Total phenolic content and antioxidant capacity of lichen extracts

• Published in: Zeitschrift für Phytotherapie
• Main Authors: Koptina, A, Shcherbakova, A, Soldati, F, Ulrich-Merzenich, G
• Format: Conference Proceeding
• Language: English
• Published: 01.03.2013
• ISSN: 0722-348X; 1438-9584
• DOI: 10.1055/s-0033-1338237

Background: Lichens are unique organisms consisting of a fungus and a photosynthetic partner growing in a symbiotic relationship [1]. Lichens have the ability to survive extreme conditions like low temperature, aridity or high UV radiation [2]. Recent data showed the resistance of the lichen symbiosis Aspicilia fruticulosa to space conditions: experiments with the European Biopan facility (a spaceflight on board of a Russian Foton retrievable satellite) revealed that space vacuum/cosmic radiation did not impair metabolic activity of lichens [3]. The effect was related to high amounts of antioxidant compounds [3] commonly equated with polyphenols. Objective: We evaluated the in vitro antioxidant activity/phenolic content of different extracts (Ex) from 4 lichen's species collected in the Republic of Mari El in Russia: Cladonia ragiferina (CR), Cladonia sylvatica (CS), Evernia prunastri (EP) and Usnea barbata (UB). Methods: Lichens were air-dried at RT and grounded to a uniform powder. The Soxhlet extraction of lichens using chloroform as a solvent or mechanochemical treatment with NaOH and further maceration with 40% ethanol were performed. The total antioxidant capacity of Ex and the total phenolics content were determined using the phosphomolybdenum method [4] and the Folin-Ciocalteau method, respectively. Results: The highest total phenolic content was determined in the chloroform Ex of EP with 401 ± 18 mg-equivalent of GA/g extract. The standard of usnic acid equals to 378 ± 13 mg of GA/g. The highest antioxidant activity was measured in CR (chloroform Ex) and CS (NaOH with ethanol Ex): 298 ± 14 mg AA/g and 286 ± 34 mg AA/g, respectively (Table 1). Conclusion: The phenolic content did not match the antioxidant capacity considering the applied methods. Further studies of lichen's antioxidant/radical scavenging activity in relation to responsible compounds are essential to identify natural compounds that can be used to reduce oxidative stress associated with many human diseases. Sample Total antioxidant activity, mg AA per g extract Total phenolics content, mg GA per g extract Usnic acid (standard) 148.9 ± 2.9 377.5 ± 13.2 CS (chloroform Ex) 170.8 ± 27.6 285.1 ± 1.0 CS (petroleum ether Ex) 161.7 ± 19.7 309.9 ± 3.0 CS (acetone Ex) 151.0 ± 19.0 301.4 ± 3.9 CS (NaOH with ethanol Ex) 285.6 ± 33.7 229.9 ± 2.5 CR (chloroform Ex) 298.4 ± 13.5 234.1 ± 7.7 UB (chloroform Ex) 206.5 ± 5.1 243.8 ± 2.0 EP (chloroform Ex) 172.6 ± 12.6 401.1 ± 18.1 AA – ascorbic acid, GA – gallic acid References: [1] Molnár K et al. Z Naturforsch C 2010; 65: 157 – 173 [2] de Vera JP. Fungal Ecology 2012; 5: 472 – 479 [3] Raggio J et al. Astrobiology 2011; 11: 281 – 292 [4] Manojlovic NT et al. Evid Based Complement Alternat Med 2012; 452431