Novel peptide derivative

摘要

A peptide derivative represented by general formula (I) or a salt thereof, having an antitumor activity more potent than that of Dolastatin 10 and being useful as anticancer and antitumor drugs, wherein A and B represent the groups of either combination (a) or combination (b): (a) A represents hydrogen; and B represents phenyl or heteroaryl substituted by halogen, hydroxy, lower alkyl or lower alkoxy; and (b) A represents -CONH-R1, -CSNH-R1, hydroxymethyl, lower alkoxycarbonyl or carboxy (wherein R1 represents lower alkyl or heteroaryl); and B represents phenyl which may be substituted by halogen, hydroxy, lower alkyl or lower alkoxy. CHEM