A compound is represented by formula:or its pharmaceutically acceptable salt, wherein Y is substituted or unsubstituted alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, cycloalkenyl, or heterocyclyl； T is —CR7═ or —N═； U is —CR8═ or —N═； R2 is hydrogen, halogen, cyano, nitro, carboxy, substituted or unsubstituted alkyl, alkenyl, acyl, carbamoyl, alkylthio, alkylsulfinyl, alkylsulfonyl, or alkyloxycarbonyl； R3 is halogen, substituted or unsubstituted alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, cycloalkenyl, heterocyclyl； and R4, R7 and R8 are each independently hydrogen, halogen, hydroxy, cyano, nitro, carboxy, substituted or unsubstituted alkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, cycloalkenyl, or heterocyclyl.
