title: Simultaneous UHPLC/DAD/(+/-)HESI-MS/MS analysis of phenolic acids and nepetalactones in methanol extracts of Nepeta species: a possible application in chemotaxonomic studies.
abstract: BACKGROUND
  Nepeta species contain a variety of secondary metabolites, including iridoid monoterpenes - nepetalactones and phenolic acids - that are considered the main bioactive constituents. This work represents the first attempt to comparatively explore variations in these two major groups of secondary metabolites within the genus.
  
  
  OBJECTIVE
  To develop an efficient analytical methodology for simultaneous analysis of nepetalactones and phenolic acids in methanol extracts of selected Nepeta species, and to evaluate its potential application in chemotaxonomic studies.
  
  
  METHODS
  A UHPLC combined with linear-trap quadrupole (LTQ) orbitrap MS method was used to characterise chemical diversity and complexity of phenolics among 12 selected Nepeta species. A targeted metabolomic approach using UHPLC coupled to a diode array detector (DAD) and combined with (+/-) heated electrospray ionisation (HESI) MS/MS was developed and validated for quantitative analysis of six hydroxycinnamic acid derivatives and four nepetalactones.
  
  
  RESULTS
  Phenolic profiling provided a valuable database of bioactive compounds in the plant group studied, including phenolic acids (hydroxybenzoic and hydroxycinnamic acids) and flavonoids (flavones, flavonols and flavanones). Principal component analysis and cluster analysis suggested the applicability of 10 targeted compounds as chemomarkers for chemotaxonomic studies. Pearson's correlation analysis revealed significant positive correlations between metabolites involved in different biosynthetic pathways (phenylpropanoid or monoterpenoid).
  
  
  CONCLUSIONS
  The described targeted metabolomic approach proved to be highly beneficial in designing a phytochemical overview of the genus Nepeta, and might have applications in further clarification of phylogenetic relations. Furthermore, it has the potential to be implemented in a routine quality control of plant material and herbal preparations.
authors.affiliation: Institute for Biological Research 'Siniša Stanković', University of Belgrade, Bulevar despota Stefana 142, 11060, Belgrade, Serbia.
authors.forename: Danijela
authors.initials: D
authors.lastname: Mišić
authors.forename: Branislav
authors.initials: B
authors.lastname: Siler
authors.forename: Uroš
authors.initials: U
authors.lastname: Gašić
authors.forename: Stevan
authors.initials: S
authors.lastname: Avramov
authors.forename: Suzana
authors.initials: S
authors.lastname: Zivković
authors.forename: Jasmina
authors.initials: J
authors.lastname: Nestorović Živković
authors.forename: Milica
authors.initials: M
authors.lastname: Milutinović
authors.forename: Zivoslav
authors.initials: Z
authors.lastname: Tešić
mesh_terms: D002851:Chromatography, High Pressure Liquid; D016000:Cluster Analysis; D000081004:Cyclopentane Monoterpenes; D003517:Cyclopentanes / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D062385:Hydroxybenzoates / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D055432:Metabolomics; D000432:Methanol; D015394:Molecular Structure; D027521:Nepeta / Q000737:chemistry*; D010636:Phenols / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D035261:Plant Components, Aerial / Q000737:chemistry; D010936:Plant Extracts / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D011753:Pyrones / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D053719:Tandem Mass Spectrometry
chemical_list: D000081004:Cyclopentane Monoterpenes; D003517:Cyclopentanes; D005419:Flavonoids; D062385:Hydroxybenzoates; D010636:Phenols; D010936:Plant Extracts; D011753:Pyrones; C115644:nepetalactone; C017616:phenolic acid; D000432:Methanol
keywords: Chemotaxonomy; Lamiaceae; Nepeta; catmint; catnip; nepetalactone; phenolic acids; targeted metabolomic analysis