Peptide, process for preparation thereof and use thereof

摘要

The invention relates to novel peptides of enhanced pharmacological activity of the formula: <IMAGE> wherein R1 is alkanoyl; R2 and Rq are each hydrogen, carboxy, protected carboxy, or a group of the formula: <IMAGE> wherein Ra2 is mono- or di-carboxy (or protected carboxy) lower alkyl or ar(carboxy or protected carboxy) lower alkyl whose aryl moiety may be substituted by hydroxy, Rb2 is hydrogen or lower alkyl; RP is hydrogen, carboxy, protected carboxy, with proviso that when one of R2 and Rq is hydrogen, then the other is carboxy or protected carboxy or a group of the formula: <IMAGE> wherein Ra2 and Rb2 are each as defined above; Rr is hydrogen or amino protective group; m is an integer 1 to 3; or its pharmaceutically acceptable salt.