title: Application of diffusion-edited and solvent suppression ¹H-NMR to the direct analysis of markers in valerian-hop liquid herbal products.
abstract: BACKGROUND
  The rising trend to consume herbal products for the treatment and/or prevention of minor ailments together with their chemical and pharmacological complexity means there is an urgent need to develop new approaches to their quality and stability.
  
  
  OBJECTIVE
  This work looks at the application of one-dimensional diffusion-edited (1)H-NMR spectroscopy (1D DOSY) and (1)H-NMR with suppression of the ethanol and water signals to the characterisation of quality and stability markers in multi-component herbal medicines/food supplements.
  
  
  METHODS
  The experiments were performed with commercial tinctures of Valeriana officinalis L. (valerian), expired and non-expired, as well as its combination with Hummulus lupulus L. (hops), which is one of the most popular blends of relaxant herbs. These techniques did not require purification or evaporation of components for the qualitative analysis of the mixture, but only the addition of D2 O and TSP.
  
  
  RESULTS
  The best diagnostic signals were found at δ 7 ppm (H-11, valerenic acid), δ 4.2 ppm (H-1, hydroxyvalerenic acid) and δ 1.5-1.8 ppm (methyl groups in prenylated moieties, α-acids/prenylated flavones).
  
  
  CONCLUSIONS
  This work concludes on the potential value of 1D DOSY (1)H-NMR to provide additional assurance of quality in complex natural mixtures.
authors.affiliation: Department of Pharmaceutical and Biological Chemistry, The School of Pharmacy, University of London, 29-39 Brunswick Square, London, WC1N 1AX, UK.
authors.forename: Jose M
authors.identifier: http://orcid.org/0000-0002-2649-1691
authors.initials: JM
authors.lastname: Prieto
authors.affiliation: Department of Pharmaceutical and Biological Chemistry, The School of Pharmacy, University of London, 29-39 Brunswick Square, London, WC1N 1AX, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Mellinas-Gomez
authors.affiliation: Department of Pharmaceutical and Biological Chemistry, The School of Pharmacy, University of London, 29-39 Brunswick Square, London, WC1N 1AX, UK.|Department of Pharmacy, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, UK.
authors.forename: Mire
authors.initials: M
authors.lastname: Zloh
mesh_terms: D029001:Herbal Medicine; D066244:Proton Magnetic Resonance Spectroscopy; D012997:Solvents / Q000737:chemistry*; D014632:Valerian / Q000737:chemistry*
chemical_list: D012997:Solvents
keywords: Herbal medicinal product; Humulus lupulus L; Valeriana officinalis; diffusion edited spectroscopy; nuclear magnetic resonance; quality marker