Patent ID: 7129232

Claim:
A compound of the formula [I]: wherein R 1 is lower alkyl, hydroxy(lower)alkyl or halo(lower)alkyl, and R 2 is hydrogen, aryl(lower)alkyl or acyl, or R 1 and R 2 are bonded together and form lower alkylene or lower alkenylene; R 3 is hydrogen or lower alkyl; R 4 is wherein A is wherein X is O or NH, R 7 is hydrogen, lower alkyl, aryl(lower)alkyl or acyl, R 8 is hydrogen or hydroxy, R 9 is amino, mono or di(lower)alkylamino, aryl(lower)alkylamino, acyl amino, guanidino, acyl guanidino or saturated 3- to 8-membered heterocyclic group containing 1 to 4 nitrogen atoms optionally substituted by amino, aryl(lower)alkylamino or acylaminio, k, m, n and q are independently 0 or 1, and p is 0, 1, 2 or 3; R 5 is carboxy or an esterfied carboxy; and R 6 is amino, aryl(lower)alkylamino or acylamino, or a pharmaceutically acceptable salt thereof.