NYA PAO DET CENTRALA NERVSYSTEMET INVERKANDE TRIPEPTIDER OCH FOERFARANDE FOER DERAS FRAMSTAELLNING

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.