A Comparative Study of Isolated Secondary Metabolites from Lichens and Their Antioxidative Properties

• Published in: Plants (Basel) Vol. 11; no. 8; p. 1077
• Main Authors: Elečko, Ján, Vilková, Mária, Frenák, Richard, Routray, Deepti, Ručová, Dajana, Bačkor, Martin, Goga, Michal
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 15.04.2022; MDPI
• Subjects: Acids; antioxidant activity; Antioxidants; Carcinogens; Carotenoids; Chemical reactions; Chromatography; Comparative studies; DPPH; Free radicals; Fungi; Lichens; Mathematical analysis; Metabolites; Mixtures; NMR; Oxidative stress; Phenolic compounds; Phenols; Scavenging; Secondary metabolites; Side effects; Stoichiometry; superoxide anion; Superoxide anions; Usnic acid; lichens; NMR; secondary metabolites; DPPH; antioxidant activity; superoxide anion
• ISSN: 2223-7747; 2223-7747
• DOI: 10.3390/plants11081077

Free radicals play a critical role in the chemical processes that occur in all cells. Pharmaceutical companies manufacture a variety of synthetically prepared antioxidants, but it is known that many of these can be carcinogenic. As a result, efforts are being made to find natural antioxidants that do not have these side effects. Lichens may be suitable candidates because they contain secondary metabolites with proven antioxidant properties. This could be explained by the presence of compounds with phenolic groups in lichens. The radical scavenging reaction is a chemical reaction governed by stoichiometry, and our aim is to determine the efficacy of these reactions. The aim of this study is to compare metabolite activity based on the same amount of substance involved in radical scavenging, calculated in micromoles rather than weight concentration. This provides an accurate way of comparing radical scavenging activity. We tested superoxide anion scavenging activity and free radical scavenging activity of isolated lichen secondary metabolites and their mixtures in different ratios. The following compounds were isolated and tested for antioxidant activity: gyrophoric acid ( ), evernic acid ( ), physodic acid, 3-hydroxyphysodic acid, physodalic acid and atranorin ( ), and usnic acid (as a synthetic compound). Of all the tested compounds, 3-hydroxyphysodic acid, as well as mixtures containing this metabolite, showed the strongest scavenging activity. The results also demonstrated that calculation by amount of substance leads to a new consideration of antioxidant activity.