HDAC inhibitor

1. A compound having the formula (I):

wherein

R 1 is hydrogen, lower alkyl, lower alkenyl, lower or higher alkynyl, cyclo(lower)alkyl, cyclo(higher)alkyl, cyclo(lower)alkyl(lower)alkyl, cyclo(higher)alkyl(lower)alkyl, cyclo(lower)alkenyl(lower)alkyl, aryl-fused cyclo(lower)alkyl, lower alkoxy, acyl, aryl, ar(lower)alkoxy, ar(lower)alkyl, heteroar(lower)alkyl, amino, heteroaryl, heterocyclyl or heterocyclyl(lower)alkyl, which may be substituted with one or more substituent(s) selected from the group consisting of lower alkyl, halogen, lower alkoxy, amino, hydroxy, cyano, aryl, aryloxy, acyl, cyclo(lower)alkyl, heteroaryl, halo(lower)alkyl and halo(lower)alkoxy,

R 2 is hydrogen or lower alkyl,

X is pyrrolidinylene or piperidinylene,

Y is pyrazinylene, pyrimidinylene, or pyridazinylene, which may be substituted with one or more substituent(s) selected from the group consisting of halogen and lower alkyl,

Z is lower alkenylene, which may be substituted with lower alkyl or halogen, or a salt thereof.

2. The compound or salt thereof of claim 1 , wherein

R 1 is hydrogen, lower alkyl, lower alkenyl, lower or higher alkynyl, cyclo(lower)alkyl, cyclo(higber)alkyl, cyclo(lower)alkyl(lower)alkyl, cyclo(higher)alkyl(lower)alkyl, cyclo(lower)alkenyl(lower)alkyl, aryl-fused cyclo(lower)alkyl, lower alkoxy, acyl, aryl, ar(lower)alkoxy, ar(lower)alkyl, heteroar(lower)alkyl, amino, heteroaryl, heterocyclyl or heterocyclyl(lower)alkyl, which may be substituted with one or more substituent(s) selected from the group consisting of lower alkyl, halogen, lower alkoxy, amino, hydroxy, cyano, aryl, aryloxy, acyl, cyclo(lower)alkyl, heteroaryl, halo(lower)alkyl and halo(lower)alkoxy, and

Z is vinylene, which may be substituted with lower alkyl or halogen.

3. The compound or salt thereof of claim 2 , wherein

R 1 is lower alkyl, cyclo(lower)alkyl, cyclo(lower)alkyl(lower)alkyl, acyl, aryl, ar(lower)alkyl, heteroar(lower)alkyl, heteroaryl or heterocyclyl, which may be substituted with one or more substituent(s) selected from the group consisting of lower alkyl, halogen, lower alkoxy, amino, hydroxy, cyano, aryl, aryloxy, acyl, cyclo(lower)alkyl, heteroaryl, halo(lower)alkyl and halo(lower)alkoxy,

R 2 is hydrogen,

Z is vinylene, which may be substituted with methyl or fluorine.

4. The compound or salt thereof of claim 3 , wherein

R 1 is ar(lower)alkyl or heteroar(lower)alkyl optionally substituted with lower alkyl, halogen, lower alkoxy, amino, hydroxy, cyano, aryl, aryloxy, acyl, cyclo(lower)alkyl, heteroaryl, halo(lower)alkyl or halo(lower)alkoxy.

5. The compound or salt thereof of claim 4 , wherein

R 1 is ar(lower)alkyl or heteroar(lower)alkyl optionally substituted with lower alkyl, halogen, lower alkoxy, di(lower)alkylamino, lower alkanoylamino, lower alkylsulfonylamino, hydroxy, cyano, arylcarbonyl, cyclo(lower)alkyl, halo(lower)alkyl or halo(lower)alkoxy, and

Z is vinylene.

6. The compound or salt thereof of claim 5 , wherein Y is pyrazinylene.

7. A pharmaceutical composition, comprising a compound or salt thereof according to ef claim 1 and a pharmaceutically acceptable, substantially non-toxic carrier or excipient.

8. A method for treating cirrhosis, acute promyelocytic leukaemia (APL), an organ transplant rejection, or a protozoal infection , which comprises administering an effective amount of a compound or salt thereof according to claim 1 to a human being or an animal in need thereof.

9. A pharmaceutical composition, comprising a compound or salt thereof according to claim 2 and a pharmaceutically acceptable, substantially non-toxic carrier or excipient.

10. A pharmaceutical composition, comprising a compound or salt thereof according to claim 3 and a pharmaceutically acceptable, substantially non-toxic carner or excipient.

11. A pharmaceutical composition, comprising a compound or salt thereof according to claim 4 and a pharmaceutically acceptable, substantially non-toxic carrier or excipient.

12. A pharmaceutical composition, comprising a compound or salt thereof according to claim 5 and a pharmaceutically acceptable, substantially non-toxic carrier or excipient.

13. A pharmaceutical composition, comprising a compound or salt thereof according to claim 6 and a pharmaceutically acceptable, substantially non-toxic carrier or excipient.

14. A method for treating cirrhosis, acute promyelocytic leukaemia (APL), an organ transplant rejection, or a protozoal infection, which comprises administering an effective amount of a compound or salt thereof according to claim 2 to a human being or an animal in need thereof.

15. A method for treating cirrhosis, acute promyelocytic leukaemia (APL), an organ transplant rejection, or a protozoal infection, which comprises administering an effective amount of a compound or salt thereof according to claim 3 to a human being or an animal in need thereof.

16. A method for treating cirrhosis, acute promyclocytic leukaemia (APL), an organ transplant rejection, or a protozoal infection, which comprises administering an effective amount of a compound or salt thereof according to claim 4 to a human being or an animal in need thereof.

17. A method for treating cirrhosis, acute promyelocytic leukaemia (APL), an organ transplant rejection, or a protozoal infection, which comprises administering an effective amount of a compound or salt thereof according to claim 5 to a human being or an animal in need thereof.

18. A method for treating cirrhosis, acute promyelocytic leukaemia (APL), an organ transplant rejection, or a protozoal infection, which comprises administering an effective amount of a compound or salt thereof according to claim 6 to a human being or an animal in need thereof.