Effect of oxygen on free radicals in DOPA-melanin complexes with netilmicin, diamagnetic Zn(II), and paramagnetic Cu(II)

► O2 affects free radicals in melanin complexes with netilmicin, Zn(II), and Cu(II). ► Free radical concentrations decrease in all the studied samples in air. ► Fast spin-lattice relaxation processes exist in evacuated melanin samples. ► EPR lines of the studied melanin complexes are homogeneously broadened.