Tricyclic compounds

A tricyclic compound represented by general formula (I):

• (wherein
• R1 represents hydrogen, substituted or unsubstituted lower alkyl, substituted or unsubstituted lower alkoxy or halogen;
• X1—X2—X3 represents CR5═CR6—CR7═CR8 (wherein R5, R6, R7 and R8, which may be the same or different, each represents hydrogen, substituted or unsubstituted lower alkyl, hydroxy, substituted or unsubstituted lower alkoxy, nitro, amino, lower monoalkyl-substituted amino, lower dialkyl-substituted amino, substituted or unsubstituted lower alkanoylamino or halogen), N(O)m═CR5—CR6═CR7 (wherein R5, R6 and R7 have the same significances as defined above, and m represents 0 or 1), CR5═CR6—N(O)m═CR7 (wherein R5, R6, R7 and m have the same significances as defined above), CR5═CR6—CR7═N(O)m (wherein R5, R6, R7 and m have the same significances as defined above), CR5═CR6—O (wherein R5 and R6 have the same significances as defined above), CR5═CR6—S (wherein R5 and R6 have the same significances as defined above), O—CR7═CR8 (wherein R7 and R8 have the same significances as defined above), S—CR7═CR8 (wherein R7 and R8 have the same significances as defined above) or O—CR7═N (wherein R7 has the same significance as defined above);
• and when R2 represents hydrogen, substituted or unsubstituted lower alkyl, substituted or unsubstituted lower alkenyl, trifluoromethyl, substituted or unsubstituted lower alkoxy, amino, substituted or unsubstituted lower monoalkyl-substituted amino, substituted or unsubstituted lower dialkyl-substituted amino, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted aralkylamino, substituted or unsubstituted arylamino, a substituted or unsubstituted alicyclic heterocyclic group, a substituted or unsubstituted N-substituted heterocyclic group or
• (wherein
• n is 0 or 1;
• R3 and R4, which may be the same or different, each represents hydrogen, substituted or unsubstituted lower alkyl, substituted or unsubstituted cyclic alkyl, substituted or unsubstituted aryl, substituted or unsubstituted aralkyl or trifluoromethyl, or R3 and R4 may be combined together to form cyclic alkyl;
• and Q represents hydroxy, substituted or unsubstituted lower alkoxy, amino or halogen),
• Y represents —CH2SO2—, —SCH2—, —SOCH2— or —SO2CH2—;
• when R2 represents hydrogen, substituted or unsubstituted lower alkenyl, trifluoromethyl, substituted or unsubstituted lower alkoxy, amino, substituted or unsubstituted lower monoalkyl-substituted amino, substituted or unsubstituted lower dialkyl-substituted amino, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted aralkylamino, substituted or unsubstituted arylamino, a substituted or unsubstituted alicyclic heterocyclic group, a substituted or unsubstituted N-substituted heterocyclic group or
• (wherein
• n, R3, R4and Q have the same significances as defined above),
• Y represents —OCH2—);
• or a pharmaceutically acceptable salt thereof.