Chiral separation of glycyrrhetinic acid by high-performance liquid chromatography

Integrated network pharmacology and experimental analysis unveil multi-targeted effect of 18α- glycyrrhetinic acid against non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is one of the most malignant types of cancer with soaring incidence rates worldwide, attributed to its heterogeneity and complex etiology. Evidently, alternative anti-cancer therapies comprising traditional medicines and natural products have gained attention for their ability to act as chemopreventive agents with minimal toxicities, either alone or in combination. Accumulating studies have substantiated the inevitability of network pharmacology studies for effectively mapping molecular targets of natural products against multifaceted diseases, including cancer. The 18α-Glycyrrhetinic acid (18α-GA), a triterpenoid found in licorice plants, has shown promising medicinal properties, although, its mechanism of action against NSCLC yet remains elusive. The present study was conducted to explore the anti- NSCLC potential of 18α-GA, employing integrative network pharmacology, molecular docking, and experimental research. Initially, network analysis revealed 181 common targets of 18α-GA in NSCLC as shown in the “compound-target- disease” network employing Cytoscape 3.8.2. Further analyses identified EGFR, AKT1, PI3KR1, MAPK1, IGF1, and SRC as the most crucial hub targets of 18α-GA against NSCLC. Moreover, molecular docking simulations and functional enrichment analyses indicated the involvement of multiple signaling pathways in suppressing NSCLC. Subsequent in-vitro studies verified the antiproliferative effect of 18α-GA on two NSCLC cancer cell lines, H1299 and A549. Mechanistically, 18α-GA arrested cell cycle at the G1 phase, induced apoptosis, decreased migratory potential, and protein expression levels of EGFR-PI3K/AKT, as examined by flow cytometry, morphological assessment, RT-PCR, and western blot. In conclusion, this study delineates the therapeutic potential and underlying mechanism(s) of 18α-GA as a putative novel drug against NSCLC. However, further studies are warranted to elucidate the complete molecular mechanism(s) using animal models of NSCLC.

A targeted strategy to identify untargeted metabolites from in vitro to in vivo: Rapid and sensitive metabolites profiling of licorice in rats using ultra-high performance liquid chromatography coupled with triple quadrupole-linear ion trap mass spectrometry

It is challenging to conduct in vivo metabolic study for traditional Chinese medicines (TCMs) because of complex components, unpredictable metabolic pathways and low metabolite concentrations. Herein, we proposed a sensitive strategy to characterize TCM metabolites in vivo at an orally clinical dose using ultra-high performance liquid chromatography-triple quadrupole-linear ion trap mass spectrometry (UHPLC-QTRAP-MS). Firstly, the metabolism of individual compounds in rat liver microsomes was studied to obtain the metabolic pathways and fragmentation patterns. The untargeted metabolites in vitro were detected by multiple ion monitoring-enhanced product ion (EPI) and neutral loss-EPI scans. Subsequently, a sensitive multiple reaction monitoring-EPI method was developed according to the in vitro results and predicted metabolites to profile the in vivo metabolites. Licorice as a model herb was used to evaluate and validate our strategy. A clinical dose of licorice water extract was orally administered to rats, then a total of 45 metabolites in urine, 21 metabolites in feces and 35 metabolites in plasma were detected. Among them, 18 minor metabolites have not been reported previously and 6 minor metabolites were first detected in vivo. Several isomeric metabolites were well separated and differentiated in our strategy. These results suggested that this new strategy could be widely used for the detection and characterization of in vivo metabolites of TCMs.

Unequivocal glycyrrhizin isomer determination and comparative in vitro bioactivities of root extracts in four Glycyrrhiza species

Glycyrrhiza glabra, commonly known as licorice, is a popular herbal supplement used for the treatment of chronic inflammatory conditions and as sweetener in the food industry. This species contains a myriad of phytochemicals including the major saponin glycoside glycyrrhizin (G) of Glycyrrhetinic acid (GA) aglycone. In this study, 2D-ROESY NMR technique was successfully applied for distinguishing 18α and 18β glycyrrhetinic acid (GA). ROESY spectra acquired from G. glabra, Glycyrrhiza uralensis and Glycyrrhiza inflata crude extracts revealed the presence of G in its β-form. Anti-inflammatory activity of four Glycyrrhiza species, G, glabra, G. uralensis, G. inflata, and G. echinata roots was assessed against COX-1 inhibition revealing that phenolics rather than glycyrrhizin are biologically active in this assay. G. inflata exhibits a strong cytotoxic effect against PC3 and HT29 cells lines, whereas other species are inactive. This study presents an effective NMR method for G isomer assignment in licorice extracts that does not require any preliminary chromatography or any other purification step.

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.

Separation and analysis of glycyrrhizin, 18beta-glycyrrhetic acid and 18alpha-glycyrrhetic acid in liquorice roots by means of capillary zone electrophoresis

Glycyrrhizin is the main active compound of Glycyrrhiza glabra root extracts; according to recent studies, glycyrrhizin and its aglycon, glycyrrhetic acid, have interesting therapeutic properties. A new capillary electrophoretic method has been developed for the separation and quantification of glycyrrhizin, beta-glycyrrhetic acid and its isomer a-glycyrrhetic acid. Separation of the analytes was achieved in less than 3 min on a fused silica capillary, by injecting the samples at the short end of the capillary (effective length: 8.5 cm). The background electrolyte was composed of pH 10.0 carbonate buffer, methanol and ethylene glycol (80/10/10) and contained 0.4% beta-cyclodextrin; indomethacin was used as the internal standard. Diode array detection was used, with quantitative assays carried out at 254 nm. Linearity was found over the 5-200 and 2.5-100 microg mL(-1) concentration ranges for glycyrrhizin and glycyrrhetic acid, respectively. This method has been applied to the determination of the analytes in different matrices (liquorice roots and commercial confectionery products), and to the purity control of beta-glycyrrhetic acid obtained from the hydrolysis of glycyrrhizin. When analysing beta-glycyrrhetic acid and its epimer in roots, the samples were purified by means of a suitable solid-phase extraction (SPE) procedure with Oasis HLB cartridges, which granted good selectivity, eliminating matrix interference.

HPLC analysis of liquorice triterpenoids--applications to the quality control of pharmaceuticals

A reversed-phase HPLC method is proposed for the separation of five liquorice triterpenoids, 18 beta glycyrrhetic acid (beta GA), 18 alpha glycyrrhetic acid (alpha GA), 24-hydroxy-18 beta-glycyrrhetic acid (24-OH-beta GA), alpha and beta liquiritic acid (alpha and beta LA), with potentially different biological activities. The method has been developed by studying the influence of the type of stationary phase, pH, amine modifier and organic modifier on the resolution of the five compounds. The optimized chromatographic conditions were then successfully applied to the analysis of alpha- and beta-GA in pharmaceutical preparations (toothpaste and creams) on a reversed-phase Phenomenex Ultracarb 5 ODS (30) column (150 x 4.6 mm i.d.), using as the mobile phase acetonitrile-THF-0.010 M dioctylammonium phosphate buffer (pH 6.5) (25:20:55, v/v/v) at a flow-rate of 0.8 ml min-1. SPE methods with diolic and C18 sorbents were developed to isolate and concentrate the analytes and to enhance the sensitivity for the determination of alpha-GA as an impurity in the beta-GA preparations. The method was found to be reliable and suitable for the quality control of beta-GA preparations.