Co-ordination of copper(II) by amikacin. Complexation equilibria in solution and oxygen activation by the resulting complexes†

Abstract

Protonation and copper(II) co-ordination properties of amikacin (A) were studied in solution by potentiometry, and NMR, UV/VIS, CD and EPR spectroscopies. Mononuclear, tetragonal and five-co-ordinate complexes of stoichiometries ranging from Cu(H₃A) to CuH_–2A were found. The effects of amikacin on copper(II) binding by physiological copper(II) carriers, histidine and albumin, and facilitation of oxidation of 2′-deoxyguanosine by copper(II)–amikacin complexes were also investigated. The results indicate that complexation of Cu^II by amikacin should not be expected to affect copper(II) homeostasis in blood, but may contribute to the intracellular activity of the drug.