Patent ID: 7169806

Claim:
A compound according to formula I, a pharmaceutically acceptable salt thereof, or an optical isomer thereof: wherein R 1 is selected from H, C 1 –C 6 alkyl (including branched alkyl and cycloalkyl), (CH 2 ) a NHW 1 , (CH 2 ) b COW 2 , (CH 2 ) c OW 3 , CH(Me)OW 4 , (CH 2 ) d —C 6 H 4 —W 5 and (CH 2 ) e SW 6 ; where a is 2–5, b is 1–4, c is 1–2, d is 1–2, e is 1–3; W 1 is COW 6 , CO 2 W 6 or SO 2 W 6 ; W 2 is OH, NH 2 , OW 6 or NHW 6 ; W 3 is H or W 6 ; W 4 is H or W 6 ; W 5 is H, OH or OMe; and W 6 is C 1 –C 6 alkyl, benzyl, optionally substituted phenyl, or optionally substituted heteroaryl, where the optional substituents are up to two groups selected from C 1 –C 3 alkyl, C 1 –C 3 alkoxy, F and Cl; R 2 is H or —(CH 2 ) n NH—C 5 H 3 N—Y, where n is 2–4 and Y is selected from H, F, Cl, NO 2 and CN; or R 1 and R 2 together are —(CH 2 ) p —, where p is 3 or 4; R 8 is H or C 1 –C 3 alkyl; and R 9 is H, C 1 –C 6 alkyl, phenyl or C 1 –C 6 alkoxy.