title: Antitubercular activity of Arctium lappa and Tussilago farfara extracts and constituents.
abstract: BACKGROUND
  Arctium lappa and Tussilago farfara (Asteraceae) are two plant species used traditionally as antitubercular remedies. The aim of this study was (i) to screen Arctium lappa and Tussilago farfara extracts for activity against Mycobacterium tuberculosis and (ii) to isolate and identify the compound(s) responsible for this reputed anti-TB effect.
  
  
  METHODS
  The activity of extracts and isolated compounds was determined against Mycobacterium tuberculosis H37Rv using a high throughput spot culture growth inhibition (HT-SPOTi) assay.
  
  
  RESULTS
  The n-hexane extracts of both plants, the ethyl acetate extract of Tussilago farfara and the dichloromethane phase derived from the methanol extract of Arctium lappa displayed antitubercular activity (MIC 62.5 μg/mL). Further chemical investigation of Arctium lappa led to the isolation of n-nonacosane (1), taraxasterol acetate (2), taraxasterol (3), a (1:1) mixture of β sitosterol/stigmasterol (4), isololiolide (5), melitensin (6), trans-caffeic acid (7), kaempferol (8), quercetin (9), kaempferol-3-O-glucoside (10). Compounds isolated from Tussilago farfara were identified as a (1:1) mixture of β sitosterol/stigmasterol (4), trans-caffeic acid (7), kaempferol (8), quercetin (9), kaempferol-3-O-glucoside (10), loliolide (11), a (4:1) mixture of p-coumaric acid/4-hydroxybenzoic acid (12), p-coumaric acid (13). All compounds were identified following analyses of their physicochemical and spectroscopic data (MS, (1)H and (13)C-NMR) and by comparison with published data. This is the first report of the isolation of n-nonacosane (1), isololiolide (5), melitensin (6) and kaempferol-3-O-glucoside (10) from Arctium lappa, and of loliolide (11) from Tussilago farfara. Amongst the isolated compounds, the best activity was observed for p-coumaric acid (13) (MIC 31.3 μg/mL or 190.9 μM) alone and in mixture with 4-hydroxybenzoic acid (12) (MIC 62.5 μg/mL).
  
  
  CONCLUSIONS
  The above results provide for the first time some scientific evidence to support, to some extent, the ethno-medicinal use of Arctium lappa and Tussilago farfara as traditional antitubercular remedies.
authors: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK.
authors: Jinlian
authors: J
authors: Zhao
authors: Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, London, UK.
authors: Dimitrios
authors: D
authors: Evangelopoulos
authors: Mycobacteria Research Laboratory, Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, University of London, London, UK.
authors: Sanjib
authors: S
authors: Bhakta
authors: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK.
authors: Alexander I
authors: AI
authors: Gray
authors: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK. Electronic address: veronique.seidel@strath.ac.uk.
authors: Véronique
authors: V
authors: Seidel
mesh_terms: D000995:Antitubercular Agents / Q000302:isolation & purification / Q000494:pharmacology*; D031170:Arctium / Q000737:chemistry*; D020834:Ethnopharmacology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D008519:Medicine, Traditional; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D031207:Tussilago / Q000737:chemistry*
chemical_list: D000995:Antitubercular Agents; D010936:Plant Extracts
keywords: Antitubercular activity; Arctium lappa; Mycobacterium tuberculosis; Tussilago farfara