Preferences of kanamycin A towards copper(II). Effect of the resulting complexes on immunological mediators production by human leukocytes

Abstract

The widespread presence of pathogenic bacteria is a cause of permanent demand for investigating the properties of antimicrobial agents. The chemical basis of several toxic effects induced by antibiotics still remains unclear. Aminoglycosides, highly ototoxic and nephrotoxic drugs, are capable of copper(II) ions chelating. In this study we established the affinity of kanamycin A towards copper(II), in contrast with other metal ions: iron(III), nickel(II), cobalt(II) and zinc(II) by means of potentiometry. Circular dichroism spectroscopy was applied to monitor the competition of copper(II) partition between kanamycin A and human serum albumin. We show, that the drug is able to digest Cu(II) ions from HSA to some extent and comparing the stability constants for metal and antibiotic with those, obtained for the N-terminal Asp–Ala–His–Lys (DAHK) sequence, which constitutes a copper(II) binding domain within albumin, we demonstrate that the Cu(II)–kanamycin A complex formation is possible also in blood plasma. Bioassays and immunoassay were used to find out the possibility of Cu(II)–kanamycin A complexes to induce cytokines: tumor necrosis factor (TNF), interferon (IFN) and interleukin-10 (IL-10) in human peripheral blood leukocytes. The effect on the cytokines release was dose and time dependent and the interdependence between IL-10 and TNF stimulation was found. We report that Cu(II)-aminoglycoside systems can act as moderate inducers of TNF-α, IFN-α/β and IL-10 released from human leukocytes. We have also found that these complexes are non-toxic for human A549 cells.