A compound of formula, or its pharmaceutically acceptable salt, solvate or isomer, wherein: whenX=N,Y=CorY=N,X=Catom; substituent group R 1 represents hydrogen atom, C 1-5 alkyl, halogen or cyano group; substituent group R 2 represents aryl or heteroaryl substituted independently by one or more groups which are selected from a group consisting of halogen, C 1-8 alkyl, R 4 OC 0-8 alkyl, R 4 SC 0-8 alkyl, cyano group, nitro group, -NR 4 R 6, -NR 4 SO 2 R 5, -SOR 5, -SO 2 R 5, -SO2NR 4 R 6 and -CONR 4 R 6; substituent group R 3 represents group -SOR 7, -SO 2 R 7 or -SR 7; substituent group R 4 represents hydrogen atom, C 1-8 alkyl, C 1-8 haloalkyl, aryl C 0-8 alkyl, wherein the aryl is optionally substituted by one or more groups selected from C 1-8 alkyl, halogen, C 1-8 haloalkyl, cyano group and nitro group; substituent group R 5 represents C 1-8 alkyl or C 1-8 haloalkyl; substituent group R 6 represents hydrogen atom, C 1-8 alkyl or aryl C 0-8 alkyl, wherein the aryl is optionally substituted by one or more groups selected from C 1-8 alkyl, halogen, C 1-8 haloalkyl, cyano group and nitro group; substituent group R 7 represents -NH 2, C 1-8 alkyl or C 1-8 haloalkyl; "aryl" means phenyl, naphthyl, anthryl or phenanthryl; and "heteroaryl" means benzofuranyl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzopyranyl, furyl, imidazolyl, indozolyl, indolizinyl, indolyl, isobenzofuranyl, isoindolyl, isoquinolyl, isothiazolyl, isoxazolyl, naphthyridinyl, oxadiazolyl, oxazinyl, oxazolyl, phthalazinyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridine [3, 4-b] indolyl, pyridyl, pyrimidyl, pyrrolyl, quinolizinyl, quinolyl, quinoxaline, thiadiazolyl, thiatriazolyl, thiazolyl, thienyl, triazinyl, triazolyl or xanthenyl. whenX=N,Y=CorY=N,X=Catom; substituent group R 1 represents hydrogen atom, C 1-5 alkyl, halogen or cyano group; substituent group R 2 represents aryl or heteroaryl substituted independently by one or more groups which are selected from a group consisting of halogen, C 1-8 alkyl, R 4 OC 0-8 alkyl, R 4 SC 0-8 alkyl, cyano group, nitro group, -NR 4 R 6, -NR 4 SO 2 R 5, -SOR 5, -SO 2 R 5, -SO2NR 4 R 6 and -CONR 4 R 6; substituent group R 3 represents group -SOR 7, -SO 2 R 7 or -SR 7; substituent group R 4 represents hydrogen atom, C 1-8 alkyl, C 1-8 haloalkyl, aryl C 0-8 alkyl, wherein the aryl is optionally substituted by one or more groups selected from C 1-8 alkyl, halogen, C 1-8 haloalkyl, cyano group and nitro group; substituent group R 5 represents C 1-8 alkyl or C 1-8 haloalkyl; substituent group R 6 represents hydrogen atom, C 1-8 alkyl or aryl C 0-8 alkyl, wherein the aryl is optionally substituted by one or more groups selected from C 1-8 alkyl, halogen, C 1-8 haloalkyl, cyano group and nitro group; substituent group R 7 represents -NH 2, C 1-8 alkyl or C 1-8 haloalkyl; "aryl" means phenyl, naphthyl, anthryl or phenanthryl; and "heteroaryl" means benzofuranyl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzopyranyl, furyl, imidazolyl, indozolyl, indolizinyl, indolyl, isobenzofuranyl, isoindolyl, isoquinolyl, isothiazolyl, isoxazolyl, naphthyridinyl, oxadiazolyl, oxazinyl, oxazolyl, phthalazinyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridine [3, 4-b] indolyl, pyridyl, pyrimidyl, pyrrolyl, quinolizinyl, quinolyl, quinoxaline, thiadiazolyl, thiatriazolyl, thiazolyl, thienyl, triazinyl, triazolyl or xanthenyl.