Distinguishing Glycyrrhiza species using NMR-based metabolomics

Abstract

Glycyrrhiza species are widely used as natural medicines and as well as food additives. Quality control during methods development is therefore critically important. In this study, we conducted NMR-based metabolomics analyses to distinguish Glycyrrhiza species (G. glabra, G. uralensis, and G. inflata). Principle component analysis (PCA) of 1H-NMR spectra of extracts of Glycyrrhiza species enabled categorization of the three species. We conducted solid-phase extraction of methanol extracts of Glycyrrhiza roots prior to NMR measurements. Most studies of Glycyrrhiza species have used mass spectra to distinguish species. By conducting solid-phase extraction prior to NMR analysis, we could distinguish species clearly by PCA score plots. These results indicate that solid-phase extraction enables clear discrimination of Glycyrrhiza species in NMR metabolomics analyses. Furthermore, saponin fractions prepared by solid-phase extraction from water extracts were also discriminated according to the species using NMR metabolomics. Saponins such as glycyrrhizin are important constituents of Glycyrrhiza species. These results thus indicate that there are species-specific differences in root saponins in Glycyrrhiza.