Effects of static magnetic field on dissolved oxygen levels in aqueous solutions containing copper(II), iron(II), and heme iron(III) complexes

Abstract

Trace metal ions like copper and iron play important roles such as binding, transport, and storage of molecular dioxygen in a wide variety of living systems. The effects of static magnetic fields on the dissolved oxygen (DO) levels in aqueous solutions containing copper(II), iron(II), and their bioligand complexes were investigated. The DO levels in aqueous solutions containing the stable copper(II) complexes such as Cu(II)–Arg, His, GGH and BSA systems increased when the applied magnetic field increased. However, the magnetic field-dependent changes of DO levels were not observed by the unstable Cu(II) complexes such as Cu(II)–Lys, Gly, Gly–His and Hb systems. Especially, DO levels in aqueous solutions containing Cu(II)–His or BSA complexes increased 1.1-fold to those of the control levels at 200 mT of the applied magnetic field. In contrast, DO levels in aqueous solutions containing iron(II) decreased significantly when the magnetic field increased, which in turn promoted the Fe(II)-induced lipidperoxidation in liposomes. DO levels in aqueous solutions containing Fe(II)–His complex decreased 0.9-fold to those of the control levels at 200 mT of the magnetic field for 30 min. While, the magnetic field-dependent changes of DO levels increased significantly in aqueous solutions containing heme iron(III)-complexes, suggesting that heme iron(III) is reduced to heme iron(II) under exposure of the magnetic field and thus the incorporation of molecular dioxygen in aqueous solutions is enhanced. These results indicate that the effect of the magnetic fields on DO levels in aqueous solutions must be discussed in terms of a concept: formation of intermediate complexes consisting of molecular dioxygen-copper or iron and bioligands under physiological conditions and the following enhancement of incorporation of molecular dioxygen by the complexes, that in turn activate the molecular dioxygen.