title: Inhibition of 5-lipoxygenase as anti-inflammatory mode of action of Plectranthus zeylanicus Benth and chemical characterization of ingredients by a mass spectrometric approach.
abstract: BACKGROUND
  The perennial herb Plectranthus zeylanicus Benth is extensively used in traditional medicine in Sri Lanka and South India for treating inflammatory conditions, but pharmacological features of Plectranthus zeylanicus are hardly explored in order to understand and rationalize its use in ethnomedicine. As 5-lipoxygenase (5-LO) is a key enzyme in inflammatory disorders such as asthma or atherosclerosis, we investigated 5-LO inhibition by Plectranthus zeylanicus extracts and analyzed relevant constituents.
  
  
  METHODS
  We applied cell-free and cell-based assays to investigate suppression of 5-LO activity. Cell viability, radical scavenger activities, and inhibition of reactive oxygen species formation (ROS) in neutrophils were analysed to exclude unspecific cytotoxic or antioxidant effects. Constituents of the extracts were characterized by bioassay-guided fractionation and by analysis using gas or liquid chromatography coupled to mass spectrometric (Orbitrap) analysis.
  
  
  RESULTS
  Extracts of Plectranthus zeylanicus prepared with n-hexane or dichloromethane potently suppressed 5-LO activity in stimulated human neutrophils (IC50=6.6 and 12µg/ml, respectively) and inhibited isolated human recombinant 5-LO (IC50=0.7 and 1.2µg/ml, respectively). In contrast, no significant radical scavenging activity or suppression of ROS formation was observed, and neutrophil viability was unaffected. Besides ubiquitously occurring ingredients, coleone P, cinncassiol A and C, and callistric acid were identified as constituents in the most active fraction.
  
  
  CONCLUSIONS
  Together, potent inhibition of 5-LO activity, without concomitant anti-oxidant activity and cytotoxic effects, rationalizes the ethnopharmacological use of Plectranthus zeylanicus as anti-inflammatory remedy. Modern chromatographic/mass spectrometric analysis reveals discrete chemical structures of relevant constituents.
authors.affiliation: Research Group Mass Spectrometry and Proteomics, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, D-07745 Jena, Germany.
authors.forename: Mayuri
authors.initials: M
authors.lastname: Napagoda
authors.affiliation: Chair of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University Jena, Philosophenweg 14, D-07743 Jena, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Gerstmeier
authors.affiliation: Chair of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University Jena, Philosophenweg 14, D-07743 Jena, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Wesely
authors.affiliation: Chair of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University Jena, Philosophenweg 14, D-07743 Jena, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Popella
authors.affiliation: Research Group Mass Spectrometry and Proteomics, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, D-07745 Jena, Germany.
authors.forename: Sybille
authors.initials: S
authors.lastname: Lorenz
authors.affiliation: Chair for Bioinformatics, Friedrich-Schiller-University Jena, Ernst-Abbe-Platz 2, D-07743 Jena, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Scheubert
authors.affiliation: Research Group Mass Spectrometry and Proteomics, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, D-07745 Jena, Germany. Electronic address: svatos@ice.mpg.de.
authors.forename: Aleš
authors.initials: A
authors.lastname: Svatoš
authors.affiliation: Chair of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University Jena, Philosophenweg 14, D-07743 Jena, Germany. Electronic address: oliver.werz@uni-jena.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Werz
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D002853:Chromatography, Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D031346:Plectranthus; D017382:Reactive Oxygen Species / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000893:Anti-Inflammatory Agents; D016859:Lipoxygenase Inhibitors; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D001094:Arachidonate 5-Lipoxygenase
keywords: 5-Lipoxygenase; Inflammation; Mass spectrometry; Neutrophils; Plectranthus zeylanicus; Radical scavenger