Antimicrobial Activity of Divaricatic Acid Isolated from the Lichen Evernia mesomorpha against Methicillin-Resistant Staphylococcus aureus
Department of Pharmacy, and Research Institute of Life Pharmaceutical Sciences, Sunchon National University, Suncheon 57922, Korea
Department of Agricultural Chemistry, Sunchon National University, Suncheon 57922, Korea
Author to whom correspondence should be addressed.
Molecules 2018, 23(12), 3068; https://doi.org/10.3390/molecules23123068
Received: 30 October 2018 / Revised: 20 November 2018 / Accepted: 23 November 2018 / Published: 23 November 2018
(This article belongs to the Section Natural Products Chemistry)
One hundred and seventy seven acetone extracts of lichen and 258 ethyl acetate extracts of cultured lichen-forming fungi (LFF) were screened for antimicrobial activity against Staphylococcus aureus and Enterococcus faecium using a disk diffusion method. Divaricatic acid was isolated from Evernia mesomorpha and identified by LC-MS, 1H-, 13C- and DEPT-NMR. Purified divaricatic acid was effective against Gram + bacteria, such as Bacillus subtilis, Staphylococcus epidermidis, Streptococcus mutans, and Enterococcus faecium, with the minimum inhibitory concentration (MIC) values ranging from 7.0 to 64.0 μg/mL, whereas vancomycin was effective in the MICs ranging from 0.78 to 25.0 μg/mL. Interestingly, the antibacterial activity of divaricatic acid was higher than vancomycin against S. epidermidis and E. faecium, and divaricatic acid was active against Candida albicans. In addition, divaricatic acid was active as vancomycin against S. aureus (3A048; an MRSA). These results suggested that divaricatic acid is a potential antimicrobial agent for the treatment of MRSA infections.