| abstract |
The present invention relates to a compound represented by the following formulan n n (I)n n n [Wherein, X denotes a -CHOH- or -CO-, R 1 and R 2 represents a hydrogen atom or a substituted oxycarbonyl group, R 3 represents a substituted oxycarbonyl group, R 4 is a hydroxyl group, a lower alkoxy group, a substituent R 5 represents a side chain of the R group of an alpha -amino acid which may be protected by a protecting group, and R 6 represents a group such as a hydroxyl group or a lower alkoxy group. m is 0 or 1, and n is an integer of 2 to 6, and a pharmaceutically acceptable salt thereof. |