Therapeutic agent for amyotrophic disorders

A method for treating an amyotrophic disease, comprising administering to a patient in need of a treatment of the amyotrophic disease, one or more compounds selected from the group consisting of compounds represented by the formula (I):

• wherein R1 represents a benzoylmethyl group having a benzene ring unsubstituted or substituted with an alkyl group having 1 to 7 carbon atoms, an alkoxyl group having 1 to 7 carbon atoms, a fluorine atom and/or a chlorine atom;
• a linear or branched alkyl group having 4 to 6 carbon atoms unsubstituted or substituted with a fluorine atom;
• or a methylene or ethylene substituted with a phenyl group or a cyclopentyl group, wherein the phenyl group is optionally further substituted with one or more phenyl groups;
• R2 is selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 7 carbon atoms, a fluorine atom and a chlorine atom with which an indole is substituted at 4, 5, 6 and/or 7 positions/position;
• R3 represents a group selected from any one of OH, OR4, NHR4 and NR4R5;
• and
• R4 and R5, which are the same or different, each represent a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms,
• the formula (II):
• wherein R6 represents hydrogen or a methyl group;
• X represents an alkylene group having 4 to 6 carbon atoms or an ether group having 4 carbon atoms;
• R3 represents a group selected from any one of OH, OR4, NHR4 and NR4R5;
• and
• R4 and R5, which are the same or different, each represent a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and
• the formula (III):
• wherein A represents indole or naphthalene, provided that when A represents indole, indole is substituted with an acetate group and R7O at positions 3 and 5, respectively, and when A represents naphthalene, naphthalene is substituted with an acetate group and R7O at positions 1 and 7, respectively, wherein R7 represents an alkyl group having 1 to 5 carbon atoms or a benzyl group, whose benzene ring is optionally substituted with one or more alkyl groups having 1 to 3 carbon atoms or one or more alkoxy groups having 1 to 3 carbon atoms;
• R3 represents a group selected from any one of OH, OR4, NHR4 and NR4R5;
• and R4 and R5, which are the same or different, each represent a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and pharmaceutically acceptable salts of the compounds when R3 represents OH.