Synthesis and pharmacological activity of analogs of the endogenous neuropeptide cycloprolylglycine

series of analogs and homologs of the endogenous cyclic dipeptide cycloprolylglycine were synthesized. The nootropic properties of the synthesized compounds were investigated on an experimental model of a passive avoidance test with electroshock- or scopolamine-induced amnesia. The anxiolytic activity was examined by an elevated plus-maze test. It is established that the pharmacophores responsible for the nootropic and anxiolytic activities are different. Hypotheses concerning the structure of the binding regions with the corresponding pharmacological targets are formulated.