Synthesis, characterization and biological evaluation of novel neutral fac-M(CO)3(SNO) complexes (M=Re, 99mTc) bearing the o-methoxyphenylpiperazine moiety

The synthesis, characterization and biological evaluation of two new neutral tricarbonyl fac-M(CO)3(SNO) (M=Re, 99mTc) bearing o-methoxyphenylpiperazine as pharmacophore and S-functionalized cysteine or penicillamine as chelators are reported. Competition binding tests showed good affinity for the 5-HT1A receptor (8 and 54 nM for 4a and 4b, respectively). Biodistribution studies in healthy animals showed high initial blood and liver uptake, fast blood and tissue depuration and negligible brain uptake.

Graphical abstractTwo new neutral tricarbonyl fac-M(CO)3(SNO) (M=Re, 99mTc) bearing o-methoxyphenylpiperazine as pharmacophore and S-functionalized cysteine or penicillamine as chelator were synthesized, characterized and evaluated as possible 5-HT1A receptor imaging agents.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► S-functionalized cysteine or penicillamine for the 5-HT1A receptors are reported. ► Novel rhenium and technetium-99m tricarbonyl complexes were synthesized and characterized. ► Competition binding tests showed good affinity for the 5-HT1A receptors. ► The 99mTc complexes showed adequate features but negligible brain uptake in mice.