Application of diffusion-edited and solvent suppression 1H-NMR to the direct analysis of markers in valerian-hop liquid herbal products

Introduction - 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. Objectives - This work looks at the application of one-dimensional diffusion-edited H-1-NMR spectroscopy (1D DOSY) and H-1-NMR with suppression of the ethanol and water signals to the characterisation of quality and stability markers in multi-component herbal medicines/food supplements. Material and 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 D2O and TSP. Results - The best diagnostic signals were found at 7ppm (H-11, valerenic acid), 4.2ppm (H-1, hydroxyvalerenic acid) and 1.5-1.8ppm (methyl groups in prenylated moieties, -acids/prenylated flavones). Conclusion - This work concludes on the potential value of 1D DOSY H-1-NMR to provide additional assurance of quality in complex natural mixtures. Copyright (c) 2016 John Wiley & Sons, Ltd. Direct One-dimensional diffusion-edited 1H-NMR spectroscopy (1D DOSY) successfully detected expired commercial tinctures of valerian, as well as the presence of phytomarkers from hops in valerian-hops commercial tinctures. This technique did not require evaporation and re-dissolution of the sample in deuterated solvents but only the addition of D2O and TSP to the commercial tincture. The best diagnostic signals were found at 4.2 (hydroxyvalerenic acid) and 1.5-1.8 ppm (-acids).