Antioxidant and antimicrobial activity of extracts of Cetraria islandica (L.) Ach. and Cladonia arbuscula (Wallr.) Flot.

Abstract

Lichens are symbiotic nature and produce unique secondary extracellular metabolites with high biological activity. In this paper, we compared the antioxidant and antimicrobial activity of two lichen species. Furthermore, we determined the quantitative content of antioxidants of low molecular weight and antimicrobial activity of 40% of the water ethyl extracts of Cetraria islandica and Cladonia arbuscula lichens depending on the layers’ treatment methods and the ratio of dilution of the dry extract with water. Live parts of dried lichens collected in an ecologically clean area of Yakutia were used for extraction. The antioxidant activity of the water-ethanol extract of lichens was performed using a spectrophotometric method. Antimicrobial activity was established using the discodiffusion method in agar in various dilutions of dry lichen extract. The highest antioxidants of low molecular weight were found in Cetraria islandica in distilled water with solid to solvent ratio of 1:1 and in the Cladonia arbuscula extract – in a ratio of 1:5. At the same time, preliminary mechanochemical processing of lichen layer raw materials from lichen layers (particle size up to 1 mm) was shown to increase the yield of low-molecular antioxidants by up to 50% compared to coarse grinding (particle size 2 mm). The antibacterial activity of the studied lichens was tested in Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli by diluting the dry extract with water 1:1, 1:2, 1:3, 1:4, 1:5. The most significant antibacterial effect was found in the extract of the studied lichens in a 1:1 ratio. The diameter of the bacteriostatic zone in Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli under the action of Cetraria islandica was 12±0.14 mm, 11±0.12 mm, and 12±0.13 mm, respectively. The suppression of the growth zone with Cladonia arbuscula against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli was 15±0.18 mm, 12±0.20 mm, and 13±0.20 mm in diameter, respectively. The results were in accordance with the action of oxacillin but were more effective than the action of penicillin, which served as a control.

Keywords

• lichens
• cetraria islandica
• cladonia arbuscula
• low molecular weight antioxidants