Saponin and sapogenol. L. On the constituents of the roots of Glycyrrhiza uralensis Fischer from Xinjiang, China. Chemical structures of licorice-saponin L3 and isoliquiritin apioside

Computational Tools to Expedite the Identification of Potential PXR Modulators in Complex Natural Product Mixtures: A Case Study with Five Closely Related Licorice Species

The genus Glycyrrhiza, comprising approximately 36 spp., possesses complex structural diversity and is documented to possess a wide spectrum of biological activities. Understanding and finding the mechanisms of efficacy or safety for a plant-based therapy is very challenging, yet it is crucial and necessary to understand the polypharmacology of traditional medicines. Licorice extract was shown to modulate the xenobiotic receptors, which might manifest as a potential route for natural product-induced drug interactions. However, different mechanisms could be involved in this phenomenon. Since the induced herb-drug interaction of licorice supplements via Pregnane X receptor (PXR) is understudied, we ventured out to analyze the potential modulators of PXR in complex mixtures such as whole extracts by applying computational mining tools. A total of 518 structures from five species of Glycyrrhiza: 183 (G. glabra), 180 (G. uralensis), 100 (G. inflata), 33 (G. echinata), and 22 (G. lepidota) were collected and post-processed to yield 387 unique compounds. Visual inspection of top candidates with favorable ligand-PXR interactions and the highest docking scores were identified. The in vitro testing revealed that glabridin (GG-14) is the most potent PXR activator among the tested compounds, followed by licoisoflavone A, licoisoflavanone, and glycycoumarin. A 200 ns molecular dynamics study with glabridin confirmed the stability of the glabridin-PXR complex, highlighting the importance of computational methods for rapid dereplication of potential xenobiotic modulators in a complex mixture instead of undertaking time-consuming classical biological testing of all compounds in a given botanical.

Quantitative Mapping of Flavor and Pharmacologically Active Compounds in European Licorice Roots (Glycyrrhiza glabra L.) in Response to Growth Conditions and Arbuscular Mycorrhiza Symbiosis

Application of a sensitive UHPLC-MS/MS_MRM method enabled the simultaneous quantitation of 23 sweet-, licorice-, and bitter-tasting saponins in Glycyrrhiza glabra L., Glycyrrhiza uralensis Fisch., different licorice plants and root compartments, processed licorice, as well as different Glycyrrhiza spp. The combination of quantitative data with sweet, licorice, and bitter taste thresholds led to the determination of dose-over-threshold factors to elucidate the sweet, licorice, and bitter impact of the individual saponins with and without mycorrhiza symbiosis to evaluate the licorice root quality. Aside from glycyrrhizin (1), which is the predominant sweet- and licorice-tasting saponin in all licorice samples, 20 out of 22 quantitated saponins contributed to the taste profile of licorice roots. Next to sweet-/licorice-tasting glycyrrhizin (1), 24-hydroxy-glycyrrhizin (9), 30-hydroxy-glycyrrhizin (11), and 11-deoxo-24-hydroxy-glycyrrhizin (14) as well as licorice tasting saponins 20α-galacturonic acid glycyrrhizin (17), 24-hydroxy-20α-glycyrrhizin (21), and 11-deoxo-glycyrrhizin (12) were determined as key contributors to licorice root's unique taste profile. A quantitative comparison of 23 saponins as well as 28 polyphenols between licorice roots inoculated with arbuscular mycorrhiza fungi and controls showed that important taste-mediating saponins were increased in mycorrhizal roots, and these alterations depended on the growth substrate and the level of phosphate fertilization.

Glycyrrhiza Genus: Enlightening Phytochemical Components for Pharmacological and Health-Promoting Abilities

The Glycyrrhiza genus, generally well-known as licorice, is broadly used for food and medicinal purposes around the globe. The genus encompasses a rich pool of bioactive molecules including triterpene saponins (e.g., glycyrrhizin) and flavonoids (e.g., liquiritigenin, liquiritin). This genus is being increasingly exploited for its biological effects such as antioxidant, antibacterial, antifungal, anti-inflammatory, antiproliferative, and cytotoxic activities. The species Glycyrrhiza glabra L. and the compound glycyrrhizin (glycyrrhizic acid) have been studied immensely for their effect on humans. The efficacy of the compound has been reported to be significantly higher on viral hepatitis and immune deficiency syndrome. This review provides up-to-date data on the most widely investigated Glycyrrhiza species for food and medicinal purposes, with special emphasis on secondary metabolites' composition and bioactive effects.

Biologically guided isolation and ADMET profile of new factor Xa inhibitors from Glycyrrhiza glabra roots using in vitro and in silico approaches

Selective factor Xa inhibitors effectively block coagulation cascade with a broader therapeutic window than multitargeted anticoagulants. They have evolved as a crucial part of prevention and treatment of thromboembolic diseases and in therapeutic protocols involved in many clinical trials in coronavirus disease 2019 (COVID-19) patients. Biologically-guided isolation of specific FXa inhibitors from licorice (Glycyrrhiza glabra) root extract furnished ten flavonoids. By detailed analysis of their 1H, 13C NMR and MS data, the structures of these flavonoids were established as 7,4'-dihydroxyflavone (1), formononetin (2), 3-R-glabridin (3), isoliquiritigenin (4), liquiritin (5), naringenin 5-O-glucoside (6), 3,3',4,4'-tetrahydroxy-2-methoxychalcone (7), liquiritinapioside (8) and the two isomers isoliquiritigenin-4'-O-β-d-apiosylglucoside (9) and isoliquiritigenin-4-O-β-d-apiosylglucoside (10). All the isolated compounds were assessed for their FXa inhibitory activity using in vitro chromogenic assay for the first time. Liquirtin (5) showed the most potent inhibitory effects with an IC50 of 5.15 μM. The QikProp module was implemented to perform ADMET predictions for the screened compounds.

Characterization of chemical profile and quantification of major representative components of Wendan decoction, a classical traditional Chinese medicine formula

Wendan decoction, a classical traditional Chinese medicine formula consisting of six herbal medicines, has been widely used in clinical treatments for thousands of years due to the expectorant effects. However, the chemical basis of Wendan decoction remains unclear, which hinders the elucidation of the scientific connotation and mechanism of its effective components. In this study, an ultra-high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry method was first developed for characterization of its chemical profile, and a total of 142 chemical components including flavonoids, triterpenoids, alkaloids, coumarins, pungent phytochemicals, and other types were detected, among which 41 components were definitively identified with authentic standards. Furthermore, 14 major representative components were simultaneously quantified by high-performance liquid chromatography with ultraviolet detector, indicating that the content levels of flavonoids were the most abundant in Wendan decoction. In summary, this study established sensitive and practical methods to systematically characterize chemical profile for the first time and simultaneous quantify representative components of Wendan decoction. These findings above would provide a solid chemical basis for disclosure of potential effective components by further in vivo disposal study, and promote therapeutic mechanism researches of Wendan decoction.

Review of Constituents and Biological Activities of Triterpene Saponins from Glycyrrhizae Radix et Rhizoma and Its Solubilization Characteristics

Glycyrrhizae Radix et Rhizoma is regarded as one of the most popular and commonly used herbal medicines and has been used in traditional Chinese medicine (TCM) prescriptions for over 2000 years. Pentacyclic triterpene saponins are common secondary metabolites in these plants, which are synthesized via the isoprenoid pathway to produce a hydrophobic triterpenoid aglycone containing a hydrophilic sugar chain. This paper systematically summarizes the chemical structures of triterpene saponins in Glycyrrhizae Radix et Rhizoma and reviews and updates their main biological activities studies. Furthermore, the solubilization characteristics, influences, and mechanisms of Glycyrrhizae Radix et Rhizoma are elaborated. Solubilization of the triterpene saponins from Glycyrrhizae Radix et Rhizoma occurs because they contain the nonpolar sapogenin and water-soluble sidechain. The possible factors affecting the solubilization of Glycyrrhizae Radix et Rhizoma are mainly other crude drugs and the pH of the decoction. Triterpene saponins represented by glycyrrhizin from Glycyrrhizae Radix et Rhizoma characteristically form micelles due to amphiphilicity, which makes solubilization possible. This overview provides guidance regarding a better understanding of GlycyrrhizaeRadix et Rhizoma and its TCM compatibility, alongside a theoretical basis for the further development and utilization of Glycyrrhizae Radix et Rhizoma.

An "essential herbal medicine"-licorice: A review of phytochemicals and its effects in combination preparations

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice (Gancao in Chinese, GC), the dried root and rhizome of Glycyrrhiza uralensis Fisch., Glycyrrhiza inflata Bat. or Glycyrrhiza glabra L., is an "essential herbal medicine" in traditional Chinese medicine (TCM). There is a classic traditional Chinese medicine theory says that "nine out of ten formulas contain licorice" and licorice is considered as one of the most important herbal medicine which can reduce toxicity and increase efficacy of certain herbal medicine while it is combined application. In addition, it is a "medicine food homology" herbal medicine and also be widely used as a health food product and natural sweetener. However, no systematic literature review has been compiled to reveal its superiority. Herein, the aim of this work is to develop an overview of the state on phytochemicals, as well as effects of licorice in combination preparations, which can provide better understand the superiority of licorice and the special position in the application of TCM. Besides, ethnobotany, ethnopharmacological uses, quality control and toxicology of licorice have also been researched, which would provide reference for future clinical and basic research needs.

MATERIALS AND METHODS

The information about licorice was collected from various sources including classic books about Chinese herbal medicine, and scientific databases including scientific journals, books, and pharmacopoeia. A total of 124 bibliographies, which are published from 1976 to 2019, have been searched and researched.

RESULTS

In this study, the interaction of chemical compounds between licorice and toxic herbal medicine, pharmacological effect of licorice, and the effect of licorice on pharmacokinetics of toxic compounds are considered as the main mechanisms underlying the effects of licorice in combination preparations. Besides, ethnobotany, ethnopharmacological uses and chemical constituents have been summarized.

CONCLUSION

This work comprehensively reviews the state on ethnobotany, ethnopharmacological uses, phytochemicals, combined applications, quality control and toxicology of licorice. It will provide systematic insights into this ancient drug for further development and clinical use.

Saponins from European Licorice Roots ( Glycyrrhiza glabra)

European licorice roots ( Glycyrrhiza glabra), used in the food and beverage industry due to their distinctive sweet and typical licorice flavor, were fractionated, with the triterpenoid saponins isolated and their chemical structures determined by means of ESIMS, ESIMS/MS, HRESIMS, and 1D/2D NMR experiments. Next to the quantitatively predominant saponin glycyrrhizin (11) and some previously known saponins, the structures of 10 monodesmosidic saponins were assigned unequivocally for the first time, namely, 30-hydroxyglycyrrhizin (1), glycyrrhizin-20-methanoate (2), 24-hydroxyglucoglycyrrhizin (3), rhaoglycyrrhizin (4), 11-deoxorhaoglycyrrhizin (5), rhaoglucoglycyrrhizin (6), rhaogalactoglycyrrhizin (7), 11-deoxo-20α-glycyrrhizin (8), 20α-galacturonoylglycyrrhizin (9), and 20α-rhaoglycyrrhizin (10).

Nitric oxide inhibitory flavonoids from traditional Chinese medicine formula Baoyuan Decoction

Three new flavonoid glycosides, (3R)-(+)-isomucronulatol-2'-O-β-D-glucopyranoside (1), (3R)-(-)-isomucronulatol-7-O-β-D-apiofuranosyl(1→2)-β-D-glucopyranoside (2), and (2S)-(-)-7,8-dihydroxylflavanone-4'-O-β-D-apiofuranosyl(1→2)-β-D-glucopyranoside (3), along with eight flavanones (4, 8, 10, 12, 15, 16, 21, and 24), four isoflavones (5, 11, 13, and 23), four chalcones (6, 14, 17, and 18), two isoflavans (19-20), one flavone (7), one flavonol (9), and one dihydrochalcone (22) were isolated from Baoyuan Decoction (BYD), a traditional Chinese medicine formula. The structures of the new compounds were established by detailed analysis of NMR and HRESIMS spectroscopic data, and their absolute configurations were determined by electronic circular dichroism (ECD) data. The inhibitory effects of the isolates were evaluated on nitric oxide production in lipopolysaccharide activated RAW 264.7 macrophage cells. Compounds 6, 9, and 10 showed the significant inhibitory activities, with IC50 values of 1.4, 13.8, and 9.3 μM, respectively, comparable to or even better than the positive control, quercetin (IC50, 16.5 μM). The assignment of these isolated flavonoids was achieved using UPLC-Q-trap-MS, and the results suggested that they were originated from Astragalus membranaceus and Glycyrrhiza uralensis.

Bioactive constituents of oleanane-type triterpene saponins from the roots of Glycyrrhiza glabra

Three new oleanane-type triterpene saponins, namely licorice-saponin M3 (1), licorice-saponin N4 (2), and licorice-saponin O4 (3), an artificial product (4), as well as five known triterpene glucuronides (5-9), were isolated from the roots of Glycyrrhiza glabra L. Their structures were established using 1D and 2D NMR spectroscopy, mass spectrometry, and by comparison with spectroscopic data reported in the literature. The inhibitory effects of the selected compounds on neuraminidase were evaluated, and the preliminary structure-activity relationship was also predicted.

24-Hydroxyoleanane-type triterpenes from the aerial parts and roots of Oxytropis falcata

Phytochemical investigation of the aerial parts of Oxytropis falcata led to the isolation of three new 24-hydroxyoleanane-type triterpenes (1-3), seven known analogues (4-10), and two rare sesquiterpenoids (12, 13). Compounds 6 and 12 were isolated as new natural products. Triterpenes (5, 6, 8, 11) were isolated from the roots of O. falcata. The structures and relative configurations of these compounds were elucidated by spectroscopic analyses, including 1D and 2D NMR spectroscopy and mass spectrometry, and by comparison of their NMR data with those of related compounds. Single-crystal X-ray diffraction analyses confirmed the structures of 1-4, and the absolute configuration of 3 was evidenced by the incorporation of DMSO (crystallization solvent) in the crystal lattice.

Chemical analysis of the Chinese herbal medicine Gan-Cao (licorice)

Gan-Cao, or licorice, is a popular Chinese herbal medicine derived from the dried roots and rhizomes of Glycyrrhiza uralensis, G. glabra, and G. inflata. The main bioactive constituents of licorice are triterpene saponins and various types of flavonoids. The contents of these compounds may vary in different licorice batches and thus affect the therapeutic effects. In order to ensure its efficacy and safety, sensitive and accurate methods for the qualitative and quantitative analyses of saponins and flavonoids are of significance for the comprehensive quality control of licorice. This review describes the progress in chemical analysis of licorice and its preparations since 2000. Newly established methods are summarized, including spectroscopy, thin-layer chromatography, gas chromatography, high-performance liquid chromatography (HPLC), liquid chromatography/mass spectrometry (LC/MS), capillary electrophoresis, high-speed counter-current chromatography (HSCCC), electrochemistry, and immunoassay. The sensitivity, selectivity and powerful separation capability of HPLC and CE allows the simultaneous detection of multiple compounds in licorice. LC/MS provides characteristic fragmentations for the rapid structural identification of licorice saponins and flavonoids. The combination of HPLC and LC/MS is currently the most powerful technique for the quality control of licorice.

Liquid chromatography/mass spectrometry analysis of PHY906, a Chinese medicine formulation for cancer therapy

PHY906 is a Chinese medicine formulation prepared from four medicinal herbs for adjuvant cancer chemotherapy. In this paper, liquid chromatography/electrospray ionization time-of-flight mass spectrometry (LC/ESI-TOFMS) was used to clarify the chemical composition of PHY906. The aqueous extract of PHY906 was separated on a Waters Atlantis C(18) column, and was eluted with acetonitrile/0.05% (v/v) formic acid. The separated compounds were identified with pure standards, or tentatively characterized by analyzing their mass spectra recorded in both negative and positive ion polarity modes. Further structural information was obtained from in-source fragmentation. Based on the LC/MS analysis, we proposed the structures for 64 bioactive compounds, including flavonoids, triterpene saponins, and monoterpene glycosides. All the compounds identified from PHY906 were further assigned in the four individual herbs, and some of them are reported for the first time.

CYP3A4 inhibitors isolated from Licorice

The extract of licorice (Glycyrrhiza uralensis FISHER, Leguminosae) showed CYP3A4 inhibitory activity with the IC50 value of 0.022 mg/ml. Bioassay-guided purification afforded nine compounds, 3-(p-hydroxyphenyl)propionic acid (1), isoliquiritigenin (2), (3R)-vestitol (3), licopyranocoumarin (4), 4-hydroxyguaiacol apioglucoside (5), liquiritin (6), liquiritigenin 7,4'-diglucoside (7), liquiritin apioside (8), and glucoliquiritin apioside (9). Among these compounds, 3, 7, and 5 showed potent CYP3A4 inhibitory activities with IC50 values of 3.6, 17, and 20 microM, respectively. Glycyrrhizin (10), a main constituent of licorice, however, was inactive for CYP3A4 inhibition.

Separation and isolation methods for analysis of the active principles of Sho-saiko-to (SST) oriental medicine

Sho-saiko-to (SST) was introduced into Japan as an oriental classical medicine from China approximately 1500 years ago, and it is currently the most representative Kampo medicine (traditional Japanese medicine). SST is manufactured in Japan as an ethical drug on a modern industrial scale in which the quality of ingredients is standardized with Good Manufacturing Practices (GMP) regulation. SST is widely used for the treatment of chronic hepatitis. Experimental and clinical studies including multi-center, placebo-controlled, double-blind studies have demonstrated the various pharmacological effects of SST. SST is prepared from the hot water extraction of seven raw materials, therefore many kinds of constituents are included. Three-dimensional (3D) HPLC analysis is useful for obtaining many kinds of constituents, especially low molecular ultraviolet (UV) quenching compounds, contained in SST as well as its fractions. Fingerprint pattern provided by 3D HPLC analysis makes possible to identify the overall-viewing of SST. Databases of UV spectra of the components of medicinal herbs obtained by reversed-phase (RP) HPLC using a photodiode array (PDA) and fingerprint patterns of crude drugs made by 3D HPLC analysis facilitate the identification, analysis and quality of herbal drugs. Studies using both PDA HPLC and an amino acid analysis with a fluorometric detector have found that SST contains fifteen major low molecular compounds (i.e. baicalin, wogonin-7-O-glucuronide, liquiritin, their three aglycons, liquiritin apioside, glycyrrhizin, saikosaponin b1, saikosaponin b2, ginsenoside Rg1, ginsenoside Rb1, (6)-gingerol, (6)-shogaol and arginine). These compounds have various pharmacological actions, and are assumed to be responsible, at least partly, for the pharmacological effects of SST. Although there have only been a few investigations on high molecular compounds with pharmacological actions contained in SST, several kinds of polysaccharides have been isolated from constituent herbs of SST. This review paper summarizes analytical methods of separation, isolation and identification of compounds with biological activities from SST, which is a mixture drug of medicinal herbs. Accordingly, this paper would not focus on methods of separation, isolation and analysis of particular compounds from each constituent herb of SST.

Separation and isolation methods for analysis of the active principles of Sho-saiko-to (SST) oriental medicine

Sho-saiko-to (SST) was introduced into Japan as an oriental classical medicine from China approximately 1500 years ago, and it is currently the most representative Kampo medicine (traditional Japanese medicine). SST is manufactured in Japan as an ethical drug on a modern industrial scale in which the quality of ingredients is standardized with Good Manufacturing Practices (GMP) regulation. SST is widely used for the treatment of chronic hepatitis. Experimental and clinical studies including multi-center, placebo-controlled, double-blind studies have demonstrated the various pharmacological effects of SST. SST is prepared from the hot water extraction of seven raw materials, therefore many kinds of constituents are included. Three-dimensional (3D) HPLC analysis is useful for obtaining many kinds of constituents, especially low molecular ultraviolet (UV) quenching compounds, contained in SST as well as its fractions. Fingerprint pattern provided by 3D HPLC analysis makes possible to identify the overall-viewing of SST. Databases of UV spectra of the components of medicinal herbs obtained by reversed-phase (RP) HPLC using a photodiode array (PDA) and fingerprint patterns of crude drugs made by 3D HPLC analysis facilitate the identification, analysis and quality of herbal drugs. Studies using both PDA HPLC and an amino acid analysis with a fluorometric detector have found that SST contains fifteen major low molecular compounds (i.e. baicalin, wogonin-7-O-glucuronide, liquiritin, their three aglycons, liquiritin apioside, glycyrrhizin, saikosaponin b1, saikosaponin b2, ginsenoside Rg1, ginsenoside Rb1, (6)-gingerol, (6)-shogaol and arginine). These compounds have various pharmacological actions, and are assumed to be responsible, at least partly, for the pharmacological effects of SST. Although there have only been a few investigations on high molecular compounds with pharmacological actions contained in SST, several kinds of polysaccharides have been isolated from constituent herbs of SST. This review paper summarizes analytical methods of separation, isolation and identification of compounds with biological activities from SST, which is a mixture drug of medicinal herbs. Accordingly, this paper would not focus on methods of separation, isolation and analysis of particular compounds from each constituent herb of SST.

Activity-guided isolation of the chemical constituents of Muntingia calabura using a quinone reductase induction assay

Activity-guided fractionation of an EtOAc-soluble extract of the leaves of Muntingia calabura collected in Peru, using an in vitro quinone reductase induction assay with cultured Hepa 1c1c7 (mouse hepatoma) cells, resulted in the isolation of a flavanone with an unsubstituted B-ring, (2R,3R)-7-methoxy-3,5,8-trihydroxyflavanone (5), as well as 24 known compounds, which were mainly flavanones and flavones. The structure including absolute stereochemistry of compound 5 was determined by spectroscopic (HRMS, 1D and 2D NMR, and CD spectra) methods. Of the isolates obtained, in addition to 5, (2S)-5-hydroxy-7-methoxyflavanone, 2',4'-dihydroxychalcone, 4,2',4'-trihydroxychalcone, 7-hydroxyisoflavone and 7,3',4'-trimethoxyisoflavone were found to induce quinone reductase activity.

Structural requirements of flavonoids and related compounds for aldose reductase inhibitory activity

The methanolic extracts of several natural medicines and medicinal foodstuffs were found to show an inhibitory effect on rat lens aldose reductase. In most cases, flavonoids were isolated as the active constituents by bioassay-guided separation, and among them, quercitrin (IC(50)=0.15 microM), guaijaverin (0.18 microM), and desmanthin-1 (0.082 microM) exhibited potent inhibitory activity. Desmanthin-1 showed the most potent activity, which was equivalent to that of a commercial synthetic aldose reductase inhibitor, epalrestat (0.072 microM). In order to clarify the structural requirements of flavonoids for aldose reductase inhibitory activity, various flavonoids and related compounds were examined. The results suggested the following structural requirements of flavonoid: 1) the flavones and flavonols having the 7-hydroxyl and/or catechol moiety at the B ring (the 3',4'-dihydroxyl moiety) exhibit the strong activity; 2) the 5-hydroxyl moiety does not affect the activity; 3) the 3-hydroxyl and 7-O-glucosyl moieties reduce the activity; 4) the 2-3 double bond enhances the activity; 5) the flavones and flavonols having the catechol moiety at the B ring exhibit stronger activity than those having the pyrogallol moiety (the 3',4',5'-trihydroxyl moiety).