Patent ID: 7718660

Claim:
A compound of the formula I, or a pharmaceutically acceptable salt thereof: wherein: Z=O or S; n=1-3; R 3 =—CO 2 R 8 , —C(O)SR 8 , —C(O)NHR 8 , —C(S)OR 8 , —C(S)SR 8 , —C(S)NHR 8 , —C(NH)SR 8 or —C(NH)NHR 8 , wherein R 8 is —H or alkyl; R 4 =—H, —CH 2 R 5 or —CH 2 CH 2 R 5 , wherein R 5 independently has one of the meanings of R 3 ; B=—NR 2 —, —CH 2 NR 2 —, —CH 2 CH 2 NR 2 —, —CH 2 CHR 7 — or —CH 2 O—, wherein R 2 is H or a C 1-3 alkyl, alkenyl or alkynyl group, and R 7 is H or a C 1-3 alkyl or alkoxy group; A= wherein R 1 =—NH 2 or —OH, C is a 5- or 6-membered, substituted or unsubstituted, aromatic or non-aromatic ring which may also contain one or more heteroatoms, and C is connected to group B in any available position.