DESTRUCTION OF VITAMIN B12 DURING INTERACTION WITH ACTIVE OXYGEN SPECIES

Abstract

One of the most attractive molecular systems in the world of chemistry and medicine is vitamin B12, which was originally discovered as a factor against deficiency (pernicious) anemia. Deficiency of this essential vitamin leads to a decrease in the number of red blood cells in the blood and a drop in hemoglobin levels. The article provides a brief overview of the processes leading to the destruction of vitamin B12 caused by hypoxia, the action hypochlorous acid, superoxide anion radical, hydrogen peroxide, hydroxyl radical, peroxynitrite. Under conditions of hypoxia, oxygen transport in the electron transport chain may be disrupted, resulting in the reduction of oxygen on ubiquinone to a superoxide radical under the action of electrons that have not reached cytochrome oxidase. Oxidative stress develops, during which oxygen-containing radicals are formed, which can cause irreversible changes in the vitamin and lead to loss of biological activity. Hydrogen peroxide formed as a result of step-by-step protonation of the formed superoxide-anion radicals can act as such oxidants. Hydrogen peroxide, in turn, is capable of reacting with metals of variable oxidation state to form a reactive hydroxyl radical, producing the Fenton reaction. In addition, hypochlorous acid formed by the enzyme myeloperoxidase in the presence of hydrogen peroxide and chloride anion, as well as peroxynitrite, an active oxidant obtained by reacting the superoxide–anion radical with nitrogen (II) oxide, can act as oxidants. The latter is produced in large quantities under hypoxia conditions due to an increase in the activity of endothelial nitric oxide synthetase. The publications devoted to the influence of various oxidants on the stability of vitamin B12 are considered. For citation: Erina A.A., Borodulin V.B., Dereven’kov I.A., Makarov S.V., Ischenko A.A. Destruction of vitamin B12 during interaction with active oxygen species. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 7. P. 6-18. DOI: 10.6060/ivkkt.20246707.7043.