Coordination pattern, solution structure and DNA damage studies of the copper(II) complex with the unusual aminoglycoside antibiotic hygromycin B

The aminoglycosidic antibiotic hygromycin B presents a peculiar chemical structure, characterized by two sugar rings joined via a spiro connection. The Cu(II) complex of hygromycin B in water solution was characterized by 1H-NMR, UV-Vis, EPR and CD spectroscopy, combined with potentiometric measurements. The spin–lattice relaxation enhancements were interpreted by the Solomon-Bloembergen-Morgan theory, allowing us to calculate copper-proton distances that were used to build a model of the complex by molecular mechanics and dynamics calculations. The fidelity of the proposed molecular model was checked by ROESY maps. Moreover DNA damage by the Cu(II)-hygromycin B system was also investigated, showing single and double strand scissions exerted by the complex at concentrations in the range 1–5 mM. Addition of either hydrogen peroxide or ascorbic acid to each sample resulted in the shift of the cleavage potency towards lower concentrations of the complex.