Patent ID: 7198776

Claim:
A metal complex compound comprising a paramagnetic chelate comprising a paramagnetic metal ion M and a chelating agent, said chelating agent is a chelating agent according to formula (I) wherein R 1 represents hydrogen or C 1 –C 15 -alkyl which may optionally be substituted with one or more hydroxy groups, A and B are the same or different and represent CHR 1 R 2 , wherein R 1 is of the definition as described above and R 2 represents hydrogen, C 1 –C 20 -alkyl, C 6 –C 20 -aryl, C 6 –C 20 -aralkyl, said residues may optionally be substituted with one or more hydroxy groups, or A and B form together a bridge (CH 2 ) m , Z represents NH 2 , NHR 2 , OH, O − or OR 3 , wherein R 3 is a base equivalent or a metal ion equivalent, X represents a molecular moiety whose coordination distance to the paramagnetic metal ion chelated by the chelating agent of formula (I) changes upon influence of enzyme activity, being selected from the group of; alkyl-O—PO 3 2− or aryl-O—PO 3 2− which are substrates for phosphatates, alkyl-(NH)-(Glu)n which is a substrate for aminopeptidase A, 4-alkyl-(C 6 R 1 R 2 R 3 R 4 )NH-aminoacid-NH 2 wherein R 1 –R 4 are hydrogen or F, Cl or NO 2 , which is a substrate for aminopeptidase, 4-alkyl -(C 6 H 4 )—CO-aminoacid-CO 2 H which is a substrate for carboxypeptidase, 4-alkyl-(C 6 H 4 )—CH 2 -NH 3 − which is a substrate for monoamine oxidase, and 1-alkyl-β-O-glucoronic acid which is a substrate for β-glucoronidase, Y represents a fluorine atom or a hydrocarbon group comprising at least one fluorine atom, D represents a saturated or unsaturated straight or branched-chain hydrocarbon group containing 1 to 4 carbon atoms or a phenyl group, m represents an integer from 2 to 3 and n and o are the same or different and represent an integer from 1 to 3, wherein the coordination distance between X and M changes upon influence of enzymatic activity and thereby changing the chemical shift of the at least one fluorine atom.