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Radionuclide internal contamination can induce chemical and radioactive intoxication and produce harmful free radicals in vivo. At present, administration of chelating agents is the most effective treatment against nuclide contamination. However, traditional studies on chelating agents have ignored the damage caused by free radicals to the body. The present study aimed to develop a type of a bifunctional sequestering agent that can chelates nuclides and scavenges free radicals simultaneously. Therefore, a novel catechol amide-derivatized polyhydroxylated fullerene was designed and prepared. The poor water solubility of fullerene was ameliorated by chemically modifying hydrophilic catechol amide and multiple hydroxyl groups, and obtaining high water-soluble fullerene derivatives. The affinities of chelators were investigated via sulfochlorophenol competitive complexing method and antioxidant capacities were examined by electron paramagnetic resonance. The results revealed the good complexation of the designed and synthesized chelating agent with uranyl ions; and its efficiency in scavenging hydroxyl radicals. This chelating agent showed extremely low toxicity and notable protective effect against oxidative stress on A549 cells. Besides, in U(VI)-exposed A549 cells, immediate treatment with catechol amide-derivatized polyhydroxylated fullerene significantly decreased the lactate dehydrogenase (LDH) release by inhibiting the cellular U(VI) intake, promoting the intracellular U(VI) release and inhibiting the production of intracellular reactive oxygen species (ROS). These results suggest that this fullerene derivative may be a valuable in vivo antioxidant and radionuclide decorporation agent., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2019. Published by Elsevier Inc.)

The special linear dioxo cation structure of the uranyl cation, which relegates ligand coordination to an equatorial plane perpendicular to the O═U═O vector, poses an unusual challenge for the rational design of efficient chelating agents. Therefore, the planar hexadentate ligand rational design employed in this work incorporates two bidentate catecholamine (CAM) chelating moieties and a flexible linker with a β-dicarbonyl chelating moiety (β-dicarbonyl(CAM) 2 ligands). The solution thermodynamics of β-dicarbonyl(CAM) 2 with a uranyl cation was investigated by potentiometric and spectrophotometric titrations. The results demonstrated that the pUO 2 2+ values are significantly higher than for the previously reported TMA(2Li-1,2-HOPO) 2 , and efficient chelation of the uranyl cation was realized by the planar hexadentate β-dicarbonyl(CAM) 2 . The efficient chelating ability of β-dicarbonyl(CAM) 2 was attributed to the presence of the more flexible β-dicarbonyl chelating linker and planar hexadentate structure, which favors the geometric arrangement between ligand and uranyl coordinative preference. Meanwhile, β-dicarbonyl(CAM) 2 also exhibits higher antiradical efficiency in comparison to butylated hydroxyanisole. These results indicated that β-dicarbonyl(CAM) 2 has potential application prospects as a chelating agent for efficient chelation of a uranyl cation.

A new tris(dopamine) derivative, containing three dopamine chelate moieties which were attached to a trimesic acid molecular scaffold, has been prepared and fully characterized by NMR, FTIR and HRMS. The solution thermodynamic stability of the chelator with Fe(III), Mg(II), Zn(II) and Fe(II) ions was investigated. Results demonstrated that the chelator exhibited effective binding ability and improved selectivity to Fe(III) ion. The chelator possessed affinity similar to that of diethylenetriaminepentaacetic acid chelator for Fe(III) ion. The high affinity could be attributed to the favorable geometric arrangement between the chelator and Fe(III) ion coordination preference. The chelator also exhibited high antioxidant activity and nontoxicity to neuron-like rat pheochromocytoma cells. Hence, the chelator could be used as chelating agent for iron overload situations without depleting essential metal ions, such as Mg(II) and Zn(II) ions., (Copyright © 2017. Published by Elsevier Inc.)

The reactions of catecholamide ligands with hexachlorofullerene via O-nucleophiles yielded new water-soluble [60] fullerene derivatives as chelators for radionuclides decorporation. The derivatives were characterized through1H NMR spectroscopy, FT-IR spectroscopy, and X-ray photoelectron spectroscopy. The affinities of the chelators were investigated through the fluorescence quenching of simulated nuclide Ce(III) via a linear Stern–Volmer plot method. Conditional stability constant (K) could also be estimated with this method. The antioxidant capacities of the chelators with a solubility of more than 150 mg/mL in water were examined through UV-vis spectroscopy by determining their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activities. Results revealed that these chelators may be used for complexation, antioxidant activity, and radionuclide decorporation. [ABSTRACT FROM PUBLISHER]