Simultaneous quantification of flavonoids and triterpenoids in licorice using HPLC

Stability Indicating Method Development and Validation of Glycyrrhizin Using RP-HPLC-DAD: Application to Glycyrrhiza glabra Extract

Glycyrrhiza glabra is commonly known as licorice. Licorice is the major source of glycyrrhizin. There is no reported stability indicating method for glycyrrhizin in the literature so far. Therefore, it was proposed to develop a stability indicating method and validate the method for glycyrrhizin and its application in G. glabra root extract. Method validation parameters were performed as per the International Council for Harmonization guidelines. The chromatographic separation was achieved on a Zorbax Extended C-18 (250 × 4.6 mm, 5 μm) column. The separation achieved using the mobile phase consisted of 0.1% formic acid in water and acetonitrile in gradient elution. The flow rate was kept at 1 mL/min, and ultraviolet-visible spectroscopy detection was at 250 nm. The average retention time of glycyrrhizin was found to be 7.30 min. Stress degradation studies were performed and confirmed that only acidic degradation has shown a degradation profile of glycyrrhizin up to 40%. The percentage of glycyrrhizin was found to be 0.40% in the G. glabra extract. This may be further explored for commercial applications.

Authentication of ten distinctive triterpenoids in Antrodia cinnamomea serves as a crucial aspect for ensuring the quality control of associated nutraceutical products

Edible mushroom Antrodia cinnamomea is distinctive for its use in many health supplement products in relieving of diverse health-related conditions. A. cinnamomea is known for its rich array of bioactive secondary metabolites, predominantly terpenoids, that possess anti-inflammatory properties. Despite the abundance of these compounds, only some compounds have demonstrated notable anti-inflammatory activity. Moreover, there is a lack of established quality control methods specifically tailored to the active constituents of these products. Consequently, there is a great need for the development of precise and effective quality control methods for A. cinnamomea-based products, targeting their active components to ensure the consistency and reliability of these products in harnessing their anti-inflammatory potential. Herein we report a quantitative HPLC method for better evaluating the quality of A. cinnamomea based dietary supplements. Based on their bioactivities, we selected ten benchmark compounds, i. e. antcin K, (25S)-antcin H, (25R)-antcin H, (25R)-antcin C, (25S)-antcin C, (25R)-antcin A, 15α-acetyl-dehydrosulphurenic acid, versisponic acid D, dehydroeburicoic acid, and eburicoic acid and developed and validated a HPLC-UV method for quantification of these compounds simultaneously with high sensitivity, linearity and range, precision, and accuracy. Furthermore, we applied our method to quantify the commercially available A. cinnamomea containing supplements and found that the quality of these supplements varies greatly with only one product containing good amount of the active compounds. Our method provides a needed solution to quality control problem of the highly priced A. cinnamomea food and nutraceutical products that show great variety and inconsistency.

Effects of dietary supplement with licorice and rutin mixture on production performance, egg quality, antioxidant capacity, and gut microbiota in quails (Turnix tanki)

This study was conducted to evaluate the effect of licorice and rutin on production performance, egg quality, and mucosa antioxidant levels in Chinese yellow quail. A total of 240 Chinese Yellow Quail (400-day-old) were randomly distributed into 5 groups: the Control group, fed with a basic diet; the LR1 group, fed with basal diet supplemented with 300 + 100 mg licorice and rutin mixture/kg diet; the LR2 group, fed with basal diet supplemented with 300 + 200 mg licorice and rutin mixture/kg diet; the LR3 group, fed with basal diet supplemented with 600 + 100 mg licorice and rutin mixture/kg diet and the LR4 group, fed with basal diet supplemented with 600 + 200 mg licorice and rutin mixture/kg diet. Compared with the control, supplementation with the licorice and rutin mixture improved the laying rate and eggshell thickness whereas decreased the feed conversion ratio of quails. Moreover, dietary supplementation with the licorice and rutin mixture improved the antioxidant capacity by increasing the activity of the superoxide dismutase (SOD) level and decreasing the concentration of malondialdehyde (MDA) in the jejunal mucosa. The licorice and rutin mixture altered the composition of intestinal microbiota by influencing the relative abundances of Bacteroidetes and Bacteroides. The relative abundances of the Bacteroidetes were significantly related to the laying rate of quails. In addition, the mixture of licorice and rutin was also effective in reducing the relative abundance of intestinal Proteobacteria and Enterobacter in quails, reducing the accumulation of antibiotic-resistance genes. The results revealed that supplementation of licorice and rutin mixture to the diet improved production performance, egg quality, and antioxidant capacity and modified the composition of intestinal microbiota in quails. This study provides a reference for Chinese herbal additives to promote production performance by modulating quail gut microbes.

Biocontrol of Plant Diseases Using Glycyrrhiza glabra Leaf Extract

The growing concern regarding the potential risks of pesticides and their impact on nontarget organisms stimulates the development and application of alternative, environmentally friendly products. It seems necessary to develop alternatives for conventional products and for those already widely used in organic agriculture, e.g., copper. Very importantly, such alternative products should not limit the productivity and profitability of agriculture. In this study, we examined the efficacy of licorice (Glycyrrhiza glabra) leaf extract as such an alternative. We tested its impact on the virulence of Pseudomonas syringae toward the model plant Arabidopsis thaliana and the crop plant tomato (Solanum lycopersicum) as well as of Clavibacter michiganensis, Xanthomonas campestris, and Phytophthora infestans toward tomato, at multiple levels. We demonstrate that licorice leaf extract acts as a direct fungicide and bactericide. Moreover, it acts against a metalaxyl-resistant P. infestans strain. In addition, the extract from licorice leaves influences the plant immune system, modulating the plant responses to the challenge with pathogen(s); this involves both salicylic acid and ethylene-based responses. Our results show that in addition to the well-known use of licorice root extract in medicine, the leaf extract can be an effective alternative in organic and integrated farming, contributing to copper reduction and resistance management.[Formula: see text] Copyright © 2022 The Author(s). This is an open-access article distributed under the CC BY 4.0 International license.

Isolation, Characterization, Pharmacology and Biopolymer Applications of Licorice Polysaccharides: Review

Licorice is known as "Gan-Cao" in traditional Chinese Medicine (TCM), belonging to the genus Glycyrrhiza (Family: Fabaceae/Leguminosae). It has a long medicinal history and wide applications in China. Polysaccharides of licorice (LPs) are one of the key bioactive components. As herbal polysaccharides attracted increasing interest in the past several decades, their extraction, isolation, structural characterization, pharmacological activities, and medicinal application have been explored extensively. It is worth heeding that the method of extraction and purification effects LPs, apart from specie and origin specificity. This review evaluates the method of extraction and purification and demonstrates its performance in gaining specific composition and its structure-activity relationship, which might lead the readers to a fresh horizon for developing advanced treatment strategies. It is recently reported that the conformation of LPs plays a vital role as biopolymers, such as selenized modification, microencapsulation, nanocomposite, liposome formulation, drug/hydrogel combinations, biosensor device, and synergistic effect with a vaccine. In addition, LPs showed a good thermodynamics profile, as these properties enable them to interact with additional supramolecular interaction by chemical modifications or copolymerization. Functional polymers that are responsive to various external stimuli, such as physical, chemical, and biological signals, are a promising study topic. Thus, LPs are emerging as a new biomaterial that can enhance intended formulation along exerting its inherent medicinal effects. It is hoped that this review will provide a basis for the utilization and further developments of licorice polysaccharides in the vast medium.

A Mini-Review on Structure-Activity Relationships of Glycyrrhetinic Acid Derivatives with Diverse Bioactivities

Pentacyclic triterpenoids, consisting of six isoprene units, are a kind of natural active substance. At present, numerous pentacyclic triterpene have been observed and classified into four subgroups of oleanane, ursane, lupane, and xylene on the basis of the carbon skeleton. Among them, oleanane is the most popular due to its rich backbone and diverse bioactivities. 18β-Glycyrrhetinic acid (GA), an oleanane-type pentacyclic triterpene isolated from licorice roots, possesses diverse bioactivities including antitumor, anti-inflammatory, antiviral, antimicrobial, enzyme inhibitor, hepatoprotective and so on. It has received more attention in medicinal chemistry due to the advantages of easy-to-access and rich bioactivity. Thus, numerous novel lead compounds were synthesized using GA as a scaffold. Herein, we summarize the structure-activity relationship and synthetic methodologies of GA derivatives from 2010 to 2020 as well as the most active GA derivatives. Finally, we anticipate that this review can benefit future research on structural modifications of GA to enhance bioactivity and provide an example for developing pentacyclic triterpene-based novel drugs.

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.

Chemometric analysis of active compounds and antioxidant and α-glucosidase inhibitory activities for the quality evaluation of licorice from different origins

Contents of total flavonoids (TFc), total phenolics (TPc), and total crude polysaccharide (TCPc) in licorice from different origins were determined by optimized colorimetric methods, whereas five monomer ingredients (liquiritin [LQ], isoliquiritin [ILQ], liquiritigenin [LQG], isoliquiritigenin [ILQG], and glycyrrhizic acid [GA]) were simultaneously identified and quantified by HPLC-MS and HPLC. The results indicated that the contents of chemical compounds in licorice showed significant difference in different origins. Hierarchical cluster analysis and principal component analysis further proved that producing area indeed affected the quality including compounds and pharmacological activity in licorice. Licorice from Inner Mongolia exhibited the excellent DPPH assay, whereas samples from Gansu and Xinjiang showed high scavenging capacity to OH and ABTS free radicals. Meanwhile, α-Glu inhibitory activity of licorice samples was four times higher than the antioxidant activity. Correlation analysis made clear that TFc and TCPc both strongly contribute to DPPH scavenge capacity at P < 0.01 level, whereas TCPc contributed to α-Glu inhibitory activity at P < 0.05 level. This study would contribute to the comprehensive quality evaluation based on the compounds and pharmacological activity of licorice, and provide a reference for the choice of producing area to ensure the quality of licorice as a medicine.

Network Pharmacology-Based Strategy for Elucidating the Molecular Basis Forthe Pharmacologic Effects of Licorice (Glycyrrhiza spp.)

Licorice (Glycyrrhiza spp.) is used widely in traditional Chinese medicine (TCM) due to its numerous pharmacologic effects. However, the mechanisms of action of the chemical constituents of licorice and their structure–function relationships are not fully understood. To address these points, we analyzed the chemical compounds in licorice listed in the TCM Systems Pharmacology database and TCM Integrated database. Target proteins of the compounds were predicted using Integrative Pharmacology-based Research Platform of TCM v2.0. Information on the pharmacologic effects of licorice was obtained from the 2020 Chinese Pharmacopoeia, and disease-related genes that have been linked to these effects were identified from the Encyclopedia of TCM database. Pathway analyses using the Kyoto Encyclopedia of Genes and Genomes database were carried out for target proteins, and pharmacologic networks were constructed based on drug target–disease-related gene and protein–protein interactions. A total of 451 compounds were analyzed, of which 211 were from the medicinal parts of the licorice plant. The 241 putative targets of 106 bioactive compounds in licorice comprised 52 flavonoids, 47 triterpenoids, and seven coumarins. Four distinct pharmacologic effects of licorice were defined: 61 major hubs were the putative targets of 23 compounds in heat-clearing and detoxifying effects; 68 were targets of six compounds in spleen-invigorating and qi-replenishing effects; 28 were targets of six compounds in phlegm-expulsion and cough-suppressant effects; 25 compounds were targets of six compounds in spasm-relieving and analgesic effects. The major bioactive compounds of licorice were identified by ultra-high-performance liquid chromatography–quadrupole time-of-flight–tandem mass spectrometry. The anti-inflammatory properties of liquiritin apioside, liquiritigenin, glycyrrhizic acid and isoliquiritin apioside were demonstrated by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis. Liquiritin apioside, liquiritigenin, isoliquiritin, isoliquiritin apioside, kaempferol, and kumatakenin were the main active flavonoids, and 18α- and 18β-glycyrrhetinic acid were the main active triterpenoids of licorice. The former were associated with heat-clearing and detoxifying effects, whereas the latter were implicated in the other three pharmacologic effects. Thus, the compounds in licorice have distinct pharmacologic effects according to their chemical structure. These results provide a reference for investigating the potential of licorice in treatment of various diseases.

Quality Assessment of Licorice Based on Quantitative Analysis of Multicomponents by Single Marker Combined with HPLC Fingerprint

Licorice is a commonly used traditional Chinese medicine and natural sweetening agent, rich in numerous bioactive compounds. Moreover, it is one of the oldest and most frequently employed folk medicines in both eastern and western countries. It is prescribed for the treatment of asthma, fever, and cough. However, with the increasing demand of licorice, its quality and safety become the important issue. The content in licorice varies significantly in materials from different geographical origins. In this study, a reasonable and feasible evaluation method for the quality assessment of licorice was developed based on the analysis of high-performance liquid chromatography (HPLC) fingerprint, combined with the quantitative analysis of multicomponents by single marker (QAMS) method. Glycyrrhizic acid was selected as the internal reference substance, and ten components were simultaneously determined based on relative correction factors. The contents of eleven components in 21 batches of licorice were determined by the QAMS and the ESM (external standard method); there was no significant difference by comparison of the quantitative results between the QAMS and the ESM method; the cosine value (Cir > 0.9999) confirmed the consistency of the two methods. According to the outcomes of 21 batches of licorice samples, the contents of the eleven components were used for further chemometric analysis. All of the samples of licorice from various geographical origins were divided into five categories based on hierarchical cluster analysis, which indicated the crucial influence of geographical origins on licorice. This study showed that QAMS combined with HPLC fingerprint and chemometrics methods could effectively control the quality of licorice. Hence, QAMS is a feasible and promising method for promoting the quality control standardization process of herbal medicines.

Recent advances in chemical analysis of licorice (Gan-Cao)

Gan-Cao, or licorice, the dried roots and rhizomes of Glycyrrhiza uralensis, G.glabra, and G.inflata, has received considerable interest due to its extensive application in traditional Chinese medicine (TCM) prescriptions (60% approximately), clinical therapy, and as food additives world-wide. Chemical analysis is an important approach to understand the active pharmaceutical components in licorice and its prescriptions, as well as to develop novel methodologies for their quality assessment and control. This comprehensive review describes the advances in the chemical analysis, including sample preparation methods, qualitative and quantitative analysis and biological specimen analysis, based on 113 references for the recent years. Newly established methods are summarized, such as high performance thin layer chromatography (HPTLC), high performance liquid chromatography (HPLC), liquid chromatography tandem mass spectrometry (LC-MS), capillary electrophoresis (CE) and near infrared spectroscopy (NIR), which allows the identification, authentication, and simultaneous detection of multiple compounds in licorice with higher throughput and sensitivity. It is anticipated that this review could provide imperative information for improving the existing quality evaluation methods of licorice and afford scientific basis for further researches on the pharmacodynamic substances of licorice.

Spectrum-Effect Relationships of Flavonoids in Glycyrrhiza uralensis Fisch

Glycyrrhiza uralensis Fisch. is used in large quantities in traditional Chinese medicine. It contains flavonoids, saponins, and polysaccharides, with flavonoids being the main active ingredients. In this study, flavonoids were isolated from the roots of Glycyrrhiza uralensis Fisch. grown in 21 areas in China by water extraction, alcohol precipitation, polyamide resin separation, and other methods. Fingerprints were established by high performance liquid chromatography (HPLC). There were 15 common peaks in the fingerprints by similarity evaluations of the chromatographic fingerprints. The spectrum-effect relationships between the HPLC fingerprints and pharmacological activities of flavonoids in G. uralensis Fisch., including the heat clearing, detoxifying effects, cough relief, and phlegm elimination effects, were assessed by gray relational analysis and partial least squares regression. After HPLC-quadrupole time-of-flight mass spectrometry and standard comparison, these five identified compounds (liquiritin apioside, neoisoliquiritin, licochalcone A, licochalcone B, and licochalcone C) could be used to evaluate licorice quality with regard to its efficacy. This research provides a scientific basis for improving licorice quality and also establishes a model for modernization of traditional Chinese medicines.

Simultaneous Determination of 6 Antiallergic Components in Asarum sieboldii Using High-Performance Liquid Chromatography

Owing to the side effects of current drugs for treating atopic dermatitis (AD), a chronic disease in the skin, traditional herbal medicine is receiving much attention as an alternative treatment. Asarum sieboldii has traditionally been used to treat colds, fevers, headaches, coughs, neuralgia, chronic bronchitis, asthma, and allergies. In this study, 6 compounds (echinacoside, vanillic acid, kakuol, methyl eugenol, sesamin, and asarinin) in A. sieboldii were analyzed simultaneously using high-performance liquid chromatography (HPLC), and the proposed analytical method was validated. In addition, the inhibitory effects of the A. sieboldii extract and the 6 analyzed compounds on the expression of chemokine were evaluated in HaCaT cells. The HPLC method showed high linearity, with a correlation coefficient of ≥0.9999. The limits of detection for the 6 compounds ranged from 0.00 to 0.02 µg/mL, and the limits of quantification ranged from 0.01 to 0.05 µg/mL. The intraday and interday precisions were 0.15%-1.90%; the accuracy was 97.36%-103.23%, and the recoveries of the 6 compounds were 97.45%-103.93%. The content of each compound in A. sieboldii, as determined using the corresponding calibration curve, was in the range of 0.380-12.062 mg/g. This optimized simultaneous quantification method will be suitable for improving the quality control of A. sieboldii. Moreover, the 6 compounds in A. sieboldii showed an inhibitory effect on the production of chemokines, which suggests that A. sieboldii has an antiallergic effect.

Determination of 12 herbal compounds for estimating the presence of Angelica Gigas Root, Cornus Fruit, Licorice Root, Pueraria Root, and Schisandra Fruit in foods by LC-MS/MS

A wide variety of plant raw materials thought to promote health are used as herbal medicines as well as foods. However, there is no legal maximum or minimum concentration limit on any herbal compound when these plant raw materials are used in processed foods. Legally, these processed foods are regulated only for harmful substances, and there is no other guarantee of their contents. Therefore, the objective of this study was to determine the concentrations of 12 herbal compounds (nodakenin, decursin, decursinol angelate, morroniside, loganin, glycyrrhizic acid, liquiritigenin, puerarin, daidzin, schisandrin, gomisin A, gomisin N) in commonly used plant raw materials, such as "Angelica Gigas root", "Cornus Fruit", "Liquorice Root", "Pueraria Root", and "Schisandra Fruit"; and also in 45 processed foods, using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Method validation was performed successfully using the parameters of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, matrix effect, extraction recovery, and stability. The 12 herbal compounds were determined to be present in all the foods advertised as containing each ingredient, although in very low concentrations in some cases. Three solid samples labelled as 100% pure material from one herbal species also contained herbal compounds found in others, so that intentional or unintentional adulteration was suspected.

The antioxidant activity and neuroprotective mechanism of isoliquiritigenin

Glycyrrhizae radix has been widely accepted as a functional food in Asia. Isoliquiritigenin is a characteristic bioactive chemical in this medicinal plant. In this work, the neuroprotective effect of isoliquiritigenin and the possible mechanisms were investigated. The results revealed that isoliquiritigenin exhibited better neuroprotective and antioxidant activities than quercetin, a commercial natural antioxidant. Isoliquiritigenin significantly inhibited the release of lactate dehydrogenase, and the generation of reactive oxygen species in H₂O₂-treated cells. The activities of superoxide dismutase, glutathione peroxidase and catalase were improved. The mRNA expression levels related to oxidative defense and cell apoptosis were reversed by isoliquiritigenin. Moreover, isoliquiritigenin might inhibit the cell apoptosis via ameliorating the loss of mitochondrial membrane potential and the change of nucleus morphology.

Network Pharmacology-Based Approaches of Rheum undulatum Linne and Glycyrriza uralensis Fischer Imply their Regulation of Liver Failure with Hepatic Encephalopathy in Mice

Rheum undulatum and Glycyrrhiza uralensis have been used as supplementary ingredients in various herbal medicines. They have been reported to have anti-inflammatory and antioxidant effects and, therefore, have potential in the treatment and prevention of various liver diseases. Considering that hepatic encephalopathy (HE) is often associated with chronic liver failure, we investigated whether an R. undulatum and G. uralensis extract mixture (RG) could reduce HE. We applied systems-based pharmacological tools to identify the active ingredients in RG and the pharmacological targets of RG by examining mechanism-of-action profiles. A CCl₄-induced HE mouse model was used to investigate the therapeutic mechanisms of RG on HE. We successfully identified seven bioactive ingredients in RG with 40 potential targets. Based on an integrated target–disease network, RG was predicted to be effective in treating neurological diseases. In animal models, RG consistently relieved HE symptoms by protecting blood–brain barrier permeability via downregulation of matrix metalloproteinase-9 (MMP-9) and upregulation of claudin-5. In addition, RG inhibited mRNA expression levels of both interleukin (IL)-1β and transforming growth factor (TGF)-β1. Based on our results, RG is expected to function various biochemical processes involving neuroinflammation, suggesting that RG may be considered a therapeutic agent for treating not only chronic liver disease but also HE.

Quantitative fingerprint and quality control analysis of Compound Liquorice Tablet combined with antioxidant activities and chemometrics methods

BACKGROUND

Herbal medicine (HM), as a complex system, is difficult to investigate their quality consistency effectively by chromatographic fingerprinting obtained in a single detection method. Moreover, active compound discovery affords no information about pharmacological activity until late in the discovery process, and the interaction between HMs in vitro is not yet clear, which requires sufficient practice to prove their effectiveness.

PURPOSE

Therefore, the purpose of this study was to improve the quality control methods of Compound Liquorice Tablet (CLT) using multi-wavelength fusion fingerprinting, explore the possible antioxidant components and assess the interaction between herbs combined with bioactivity evaluation.

METHODS AND DESIGN

Once the theoretical standard preparation obtained in combination of multi-wavelength fusion fingerprinting and hierarchical clustering analysis, averagely linear quantified fingerprint method could rapidly calculate the composition similarities and efficiently quantify the multiple components of CLTs without any chemical standard. Furthermore, the fingerprint-efficacy relationship was investigated by integrating high performance liquid chromatography fingerprints with antioxidant activity assessment using the partial least squares model, which was capable of directly discovering the bioactive ingredients. Hereafter, combination index value was introduced to evaluate the correlation between the two antioxidant herbs in CLT formula.

RESULTS

The results showed that CLT samples were effectively identified and quantified, and their quality was accurately distinguished. By analyzing the antioxidant evaluation results, it was found that CLT had strong antioxidant activity, and through the study on PLS model and antioxidant activity assay of individual compounds, it was found that the order of chemical constituents responsible for antioxidant activity in CLT was as follows: flavonoids > saponins > alkaloids. Finally, it was determined that the CI value of GE-PPCE was in the range of 1.20-1.61, indicating that the interaction of the GE-PPCE pair was a slight antagonism.

CONCLUSION

Thus, this study provided a preferred way for monitoring the quality consistency of HM, exploring possible bioactive components of HMs and assessing the interaction between herbs.

A novel symmetrical cyclooctenone from Radix Glycyrrhizae

A novel symmetrical structure, Gancao cyclooctenone A (1), was isolated from Radix Glycyrrhizae. The structure of the compound was established on the basis of the spectroscopic data including 1D and 2D NMR spectroscopy and mass spectrometry. Cytotoxic activities of compound 1 on A549 and Hela cell lines were evaluated and the IC₅₀ values were determined to be 63.21 and 45.82 μΜ, respectively.

A strategy for qualitative and quantitative profiling of glycyrrhiza extract and discovery of potential markers by fingerprint-activity relationship modeling

This study was to evaluate the quality consistency of glycyrrhiza extract and to explore the possible anti-oxidant components in combination with chromatographic fingerprint and bioactivity evaluation. Characteristic fingerprints of glycyrrhiza extract samples from different sources were generated by high performance liquid chromatography with diode array detector (HPLC-DAD) and evaluated using hierarchical clustering and similarity analysis. Compared with the conventional qualitative similarity evaluation method, the averagely linear quantified fingerprint method had an important quantitative similarity parameter supported by quantitative analysis, which was recommended in the fingerprint evaluation. Antioxidant activities of the glycyrrhiza extract samples were determined by DPPH (2, 2-diphenyl-1-picryldrazyl) radical scavenging assays. In addition, the fingerprint-efficacy relationship was investigated by the chemical fingerprints and the anti-oxidant activities utilizing partial least squares model, which was capable of exploring and discovering the bioactive components of glycyrrhiza extracts. Therefore, the present study provided a powerful strategy to evaluate the holistic quality consistency of medicinal plant.

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).

Effect of seedling grade standard on improving the quality of licorice (Glycyrrhiza uralensis F.): changes in the seven bioactive components and root biomass during two-year growth

Licorice cultivated is one of the most popular herbal medicines, while its quality is unstable. The aim of present study is to investigate the effect of licorice seedling grade standard on improving its quality. One-year-old Glycyrrhiza uralensis seedlings were classified into three grades 1, 2, and 3 by weight per plant. The major root biomass indexes (root fresh weight, root dry weight and taproot diameter) and contents of 7 bioactive components (glycyrrhizin, liquiritin, liquiritin apioside, liquiritigenin, isoliquiritin, isoliquiritin apioside, and isoliquiritigenin) varied in different grades seedlings. Further, the contents of 7 investigated compounds of 3-year-old licorice produced by grade 1 seedlings were 1.5-2 times as much as those produced by grade 2 and 3. Additionally, the contents of liquiritin apioside and isoliquiritin apioside were positively correlated with licorice root biomass. These results indicated that establishing licorice seedling grade standard is an effective way to improve and control its quality.

Untargeted profiling of Glycyrrhiza glabra extract with comprehensive two-dimensional liquid chromatography-mass spectrometry using multi-segmented shift gradients in the second dimension: Expanding the metabolic coverage

Metabolic profiling of Glycyrrhiza glabra using comprehensive two-dimensional liquid chromatography (LC × LC) coupled with photodiode array (PDA) and mass spectrometry (MS) detection is described. The separation was conducted under reversed-phase conditions, using a combination of first dimension (1 D) 150 mm microbore cyano column utilising 2.7 μm diameter (dp ) particles, and second dimension (2 D) 50 mm superficially porous octadecylsilica column with 2.7 μm dp particles. A multi-segmented shift gradient (MSG) for the 2 D separation was developed, and the orthogonality achieved was compared with other modes of gradients, such as full in-fraction, and shift gradient systems. Results demonstrated a significant expansion of metabolic coverage using MSG in 2 D, providing the highest measure of orthogonality compared to other gradient modes. Compound identifications were performed by employing complementary data from PDA and MS detection, with reference to structural group-type distribution in 2D space. A total of ca. 120 compounds were detected, and among them 37 were tentatively identified, distributed over the chemical families of glycosylated flavanones, triterpene saponins, and others. In comparison with one-dimensional LC, the total number of compounds detected was ca. 2-fold greater when LC × LC was employed. To the best of our knowledge, this is the first demonstration of the MSG mode in LC × LC, representing a powerful strategy to expand the metabolic coverage for analysis of plant-derived extracts, containing a multitude of different phytochemical classes.

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.

From Vegetable Waste to New Agents for Potential Health Applications: Antioxidant Properties and Effects of Extracts, Fractions and Pinocembrin from Glycyrrhiza glabra L. Aerial Parts on Viability of Five Human Cancer Cell Lines

Glycyrrhiza glabra cultivation and harvesting produces substantial quantities of aerial parts as waste. With the aim to prospect an innovative valorization of these byproducts, the aerial parts were harvested in May and October and analyzed for their chemical profile, antioxidant properties, and effects on viability of five cancer cell lines. Pinocembrin was the main constituent. A significant protection of lipid peroxidation was observed with the May total extract (IC₅₀ of 4.2 ± 0.4 μg/mL at 30 min of incubation). The effects on viability of HeLa, MCF-7, MDA-MB-231, Caco-2, and PC3 human cancer cells were investigated. All samples shown a remarkable activity with IC₅₀ values below 25 μg/mL. Samples from plants harvested in May exhibited greater activity than those harvested in October. MCF-7 and HeLa were the most sensitive cells with IC₅₀ in the range 2.73-3.01 and 3.28-5.53 μg/mL, respectively. G. glabra aerial parts represent a good source of valuable products.

Purification of flavonoids from licorice using an off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method

An orthogonal (71.9%) off-line preparative two-dimensional normal-phase liquid chromatography/reversed-phase liquid chromatography method coupled with effective sample pretreatment was developed for separation and purification of flavonoids from licorice. Most of the nonflavonoids were firstly removed using a self-made Click TE-Cys (60 μm) solid-phase extraction. In the first dimension, an industrial grade preparative chromatography was employed to purify the crude flavonoids. Click TE-Cys (10 μm) was selected as the stationary phase that provided an excellent separation with high reproducibility. Ethyl acetate/ethanol was selected as the mobile phase owing to their excellent solubility for flavonoids. Flavonoids co-eluted in the first dimension were selected for further purification using reversed-phase liquid chromatography. Multiple compounds could be isolated from one normal-phase fraction and some compounds with bad resolution in one-dimensional liquid chromatography could be prepared in this two-dimensional system owing to the orthogonal separation. Moreover, this two-dimensional liquid chromatography method was beneficial for the preparation of relatively trace flavonoid compounds, which were enriched in the first dimension and further purified in the second dimension. Totally, 24 flavonoid compounds with high purity were obtained. The results demonstrated that the off-line two-dimensional liquid chromatography method was effective for the preparative separation and purification of flavonoids from licorice.

Importance of Accurate Measurements in Nutrition Research: Dietary Flavonoids as a Case Study

Accurate measurements of the secondary metabolites in natural products and plant foods are critical for establishing relations between diet and health. There are as many as 50,000 secondary metabolites that may influence human health. Their structural and chemical diversity presents a challenge to analytical chemistry. With respect to flavonoids, putative identification is accessible, but positive identification and quantification are limited by the lack of standards. Quantification has been tested with use of both nonspecific and specific methods. Nonspecific methods, which include antioxidant capacity methods, fail to provide information on the measured components, suffer from numerous interferences, are not equatable, and are unsuitable for health research. Specific methods, such as LC with diode array and mass spectrometric detection, require the use of internal standards and relative molar response factors. These methods are relatively expensive and require a high level of expertise and experimental verification; however, they represent the only suitable means of relating health outcomes to specific dietary components.

Chemical and Metabolic Profiling of Si-Ni Decoction Analogous Formulae by High performance Liquid Chromatography-Mass Spectrometry

Along with an indispensable role in healthcare system of China for centuries, Traditional Chinese Medicine (TCM) shows increasing usages as complementary therapy in western countries. To improve our understanding on their therapeutic effects, it’s critical to unveil chemical compositions of TCM formula, the predominant form of therapy in TCM. However, intrinsic chemical complexity makes it a challenging task to perform analysis on each individual TCM formula even with most current state-of-art analytic techniques available. In this work we approached this question by focusing on analogous formulae, a unique category of TCM formulae grouped together based on shared herbs and/or similar TCM syndromes. Systematic chemical profiling on five Si-Ni decoctions (SNs) for cardiovascular diseases was performed by multistage MS and high-resolution MS (HR-MS) experiments. A total of 83 compounds, including alkaloids, flavonoids, ginsenosides, bile acids and triterpenoids, were described. Analysis on SNs-treated rats detected 55 prototype compounds and 39 metabolites in the systemic circulation in vivo, which may contribute directly to their observed clinical efficacies. This approach offers great advantage to speed up identification of chemical compositions of formula and reveal the difference among these analogous formulae that may be related to diverse clinical effects.

The mechanism of hydrothermal hydrolysis for glycyrrhizic acid into glycyrrhetinic acid and glycyrrhetinic acid 3-O-mono-β-D-glucuronide in subcritical water

To improve the bioactivity and sweetness properties of glycyrrhizic acid (GL), the hydrothermal hydrolysis of GL into glycyrrhetinic acid (GA) and glycyrrhetinic acid 3-O-mono-β-D-glucuronide (GAMG) in subcritical water was investigated. The effects of temperature, time and their interaction on the conversion ratios were analyzed and the reactions were elaborated with kinetics and thermodynamics. The results showed that GL hydrothermal hydrolysis was significantly (P < 0.05) affected by reaction time and temperature, as well as their interaction, and could be fitted into first-order kinetics. The thermodynamic analysis indicated that the hydrolysis of GL was endergonic and non-spontaneous. The hydrolytic pathways were composed of complex consecutive and parallel reactions. It was concluded that subcritical water may be a potential medium for producing GAMG and GA.

Recommendations on reporting requirements for flavonoids in research

Numerous observational and intervention-based human studies support the notion of a beneficial role for dietary flavonoids in human health. Despite these studies, it is not yet possible to make dietary recommendations with regard to the types and amounts of flavonoids to be consumed. The inherent diversity of flavonoid structure, chemistry, and natural distribution in foods lends itself to errors in reporting the types and/or amounts of flavonoids consumed, as well as incomplete recognition of requirements for intervention studies that aim to assess their benefits in a clinical setting. A need exists for guidelines that facilitate the design and reporting of flavonoid research. With a focus on clinical studies, this article 1) outlines limitations commonly encountered in the field of flavonoid research, including the inconsistent use of nomenclature, inappropriate analytic methods, inconsistent use of existing flavonoid databases, and the lack of full consideration in the design of test materials for intervention trials, and 2) provides guidance for future studies with a focus on clinical intervention trials. Adoption of this guidance will facilitate more accurate and interpretable research that will support the development of dietary recommendations regarding the intake of flavonoids.

Simultaneous determination and assignment of 13 major flavonoids and glycyrrhizic acid in licorices by HPLC-DAD and Orbirap mass spectrometry analyses

To determine 13 flavonoids and glycyrrhizic acid in licorice (Glycyrrhiza spp.), several samples from different areas were examined by HPLC-DAD analysis. The analysis was performed on a Zorbax Extend-C18 (250 mm × 4.6 mm, 5 μm) column connected with a Zorbax Extend guard column (20 mm × 4.6 mm, 5 μm). The mobile phase consisted of (A) acetonitrile and (B) 0.026% aqueous H3PO4 (VV) using a gradient elution of 20%-25% A at 0-20 min, 25%-33% A at 20-30 min, 33%-50% A at 30-55 min, 50%-60% A at 55-65 min, and 60% A between 65 min and 80 min, and peaks were detected at 280 nm. The fourteen compounds were assigned by HPLC-Orbitrap MS methods. The regression coefficient for the linear equations for the 14 compounds ranged between 0.9998 and 1. The limits of detection and quantification lay in the range of 0.032-2.461 and 0.154-8.202 μg·mL(1), respectively. The relative recovery rates for the 14 compounds were in the range of 93.90%-106.73% with RSDs being less than 5%. Coefficient variations for intra-day and inter-day precisions were in the range of 0.27%-2.38% and 0.31%-3.51%, respectively. In summary, the validated method was applied to the simultaneous determination of the 14 components in 29 different licorice samples and was proven to be suitable for quality evaluation of licorices and their active fractions.

Potential drug interactions associated with glycyrrhizin and glycyrrhetinic acid

Glycyrrhizin (GZ), the main active component of licorice, is a widely used therapeutic in the clinic. Depending on the disease, the treatment may involve a long course of high dose GZ. Another component of licorice, glycyrrhetinic acid (GA), is the main active metabolite of GZ and is thought to be responsible for the majority of the pharmacological properties of GZ. Therefore, GZ and GA are both used for therapeutic purposes. In addition, GZ and GA are also widely used to sweeten and flavor foods. Due to this widespread, multifaceted use of these substances, potential drug interactions with GZ and GA have recently gained attention. Along these lines, this review covers the known effects of GZ and GA on drug-metabolizing enzymes and efflux transporters. We conclude that both GZ and GA may have an effect on the activity of CYPs. For example, GZ may induce CYP3A activity through activation of PXR. Also, GZ and GA may affect glucuronidation in rats and humans. Furthermore, 18β-GA is a potent inhibitor of P-gp, while GZ and GA are inhibitors of MRP1, MRP2 and BCRP. The pharmacokinetics and pharmacodynamics of many medications may be altered when used concurrently with GZ or GA, which is also covered in this review. Overall, GZ, GA or related products should be taken with caution when taken with additional medications due to the possible drug interactions.

Rapid screening and identification of active ingredients in licorice extract interacting with V3 loop region of HIV-1 gp120 using ACE and CE-MS

The binding of envelope protein gp120 to glycosphingolipids is very important during the human immunodeficiency virus entering into the host cell. This step occurs in the V3 loop region in particularly. The conserved core sequence of V3 loop in gp120 was named R15K. Anti-HIV drug targeting to R15K would avoid the drug-resistance caused by HIV-1 genetic diversity. Here, for the first time, affinity capillary electrophoresis (ACE) and capillary electrophoresis-mass spectrometry (CE-MS) were used for establishing a simple, rapid and effective method of screening the licorice extract for biological activity (anti-HIV), which avoided the complicated isolation and purification process. R15K, 3'-sialyllactose (the positive control), and d-galactose (the negative control) were used for the development and validation of ACE method. After the interaction between licorice extract and R15K was confirmed by ACE, the relative active ingredients were isolated by SPE and their structures were determined by CE-ESI-MS online. In this research, two mixtures from licorice extract were found to be active. Furthermore, glycyrrhizin and licorice saponin G2 were verified as the main ingredients that significantly interacted with R15K via CE-MS and LC-MS. The results of quantitative assays showed that the active mixture contained glycyrrhizin of 74.23% and licorice saponin G2 of 9.52%. Calculated by Scatchard analysis method, glycyrrhizin/R15K complex had the highest binding constant (1.69 ± 0.08) × 10(7)L/mol among 27 compounds isolated from licorice extract. The anti-HIV activity of glycyrrhizin was further confirmed by bioactive experiment of cellular level. This strategy might provide a high throughput screening and identifying platform for seeking HIV-1 inhibitors in natural products.

Rapid analysis and identification of multi-class mycotoxins in Morinda officinalis by UFLC-ESI-MS/MS

Simultaneous quantification and identification of multi-class mycotoxins in Morinda officinalis by DAS-UFLC-MS/MS.

A simple semi-preparative reversed-phase HPLC/PDA method for separation and quantification of glycyrrhizin in nine samples of Glycyrrhiza glabra root collected from different geographical origins

INTRODUCTION

Glycyrrhiza glabra L. (Fabaceae), commonly known as 'liquorice', is one of the most popular ingredients in several traditional herbal medicinal preparations, and glycyrrhizin is the major glycoside present in this plant. The content of glycyrrhizin may vary among G. glabra samples collected from various geographical origins, which may affect the therapeutic efficacy. Thus, quantification of glycyrrhizin in G. glabra samples is important.

OBJECTIVE

To develop and validate a simple semi-preparative reversed-phase HPLC with photodiode array (PDA) method for separation and quantification of glycyrrhizin in nine samples of G. glabra root collected from various geographical origins.

METHODS

Dried and ground root of G. glabra was Soxhlet-extracted sequentially with n-hexane and methanol (MeOH). The separation and quantification of glycyrrhizin was achieved on a C18 reversed-phase semi-preparative column using a gradient mobile phase, 30-100% solvent B in solvent A in 30 min (solvent A: 0.1% v/v trifluoroacetic acid (TFA) in water and solvent B: 0.1% v/v of TFA in MeOH), at a flow rate of 3.00 mL/min and UV detection at 254 nm.

RESULTS

A simple semi-preparative reversed-phase HPLC/PDA method allowing clear separation and quantification of glycyrrhizin content in nine samples has been validated in terms of linearity, selectivity, limits of detection, precision, accuracy and detection. Concentration levels of glycyrrhizin were between 0.177 and 0.688% w/w of dry materials.

CONCLUSION

This method is precise, less time consuming and more cost effective, and can be used for the quality control of any G. glabra sample with regard to its glycyrrhizin contents.

Species-specific Standardisation of Licorice by Metabolomic Profiling of Flavanones and Chalcones

INTRODUCTION

Major phenolics from licorice roots (Glycyrrhiza sp.) are glycosides of the flavanone liquiritigenin (F) and its 2′-hydroxychalcone isomer, isoliquiritigenin (C). As the F and C contents fluctuate between batches of licorice, both quality control and standardisation of its preparations become complex tasks.

OBJECTIVE

To characterise the F and C metabolome in extracts from Glycyrrhiza glabra L. and Glycyrrhiza uralensis Fisch. ex DC. by addressing their composition in major F–C pairs and defining the total F:C proportion.

MATERIAL AND METHODS

Three types of extracts from DNA-authenticated samples were analysed by a validated UHPLC/UV method to quantify major F and C glycosides. Each extract was characterised by the identity of major F–C pairs and the proportion of Fs among all quantified Fs:Cs.

RESULTS

The F and C compositions and proportions were found to be constant for all extracts from a Glycyrrhiza species. All G. uralensis extracts contained up to 2.5 more Fs than G. glabra extracts. Major F–C pairs were B-ring glycosidated in G. uralensis, and A-/B-ring apiosyl-glucosidated in the G. glabra extracts. The F:C proportion was found to be linked to the glycosidation site: the more B-ring F-C glycosides were present, the higher was the final F:C proportion in the extract. These results enable the chemical differentiation of extracts from G. uralensis and G. glabra, which are characterised by total F:C proportions of 8.37:1.63 and 7.18:2.82, respectively.

CONCLUSION

Extracts from G. glabra and G. uralensis can be differentiated by their respective F and C compositions and proportions, which are both useful for further standardisation of licorice botanicals.

Aqueous extract of Glycyrrhiza inflata inhibits aggregation by upregulating PPARGC1A and NFE2L2-ARE pathways in cell models of spinocerebellar ataxia 3

Spinocerebellar ataxia (SCA) types 1, 2, 3, 6, 7, and 17 and dentatorubropallidoluysian atrophy, as well as Huntington disease, are a group of neurodegenerative disorders caused by a CAG triplet-repeat expansion encoding a long polyglutamine (polyQ) tract in the respective mutant proteins. The cytoplasmic and nuclear aggregate formation, a pathological hallmark of polyQ diseases, is probably the initial process triggering the subsequent pathological events. Compromised oxidative stress defense capacity and mitochondrial dysfunction have emerged as contributing factors to the pathogenesis of polyQ diseases. The roots of licorice (Glycyrrhiza species) have long been used as an herbal medicine. In this study, we demonstrate the aggregate-inhibitory effect of Glycyrrhiza inflata herb extract and its constituents licochalcone A and ammonium glycyrrhizinate (AMGZ) in both 293 and SH-SY5Y ATXN3/Q75 cells, SCA3 cell models. The reporter assay showed that G. inflata herb extract, licochalcone A, and AMGZ could enhance the promoter activity of peroxisome proliferator-activated receptor γ, coactivator 1α (PPARGC1A), a known regulator of mitochondrial biogenesis and antioxidative response genes. G. inflata extract, licochalcone A, and AMGZ upregulated PPARGC1A expression and its downstream target genes, SOD2 and CYCS, in the 293 ATXN3/Q75 cell model. The expression of nuclear factor erythroid 2-related factor 2 (NFE2L2), the principal transcription factor that binds to antioxidant-responsive elements (AREs) to promote ARE-dependent gene expression when the cells respond to oxidative stress, and its downstream genes, HMOX1, NQO1, GCLC, and GSTP1, was also increased by G. inflata herb extract, licochalcone A, and AMGZ. Knockdown of PPARGC1A increased aggregates in ATXN3/Q75 cells and also attenuated the aggregate-inhibiting effect of the tested compounds. G. inflata extract and its constituents significantly elevated GSH/GSSG ratio and reduced reactive oxidative species in ATXN3/Q75 cells. The study results suggest that the tested agents activate PPARGC1A activity and NFE2L2-ARE signaling to increase mitochondrial biogenesis, decrease oxidative stress, and reduce aggregate formation in SCA3 cellular models.

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.

Glycyrrhetinic acid suppressed NF-κB activation in TNF-α-induced hepatocytes

Tumor necrosis factor-alpha (TNF-α) is a crucial inflammatory cytokine when hepatocytes are damaged. Glycyrrhiza uralensis Fisch. (Chinese licorice) has been widely used in Chinese herbal prescriptions for the treatment of liver diseases and as a food additive. Nuclear factor-kappa B (NF-κB) reporter gene assay in TNF-α-induced HepG2 was used as a screening platform. IκBα phosphorylation and p65 translocation were measured by Western blotting, and nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) gene expression were further confirmed in rat primary hepatocytes. Results showed that TNF-α enhanced NF-κB activity was significantly attenuated by glycyrrhetinic acid in a concentration-dependent manner in the NF-κB reporter gene assay. Glycyrrhetinic acid decreased the gene expression of iNOS through inhibited IκBα phosphorylation and p65 translocation in protein level. Furthermore, NO production and iNOS expression were reduced by glycyrrhetinic acid in TNF-α-induced rat primary hepatocytes. These results suggest that glycyrrhetinic acid may provide hepatoprotection against chronic liver inflammation through attenuating NF-κB activation to alleviate the inflammation.