-hydroxyphenyl)-2-imidazolines.
Basic side chains determine the pharmacology of selective estrogen receptor modulators such as tamoxifen or raloxifene. In this study we tried to turn the hormonal profile of (4R,5S)/(4S,5R)-4,5-bis(4-hydroxyphenyl)-2-imidazolines from agonistic to antagonistic by introduction of a dimethylaminoethane, a piperidin-1-ylethane, or a pyrrolidin-1-ylethane side chain into one of the 4-hydroxyphenyl rings. The compounds were tested for agonistic and antagonistic activity on hormone sensitive, ERalpha-positive MCF7-2a cells, stably transfected with the plasmid ERE(wtc)luc and on U-2 OS cells transiently transfected with plasmids encoding for ERalpha (pSG5-ERalpha) or ERbeta (pSG5-ERbeta FL) as well as the reporter plasmid (ERE)(2)luc(+). Despite the presence of a basic side chain, the majority of the 4,5-diaryl-2-imidazolines showed agonistic effects. The most active compound, (4R,5S)/(4S,5R)-4-(2-chloro-4-(2-piperidin-1-ylethoxy)phenyl)-5-(2,6-dichloro-4-hydroxyphenyl)-2-imidazoline (5a), achieved at ERalpha an EC(50) value of 0.085 microM and at ERbeta an EC(50) = 0.40 microM. High antagonistic properties only possessed the C2 ethyl substituted compounds 2a and 4a. (4R,5S)/(4S,5R)-2-Ethyl-4-(4-hydroxyphenyl)-5-(4-(2-piperidin-1-ylethoxy)phenyl)-2-imidazoline (2a) reduced the effect of estradiol at ERalpha strongly with IC(50) = 0.038 microM, while its antagonistic properties at ERbeta were distinctly lower (IC(50) = 9.00 microM), probably due to the partial agonistic effects (EC(50) = 0.50 microM).
von Rauch
Moriz
M
Institute of Pharmacy, Free University of Berlin, Königin-Luise Str. 2+4, D-14195 Berlin, Germany.
Busch
Sandra
S
Gust
Ronald
R
D045744:Cell Line, Tumor; D047628:Estrogen Receptor alpha / Q000819:agonists* / Q000037:antagonists & inhibitors*; D047629:Estrogen Receptor beta / Q000819:agonists / Q000037:antagonists & inhibitors; D006801:Humans; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D048288:Imidazolines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D008958:Models, Molecular; D015394:Molecular Structure; D010636:Phenols / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D010880:Piperidines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D011759:Pyrrolidines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D020845:Selective Estrogen Receptor Modulators / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
C496953:2-ethyl-4-(4-hydroxyphenyl)-5-(4-(2-piperidin-1-ylethoxy)phenyl)-2-imidazoline; C496952:4-(2-chloro-4-(2-piperidin-1-ylethoxy)phenyl)-5-(2,6-dichloro-4-hydroxyphenyl)-2-imidazoline; C496954:4-(2-chloro-4-hydroxyphenyl)-5-(2-chloro-4-(2-piperidin-1-ylethoxy)phenyl)-2-ethyl-2-imidazoline; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D007093:Imidazoles; D048288:Imidazolines; D010636:Phenols; D010880:Piperidines; D011759:Pyrrolidines; D020845:Selective Estrogen Receptor Modulators