A compound represented by formula:or its pharmaceutically acceptable salt,whereinL is NR2R3, SR7, SO2R8, substituted or unsubstituted alkyl, or substituted or unsubstituted alkenylR2 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the likeR3 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the likeR7 is hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the likeR8 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 trifluoromethylY 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 ethylZ is —CR6═, or —N═R1 is hydrogen, or substituted or unsubstituted alkylR4, 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.
