Molecular Pharmacology, Vol 9, 514-519, Copyright © 1973 by the American Society for Pharmacology and Experimental Therapeutics

Kinetics of Aqueous Iron(III) Complexation by Desferrioxamine B

¹ Department of Chemistry, University of Utah, Salt Lake City, Utah 84112

Light absorbance stopped-flow rate measurements have been made of the formation of a complex between iron(III) and desferrioxamine B in 0.1 M ionic strength, acidic, aqueous solution at and below 36°. The over-all second-order rate constant for the reaction iron(III) + desferrioxamine B 1:1 complex is k₂ = 2.5 x 10³ M^-1 sec^-1 at pH 3.92 and 36°. This is of the same order of magnitude as previously reported rate constants for aqueous iron(III) complexation by various ligands. The over-all second-order rate constant for the same reaction in blood plasma for pH values ranging from 4.1 to 7.1 at 36° is the same as in aqueous solution to within experimental error. Thus, at physiological pH and temperatures the actual complexation reaction is sufficiently rapid that one may expect this ligand attached to a polymeric substrate to remove excess iron from blood more rapidly than the blood can be circulated in an extracorporeal cleansing device.

Note:
ACKNOWLEDGMENTS This work was suggested by Professors Joseph D. Andrade and René S. Ramirez, who also graciously supplied much of the desferrioxamine B.