A Chain Reaction of Adrenaline Autoxidation is a Model of Quinoid Oxidation of Catecholamines
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CULAR BIOPHYSICS
A Chain Reaction of Adrenaline Autoxidation Is a Model of Quinoid Oxidation of Catecholamines T. V. Sirota* Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow oblast, 142290 Russia *e-mail: [email protected] Received November 18, 2019; revised April 7, 2020; accepted April 7, 2020
Abstract—This review is focused on literature data and our own research of the nontrivial quinoid pathway for the oxidation of adrenaline. All catecholamines can be oxidized similarly with formation of corresponding aminochromes. This process is simulated in vitro in an alkaline medium and is known as the adrenaline autoxidation chain reaction, whose products are adrenochrome and radical compounds, superoxide anions −i (O2 ), and other. This reaction was previously used to determine the activity of superoxide dismutase as a model of superoxide generation. We have proposed various new methodical approaches that allow the determination of the enzyme activity and reveal the anti/prooxidant properties of various compounds and materials. This pathway of conversion of one of the catecholamines (dopamine) is currently described as a “preclinical model of Parkinson’s disease.” In this regard, we have proposed the reaction of adrenaline autoxidation to be used in search for substances that can inhibit the process of quinoid oxidation, that is, to identify potential neuroprotective agents. Experimental and theoretical studies of this reaction expand the understanding of the mechanisms of free radical processes that occur in the body. Keywords: catecholamines, aminochromes, аdrenaline, adrenochrome, superoxide, quinoid oxidation DOI: 10.1134/S0006350920040223
THE QUINOID PATHWAY OF ADRENALINE OXIDATION The hormone mediator adrenaline, which is involved in the regulation of the functional state of the sympathoadrenal system, is produced mainly by the chromaffin tissue of the adrenal medulla; it is metabolized in the body in several ways, like other catecholamines. Oxymethylation with the formation of metanephrine (~70%) and oxidative deamination with the participation of monoamine oxidase (~20%) are the main paths of its transformation. In addition, the socalled quinoid oxidation of adrenaline can occur under certain conditions with the formation of quinones, such as adrenochrome, and then, possibly, to adrenolutin and indole [1, 2]. Specific enzymes of this pathway of adrenaline oxidation have not been identified; however, the resulting products exist and enzymes that utilize them are known [2–6]. Removal of the products of quinoid oxidation of adrenaline and other aminochromes occurs with the participation of the enzymes glutathione-S-transferase [2, 3] and quinone reductase [4]. Adrenochrome can also be a substrate of hydrolase, lipase, esterase [5] and xanthine oxidase [6]. All known natural catecholamines (bioAbbreviations: ROS, reactive oxygen species; PD, Parkinson’s disease; SOD, superoxide dismutase.
genic amines) can be oxidized to the corresponding aminochromes in a sim
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