Deferiprone: new environmental perspectives. Insights into its sequestering ability vs. different metal cations.

Deferiprone, generally, is considered an important chelating agent for Fe ³⁺ overload. From a literature data analysis, a lack of information on the interaction of this molecule toward a series of metal cations emerged, inducing to fill out the topic. The complexing ability of deferiprone toward Ca ²⁺ , Mg ²⁺ , Cd ²⁺ and Pb ²⁺ was studied by potentiometry and ¹ H NMR spectroscopy, in KCl aqueous solutions at different ionic strength values (0.1 ≤ I/mol dm ^-3 ≤ 1.0) and T = 298.15 K. The same speciation model featured by the ML, ML ₂ , ML ₃ and ML(OH) (M = metal and L = deferiprone or DFP) species was obtained for Cd ²⁺ and Pb ²⁺ ; the formation constants calculated at infinite dilution are: log ^T β = 7.23±0.02, 12.47±0.03, 16.70±0.04, and -2.53±0.04, respectively for Cd ²⁺ and 9.91±0.01, 15.99±0.02, 19.93±0.05 and 0.99±0.02 for Pb ²⁺ . Only two species, namely ML and ML ₂ , were determined for Ca ²⁺ and Mg ²⁺ , whose formation constants at infinite dilution are respectively: 3.72±0.01 and 6.50±0.02, for the first one, 5.31±0.01 and 9.58±0.01, for the second. The ligand sequestering ability and affinity toward M ²⁺ were evaluated by determining the pL _0.5 and pM parameters at different pHs and ionic strengths. The results suggest that deferiprone has the best complexing and sequestering ability toward Pb ^{2 +} , followed by Cd ²⁺ , Mg ²⁺ and Ca ²⁺ , respectively. ¹ H NMR studies confirmed the DFP affinity for Cd ²⁺ and Pb ²⁺ , and in combination with DFT calculations showed that metal cations are bound to the hydroxo-oxo moiety of the pyridinone ring. The data reported in this study provide information on the possible employment of a small molecule like deferiprone, as a chelating and sequestering agent for Pb ²⁺ accumulation or overload from environmental and biological matrices.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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