Abstract

Natural and synthetic antioxidants are widely used in modern medicine. In vitro, antioxidants effectively scavenge active free radicals thereby inhibiting free-radical chain reactions of oxidation of fatty acids, edible fats, etc. In vivo, however, neither natural antioxidants, like vitamin E and flavonoids, nor synthetic antioxidants, like butylated hydroxytoluene (BHT), are able to serve as efficient scavengers of oxygen free radicals. The reason is that the rate constants of the antioxidants in the reactions with oxygen free radicals and the concentrations of the antioxidants in cells and tissues are negligible as compared with the natural antioxidant enzymes to compete with the antioxidant enzymes for reactive oxygen species (ROS). Actually, the so-called antioxidants provide prophylactic maintenance against ROS by preventing the formation of oxygen radicals and free radical oxidation in cells and tissues. The protection mechanisms are different for antioxidants of different types. For example, synthetic BHT prevents generation of the oxygen anion–radical (“superoxide”, O₂•–) as the by-product of the mitochondrial electron transport, while natural flavonoids exert a preventive antioxidant action by inducing the expression of the antioxidant enzymes, superoxide dismutase and catalase. At this, the endocrine system, i.e. - prophylactic maintenance via the organism’s neuro-hormonal system plays the significant role in the antioxidant therapy. Besides, there are more and more data indicating that the therapeutic effects of many pharmaceutical drugs, including antioxidants, are due to their beneficial action not only on cells and tissues of host organism but also on gastric and intestinal the organism’s microbiota. Thus, true mechanisms of the antioxidant prophylaxis are to be studied on the ways of systems biology instead of free-radical chemistry. It might be said now that antioxidant biomedicine has passed a long way from “false knowledge to true ignorance”.

Keywords: Antioxidants; Free radicals; Oxygen; Prophylaxis; Preventive maintenance; Biosystems; Reliability; robustness.