Chemometric analysis and chemical characterization for the botanical identification of Glycyrrhiza species (G. glabra, G. uralensis, G. inflata, G. echinata and G. lepidota) using liquid chromatography-quadrupole time of flig

Authors: AVULA, BHARATHI - University Of Mississippi; BAE, JI-YEONG - University Of Mississippi; CHITTIBOYINA, AMAR - University Of Mississippi; WANG, YAN-HONG - University Of Mississippi; Wang, Mei; ZHAO, JIANPING - University Of Mississippi; ZULFIQAR, ALI - University Of Mississippi; LI, JING - Food And Drug Administration(FDA); WU, CHARLES - Food And Drug Administration(FDA); KHAN, IKHLAS - University Of Mississippi

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2022
Publication Date: 6/9/2022
Citation: Avula, B., Bae, J., Chittiboyina, A.G., Wang, Y., Wang, M., Zhao, J., Zulfiqar, A., Li, J., Wu, C., Khan, I.A. 2022. Chemometric analysis and chemical characterization for the botanical identification of Glycyrrhiza species (G. glabra, G. uralensis, G. inflata, G. echinata and G. lepidota) using liquid chromatography-quadrupole time of flig. Journal of Agricultural and Food Chemistry. https://doi.org/10.1016/j.jfca.2022.104679.
DOI: https://doi.org/10.1016/j.jfca.2022.104679

Interpretive Summary: The licorice in commerce is supplied by the root and stolons of various species of Glycyrrhiza (Fabaceae), a genus which contains between 16 to 20 species, mainly occurring in Asia and Europe. Both beneficial (viz., anti-inflammatory and demulcent) and deleterious (viz., hypokalemia) effects of licorice extracts, while dose-dependent, are also attributed to the relative proportions of species-specific saponin and phenolic components. However, most national pharmacopeias include two or three specified Glycyrrhiza species as acceptable and interchangeable under the common name of ‘licorice’. Aiming to unambiguously differentiate licorice roots of the most widely traded Glycyrrhiza species (G. glabra, G. uralensis, G. inflata, G. echinata, and G. lepidota), an LC-QToF method integrated with chemometric tools has been applied based on chemical profiling of two major classes of saponins and phenolics. Eleven dietary supplements claiming to contain licorice were analyzed, and all supplements were identified to be derived from a single licorice species, G. glabra. Furthermore, the developed method in the present study might be useful in providing chemically supportive information for five Glycyrrhiza species authentication, as well as in quality assessment and standardization of licorice raw materials and their finished products.

Technical Abstract: The licorice in commerce is supplied by the root and stolons of various species of Glycyrrhiza (Fabaceae), a genus which contains between 16 to 20 species, mainly occurring in Asia and Europe. Both beneficial (viz., anti-inflammatory and demulcent) and deleterious (viz., hypokalemia) effects of licorice extracts, while dose-dependent, are also attributed to the relative proportions of species-specific saponin and phenolic components. However, most national pharmacopeias include two or three specified Glycyrrhiza species as acceptable and interchangeable under the common name of ‘licorice’. Aiming to unambiguously differentiate licorice roots of the most widely traded Glycyrrhiza species (G. glabra, G. uralensis, G. inflata, G. echinata, and G. lepidota), an LC-QToF method integrated with chemometric tools has been applied based on chemical profiling of two major classes of saponins and phenolics. Multivariate statistical analysis together with mass fragmentation of protonated/deprotonated molecular species resulted in diagnostic fragment ions which were helpful in successful identification of core skeleton, functional groups tethered to core structures. Roots of G. glabra, G. uralensis, and G. inflata showed high content of the triterpene saponin, glycyrrhizin and phenolics including several species-specific components. Most of the species-specific components were confirmed by comparison with reference standards and utilized in statistical models to differentiate aerial from subterranean plant parts. Furthermore, we demonstrated the utility of these tools for quality assessment of raw materials used in licorice-based botanical dietary supplement products.