NYA TRIPEPTIDER, SOM INVERKAR PA DET CENTRALA NERVSYSTEMET

The invention relates to new peptide derivatives which act on the central nervous system and correspond to the general formula (I), X-Y-W-NH2 (I) wherein X is L-pyroglutamyl, D-pyroglutamyl, L-2-keto-imidazolidine-4-carbonyl, L-6-keto-pipecolyl, L-thiazolidine-4-carbonyl, L-prolyl or orotyl group, Y is L-leucyl, L-norvalyl or L-histidyl group, and W is L-prolyl, D-prolyl, L-thiazolidine-4-carbonyl, L-pipecolyl, L-homoprolyl, L-leucyl, L-isoleucyl, L-methionyl or D-pipecolyl group, or the W-NH2 group stands for pyrrolidyl or piperidyl group, with the proviso that if X is L-pyroglutamyl and Y is L-histidyl group, W is other than L-prolyl group, and pharmaceutically acceptable complexes thereof. These compounds are prepared by methods commonly applied in the peptide chemistry.