1. The compound of formula (I): or a pharmaceutically acceptable salt or prodrug thereof, wherein A is selected from the group consisting of R, R, R and R are independently selected from the group consisting of hydrogen, alkenyl, alkyl, haloalkyl, G, G, - (CRR) -G and - (CRR) -G； R and R in each case, each independently represent hydrogen, halogen, alkyl or haloalkyl； G in each case independently represents aryl or heteroaryl, where each G independently represents unsubstituted or substituted 1, 2, 3 , 4 or 5 substituents selected from the group consisting of alkyl, alkenyl, alkin la, halogen, cyano, -NO, -OR, -OC (O) R, -OC (O) N (R) (R), -SR, -S (O) R, -S (O) R, - S (O) N (R) (R), -C (O) R, -C (O) OR, -C (O) N (R) (R), -N (R) (R), -N (R) C (O) R, -N (R) C (O) O (R), -N (R) C (O) N (R) (R), - (CRR) -NO, -N ( R) S (O) (R), - (CRR) -OR, -C (OH) [(CRR) -R], - (CRR) -OC (O) R, - (CRR) -OC (O) N (R) (R), - (CRR) -SR, - (CRR) -S (O) R, - (CRR) -S (O) R, - (CRR) -S (O) N (R) (R), - (CRR) -C (O) R, - (CRR) -C (O) OR, - (CRR) -C (O) N (R) (R), - (CRR) -N ( R) (R), - (CRR) -N (R) C (O) R, - (CRR) -N (R) C (O) O (R), - (CRR) -N (R) C ( O) N (R) (R), - (CRR) -N (R) S (O) (R), cyanoalkyl and haloalkyl； G is cycloalkyl, cycloalkenyl or heterocycle unsubstituted or substituted by 1, 2, 3, 4 or 5 substituents selected from the group consisting of alkyl, alkenyl, alkynyl, halogen, cyano, oxo, —SR, —S (O) R, —S (O) R, —S (O) N (R) (R) , -C (O) R, -C (O) OR, -C (O) N (R) (R), -N (R) (R), -N (R) C (O) R, -N ( R) C (O) O (R), -N (R) C (O) N (R) (R), - (CRR) -NO, -N (R) S (O) (R), - ( CRR) -OR, - (CRR) -OC (O) R, - (CRR) -OC (O) N (R) (R), - (CRR) -SR, - (CRR) -S (O) R , - (CRR) -S (O) R, - (CRR) -S (O) N (R) (R), - (CRR) -C (O) R, - (CRR) -C (O) OR , - (CRR) -C (O) N (R) (R), - (CRR) -N (R) (R), - (CRR) -N (R) C (O) R, - (CRR) -N (R) C (O) O (R), - (CRR) -N (R) C (O) N (R) (R), - (CRR) -N (R) S (O) (R ), cyanoalkyl and haloalkyl； R and R in each case, each independently represent hydro
