1. The compound of formula I or its pharmaceutically acceptable salts:! ! where Ar is selected from the group consisting of phenyl and thiophenyl； ! R1 is selected from the group consisting of unsubstituted imidazolyl, substituted imidazolyl, chloro, bromo, fluoro, hydroxy and methoxy； ! R2 is selected from the group consisting of hydrogen, methyl, chloro, fluoro, hydroxy, methoxy, ethoxy, propoxy, carbamoyl, dimethylamino, amino, formamido and trifluoromethyl； and! X is selected from the group consisting of CO and SO2. ! 2. The compound according to claim 1, where R1 is selected from the group consisting of unsubstituted imidazolyl and substituted imidazolyl. ! 3. The compound of claim 2, wherein the substituted imidazolyl group is substituted with C1-C6 alkyl. ! 4. The compound according to claim 2, where ArR1R2 is selected from the group consisting of:! ； ； ； ! ； ! where R3 is selected from H, methyl and ethyl. ! 5. The compound according to claim 2, selected from the group consisting of the following compounds:! 3- (5- (4- (1H-imidazol-1-yl) phenyl) -1- (4-carbamoyl-2-methylphenyl) -1H-pyrrol-2-yl) propanoic acid； ! 3- (5- (5- (1H-imidazol-1-yl) thiophen-2-yl) -1- (4-carbamoyl-2-methylphenyl) -1H-pyrrol-2-yl) propanoic acid； ! 3- (1- (4-carbamoyl-2-methylphenyl) -5- (4- (2-methyl-1H-imidazol-1-yl) phenyl) -1H-pyrrol-2-yl) propanoic acid； ! 3- (1- (4-carbamoyl-2-methylphenyl) -5- (4- (4-methyl-1H-imidazol-1-yl) phenyl) -1H-pyrrol-2-yl) propanoic acid； ! 3- (1- (4-carbamoyl-2-methylphenyl) -5- (4- (2-ethyl-1H-imidazol-1-yl) phenyl) -1H-pyrrol-2-yl) propanoic acid； ! 3- (5- (4- (1H-imidazol-1-yl) thiophen-2-yl) -1- (4-carbamoyl-2-methylphenyl) -1H-pyrrol-2-yl) propanoic acid； ! 3- (1- (4-carbamoyl-2-methylphenyl) -5- (5- (2-methyl-1H-imidazol-1-yl) thiophen-2-yl) -1H-pyrrole-2-yl) propanoic acid ； ! 3- (1- (4-carbamoyl-2-methylphenyl) -5- (3-fluoro-4- (1H-imidazol-1-yl) phenyl) -1H-pyrrol-2-yl) propanoic acid； ! 3- (1. Соединение формулы I или его фармацевтически п
