Patent ID: 7732582

Claim:
A compound represented by the general formula (A) or a pharmaceutically acceptable salt thereof: wherein: R 1 represents hydrogen atom, methyl, or hydroxymethyl, R 2 represents hydroxy, amino, or mono- or di-C 1 -C 6 alkyl-substituted amino, R 3 represents hydroxy, amino, monomethylamino, or dimethylamino, L 1 represents a group represented by the formula (B): wherein R a and R b represent carboxyl, R c represents hydrogen atom or hydroxymethyl, or when R 3 is amino or monomethylamino, R 3 and R b in L 1 combine together to represent a bridging group: wherein R a and R c have the same meanings as defined above, and R d represents hydrogen atom or methyl, and L 2 represents hydrogen atom, methyl or a group represented by the formula (C):