1. Dialkylhydroxybenzoic acid derivatives containing metal chelating groups with the following formula (I), and pharmaceutically acceptable salts thereof: 9 R 1 denotes hydrogen, or a straight or branched acyl; R 2 denotes hydrogen or alkyl; and R 3 denotes metal chelating groups such as CO 2 H, CONH 2, CONR 4 R 5 (where, R 4 denotes hydrogen, alkyl or aryl; and R 5 denotes heterocyclic unsaturated or saturated radical having 1 to 4 heteroatoms of elements nitrogen, oxygen and/or sulfur from the group comprising furanyl, oxazolyl, isooxazolyl, thiophenyl, thiazolyl, isothiazolyl, pyrrolyl, imidazolyl, pyrazolyl, oxadiazolyl, thiadiazoyl, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, triazolyl, tetrazolyl, it being possible for the heterocyclic radical to be substituted once or twice, identically or differently, by halogen, C 1-2 -alkyl, C 1-4 -alkoxy, C 1-4 -alkylthio, hydroxy, mercapto, trifluoromethyl, nitro, phenyl, nitrile, carboxy or C 1-4 -alkoxycarbonyl).