Simultaneous extraction and separation of liquiritin, glycyrrhizic acid, and glabridin from licorice root with analytical and preparative chromatography

Isolating and Purification Technologies for Glycyrrhizic Acid

Glycyrrhizic acid (GA) is the primary active component of the traditional Chinese medicinal herb licorice. It possesses antimicrobial, anti-inflammatory, and antitumor activities. In addition, due to its unique sweetness, it can also be used as a food additive. Traditional Chinese medicines are typically used directly as drugs. However, the chemical composition of Chinese medicinal materials such as licorice is complex, containing not only effective components but also ineffective and even toxic substances. To efficiently exert their medicinal value and minimize the side effects of harmful substances, the extraction and separation of the active components is an important means to achieve the modernization of traditional Chinese medicine utilization. This article focuses on the extraction of GA, summarizes the current technologies related to the extraction and separation of GA, reveals the underlying chemical principles, and evaluates the advantages and disadvantages of the corresponding technologies. On this basis, it proposes challenges faced in the separation of GA and provides corresponding solutions. The author believes that with the continuous introduction of precise chemical synthesis and other methods in separation, the extraction and separation of the active substance will become greener and more efficient. It will also provide a reference for the extraction of other effective components of traditional Chinese medicine.

The specific extraction of glabridin from licorice residues using molecular imprinting technique

The large-scale production of glycyrrhizic acid inevitably generates a large amount of licorice residues waste, which contains a wealth of active ingredients, especially glabridin, a natural preservative. However, traditional extraction methods for glabridin are often limited by bottlenecks such as time-consuming, inefficient, and insufficient specificity. To overcome these challenges, this study innovatively introduced 2-phenylimidazole as a functional monomer by computer simulations and successfully developed magnetic molecularly imprinted polymers (MMIPs) for glabridin. The adsorption capacity of MMIPs could reach 25.61 mg/g at 300 min, and the MMIPs had high specificity with an imprinting factor of 1.9. In addition, the MMIPs had high selectivity and reproducibility with a selectivity factor of 2.34, and the adsorption capacity could be maintained at 90 % after six times of repeated use. It can increase the purity of glabridin from 20 % to about 77 % in the complex environment of licorice residues, showing good specificity and promising application.

Metabolite profiling and nephroprotective potential of Glycyrrhiza glabra L. roots against cisplatin-induced nephrotoxicity in vitro and in vivo

OBJECTIVES

The present study was conducted to investigate the phytochemical analysis and demonstrate the nephroprotective potential of root extract of Glycyrrhiza glabra L. against cisplatin (CP) -induced nephrotoxicity in vitro and in vivo.

MATERIALS AND METHODS

The HPTLC analysis and UPLC-MS were carried out for standardizing and metabolite profiling of methanolic extract of roots of G. glabra (GGE). Further, in vitro studies were conducted in human embryonic kidney (HEK)-293 cells to evaluate the cytotoxicity and anti-oxidant potential of GGE with CP as a toxicant and ascorbic acid as standard. Also, in vivo nephroprotective potential at doses of 31.5, 63, and 126 mg/kg/day on CP (6 mg/kg, bw, IP) induced nephrotoxicity was evaluated on rodents.

RESULTS

Phytochemical analysis by HPTLC and UPLC-MS revealed the presence of glycyrrhizin, glabridin, and liquiritin along with other bioactive constituents. The in vitro assay of GGE showed significant (P<0.001 nephroprotective, cellular anti-oxidant potential and improvement in morphological changes induced by CP. Further, administration of CP caused significant (P<0.001) elevation in biochemical, inflammatory, oxidative stress, caspase-3, as well as histopathological changes in kidney tissue. Pre-treatment with GGE attenuated the elevated biochemical markers significantly, improved histopathological damage, and showed a comparable result to ascorbic acid and α-ketoanalogue.

CONCLUSION

Present study concluded the nephroprotective potential of GGE which supports the traditional claim of G. glabra roots in various kidney and its related disorders. The nephroprotective activity may be attributed to its anti-oxidant, anti-inflammatory, and anti-apoptosis effects. Thus, it holds promising potential in management of nephrotoxicity.

Prevention of MEK-ERK-1/2 hyper-activation underlines the neuroprotective effect of Glycyrrhiza glabra L. (Yashtimadhu) against rotenone-induced cellular and molecular aberrations

ETHNOPHARMACOLOGICAL RELEVANCE

Yashtimadhu choorna (powder) is prepared from the dried root of Glycyrrhiza glabra L., commonly known as licorice. The Indian Ayurvedic system classifies Yashtimadhu as a Medhya Rasayana that can enhance brain function, improves memory, and possess neuroprotective functions, which can be used against neurodegenerative diseases like Parkinson's disease (PD).

AIM OF THE STUDY

We aimed to decipher the neuroprotective effects of G. glabra L., i.e., Yashtimadhu, in a rotenone-induced PD model.

MATERIALS AND METHODS

Retinoic acid-differentiated IMR-32 cells were treated with rotenone (PD model) and Yashtimadhu, and were assessed for cellular toxicity, live-dead staining, cell cycle, oxidative stress, protein abundance, and kinase phosphorylation.

RESULTS

Yashtimadhu conferred protection against rotenone-induced cytotoxicity, countered cell death, reduced expression of pro-apoptotic proteins (cleaved-caspases-9, and 3, cleaved-PARP, BAX, and BAK) and increased anti-apoptotic protein, BCL-2. Rotenone-induced cell cycle re-entry (G2/M transition), was negated by Yashtimadhu and was confirmed with PCNA levels. Yashtimadhu countered rotenone-mediated activation of mitochondrial proteins involved in oxidative stress, cytochrome-C, PDHA1, and HSP60. Inhibition of rotenone-induced ERK-1/2 hyperphosphorylation prevented activation of apoptosis, which was confirmed with MEK-inhibitor, highlighted the action of Yashtimadhu via ERK-1/2 modulation.

CONCLUSIONS

We provide the evidence for neuroprotection conferred by G. glabra L. (Yashtimadhu) and its mechanism via inhibiting MEK-ERK-1/2 hyper-phosphorylation, prevention of mitochondrial stress, and subsequent prevention of apoptosis. The study highlights Yashtimadhu as a promising candidate with neuroprotective effects, the potential of which can be harnessed for identifying novel therapeutic targets.

Preparation and Characterization of Licorice-Chitosan Coatings for Postharvest Treatment of Fresh Strawberries

Several plant extracts are being investigated to produce edible coatings, mainly due to their antioxidant and antimicrobial activities. In this study, licorice root extracts were produced by ultrasound-assisted extraction and were combined with chitosan to elaborate edible coatings. Different solvents and temperatures were used in the extraction process, and the antioxidant and antimicrobial activity of the extracts were assessed. The most bioactive extracts were selected for the development of the edible coatings. The rheological properties of the coatings were studied, and they were applied on strawberry to evaluate their physicochemical and microbiological properties. The addition of licorice extract to chitosan resulted in positive effects on the rheological properties of the coatings: the incorporation of phytochemicals to chitosan decreased the shear stress and improved the restructuring ability of the coating solutions. The films presented a reduction of the Burger model parameter, indicating a reduction of rigidity. Furthermore, the strawberry coated with chitosan and licorice extract maintained good quality parameters during storage and showed the best microbiological preservation in comparison with controls. Hence, the use of chitosan with licorice extract is a potential strategy to produce edible coating for improving the postharvest quality of fruits.

Glabridin attenuates airway inflammation and hyperresponsiveness in a mice model of ovalbumin-induced asthma

Asthma is an inflammatory disease of the airways of the lungs, which is characterized by airflow obstruction and bronchospasms. Glabridin is a major flavonoid, especially found in root of Glycyrrhiza glabra, and has several pharmacological activities, including antioxidant and anti-inflammatory effects. The anti-asthmatic effect and possible mechanism of glabridin, however, have not been revealed so far. The aim of this study is to investigate the effects and possible mechanisms of glabridin against ovalbumin (OVA)-induced airway hyperresponsiveness (AHR) and inflammation in mice. In male BALB/c mice, asthma was induced by intraperitoneal (i.p) injection of OVA mixed with 2 mg aluminium hydroxide on days 0, 14 and boosted with OVA aerosol challenge on days 21, 22, and 23. Mice were either treated with dexamethasone (i.p, 1 mg/kg) or glabridin (10, 20, and 30 mg/kg) from days 18-23. Pulmonary function parameters such as peak inspiratory flow, peak expiratory flow, tidal volume, expiratory volume, the frequency of breathing, enhanced pause values were evaluated by using whole-body plethysmography. Measurements were performed at baseline and following methacholine (50 mg/mL) challenges. In addition, white blood cells (WBC) count, total protein, and IgE levels were measured in bronchial alveolar lavage fluid (BALF), lung, and serum, respectively. Glabridin (20 or 30 mg/kg) significantly attenuated (p < 0.05) OVA-induced alteration in respiratory parameters. Elevated counts of total WBC, differential WBC (neutrophils, lymphocytes, monocytes, and eosinophils) in BALF and the total protein in lungs and BALF were significantly decreased (p < 0.05) by glabridin (20 or 30 mg/kg). It also significantly attenuated the increased serum IgE levels (p < 0.05). As glabridin reduces the level of serum IgE, the total protein and the count of WBC and improves respiratory function, it may be a novel therapeutic agent in asthma.

Optimization of ultrasound-assisted extraction of glycyrrhizic acid from licorice using response surface methodology

BACKGROUND

The present study optimized ultrasound-assisted extraction conditions to maximize extraction yields of glycyrrhizic acid from licorice.

METHODS

The optimal extraction temperature (X1), extraction time (X2), and methanol concentration (X3) were identified using response surface methodology (RSM). A central composite design (CCD) was used for experimental design and analysis of the results to obtain the optimal processing parameters.

RESULTS

Statistical analyses revealed that three variables and the quadratic of X1, X2, and X3 had significant effects on the yields and were followed by significant interaction effects between the variables of X2 and X3 (p < 0.01). A 3D response surface plot and contour plots derived from the mathematical models were applied to determine the optimal conditions. The optimum ultrasound-assisted extraction conditions were as follows: extraction temperature, 69 °C; extraction time, 34 min; and methanol concentration, 57%. Under these conditions, the experimental yield of glycyrrhizic acid was 3.414%, which agreed closely with the predicted value (3.406%).

CONCLUSION

The experimental values agreed with those predicted by RSM models, thus indicating the suitability of the model employed and the success of RSM in optimizing the extraction conditions.

Liquiritin induces apoptosis and autophagy in cisplatin (DDP)-resistant gastric cancer cells in vitro and xenograft nude mice in vivo

Gastric cancer is reported as one of the leading factors resulting in tumor-related death worldwide. However, the therapies to suppress gastric cancer are still limited and the emergence of drug resistance makes it necessary to develop new and effective anticancer drugs and combinational chemotherapy schemes. Liquiritin (LIQ) is a major constituent of Glycyrrhiza Radix, exhibiting various pharmacological activities, including anticancer. In this study, we investigated the role of LIQ in human gastric cancer cells with cisplatin (DDP) resistance. The findings suggested that LIQ, when applied in single therapy, could moderately inhibit the proliferation and migration of DDP-resistant gastric cancer cells, SGC7901/DDP. DDP and LIQ in combination induced G0/G1 cell cycle arrest to suppress the proliferation of gastric cancer cells, which were associated with the decrease of cyclin D1, cyclin A and cyclin-dependent kinase 4 (CDK4) and increase of p53 and p21. In addition, LIQ combined with DDP significantly induce apoptosis and autophagy both in vitro and in vivo through enhancing cleavage of caspase-8/-9/-3 and PARP, as well as LC3B and Beclin 1 expression. Significantly, the two drugs, when used in combination, prevented gastric cancer cell xenografts in nude mice in vivo. Together, the results revealed that application of DDP and LIQ in combination possessed a potential value against the growth of human gastric cancer with DDP resistance.

Purification of high-purity glycyrrhizin from licorice using hydrophilic interaction solid phase extraction coupled with preparative reversed-phase liquid chromatography

Glycyrrhizin (GA), a major bioactive compound in licorice, has been extensively used throughout the world as a medicine to treat chronic viral hepatitis and allergic dermatitis. In this study, a new method based on hydrophilic interaction solid phase extraction (HILIC-SPE) and preparative reversed-phase liquid chromatography (prep-RPLC) was developed to purify GA with high purity from the complex licorice extract. Via evaluation of retention behavior of GA and flavonoids in different commercially available columns, a hydrophilic column--Click XIon was finally chosen for the purification due to its excellent resolution toward GA and flavonoids under HILIC mode. To optimize the SPE elution conditions, relative factors including water content, pH and ionic strength had been investigated in chromatographic condition. The result indicated that the most appropriate water content was 30% and pH at 4.00, as well as salt concentration should be controlled at 5mM. In addition, the optimization revealed that GA experiences both hydrophilic interaction and ion-exchange interaction on the Click XIon material. According to the chromatographic evaluation, the optimized conditions were applied to HILIC-SPE to enrich GA from licorice, which leads to an increased content of GA from 13.67% to 64.22%. Finally, prep-RPLC was performed to obtain GA with purity higher than 99.00%，which demonstrating great prospect in large-scale preparation of GA.

Phytochemistry and biological properties of glabridin

Glabridin, a prenylated isoflavonoid of G. glabra L. roots (European licorice, Fabaceae), has been associated with a wide range of biological properties such as antioxidant, anti-inflammatory, anti-atherogenic, regulation of energy metabolism, estrogenic, neuroprotective, anti-osteoporotic, and skin-whitening. While glabridin is one of the most studied licorice flavonoids, a comprehensive literature survey linked to its numerous bioactivities is unavailable. The present review provides a comprehensive description of glabridin as a key chemical and biological marker of G. glabra, by covering both its phytochemical characterization and reported biological activities. Both glabridin and standardized licorice extracts have significant impact on food, dietary supplements (DSs) and cosmetic markets, as evidenced by the amount of available patents and scientific articles since 1976, when glabridin was first described. Nevertheless, a thorough literature survey also reveals that information about the isolation and chemical characterization of this important marker is scattered and less detailed than expected. Accordingly, the first part of this review gathers and provides all analytical and spectroscopic data required for the comprehensive phytochemical characterization of glabridin. The four most frequently described and most relevant bioactivities of glabridin are its anti-inflammatory, anti-atherogenic, estrogenic-like effects, and its capacity to regulate energy metabolism. While all bioactivities reported for glabridin belong to a wide array of targets, its principal biological properties are likely interconnected. To this end, the current state of the literature suggests that the biological activity of glabridin mainly results from its capacity to down-regulate intracellular reactive oxygen species, bind to antioxidant effectors, and act on estrogen receptors, potentially as a plant-based Selective Estrogen Receptor Modulator (phytoSERM).

Solid-phase extraction of liquiritin and glycyrrhizin from licorice using porous alkyl-pyridinium polymer sorbent

INTRODUCTION

Liquiritin and glycyrrhizin are valuable components of licorice. An effective separation and determination procedure is needed to separate the liquiritin and glycyrrhizin from the licorice extract.

METHODOLOGY

A polymer-confined, ionic liquid sorbent was developed using a process involving polymerisation and modification. The obtained porous particles were used as a sorbent in a solid-phase extraction process to isolate liquiritin and glycyrrhizin from licorice with different washing and elution solvents. The porous alkyl-pyridinium polymer sorbent was compared with the C(18) sorbent.

RESULTS

A simple and convenient method was established to the selectively separate and determinate of liquiritin and glycyrrhizin using a porous ionic liquid-based polymer coupled with HPLC. Additionally, this study evaluated the application of this sorbent for the detection of these two compounds in commercial medicines.

CONCLUSION

This method was a viable tool that was compatible with the existing HPLC methods and was used to separate and analyse the content of liquiritin and glycyrrhizin in licorice.

Solid-phase extraction of liquiritin and glycyrrhizic acid from licorice using ionic liquid-based silica sorbent

A new ionic liquid-based silica sorbent was developed by a process involving surface chemical modification of commercial silica using a synthesized ionic liquid. The obtained particles were successfully used as a special sorbent in a solid-phase extraction process to isolate liquiritin and glycyrrhizic acid from licorice. Different washing and elution solvents, such as water, methanol/water (v/v), and pure methanol were evaluated. Ionic liquid-based silica sorbent was compared with traditional C(18) sorbent and it exhibited higher selectivity. Quantitative analysis was carried out by using a C(18) column. Good linearities of two compounds were obtained from 5x10(-4) to 0.2 mg/mL (r(2)>0.99) with the relative standard deviations <1.0%. The target compounds in commercial herbal medicines containing licorice were determined, and the bound rates between the target compounds and protein were obtained by this sorbent.