RESUMEN
Towards addressing the knowledge gap of how bupropion interacts with the dopamine transporter (DAT) and nicotinic acetylcholine receptors (nAChRs), a ligand was synthesized in which the chlorine of bupropion was isosterically replaced with an iodine and a photoreactive azide was added to the 4'-position of the aromatic ring. Analog (±)-3 (SADU-3-72) demonstrated modest DAT and α4ß2 nAChR affinity. A radioiodinated version was shown to bind covalently to hDAT expressed in cultured cells and affinity-purified, lipid-reincorporated human α4ß2 neuronal nAChRs. Co-incubation of (±)-[(125)I]-3 with non-radioactive (±)-bupropion or (-)-cocaine blocked labeling of these proteins. Compound (±)-[(125)I]-3 represents the first successful example of a DAT and nAChR photoaffinity ligand based on the bupropion scaffold. Such ligands are expected to assist in mapping bupropion-binding pockets within plasma membrane monoamine transporters and ligand-gated nAChR ion channels.
Asunto(s)
Azidas/síntesis química , Azidas/farmacología , Bupropión/análogos & derivados , Bupropión/farmacología , Química Farmacéutica/métodos , Receptores Nicotínicos/metabolismo , Azidas/química , Bupropión/síntesis química , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Diseño de Fármacos , Humanos , Yodo/química , Radioisótopos de Yodo/química , Cinética , Ligandos , Modelos Químicos , Fotoquímica/métodosRESUMEN
In contrast to tropane-based compounds such as benztropine and cocaine, non-tropane-based photoaffinity ligands for the dopamine transporter (DAT) are relatively unexplored. Towards addressing this knowledge gap, ligands were synthesized in which the piperidine nitrogen of 3- and 4-iodomethylphenidate was substituted with a benzyl group bearing a photoreactive azide. Analog (±)-3a demonstrated modest DAT affinity and a radioiodinated version was shown to bind covalently to rat striatal DAT and hDAT expressed in cultured cells. Co-incubation of (±)-3a with nonradioactive d-(+)-methylphenidate or (-)-2-ß-carbomethoxy-3-ß-(4-fluorophenyl)tropane (ß-CFT, WIN-35,428, a cocaine analog) blocked DAT labeling. Compound (±)-3a represents the first successful example of a DAT photoaffinity ligand based on the methylphenidate scaffold. Such ligands are expected to assist in mapping non-tropane ligand-binding pockets within plasma membrane monoamine transporters.
