| 摘要 |
A compound of formula (I), or a pharmaceutically acceptable salt thereof: <CHEM> wherein R1 is a carboxylic acid group, a derivative thereof, a ketone residue, an aldehyde function or optionally substituted methyl; R2 is hydroxy, C1-8 alkoxy or a fluorine atom; and R3 is an amino group or a derivative thereof. |
