Structure-selectivity investigations of D2-like receptor ligands by CoMFA and CoMSIA guiding the discovery of D3 selective PET radioligands.
Elucidation of the physiological role of the D3 receptor and its distribution in the brain using positron emission tomography (PET) is hampered by the lack of bioavailable subtype selective tracer ligands. To develop appropriate D3 radioligands, we designed an integrative procedure involving the elucidation of structural features determining D3 selectivity over both congeners D2 and D4 by comparative molecular analysis. Thus, we have successfully generated CoMFA and CoMSIA models based on the affinitiy differences of a series of 79 ligands representing a broad range of selectivities. These models yielded highly significant cross-validations (q2cv(D3/D2) = 0.86; q2cv(D3/D4) = 0.92) and excellent predictions of a 16-ligand test set (r2pred = 0.79-0.93). Exploiting this information, synthesis and receptor binding studies directed us to the fluorinated lead compounds 78 and 79, featuring subnanomolar D3 affinities and considerable selectivities over D2 and D4 and, subsequently, to the subtype selective PET tracers [18F]78 and [18F]79.
Salama
Ismail
I
Department of Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany.
Hocke
Carsten
C
Utz
Wolfgang
W
Prante
Olaf
O
Boeckler
Frank
F
Hübner
Harald
H
Kuwert
Torsten
T
Gmeiner
Peter
P
D000818:Animals; D001549:Benzamides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D005462:Fluorine Radioisotopes; D066298:In Vitro Techniques; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D010879:Piperazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D049268:Positron-Emission Tomography; D021281:Quantitative Structure-Activity Relationship; D011869:Radioligand Assay; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D017448:Receptors, Dopamine D2 / Q000737:chemistry* / Q000378:metabolism; D050637:Receptors, Dopamine D3 / Q000737:chemistry* / Q000378:metabolism; D013552:Swine
D001549:Benzamides; D005462:Fluorine Radioisotopes; D008024:Ligands; C517644:N-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)-4-(6-fluoropyridin-2-yl)benzamide; C517645:N-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)-4-(6-fluoropyridin-3-yl)benzamide; D010879:Piperazines; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3