CHEMICAL AND BIOLOGICAL CHARACTERIZATION OF DIFFERENT TC COMPLEXES OF CYSTEINE AND CYSTEINE DERIVATIVES

Abstract

Labeling of cysteine and its derivatives (penicillamine, N-acetylcysteine and cysteine ethyl ester) with 99mTc was studied as a model for the radiopharmaceutical preparation of 99mTc-mercaptide complexes. After use of TcO4-, TcOCl52- and TcBr62- as labeling agents for the Tc oxidation states VII, V and IV, respectively, complexes of Tc(V) and Tc(IV) were prepared and characterized. Biologic behavior of these complexes was studied in rats. Substitutions in cysteine were responsible for substantial changes of net charge and lipophilicity in the Tc complexes and consequences on excretion patterns in Wistar rats were discussed.