Novel 4'-Substituted and 4',4"-Disubstituted 3α-(Diphenylmethoxy)tropane Analogs as Potent and Selective Dopamine Uptake Inhibitors

Article abstract of DOI:10.1021/jm00020a006

A series of 4'-substituted and 4',4"-disubstituted 3α-(diphenylmethoxy)tropane analogs were prepared as novel probes for the dopamine transporter.These compounds were evaluated in radiolabeled binding assays for the dopamine, norepinephrine, and serotonin transporters.All of these compounds monophasically displaced <3H>WIN 35,428 binding in rat caudate putamen with K_i values ranging from 11.8 to 2000 nM.The most potent compound in this series was 4',4"-difluoro 3α-(diphenylmethoxy)tropane 7c with K_i=11.8 nM.All of the compounds inhibited dopamine uptake in rat caudate putamen (IC50 = 24-4456 nM) which correlated significantly (r = 0.907; p > 0.0001) with binding affinities at the dopamine transporter.None of the compounds demonstrated high-affinity binding at the norepinephrine (K_i > 4800 nM) or serotonin (K_i > 690 nM)transporters.Therefore, the most potent dopamine uptake inhibitors in this series were highly selective for the dopamine transporter.Preliminary behavioral studies of several of these analogs (7a-e) suggested that the compounds did not display a cocaine-like behavioral profile, despite their ability to inhibit dopamine uptake.The present data coupled with the 3α-(diphenylmethoxy)tropane analogs may be interacting at a different active site than cocaine on the dopamine transporter and that an additional binding domain might be exploited for the identification of potential therapeutics for the treatment of cocaine abuse.