The present invention provides a peptide derivative of formula (I) ##STR1##

wherein X is —CHOH— or —CO—; R¹ and R² are hydrogen or substituted oxycarbonyl; R³ is substituted oxycarbonyl; R⁴ is hydroxyl, lower alkoxy, optionally substituted piperazinyl or the like; R⁵ is a R-group side chain of an -amino acid optionally protected by a protective group, R⁶ is hydroxyl, lower alkoxy or the like; m is 0 or 1; and n is an integer of 2 to 6; or

a pharmaceutically acceptable salt thereof. The present invention further provides a production process and use thereof.