Patent ID: 8088916

Claim:
A hyaluronic acid-methotrexate conjugate, wherein methotrexate is conjugated with a carboxyl group of hyaluronic acid, a hyaluronic acid derivative, or a salt thereof through a linker containing a peptide chain consisting of 1 to 8 amino acids; or a salt of the conjugate, wherein the linker containing a peptide chain and methotrexate conjugated with the linker is represented by formula (I′) or (II′): wherein R 1 and R 2 are each independently a hydroxy group, an amino group a C 1-6 alkoxy group, a C 1-6 alkylamino group, or a di-C 1-6 alkylamino group; L is a linker represented by formula (x): wherein Q 1 forms, together with —NH— binding thereto, a peptide chain consisting of 1 to 8 amino acids; residues of amino acids contained in the peptide chain are each independently optionally substituted or protected by one or more groups selected from the group consisting of a C 1-6 alkyl group, a C 1-6 alkylcarbonyl group, a C 1-6 alkoxycarbonyl group, a formyl group, a C 1-6 alkylsulfonyl group, and a C 6-10 arylsulfonyl group; amide bonds contained in the peptide chain are each independently optionally substituted on the nitrogen atom by one or more C 1-6 alkyl groups and/or C 1-6 alkylcarbonyl groups; and carboxyl groups contained in the residues are each independently optionally converted to an amide group optionally substituted by one or two C 1-6 alkyl groups; R 11 and R 12 are each independently a hydrogen atom or a C 1-6 alkyl group; Q 2 is C 2-20 alkylene, wherein the alkylene optionally has 1 to 5 oxygen atoms inserted thereinto and/or is optionally substituted by a carboxyl group or a C 1-6 alkoxvcarbonyl group; and [HA] represents the position of conjugation with the hyaluronic acid, derivative, or salt thereof, and the linker forms an amide bond with a carboxyl group contained in the hyaluronic acid, derivative or salt thereof.