This compounds correspond to the formula (I), where: R1 represents and aryl or heteroaryl group optionally substituted by one or more substituents selected from the group consisting of halogen atoms, straight or branched optionally substituted lower alkyl, cycloalkyl, hydroxy, straight or branched, optionally substituted lower alkoxy, cyano, or —CO2R′, wherein R′ represents a hydrogen atom or a straight or branched, optionally substituted lower alkyl group; R2 represents a group selected from: a) a straight or branched lower alkyl group substituted by one or more carboxylic groups (—COOH) and optionally substituted by one or more halogen atoms; b) a cycloalkyl group substituted by one or more carboxylic groups (—COOH) and optionally substituted by one or more halogen atoms; c) a straight or branched alkylcycloalkyl or cycloalkylalkyl group substituted by one or more carboxylic groups (—COOH) and optionally substituted by one or more halogen atoms. Formula (I).