Patent ID: 7115578

Claim:
A compound represented by formula V wherein R 20 CO— is a natural or unnatural amino acid moiety represented by the formulas Y═H, CH 3 ; CH 3 CH 2 —; CH 3 CH 2 CH 2 —; Me 2 CH—; Me 2 CH 2 CH 2 —; CH 3 CH 2 CH(Me)—PhCH 2 —; HOOCCH 2 CH 2 —; HSCH 2 —; HOOCCH 2 —; MeSCH 2 CH 2 —; HOCH 2 —; or Y is H 2 N(CH 2 ) 4 — or CH 3 CH(OH)—; or a pharmaceutically acceptable salt thereof; or Y taken together with the α carbon and N form or a phamaceutically acceptable salt thereof; or Y taken together with the α carbon and N form or a phamaceutically acceptable salt thereof, and wherein R 21 is H, alkyl, alkanoyl, or aryl, or is alkyl, alkanoyl or aryl substituted by halo, phenyl, CN, NO 2 OH, CO 2 H or alkoxy.