Metabolite Profiling and Classification of DNA-Authenticated Licorice Botanicals

Abstract

Raw licorice roots represent heterogeneous materials obtained from mainly three Glycyrrhiza species. G. glabra, G. uralensis, and G. inflata exhibit marked metabolite differences in terms of flavanones (Fs), chalcones (Cs), and other phenolic constituents. The principal objective of this work was to develop complementary chemometric models for the metabolite profiling, classification, and quality control of authenticated licorice. A total of 51 commercial and macroscopically verified samples were DNA authenticated. Principal component analysis and canonical discriminant analysis were performed on 1H NMR spectra and area under the curve values obtained from UHPLC-UV chromatograms, respectively. The developed chemometric models enable the identification and classification of Glycyrrhiza species according to their composition in major Fs, Cs, and species specific phenolic compounds. Further key outcomes demonstrated that DNA authentication combined with chemometric analyses enabled the characterization of mixtures, hybrids, and species outliers. This study provides a new foundation for the botanical and chemical authentication, classification, and metabolomic characterization of crude licorice botanicals and derived materials. Collectively, the proposed methods offer a comprehensive approach for the quality control of licorice as one of the most widely used botanical dietary supplements.

Cytochrome P450 inhibition by three licorice species and fourteen licorice constituents

“…Glycyrrhiza inflata Batalin was collected in Xinjiang province, China in 2012. Licorice powders were botanically identified through DNA-based identification, macroscopic and microscopic analyses, and comparison with voucher specimens at the Field Museum of Natural History (Chicago, IL) as well as DNA barcoding as described previously (Simmler et al , 2015a). The root powders from each species were extracted by maceration at room temperature with a solvent mixture consisting of ethanol (200 USP proof), isopropanol and water (90:5:5, v/v/v) and a plant powder/volume of solvent ratio of 1:15 (Hajirahimkhan et al , 2015).…”

“…In the European and Chinese Pharmacopoeias, G. glabra, G. uralensis and G. inflata are used interchangeably (World Health Organization, 1999). Because of this botanical ambiguity, many licorice dietary supplements do not disclose which species are used in their formulation (Zhang and Ye, 2009; Simmler et al , 2015a). …”

Identification and Chemical Standardization of Licorice Raw Materials and Dietary Supplements Using UHPLC-MS/MS

“…All 12 plant materials were botanically identified through macroscopic/microscopic analyses and comparison with voucher specimens at the Field Museum of Natural History (Chicago, IL), as well as DNA barcoding, as described previously. 7 …”

“…15,16 Quality control of dietary supplements also requires quantitative measurement of chemical constituents in the starting material and in the finished product. In the case of licorice, a variety of analytical methods such as capillary-zone electrophoresis, 17 HPLC-UV, 18–22 nuclear magnetic resonance (NMR), 7 HPLC-mass spectrometry, 10 and HPLC-tandem mass spectrometry (MS/MS) 23–24 have been used to measure chemical constituents in crude extracts, but rarely in the complex matrices of commercial botanical dietary supplements.…”

Isolation and structural characterization of dihydrobenzofuran congeners of licochalcone A

“…Such coloration can be attributed to the abundance of diverse chalcones, as the phytochemical composition of G. inflata has been demonstrated to greatly differ from the other widely used Glycyrrhiza species, due to the presence and abundance of structurally related “retrochalcones”. These compounds are structurally related to echinatin and licochalcone A [3][4][5][6]. In fact, the term retrochalcone has been coined initially for echinatin as a result of a biosynthetic investigation in G. echinata callus cultures [7][8] [9].…”