On the True Role of Oxygen Free Radicals in the Living State, Aging, and Degenerative Disorders

Abstract

Oxyradicals are generally considered harmful byproducts of oxidative metabolism, causing molecular damage in living systems. They are implicated in various processes such as mutagenesis, aging, and series of pathological events. Although all this may be justified, evidence is accumulating that it is an oversimplified view of the real situation. We can assume nowadays that the living state of cells and organisms implicitly requires the production of oxyradicals. This idea is supported by experimental facts and arguments as follows. (1) Complete inhibition of the oxyradical production by KCN (or by any block of respiration) kills the living organisms much before the energy reserves would be exhausted. (2) Construction of the supramolecular organization of the cells (especially of their membranous compounds) requires the cross‐linking effect of oxyradicals, particularly that of OH· radicals. (3) Blast type cells produce much fewer oxyradicals than do differentiated ones, and interventions increasing the production of OH· radicals induce differentiation of various lines of leukemic (HL‐60 and K562) and normal (fibroblasts, chondroblasts, etc.) cells, while SOD expression increases greatly. (4) It is reasonable to assume that the continuous flux of OH· radicals is prerequisite to maintenance of constant electron delocalization on the proteins, which is a semiconductive phenomenon suggested in 1941 by Szent‐Györgyi, but it has never been proven experimentally. It is theoretically possible to describe the function of the synapses as that of a single p‐n‐p transistor, assuming that the free radical flux maintains electron movements on the subsynaptic structures, while the actual membrane potential is governing the electron flux. This theoretical approach may open completely new possibilities for our understanding of the normal functions of living organisms, such as basic memory mechanisms in brain cells, their aging processes, and therapeutic approaches to many degenerative disorders, such as various types of dementia.

Reactive oxygen species are indispensable in ovulation

“…We also show that H 2 O 2 retains, at least partially, the ability to induce the abovementioned events in an LH-independent manner. ROS such as superoxide anion radical (O 2 − ), hydrogen peroxide (H 2 O 2 ), and hydroxyl radical (OH − ) that are produced in measurable quantities by every aerobic system were considered toxic to living cells (30,31). However, recent reports in the field of free-radical biology describes oxyradicals as mediators of functionally significant events in a variety of biological systems (32)(33)(34).…”

Statins: Are they also memory enhancers? A study in relation to their hypocholesterolemic and antioxidant effects in Swiss albino mice

“…[3][4][5][6] Oxygen free radicals produced within the neurons National Journal of Physiology, Pharmacy and Pharmacology 1294 2017 | Vol 7 | Issue 12 can cause tissue damage and are also implicated in aging and neurodegenerative process. [7,8] The most widely used treatments for AD at present are the reversible acetylcholinesterase inhibitors, which aim at prolonging cognitive functions through decreased degradation of acetylcholine at synaptic cleft. The treatment is only symptomatic, without any neuroprotection and provides only modest outcome for the patients.…”

Oxidative hemolysis of erythrocytes

“…1A). However, even in fully operational mitochondria, the electron transfer is "leaky," and some of them "leak" on their way reducing oxygen to superoxide anion radical O 2 . in one-electron reactions and to hydrogen peroxide H 2 O 2 in two-electron reactions.…”

“…When inflammatory foci caused by viruses or bacteria are present in the body, oxygen consumption by phagocytic cells rises dramatically several tens of times, which is called an "oxidative burst." This is a state of the elevated O 2 . production in the reaction catalyzed by NADPH oxidase in granulocytic membranes (Reaction 5) [4].…”

“…In a majority of biological reactions, O 2 . is formed first, and then it is transformed into H 2 O 2 in dismutation reaction catalyzed by superoxide dismutase or occurring spontaneously (Reaction 1).…”