A compound represented by formula:or its pharmaceutically acceptable salt,whereinL is NR2R3, SR7, SO2R8, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenyl；R2 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the like；R3 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the like；R7 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the like；R8 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the like, provided that R8 is not unsubstituted methyl or trifluoromethyl；Y is substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, or the like, provided that Y is not unsubstituted methyl or unsubstituted ethyl；Z is -CR6=, or -N=；R1 is hydrogen, or substituted or unsubstituted alkyl；R4, R5 and R6 are each independently hydrogen, halogen, hydroxy, cyano, nitro, carboxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the like.
