Medicinal Chemistry Research

, Volume 27, Issue 5, pp 1443–1448 | Cite as

Potentiation effects by usnic acid in combination with antibiotics on clinical multi-drug resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA)

  • Guo-Ying Zuo
  • Rui-Chun Fu
  • Wei Yu
  • Yun-Ling Zhang
  • Gen-Chun Wang
Original Research


The in vitro antibacterial activities of usnic acid (UA) in combination with six currently available antibiotics were evaluated through checkerboard microdilution and dynamic time-killing assays against Staphylococcus aureus and 10 clinical isolates of methicillin-resistant S. aureus (MRSA). The six antibiotics include three aminoglycosides (i.e., amikacin (AK), etimicin (EM), streptomycin (SM)), two glycopeptides (i.e., teicoplanin (TP), vancomycin (VA)) and a tetracycline (i.e., minocycline (MC)). UA alone showed MIC of 16 μg/mL against both S. aureus and MRSA strains. The checkerboard assay showed the range of fractional inhibitory indices (FICIs) as 0.156–1.500 against all the pathogens when UA was used in combination with the antibiotics. Significant bacteriostatic interactions of UA with TP and MC were observed. The enhancement of antibacterial activities against the tested pathogens were revealed by the bacteriostatic dose reduction indices (DRIs) ranges at 1–64 of UA and 1–32 of the antibiotics, especially the synergy of UA with TP by 90% and additive effects with VA by 50% isolates of MRSA strains, respectively. MC also showed 60% strains of synergy with UA. The time-killing curves further confirmed the bactericidal synergy among the combinations of UA with TP, AK, EM, and SM (1 × MIC, △LC24 = 3.406–4.344 log10CFU/mL) against one of the 10 MRSA strains, respectively. Other combinations showed additive effects or indifferences, while no antagonism occurred in all the tested combinations. The anti-MRSA potentiation is promising for further investigations in order to form a possible scenario of UA/antibiotics combinatory chemotherapy which would reduce their dosages and toxicological responses.


Anti-MRSA activity Usnic acid Synergy Glycopeptides Minocycline 



This work was supported by the National Natural Science Foundation of China (NSFC 81173504) and the supporting fund of Yunnan Province of China (2008PY001).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. Araujo AA, de Melo MG, Rabelo TK, Nunes PS, Santos SL, Serafini MR, Santos MR, Quintans-Junior LJ, Gelain DP (2015) Review of the biological properties and toxicity of usnic acid. Nat Prod Res 29:2167–2180CrossRefPubMedGoogle Scholar
  2. Bruniera FR, Ferreira FM, Saviolli LR, Bacci MR, Feder D, Da LGPM, Sorgini Peterlini MA, Azzalis LA, Campos Junqueira VB, Fonseca FL (2015) The use of vancomycin with its therapeutic and adverse effects: a review. Eur Rev Med Pharmacol Sci 19:694–700PubMedGoogle Scholar
  3. Chin JN, Jones RN, Sader HS, Savage PB, Rybak MJ (2008) Potential synergy activity of the novel ceragenin, CSA-13, against clinical isolates of Pseudomonas aeruginosa, including multidrug-resistant P. aeruginosa. J Antimicrob Chemother 61:365–370CrossRefPubMedGoogle Scholar
  4. Clinical and Laboratory Standards Institute (2012) Table 2C. Zone diameter and MIC interpretive standards for Staphylococcus spp. performance standards for antimicrobial susceptibility testing. Twenty Second Informational Supplement. CLSI, Wayne, PA Approved Standard M100–S22Google Scholar
  5. Cocchietto M, Skert N, Nimis PL, Sava G (2002) A review on usnic acid, an interesting natural compound. Naturwissenschaften 89:137–146CrossRefPubMedGoogle Scholar
  6. Cole ST (2014) Who will develop new antibacterial agents? Philos Trans R Soc Lond B Biol Sci 369:20130430CrossRefPubMedPubMedCentralGoogle Scholar
  7. Elo H, Matikainen J, Pelttari E (2007) Potent activity of the lichen antibiotic (+)-usnic acid against clinical isolates of vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus. Naturwissenschaften 94:465–468CrossRefPubMedGoogle Scholar
  8. Esposito S, Purrello SM, Bonnet E, Novelli A, Tripodi F, Pascale R, Unal S, Milkovich G (2013) Central venous catheter-related biofilm infections: an up-to-date focus on meticillin-resistant Staphylococcus aureus. J Glob Antimicrob Resist 1:71–78CrossRefPubMedGoogle Scholar
  9. Felczykowska A, Pastuszak-Skrzypczak A, Pawlik A, Bogucka K, Herman-Antosiewicz A, Guzow-Krzeminska B (2017) Antibacterial and anticancer activities of acetone extracts from in vitro cultured lichen-forming fungi. BMC Complement Altern Med 17:300CrossRefPubMedPubMedCentralGoogle Scholar
  10. Ferraz-Carvalho RS, Pereira MA, Linhares LA, Lira-Nogueira MC, Cavalcanti IM, Santos-Magalhaes NS, Montenegro LM (2016) Effects of the encapsulation of usnic acid into liposomes and interactions with antituberculous agents against multidrug-resistant tuberculosis clinical isolates. Mem Inst Oswaldo Cruz 111:330–334CrossRefPubMedPubMedCentralGoogle Scholar
  11. Francolini I, Norris P, Piozzi A, Donelli G, Stoodley P (2004) Usnic acid, a natural antimicrobial agent able to inhibit bacterial biofilm formation on polymer surfaces. Antimicrob Agents Chemother 48:4360–4365CrossRefPubMedPubMedCentralGoogle Scholar
  12. Hemaiswarya S, Kruthiventi AK, Doble M (2008) Synergism between natural products and antibiotics against infectious diseases. Phytomedicine 15:639–652CrossRefPubMedGoogle Scholar
  13. Hu ZQ, Zhao WH, Asano N, Yoda Y, Hara Y, Shimamura T (2002) Epigallocatechin gallate synergistically enhances the activity of carbapenems against methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 46:558–560CrossRefPubMedPubMedCentralGoogle Scholar
  14. Levine DP (2006) Vancomycin: a history. Clin Infect Dis 42(Suppl):S5–S12CrossRefPubMedGoogle Scholar
  15. Lodise TP, Lomaestro B, Graves J, Drusano GL (2008) Larger vancomycin doses (at least four grams per day) are associated with an increased incidence of nephrotoxicity. Antimicrob Agents Chemother 52:1330–1336CrossRefPubMedPubMedCentralGoogle Scholar
  16. Lu X, Zhao Q, Tian Y, Xiao S, Jin T, Fan X (2011) A metabonomic characterization of (+)-usnic acid-induced liver injury by gas chromatography-mass spectrometry-based metabolic profiling of the plasma and liver in rat. Int J Toxicol 30:478–491CrossRefPubMedGoogle Scholar
  17. Maciag-Dorszynska M, Wegrzyn G, Guzow-Krzeminska B (2014) Antibacterial activity of lichen secondary metabolite usnic acid is primarily caused by inhibition of RNA and DNA synthesis. FEMS Microbiol Lett 353:57–62CrossRefPubMedGoogle Scholar
  18. Mcguinness WA, Malachowa N, Deleo FR (2017) Vancomycin resistance in Staphylococcus aureus. Yale J Biol Med 90:269–281PubMedPubMedCentralGoogle Scholar
  19. Moreira CT, Oliveira AL, Comar JF, Peralta RM, Bracht A (2013) Harmful effects of usnic acid on hepatic metabolism. Chem Biol Interact 203:502–511CrossRefPubMedGoogle Scholar
  20. Nanjing University of Traditional Chinese Medicine (NUTCM) (ed) (2005) Dictionary of Chinese crude drugs. second ed. Shanghai Scientific Technologic Publisher, Shanghai, China, pp 1815–1816Google Scholar
  21. Nithyanand P, Beema Shafreen RM, Muthamil S, Karutha Pandian S (2015) Usnic acid inhibits biofilm formation and virulent morphological traits of Candida albicans. Microbiol Res 179:20–28CrossRefPubMedGoogle Scholar
  22. Prestinaci F, Pezzotti P, Pantosti A (2015) Antimicrobial resistance: a global multifaceted phenomenon. Pathog Glob Health 109:309–318CrossRefPubMedPubMedCentralGoogle Scholar
  23. Sanchez W, Maple JT, Burgart LJ, Kamath PS (2006) Severe hepatotoxicity associated with use of a dietary supplement containing usnic acid. Mayo Clin Proc 81:541–544CrossRefPubMedGoogle Scholar
  24. Segatore B, Bellio P, Setacci D, Brisdelli F, Piovano M, Garbarino JA, Nicoletti M, Amicosante G, Perilli M, Celenza G (2012) In vitro interaction of usnic acid in combination with antimicrobial agents against methicillin-resistant Staphylococcus aureus clinical isolates determined by FICI and DeltaE model methods. Phytomedicine 19:341–347CrossRefPubMedGoogle Scholar
  25. Shibata S, Ukita T (1948) Relation between chemical constitutions and antibacterial effects of usnic acid and its derivatives. Jpn J Med 1:152–155CrossRefPubMedGoogle Scholar
  26. Wagner H, Ulrich-Merzenich G (2009) Synergy research: approaching a new generation of phytopharmaceuticals. Phytomedicine 16:97–110CrossRefPubMedGoogle Scholar
  27. Walters MS, Eggers P, Albrecht V, Travis T, Lonsway D, Hovan G, Taylor D, Rasheed K, Limbago B, Kallen A (2015) Vancomycin-resistant Staphylococcus aureus - Delaware, 2015. MMWR Morb Mortal Wkly Rep 64:1056CrossRefPubMedGoogle Scholar
  28. Zuo GY, Li Y, Wang GC, Li ZS, Han J (2014) Synergistic effects of berberines with antibiotics on clinical multi-drug resistant isolates of methicillin-resistant Staphylococcus aureus (MRSA). Med Chem Res 23:2439–2444CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Guo-Ying Zuo
    • 1
  • Rui-Chun Fu
    • 1
    • 2
  • Wei Yu
    • 1
  • Yun-Ling Zhang
    • 1
  • Gen-Chun Wang
    • 1
  1. 1.Research Center for Natural MedicinesKunming General Hospital of Chengdu Military CommandKunmingChina
  2. 2.School of PharmacyKunming Medical UniversityKunmingChina

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