Kynurenine production inhibitor

A method for preventing or treating a disease in which kynurenine production is involved, comprising a step of administering an effective amount of a nitrogen-containing heterocyclic compound represented by formula (I):

• {wherein R50 and R51 may be the same or different and each represent a hydrogen atom, optionally substituted lower alkoxy or halogen, or R50 and R51 are combined together with the two respective adjacent carbon atoms to form ring A selected from a benzene ring, a naphthalene ring and a pyridine ring (wherein the ring A may have a substituent(s), the number of which is from 1 to the substitutable number, and the substituent(s) may be the same or different and each is halogen, optionally substituted lower alkyl or optionally substituted lower alkoxy), G1 and G2 may be the same or different and each represent a nitrogen atom or CH with the proviso that G1 and G2 do not represent CH at the same time,
• X represents formula (III):
• [wherein m1 and m2 may be the same or different and each represent an integer of 0 or 1, Y represents an oxygen atom, —S(O)m3- (wherein m3 represents an integer from 0 to 2) or —NR8— (wherein R8 represents a hydrogen atom or optionally substituted lower alkyl), and R6 and R7 may be the same or different and each represent a hydrogen atom, halogen, cyano, carboxy, optionally substituted lower alkyl, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted heterocyclic group, optionally substituted lower alkanoyl, optionally substituted lower alkoxycarbonyl or —CONR12R13 (wherein R12 and R13 may be the same or different and each represent a hydrogen atom or optionally substituted lower alkyl, or R12 and R13 are combined together with the adjacent nitrogen atom to form an optionally substituted nitrogen-containing heterocyclic group)],
• R1 represents optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkynyl, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted heterocyclic group or —NR24R25 (wherein R24 and R25 may be the same or different and each represent a hydrogen atom, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkynyl or optionally substituted cycloalkyl),
• R2 represents a hydrogen atom or optionally substituted lower alkyl, or R1 and R2 are combined together with the adjacent sulfur atom and nitrogen atom to form an optionally substituted sulfur-containing and nitrogen-containing heterocyclic group, and
• R3 represents optionally substituted lower alkyl, optionally substituted cycloalkyl, optionally substituted aryl, an optionally substituted heterocyclic group, optionally substituted lower alkanoyl, optionally substituted lower alkoxycarbonyl or —CONR28R29 (wherein R28 and R29 may be the same or different and each represent a hydrogen atom or optionally substituted lower alkyl, or R28 and R29 are combined together with the adjacent nitrogen atom to form an optionally substituted nitrogen-containing heterocyclic group)},
• or a pharmaceutically acceptable salt thereof.