RESUMEN
A series of 6alpha- and 6beta-substituted benztropines were synthesized. A marked enantioselectivity was observed for the 6beta-methoxylated benztropines, the (1R)-isomers being more potent than the corresponding (1S) compounds. The racemic 6alpha-methoxy-3-(4',4' '-difluorodiphenylmethoxy)tropane (5 g) was the most potent compound. It has been found that modifications at the 6-position of benztropine might reduce the DAT binding affinity, maintaining otherwise a significant dopamine uptake inhibitory activity. A reinvestigation of the absolute configuration of 6beta-methoxytropinone proved the 6R configuration for the (+)-enantiomer.
Asunto(s)
Benzotropina/análogos & derivados , Benzotropina/síntesis química , Inhibidores de Captación de Dopamina/síntesis química , Glicoproteínas de Membrana/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Tropanos/síntesis química , Animales , Benzotropina/farmacología , Unión Competitiva , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Dopamina/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática , Inhibidores de Captación de Dopamina/farmacología , Técnicas In Vitro , Conformación Molecular , Terminaciones Nerviosas/efectos de los fármacos , Terminaciones Nerviosas/metabolismo , Putamen/efectos de los fármacos , Putamen/metabolismo , Ensayo de Unión Radioligante , Ratas , Estereoisomerismo , Relación Estructura-Actividad , Tropanos/farmacologíaRESUMEN
A combinatorial synthesis of benztropine analogues is presented. Radical azidonation of 3-benzyloxy-8-azabicyclo[3.2.1]octane-8-carboxylic acid tert-butyl ester 3 to 3-(1-azidobenzyloxy)-8-azabicyclo[3.2.1]octane-8-carboxylic acid tert-butyl ester 4 was used as a key step in the synthesis. This step was optimized by adding 10% DMF to the reaction. Reaction of 4 with phenyl magnesium bromide followed by Boc removal and N-methylation gave benztropine 1. Reaction of five-component Grignard reagents with 4 was used to create a two-dimensional library of 25 N-normethylbenztropine analogues. Further reaction of this library with five alkyl bromides was carried out to create a three-dimensional library containing 125 compounds. Screening of the libraries towards binding and inhibition of uptake of the human dopamine (hDAT), serotonin (hSERT) and norepinephrine transporters (hNET) was carried out. None of the synthesized compounds were found to be stronger than benztropine, and none were selective for inhibition of binding over monoamine uptake.
Asunto(s)
Benzotropina/síntesis química , Técnicas Químicas Combinatorias , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/efectos de los fármacos , Inhibidores de Captación de Dopamina/síntesis química , Proteínas de Transporte de Noradrenalina a través de la Membrana Plasmática/efectos de los fármacos , Proteínas de Transporte de Serotonina en la Membrana Plasmática/efectos de los fármacos , Benzotropina/análogos & derivados , Benzotropina/química , Línea Celular , Células Cultivadas , Dopamina/farmacocinética , Inhibidores de Captación de Dopamina/química , Inhibidores de Captación de Dopamina/farmacología , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Humanos , Estructura Molecular , Norepinefrina/farmacocinética , Serotonina/farmacocinéticaRESUMEN
3alpha-(diphenylmethoxy)tropane (benztropine) and its analogues are tropane ring-containing dopamine uptake inhibitors that display binding and behavioral profiles that are distinct from cocaine. We previously prepared a benztropine-based photoaffinity label [125I]-(N-[4-(4'-azido-3'-iodophenyl)butyl]-3alpha-[bis(4'-fluorophenyl)methoxy]tropane, [125I]1, that covalently attached to the 1-2 transmembrane spanning region of the dopamine transporter (DAT). This was in contrast to the 4-7 transmembrane spanning region labeled by a cocaine-based photoaffinity label, [125I] 2 (RTI 82). To characterize further these different binding domains, photoaffinity ligands that had the 4'-azido-3'-iodophenyl substituent extended from the same position on the tropane ring were desirable. Thus, identification of the optimal alkyl linker between this substituent and the tropane nitrogen in the benztropine series was investigated to ultimately prepare the identical N-substituted analogue of 2. In this pursuit, the N-[4-(4'-azido-3'-iodophenyl)propyl] analogue of 3alpha-[bis(4'-fluorophenyl)methoxy]tropane (9a) was synthesized as well as two isothiocyanate analogues that do not require photoactivation (10a,b) for irreversible binding. The synthesis of these target compounds was achieved using a modification of the strategy developed for 1. Evaluation of these compounds for displacing [3H]WIN 35 428 binding at DAT in rat caudate putamen revealed that the 4'-azido-3'-iodophenylbutyl substituent, found in 1, provided optimal binding affinity and was chosen to replace the N-CH3 group on 2. Both the 4'-azido-3'-iodophenyl- and the 4'-isothiocyanatophenylbutyl analogues of 2 (25 and 26, respectively) were synthesized. Both products bound to DAT with comparable potency (IC(50) = 30 nM) to RTI 82 (2). In addition, compound 26 demonstrated wash-resistant displacement of [3H]WIN 35 428 in HEK 293 cells stably transfected with hDAT. These ligands will provide important tools for further characterizing the binding domains for tropane-based dopamine uptake inhibitors at the DAT.
Asunto(s)
Benzotropina/análogos & derivados , Benzotropina/síntesis química , Cocaína/análogos & derivados , Inhibidores de Captación de Dopamina/síntesis química , Dopamina/metabolismo , Isotiocianatos/síntesis química , Glicoproteínas de Membrana , Proteínas de Transporte de Membrana/metabolismo , Proteínas del Tejido Nervioso , Tropanos/síntesis química , Animales , Azidas/metabolismo , Benzotropina/química , Benzotropina/metabolismo , Unión Competitiva , Línea Celular , Cocaína/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática , Inhibidores de Captación de Dopamina/química , Inhibidores de Captación de Dopamina/metabolismo , Humanos , Técnicas In Vitro , Isotiocianatos/química , Isotiocianatos/metabolismo , Ligandos , Masculino , Putamen/metabolismo , Ensayo de Unión Radioligante , Ratas , Ratas Sprague-Dawley , Relación Estructura-Actividad , Tropanos/química , Tropanos/metabolismoRESUMEN
A series of 2'- and 3'-substituted and 3',3"-disubstituted 3 alpha-(diphenylmethoxy)tropane analogs were designed and synthesized as novel probes for the dopamine transporter. All the analogs were evaluated for displacement of [3H]WIN 35,428 binding at the dopamine transporter and for inhibition of [3H]dopamine uptake in rat caudate putamen. Compounds were observed to monophasically displace [3H]WIN 35,428 binding to the dopamine transporter with affinities of 21.6-1836 nM (Ki). Generally, meta-substituted compounds were more potent than benztropine and equipotent to or slightly less potent than their previously reported para-substituted homologs in inhibiting [3H]WIN 35,428 binding. However, these same meta-substituted analogs were typically less potent than the 4'-substituted analogs in inhibiting [3H]dopamine uptake. Ortho-substituted analogs were generally less potent in both binding and inhibition of uptake at the dopamine transporter than either benztropine or other aryl-substituted homologs. The analogs were also tested for binding at norepinephrine and serotonin transporters as well as muscarinic m1 receptors. None of the compounds in the present study bound with high affinity to either the norepinephrine or serotonin transporters, but all bound to muscarinic m1 receptors with high affinity (K1 = 0.41-2.52 nM). Interestingly, 3'-chloro-3 alpha-(diphenylmethoxy)tropane (5c) produced effects like cocaine in animals trained to discriminate 10 mg/kg cocaine from saline, unlike its 4'-Cl homolog and all of the previously evaluated benztropine analogs. Further evaluation of compound 5c and the other benztropine analogs will undoubtedly prove useful in the elucidation of the role of the dopamine transporter in the reinforcing effects of cocaine and the ultimate identification of a cocaine-abuse treatment.
Asunto(s)
Benzotropina/análogos & derivados , Proteínas Portadoras/metabolismo , Cocaína/farmacología , Inhibidores de Captación de Dopamina/farmacología , Glicoproteínas de Membrana , Proteínas de Transporte de Membrana , Proteínas del Tejido Nervioso , Tropanos/farmacología , Animales , Benzotropina/síntesis química , Benzotropina/química , Benzotropina/metabolismo , Benzotropina/farmacología , Unión Competitiva , Proteínas Portadoras/antagonistas & inhibidores , Proteínas Portadoras/efectos de los fármacos , Cocaína/análogos & derivados , Cocaína/metabolismo , Discriminación en Psicología/efectos de los fármacos , Dopamina/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática , Inhibidores de Captación de Dopamina/síntesis química , Inhibidores de Captación de Dopamina/química , Inhibidores de Captación de Dopamina/metabolismo , Relación Dosis-Respuesta a Droga , Espectroscopía de Resonancia Magnética , Masculino , Espectrometría de Masas , Estructura Molecular , Actividad Motora/efectos de los fármacos , Neostriado/efectos de los fármacos , Neostriado/metabolismo , Unión Proteica , Ratas , Ratas Sprague-Dawley , Receptores Muscarínicos/metabolismo , Tropanos/síntesis química , Tropanos/química , Tropanos/metabolismoRESUMEN
We recently reported a new class of tropanes, based on benztropine, that bind uniquely, in the S-configuration, to the dopamine transporter. We have now extended this series to evaluate the effects of substituents on the nitrogen and the diarylmethoxy group. Herein we have described the synthesis and biological evaluation of a series of 2-carbomethoxy-3-(diaryl-methoxy)-1 alpha H, 5 alpha H-tropane (2-carbomethoxybenztropine) analogs. Examination of the binding data obtained for these compounds shows that while the 4,4'-difluoro compound is potent and selective for the dopamine transporter, introduction of larger groups such as 4,4'-dichloro, 4,4'- dibromo, 4,4'-diiodo, or 4,4'dimethyl on the 3-diphenylmethoxy moiety reduces this potency. However, although introduction of only one group (e.g., 4-chloro, 4-bromo, 4-iodo, or 4-methyl) leads to a similar reduction of binding affinity, these monosubstituted 2-carbomethoxybenztropines are significantly more potent than the related disubstituted compounds. Finally, from the data for the N-substituted 2-carbomethoxybenztropine analogs, it is evident that steric bulk can be tolerated at the nitrogen site. A comparison of structure-activity relationship data for the tropanes, GBR analogs, and these benztropines indicates that the 2-carbomethoxybenztropine analogs may be more like the GBR analogs in their mode of binding to the dopamine transporter than like the tropanes. This conclusion supports the notion that the binding site for (-)-cocaine [and the (1R)-tropanes] may differ from of the 2-carbomethoxybenztropine analogs.