Antimicrobial activity of Evernia prunastri extracts and its isolates

Aim Lichens are symbiotic organisms known for their antimicrobial activity. In this study we investigated the antimicrobial potential of different extracts from the lichen Evernia prunastri (L.) Ach.

Methods Lichen E. prunastri was sequentially extracted by hexane (Hex), dichloromethane (DCM) and acetonitrile (ACN). Antimicrobial activity was determined using the Minimal Inhibitory Concentration (MIC) method against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. The ACN extract of E. prunastri was separated by silica gel column chromatography. The active fraction was characterized by ¹H and ¹³C-NMR spectroscopy. Analysis of structural similarity with main structures of antibiotics was performed by the Analyse Similarity/ Activity Cliffs tool.

Results The DCM and Hex extracts were both active against S. aureus (MICs: 4 and 21 µg/ml,

respectively) but were less active against Gram-negative bacteria and yeast. The ACN extract exhibited activity on both S. aureus (MIC 14 µg/ml) and C. albicans (MIC 38 µg/ml) and was therefore further fractionated.

Two fractions (V, VI) inhibited the growth of all tested microorganisms and, besides that, fraction VI showed a higher effect against S. aureus. Evernic acid was identified as a main component of this fraction.

Evernic acid as well as other compounds of E. prunastri did not have structural similarity to the main antibiotics representing a novel class of substances with antimicrobial activity.

Conclusion. Analysed compounds could possibly be candidates for development of novel antibiotics [1].

Publication History

Article published online:
13 December 2021

• Reference

• 1 Shcherbakova et al. Antimicrobial and Antioxidant Activity of Evernia prunastri Extracts and their Isolates. World J. Microbiol. Biotechnol. (accepted June 2021)