Patent ID: 8314085

Claim:
A method for overcoming anti-cancer chemotherapeutic drug resistance comprising contacting a chemotherapeutic drug-resistant cell with an agent containing a compound having the following formula (I) or a salt thereof as an active ingredient for overcoming anti-cancer chemotherapeutic drug resistance: wherein R 1 is C 2-8 alkenyl, C 6-10 aryl, or heteroaryl in which the aryl and heteroaryl can have a substituent selected from the group consisting of C 1-8 alkyl, C 1 -8 alkyl substituted with halogen, C 1-8 alkoxy, C 1-8 alkoxy substituted with halogen, C 2-8 alkoxycarbonyl, formyl, carboxyl, halogen, hydroxyl, nitro, cyano, amino, C 6-10 aryl, and C 6-10 aryloxy; R 2 is cyano, nitro, formyl, carboxyl, carbamoyl, or C 2-8 alkoxycarbonyl; X is oxygen, —N(R 3 )—, or —S(O) n —, and R 3 is a hydrogen, C 1-8 alkyl, or the group mentioned above for R 1 , or R 1 and R 3 are combined to form morpholinyl, thiomorpholinyl, or piperazinyl, and n is an integer of 0 to 2; and Y is oxygen, sulfur, or NH, wherein said drug-resistant cell over-expresses breast cancer resistance protein (BCRP).