Planta Med 2015; 81 - PM_151
DOI: 10.1055/s-0035-1565528

Antibacterial activity of 19 species from the Juncaceae family, and bioactivity guided fractionation of the most active species Juncus inflexus

B Tóth 1, E Liktor-Busa 1, E Urban 2, G Jakab 3, J Hohmann 1, A Vasas 1
  • 1Department of Pharmacognosy, University of Szeged, Szeged, Hungary
  • 2Institute of Clinical Microbiology, University of Szeged, Szeged, Hungary
  • 3Institute of Environmental Sciences, Faculty of Water and Environmental Management, Szent István University, Szarvas, Hungary

The increasing prevalence of multidrug resistant pathogens encourages the development of new antimicrobial agents. Plants of the Juncaceae family accumulate a high diversity of phenanthrene type compounds, which have attracted great interest from phytochemical and pharmacological points of view. Previously the cytotoxic, antimicrobial, antiviral and anti-inflammatory activities of the phenanthrenes were reported.

The main object of this work was to investigate the antibacterial activity of 96 extracts (n-hexane, CH2Cl2, EtOAc and remaining aqueos MeOH) of 19 species from the Juncaceae family against methicillin-resistant S. aureus, extended-spectrum β-lactamase (ESBL)-producing C. freundii, E. coli, E. cloacae, K. pneumoniae, multiresistant A. baumannii and P. aeruginosa. Antibacterial susceptibilities were screened for inhibitory zones and MICs determined by the microdilution method.

16 extracts (CH2Cl2) from Juncus species and 3 extracts (CH2Cl2) from Luzula species showed mild to strong (inhibition zones = 6.7 – 14.6 mm) inhibitory activities against MRSA strains. Among them the CH2Cl2-soluble fraction of the roots of J. inflexus showed the highest activity (MIC = 9.75 µg/mL). Therefore this extract was subjected to bioactivity guided fractionation. The extract was chromatographed by CC on polyamide, and then on silica gel vacuum CC, MPLC, preparative TLC and finally by RP-HPLC. Structure determinations were carried out by means of MS and NMR spectroscopy and comparison of the spectral data with literature values. The results allowed to the identification of 5 phenantherenes, substituted with vinyl, hydroxyl, methyl and aldehyde groups. These compounds were evaluated for their antibacterial activity, and juncusol showed significant activity (inhibition zone = 12 mm) against MRSA strains.

Acknowledgement: This work was supported by the Hungarian Scientific Research Fund (OTKA K109846) and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences.