Synthesis and evaluation of optically pure [3 H]-(+)-pentazocine, a highly potent and selective radioligand for σ receptors

摘要: Tritium-labeled (+)-pentazocine ([3H]-1b) of specific activity 26.6 Ci/mmol was synthesized in 3 steps starting with (+)-normetazocine (2) defined optical purity. [3H]-1b has been characterized as a highly selective ligand for labeling sigma receptors. Competition data revealed that could be displaced from guinea pig brain membrane preparations number commonly used receptor ligands. exhibited saturable, enantioselective binding Kd 5.13 +/- 0.97 nM and Bmax 1146 122 fmol/mg protein. Phencyclidine (PCP) low affinity while MK-801 inactive, thus indicating insignificant at the PCP-binding site; apomorphine failed to displace lack dopamine cross-reactivity. Since is about 6 times two employed ligands ((+)-3-[3H]PPP [3H]DTG) since it more receptors than benzomorphan [3H]SKF-10,047, represents first example based ligand. should prove useful further study structure function