Synthesis, radiolabeling and preliminary biological evaluation of radiolabeled 5-methyl-6-nitroquipazine, a potential radioligand for the serotonin transporter.

5-Methyl-6-nitroquipazine, a novel analogue of the potent and selective serotonin transporter inhibitor 6-nitroquipazine was synthesized and radiolabeled with tritium and the positron emitter carbon-11. [3H]5-methyl-6-nitroquipazine was found to have a K(d)=51+/-7 pM. The high affinity and the facile labeling of [11C]5-methyl-6-nitroquipazine makes it a promising radioligand for visualization of the serotonin transporter with positron emission tomography.