Structure-activity relationships at monoamine transporters for a series of N-substituted 3alpha-(bis[4-fluorophenyl]methoxy)tropanes: comparative molecular field analysis, synthesis, and pharmacological evaluation.
The development of structure-activity relationships (SAR) with divergent classes of monoamine transporter ligands and comparison of their effects in animal models of cocaine abuse have provided insight into the complex relationship among structure, binding profiles, and behavioral activity. Many 3alpha-(diphenylmethoxy)tropane (benztropine) analogues are potent dopamine uptake inhibitors but exhibit behavioral profiles that differ from those of cocaine and other compounds in this class. One of the most potent and dopamine transporter (DAT) selective N-substituted benztropine analogues (N-(4-phenyl-n-butyl)-3alpha-(bis[4-fluorophenyl]methoxy)tropane, 1c) is devoid of cocaine-like behaviors in rodent models but is also highly lipophilic (cLogD = 5.01), which compromises its water solubility and may adversely affect its pharmacokinetic properties. To further explore the SAR in this series and ultimately to design dopamine uptake inhibitors with favorable lipophilicities for drug development, a comparative molecular field analysis (CoMFA) was performed on a set of benztropine analogues previously synthesized in our laboratory. The CoMFA field analysis on the statistically significant (r2(cv) = 0.632; r2(ncv) = 0.917) models provided valuable insight into the structural features required for optimal binding to the DAT, which was used to design a series of novel benztropine analogues with heteroatom substitutions at the tropane N-8. These compounds were evaluated for binding at DAT, serotonin (SERT) and norepinephrine (NET) transporters, and muscarinic M1 receptors in rat brain. Inhibition of [3H]DA uptake in synaptosomes was also evaluated. Most of the analogues showed high DAT affinity (12-50 nM), selectivity (10- to 120-fold), potent inhibition of dopamine uptake, and lower lipophilicities as predicted by cLogD values.
Kulkarni
Santosh S
SS
Medicinal Chemistry Section, National Institute on Drug Abuse--Intramural Research Program, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, Maryland 21224, USA.
Grundt
Peter
P
Kopajtic
Theresa
T
Katz
Jonathan L
JL
Newman
Amy Hauck
AH
D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D050484:Norepinephrine Plasma Membrane Transport Proteins; D011485:Protein Binding; D021281:Quantitative Structure-Activity Relationship; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D043643:Receptor, Muscarinic M1 / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins; D027981:Symporters / Q000378:metabolism*; D014326:Tropanes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D050484:Norepinephrine Plasma Membrane Transport Proteins; D043643:Receptor, Muscarinic M1; D050486:Serotonin Plasma Membrane Transport Proteins; C493226:Slc6a2 protein, rat; C493216:Slc6a3 protein, rat; C493232:Slc6a4 protein, rat; D027981:Symporters; D014326:Tropanes