Patent ID: 6951843

Claim:
A peptide derivative of formula (I) wherein X is —CHOH— or —CO—; R 1 and R 2 may be the same or different and are hydrogen or substituted oxycarbonyl; R 3 is substituted oxycarbonyl; R 4 is hydroxyl, lower alkoxy, optionally substituted piperazinyl, or —NR 7 R 8 (wherein R 7 and R 8 may be the same or different and are hydrogen, optionally substituted lower alkyl, or amino optionally substituted with lower alkyl(s) or aryl(s)); R 5 is a R-group side chain of an α-amino acid optionally protected by a protective group; R 6 is hydroxyl, lower alkoxy, or —NR 9 R 10 (wherein R 9 and R 10 may be the same or different and are hydrogen, lower alkyl, aryl or aralkyl); m is 0 or 1; and n is an integer of 2 to 6; or a pharmaceutically acceptable salt thereof.