A compound of following formula: where: - R 1 is H or OH, - R 2 is a (C 1 -C 6)alkyl, COOH, COO-((C 1 -C 6)alkyl) or thiazolyl group, - R 3 is H or a (C 1 -C 6)alkyl group, and - R 4 is: ▪ an aryl-(C 1 -C 8)alkyl group substituted by one or more groups chosen from among OH and NR 9 R 10 groups with R 9 and R 10 each independently of one another representing H or a (C 1 -C 6)alkyl group, or ▪ a heterocycle-(C 1 -C 8)alkyl group optionally substituted by one or more groups chosen from among (C 1 -C 6)alkyl, OH and NR 12 R 13 groups with R 12 and R 13 each independently of one another representing H or a (C 1 -C 6)alkyl group, wherein: an aryl-(C 1 -C 8)alkyl group is an aryl group linked to the remainder of the molecule via an alkyl group comprising 1 to 8 carbon atoms, the aryl group being an aromatic hydrocarbon group having 6 to 10 carbon atoms and comprising one or two fused rings, and a heterocycle-(C 1 -C 8)alkyl group is a heterocycle group linked to the remainder of the molecule via an alkyl group comprising 1 to 8 carbon atoms, the heterocycle group being a saturated, unsaturated or aromatic hydrocarbon group having 1 or 2 fused rings and in which 1 to 4 of the carbon atoms are each replaced by a heteroatom chosen from among oxygen, nitrogen and sulfur, or a pharmaceutically acceptable salt, hydrate or solvate thereof. - R 1 is H or OH, - R 2 is a (C 1 -C 6)alkyl, COOH, COO-((C 1 -C 6)alkyl) or thiazolyl group, - R 3 is H or a (C 1 -C 6)alkyl group, and - R 4 is: ▪ an aryl-(C 1 -C 8)alkyl group substituted by one or more groups chosen from among OH and NR 9 R 10 groups with R 9 and R 10 each independently of one another representing H or a (C 1 -C 6)alkyl group, or ▪ a heterocycle-(C 1 -C 8)alkyl group optionally substituted by one or more groups chosen from among (C 1 -C 6)alkyl, OH and NR 12 R 13 groups with R 12 and R 13 each independently of one another representing H or a (C 1 -C 6)alkyl group, wherein: an aryl-(C 1 -C 8)alkyl group is an aryl group linked to the remainder of the molecule via an alkyl group comprising 1 to 8 carbon atoms, the aryl group being an aromatic hydrocarbon group having 6 to 10 carbon atoms and comprising one or two fused rings, and a heterocycle-(C 1 -C 8)alkyl group is a heterocycle group linked to the remainder of the molecule via an alkyl group comprising 1 to 8 carbon atoms, the heterocycle group being a saturated, unsaturated or aromatic hydrocarbon group having 1 or 2 fused rings and in which 1 to 4 of the carbon atoms are each replaced by a heteroatom chosen from among oxygen, nitrogen and sulfur, or a pharmaceutically acceptable salt, hydrate or solvate thereof. ▪ an aryl-(C 1 -C 8)alkyl group substituted by one or more groups chosen from among OH and NR 9 R 10 groups with R 9 and R 10 each independently of one another representing H or a (C 1 -C 6)alkyl group, or ▪ a heterocycle-(C 1 -C 8)alkyl group optionally substituted by one or more groups chosen from among (C 1 -C 6)alkyl, OH and NR 12 R 13 groups with R 12 and R 13 each independently of one another representing H or a (C 1 -C 6)alkyl group, an aryl-(C 1 -C 8)alkyl group is an aryl group linked to the remainder of the molecule via an alkyl group comprising 1 to 8 carbon atoms, the aryl group being an aromatic hydrocarbon group having 6 to 10 carbon atoms and comprising one or two fused rings, and a heterocycle-(C 1 -C 8)alkyl group is a heterocycle group linked to the remainder of the molecule via an alkyl group comprising 1 to 8 carbon atoms, the heterocycle group being a saturated, unsaturated or aromatic hydrocarbon group having 1 or 2 fused rings and in which 1 to 4 of the carbon atoms are each replaced by a heteroatom chosen from among oxygen, nitrogen and sulfur,