6-Bromo-3′-nitroflavone, a new high affinity benzodiazepine receptor agonist recognizes two populations of cerebral cortical binding sites

The synthesis and biochemical characterization of 6-bromo-3′-nitroflavone ( 1 ) is presented. Compound 1 has higher affinity for cerebellar and cerebral cortical than for striatal, hippocampal, or spinal cord benzodiazepine receptors (BDZ-Rs). In the cerebral cortex it recognizes two populations of binding sites (K i s 1.2 nM and 15.5 nM, respectively), and at doses of 0.01 to 0.3 mg/kg, ip produces anxiolytic effects in mice.