A compound represented by formula 1, an optical isomer thereof, or a pharmaceutically acceptable salt thereof: in the formula 1, - - - - is single bond or double bond; A is carbon (C) or nitrogen (N); R 1 is hydrogen (H) or -NH 2 ; R 2 is H, -CN, C 1-5 straight or branched alkyl, unsubstituted C 3-7 cycloalkyl or halogen; R 3 and R 4 are independently H or C 1-5 straight or branched alkyl; or R 3 and R 4 can form 5 - 7 membered unsubstituted heterocycloalkyl containing one atom of N along with the atoms which are conjugated to the same; and R 5 is or wherein, n is an integer from 0 - 3, R 6 is unsubstituted or substituted C 6-10 aryl or unsubstituted or substituted 5 - 10 membered heteroaryl containing one or more hetero atoms selected from the group consisting of N, O, and S, in which said substituted aryl and said substituted heteroaryl can have one or more substituents selected from the group consisting of halogen, C 1-5 straight or branched alkyl, and C 1-5 straight or branched alkylsulfonyl, R 7 and R 8 are independently H, halogen, -CN, unsubstituted or substituted C 6-10 aryl, unsubstituted or substituted 5 - 10 membered heteroaryl containing one or more hetero atoms selected from the group consisting of N, O, and S, C 1-5 straight or branched alkyl, C 1-5 straight or branched alkoxy, or - NR 9 R 10 , wherein R 9 and R 10 are independently H, C 1-5 straight or branched alkyl, C 1-5 straight or branched alkylamino, unsubstituted or substituted C 6-10 aryl, unsubstituted or substituted 5 - 10 membered heteroaryl containing one or more hetero atoms selected from the group consisting of N, O, and S, or unsubstituted or substituted 3 - 8 membered heterocycloalkyl containing one or more hetero atoms selected from the group consisting of N, O, and S, in which said substituted C 6-10 aryl, said substituted 5 - 10 membered heteroaryl, and said substituted 3 - 8 membered heterocycloalkyl can have one or more substituents selected from the group consisting of halogen and C 1-5 straight or branched alkyl. - - - - is single bond or double bond; A is carbon (C) or nitrogen (N); R 1 is hydrogen (H) or -NH 2 ; R 2 is H, -CN, C 1-5 straight or branched alkyl, unsubstituted C 3-7 cycloalkyl or halogen; R 3 and R 4 are independently H or C 1-5 straight or branched alkyl; or R 3 and R 4 can form 5 - 7 membered unsubstituted heterocycloalkyl containing one atom of N along with the atoms which are conjugated to the same; and R 5 is or wherein, n is an integer from 0 - 3, R 6 is unsubstituted or substituted C 6-10 aryl or unsubstituted or substituted 5 - 10 membered heteroaryl containing one or more hetero atoms selected from the group consisting of N, O, and S, in which said substituted aryl and said substituted heteroaryl can have one or more substituents selected from the group consisting of halogen, C 1-5 straight or branched alkyl, and C 1-5 straight or branched alkylsulfonyl, R 7 and R 8 are independently H, halogen, -CN, unsubstituted or substituted C 6-10 aryl, unsubstituted or substituted 5 - 10 membered heteroaryl containing one or more hetero atoms selected from the group consisting of N, O, and S, C 1-5 straight or branched alkyl, C 1-5 straight or branched alkoxy, or - NR 9 R 10 , wherein R 9 and R 10 are independently H, C 1-5 straight or branched alkyl, C 1-5 straight or branched alkylamino, unsubstituted or substituted C 6-10 aryl, unsubstituted or substituted 5 - 10 membered heteroaryl containing one or more hetero atoms selected from the group consisting of N, O, and S, or unsubstituted or substituted 3 - 8 membered heterocycloalkyl containing one or more hetero atoms selected from the group consisting of N, O, and S, in which said substituted C 6-10 aryl, said substituted 5 - 10 membered heteroaryl, and said substituted 3 - 8 membered heterocycloalkyl can have one or more substituents selected from the group consisting of halogen and C 1-5 straight or branched alkyl. <EOS>