Identification And Characterization Of Chemical Constituents From Licorice Roots Using UHPLC-QTOF-MS

Dried roots and rhizomes of Glycyrrhiza species are named licorice. It is also considered one of the oldest and most widely used natural products in both Eastern and Western countries. Phenolic, triterpenoid, triterpene saponin compounds are normally considered as the main bioactive compounds of licorice [1]. Biological studies have demonstrated that licorice has a variety of biological effects [2 – 4]. A simple and effective UHPLC-QToF-MS method was developed for identification and characterization of chemical constituents in licorice, based on authenticated materials of Glycyrrhiza species (G. glabra and G. uralensis). Chromatographic separation was achieved using a Poroshell 120 EC-C18 (150 × 2.1 mm, 2.7µ) column. The mobile phase consists of acetonitrile and water, both containing 0.1% formic acid. UHPLC-coupled with electrospray ionization (ESI)-mass spectrometry method offered more information about the chemical constituents of Glycyrrhiza species. This method involved the use of the [M+H] ⁺ ions in the positive ion mode with extractive ion chromatogram (EIC). Thirty-five known compounds including, glycyrrhizin, glabridin, liquiritigenin, gycyrrehetic acid, isoliquiritin, 3, 4-didehydroglabridin, formononetin, glyasperin D from G. glabra and G. uralensis were characterized by QToF-MS. The product ion spectrum of glycyrrhizin showed ions at m/z = 647.3778, 453.3358, 357.2377, 317.0503 generated at a collision energy (CE) of 20 eV, suggesting that the precursor ion m/z = 823.4105 [M+H] ⁺ is readily converted to the product ions m/z = 647[M-C₆H₁₀O₆], 453 [M-2(C₆H₁₀O₆)-H₂O], 357, 317 under collisional activated dissociation (CAD) conditions. Thirty plant samples of Glycyrrhiza species and 11 commercial products were analyzed in this study.

Acknowledgements: This research is supported in part by “Science Based Authentication of Dietary Supplements” funded by the Food and Drug Administration grant number 1U01FD004246 – 05, the United States Department of Agriculture, Agricultural Research Service, Specific Cooperative Agreement No. 58 – 6408 – 1-603 – 07.

References: [1] Zhang Q, Ye M. (2009)J. Chromatogr. A 1216: 1954. [2] Fiore C, Eisenhut M, (2008) Phytotherapy Res. 22: 141 – 148. [3] Dhingra D, Sharma A (2006) Prog Neuropsychopharmacol Biol Psychiatry 30: 449 – 454. [4] Lee JR, Park SJ, et al. (2009) Evid. Based Complement. Alternat. Med. 6: 195 – 201.