Abiotic reductive deiodination of iodinated organic compounds and X-ray contrast media catalyzed by free corrinoids. (April 2019)

• Record Type: Journal Article
• Authors: El-Athman, Fatima; Adrian, Lorenz; Jekel, Martin; Putschew, Anke
• Is Part Of: Chemosphere. Volume 221(2019)
• Page Start: 212
• Page End: 218
• Publication Date: 2019-04
• Subjects: Deiodination -- X-ray contrast media -- Corrinoids -- Vitamin B12 -- Abiotic -- Bank filtration; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.01.003
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Iodinated X-ray contrast media are known for their stability concerning deiodination in the aquatic environment under aerobic conditions. In this study, we demonstrate the abiotic reductive deiodination of the iodinated contrast media iopromide, iopamidol and diatrizoate in the presence of corrinoids. In addition, triiodinated benzoic acid derivatives with iodine atoms bound at different positions were investigated. Corrinoids like cyanocobalamin (vitamin B12 ) and dicyanocobinamide served as electron shuttles and as catalysts between the reducing agent (e.g., titanium (III) citrate) and the electron accepting iodinated compound. The concentration decrease of the iodinated compounds followed first-order kinetics with rate constant kobs depending on the iodinated compound. A linear correlation between the rate of iodide release and the corrinoid concentration was observed, with deiodination rates for dicyanocobinamide twice as high as for vitamin B12 . Reducing agents with a less negative standard redox potential like dithiothreitol or cysteine caused slower deiodination as the cobalt center was only reduced to its Co II oxidation state. With a temperature increase from 11 to 23 °C, the concentrations of released iodide doubled. A complete deiodination was only observed for the iodinated contrast media but not for structurally similar iodinated benzoic acid derivatives. Graphical abstract: Image 1 Highlights: Deiodination of iodinated contrast media can be catalyzed by B12 derivatives. Linear correlation between iodide release rate and corrinoid concentration. Deiodination degree depends on the oxidation state of the cobalt center of B12 . Decrease of the iodinated compounds follows first-order kinetics. Deiodination is influenced by the substitution pattern of bound iodine.