Liquiritigenin, an aglycone of liquiritin in Glycyrrhizae radix, prevents acute liver injuries in rats induced by acetaminophen with or without buthionine sulfoximine

Chemical and pharmacological difference between honey-fried licorice and fried licorice

ETHNOPHARMACOLOGICAL RELEVANCE

According to textual research of books from ancient times till now, there are three main preparation methods of "fried licorice", including frying licorice without excipients (F), frying licorice after dipping with water (W), and frying licorice with honey (H). However, with the development over many successive generations, honey frying has gradually become the main processing form of licorice, whereas the fried licorice is nowadays rarely used.

AIM OF THE STUDY

The objectives of this study were to clarify the differences of the three forms of "fried licorice" in chemical composition and pharmacological activities, and to screen quality markers for differently processed licorice. It is expected to provide a scientific basis for the rational choice of "fried licorice" as medicine.

MATERIALS AND METHODS

Non-target metabolomic analysis based on UHPLC-QE-Orbitrap-MS was conducted to compare the chemical differences between the differently processed licorice material. Pharmacodynamically, the differences in immunomodulatory activity (including intestinal flora experiment), anti-inflammatory activity, and hepatoprotective activity of the differently processed licorice were evaluated. Furthermore, multivariate statistical analysis was performed to screen potential quality markers of honey-fried licorice. The serum concentration of selected markers was determined by UHPLC-QqQ-MS.

RESULTS

Metabolomic analysis showed no difference in the chemical composition of F and W, whereas the chemical composition of H was significantly different from that of F and R. The immunomodulatory activity, anti-acute inflammatory effect, and hepatoprotective effect of licorice were significantly improved after frying with honey; No significant differences were observed between F and H in term of immunomodulatory activity and anti-acute inflammatory effect, whereas, H is better than F in terms of liver-protective activity. The intestinal flora experiment confirmed that H does have immunomodulatory activity, while F may induce an increased abundance of certain pathogenic bacteria in the intestine. Multivariate statistical analysis suggests that the content of liquiritin (2), liquiritigenin (3), isoliquiritin (5), isoliquiritigenin (6) and glycyrrhizic acid (7) plusing glycyrrhetinic acid (8) in H group is closely correlated with its improved effects.

CONCLUSIONS

This study provides a scientific rational for the selection of "fried licorice" processing methods. In addition, it provides a scientific basis for the selection of quality markers of differently processed licorice.

Liquiritigenin Inhibits Lipid Accumulation in 3T3-L1 Cells via mTOR-Mediated Regulation of the Autophagy Mechanism

Liquiritigenin (LQG) is a natural flavonoid from the herb Glycyrrhiza uralensis Fisch that exhibits multiple biological activities. However, its specific role in antiobesity and its related underlying molecular mechanisms remain unknown. The primary purpose of this study is to explore the effects and regulatory mechanisms of LQG on lipid accumulation in 3T3-L1 adipocytes. The results show that LQG significantly reduced triglyceride levels and downregulated the expression of transcription factors such as CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) in 3T3-L1 adipocytes. Additionally, the expression of sterol-regulatory element-binding protein 1c (SREBP1c), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FASN) involved in lipogenesis was reduced by treatment with LQG. The protein expression levels of light chain 3B (LC3B), autophagy-related protein 7 (ATG7) and p62 were also modulated by LQG, leading to the suppression of autophagy. Further, LQG activated the phosphorylation of the mammalian target of rapamycin (mTOR), the inhibition of which was followed by the restored expression of autophagy-related proteins. Pretreatment with an mTOR inhibitor also reverted the expression of several genes or proteins involved in lipid synthesis. These results suggest that LQG inhibited lipid accumulation via mTOR-mediated autophagy in 3T3-L1 white adipocytes, indicating the role of LQG as a potential natural bioactive component for use in dietary supplements for preventing obesity.

Liquiritigenin alleviates doxorubicin-induced chronic heart failure via promoting ARHGAP18 and suppressing RhoA/ROCK1 pathway

Chronic heart failure (CHF) is one of the most common chronic diseases with increasing incidence and mortality. Liquiritigenin (LQG) is shown to protect mice from cardiotoxicity. However, its underlying mechanism remains unclear. Our study aimed to reveal the role of ARHGAP18 in LQG-mediated cardioprotective effects in CHF. In the current study, CHF cell model and rat model were established by the application of doxorubicin (DOX). The reactive oxygen species (ROS) level and cell apoptosis were determined by flow cytometry. The cardiac function of rats was evaluated by measuring left ventricular systolic pressure, left ventricular end diastolic pressure, and serum level of lactate dehydrogenase and brain natriuretic peptide. The expression of active RhoA was elevated and that of ARHGAP18 was decreased in DOX-induced CHF cell model. ARHGAP18 could reduce DOX-induced RhoA activation, ROS elevation, and cell apoptosis. Meanwhile, the knockdown of ARHGAP18 could promote the activation of RhoA, the level of ROS, and the rate of cell apoptosis, which could be reversed by the application of RhoA inhibitor. LQG promoted the expression of ARHGAP18 and exerted similar effects of ARHGAP18 in CHF cell model. The application of LQG could also reverse the effects mediated by ARHGAP18 knockdown. Moreover, LQG significantly improved cardiac function and ameliorated DOX-induced cardiotoxicity of CHF rats. In conclusion, LQG could alleviate DOX-induced CHF via promoting ARHGAP18 and suppressing RhoA/ROCK1 pathway. LQG was a potential agent for CHF treatment.

Licorice (Glycyrrhiza glabra) Extracts-Suitable Pharmacological Interventions for COVID-19? A Review

Even though vaccination has started against COVID-19, people should continue maintaining personal and social caution as it takes months or years to get everyone vaccinated, and we are not sure how long the vaccine remains efficacious. In order to contribute to the mitigation of COVID-19 symptoms, the pharmaceutical industry aims to develop antiviral drugs to inhibit the SARS-CoV-2 replication and produce anti-inflammatory medications that will inhibit the acute respiratory distress syndrome (ARDS), which is the primary cause of mortality among the COVID-19 patients. In reference to these tasks, this article considers the properties of a medicinal plant named licorice (Glycyrrhiza glabra), whose phytochemicals have shown both antiviral and anti-inflammatory tendencies through previous studies. All the literature was selected through extensive search in various databases such as google scholar, Scopus, the Web of Science, and PubMed. In addition to the antiviral and anti-inflammatory properties, one of the licorice components has an autophagy-enhancing mechanism that studies have suggested to be necessary for COVID-19 treatment. Based on reviewing relevant professional and historical literature regarding the medicinal properties of licorice, it is suggested that it may be worthwhile to conduct in vitro and in vivo studies, including clinical trials with glycyrrhizic and glycyrrhetinic acids together with other flavonoids found in licorice, as there is the potentiality to provide natural interventions against COVID-19 symptoms.

The genus Glycyrrhiza (Fabaceae family) and its active constituents as protective agents against natural or chemical toxicities

Licorice is the dried roots and rhizomes of various species of the genus Glycyrrhiza (Fabaceae) that have been used in folk medicine from ancient times. Many important research projects have established several beneficial effects for this medicinal herb, including antiinflammatory, antimicrobial, antiviral, antiprotozoal, antioxidant, antihyperglycemic, antihyperlipidemic, hepatoprotective, and neuroprotective. Licorice contains important bioactive components, such as glycyrrhizin (glycyrrhizic, glycyrrhizinic acid), liquiritigenin, liquiritin, and glycyrrhetinic acid. The protective effects of licorice and its main chemical components against toxins and toxicants in several organs including the brain, heart, liver, kidney, and lung have been shown. In this comprehensive review article, the protective effects of these constituents against natural, industrial, environmental, and chemical toxicities with attention on the cellular and molecular mechanism are introduced. Also, it has been revealed that this plant and its main compounds can inhibit the toxicity of different toxins by the antioxidant, antiinflammatory, and anti-apoptotic properties as well as the modulation of Inhibitor of kappaB kinase (IKK), Extracellular signal-regulated protein kinase1/2 (ERK1/2), p38, inducible nitric oxide synthase, and nuclear factor-κB (NF-κB) signaling pathways. More high-quality investigations in both experimental and clinical studies need to firmly establish the efficacy of licorice and its main constituents against toxic agents.

Targeting Hippo signaling pathway by phytochemicals in cancer therapy

The current era of cancer research has been continuously advancing upon identifying novel aspects of tumorigenesis and the principal mechanisms behind the unleashed proliferation, invasion, drug resistance and immortality of cancer cells in hopes of exploiting these findings to achieve a more effective treatment for cancer. In pursuit of this goal, the identification of the first components of an extremely important regulatory pathway in Drosophila melanogaster that largely determines cell fate during the developmental stages, ended up in the discovery of the highly sophisticated Hippo signaling cascade. Soon after, it was revealed that deregulation of the components of this pathway either via mutations or through epigenetic alterations can be observed in a vast variety of tumors and these alterations greatly contribute to the neoplastic transformation of cells, their survival, growth and resistance to therapy. As more hidden aspects of this pathway such as its widespread entanglement with other major cellular signaling pathways are continuously being uncovered, many researchers have sought over the past decade to find ways of therapeutic interventions targeting the major components of the Hippo cascade. To date, various approaches such as the use of exogenous targeting miRNAs and different molecular inhibitors have been recruited herein, among which naturally occurring compounds have shown a great promise. On such a basis, in the present work we review the current understanding of Hippo pathway and the most recent evidence on targeting its components using natural plant-derived phytochemicals.

Liquiritigenin-Loaded Submicron Emulsion Protects Against Doxorubicin-Induced Cardiotoxicity via Antioxidant, Anti-Inflammatory, and Anti-Apoptotic Activity

Background

The clinical use of doxorubicin (DOX) is severely limited due to its cardiotoxicity. Thus, there is a need for prophylactic and treatment strategies against DOX-induced cardiotoxicity.

Purpose

The purpose of this study was to develop a liquiritigenin-loaded submicron emulsion (Lq-SE) with enhanced oral bioavailability and to explore its efficacy against DOX-induced cardiotoxicity.

Methods

Lq-SE was prepared using high-pressure homogenization and characterized using several analytical techniques. The formulation was optimized by central composite design response surface methodology (CCD-RSM). In vivo pharmacokinetic studies, biochemical analyses, reactive oxygen species (ROS) assays, histopathologic assays, and Western blot analyses were performed.

Results

Each Lq-SE droplet had a mean particle size of 221.7 ± 5.80 nm, a polydispersity index (PDI) of 0.106 ± 0.068 and a zeta potential of -28.23 ± 0.42 mV. The area under the curve (AUC) of Lq-SE was 595% higher than that of liquiritigenin (Lq). Lq-SE decreased the release of serum cardiac enzymes and ameliorated histopathological changes in the hearts of DOX-challenged mice. Lq-SE significantly reduced oxidative stress by adjusting the levels of ROS, increasing the activity of antioxidative enzymes and inhibiting the protein expression of NOX4 and NOX2. Furthermore, Lq-SE significantly improved the inflammatory response through the mitogen-activated protein kinase (MAPK)/nuclear factor-κB (NF-κB) signalling pathway and induced cardiomyocyte apoptosis.

Conclusion

Lq-SE could be used as an effective cardioprotective agent against DOX in chemotherapy to enable better treatment outcomes.

Lactobionic Acid Conjugated Quercetin Loaded Organically Modified Silica Nanoparticles Mitigates Cyclophosphamide Induced Hepatocytotoxicity

OBJECTIVE

The study was designed to investigate the therapeutic potential of lactobionic acid (LA) conjugated quercetin (Q) loaded organically modified silica nanoparticles (LA-Q-ORMOSIL) with bulk quercetin to mitigate cyclophosphamide (CP) induced liver injury.

METHODOLOGY

Q-ORMOSIL nanoparticles were synthesized and characterized using UV-Vis spectroscopy, TEM, Zeta sizer, FTIR and EDX. Further, encapsulation efficiency and in vitro release kinetic study was done. Q-ORMOSIL nanoparticles surface were modified with lactobionic acid, a ligand for the asialoglycoprotein receptor on the hepatocyte surface. The hepatoprotective effects of Q-ORMOSIL and LA-Q-ORMOSIL nanoparticles were evaluated in vivo. Cyclophosphamide (20 mg/kg/day, i.p) was co-administered for seven days with bulk quercetin (50mg/kg/day) and quercetin nanoparticles (50µg/kg/day). After seven days, the number of biomarkers for liver function test and oxidative stress were determined in liver homogenate. Histopathological changes were also analyzed in control and treated liver tissues.

RESULTS

Physiochemical characterization of LA-Q-ORMOSIL nanoparticles depicts that the particles formed were of approx. 80 nm, spherical, monodispersed in nature and showed sustain drug release in in vitro study. Our results further suggested that Q-ORMOSIL and LA-Q-ORMOSIL nanoparticles significantly decreased tissue TBARS, ROS levels and ALT, AST, and ALP activities compared to CP induced group. On the other hand, tissue antioxidant levels (GSH, GST, and catalase) showed a significant increase in LA-Q-ORMOSIL treated group compared to the CP treated group confirming its high therapeutic efficacy during liver injury.

CONCLUSION

Targeted nanoquercetin demonstrated a significant hepatoprotective effect compared to bulk quercetin against CP-induced hepatotoxicity and it considerably reduced bulk quercetin dose level to many folds. Bulk quercetin has low bioavailability and thus, from obtained data we suggest that LA-Q-ORMOSIL nanoparticles provide high therapeutic value in protecting experimental animals against CP-induced liver injury. We also propose multifunctional dye-doped LA-modified ORMOSIL nanoparticles for future studies in facilitating nanoparticles uptake to hepatocytes for liver diagnosis and treatment.

Liquiritigenin inhibits hepatic fibrogenesis and TGF-β1/Smad with Hippo/YAP signal

BACKGROUND

Recent reports highlighted the possibility that Yes-associated protein (YAP) and transforming growth factor-β1 (TGF-β1) can act as critical regulators of hepatic stellate cells (HSCs) activation; therefore, it is natural for compounds targeting Hippo/YAP and TGF-β1/Smad signaling pathways to be identified as potential anti-fibrotic candidates.

PURPOSE

Liquiritigenin (LQ) is an aglycone of liquiritin and has been reported to protect the liver from injury. However, its effects on the Hippo/YAP and TGF-β1/Smad pathways have not been identified to date.

METHODS

We conducted a series of experiments using CCl₄-induced fibrotic mice and cultured LX-2 cells.

RESULT

LQ significantly inhibited liver fibrosis, as indicated by decreases in regions of hepatic degeneration, inflammatory cell infiltration, and the intensity of α-smooth muscle actin (α-SMA) staining in mice. Moreover, LQ blocked the TGF-β1-induced phosphorylation of Smad 3, and the transcript levels of plasminogen activator inhibitor-1 (PAI-1) and matrix metalloproteinase-2 (MMP-2) in LX-2 cells, which is similar with resveratrol and oxyresveratrol (positive controls). Furthermore, LQ increased activation of large tumor suppressor kinase 1 (LATS1) with the induction of YAP phosphorylation, thereby preventing YAP transcriptional activity and suppressing the expression of exacerbated TGF-β1/Smad signaling molecules.

CONCLUSION

These results clearly show that LQ ameliorated experimental liver fibrosis by acting on the TGF-β1/Smad and Hippo/YAP pathways, indicating that LQ has the potential for effective treatment of liver fibrosis.

Prevention of ochratoxin A-induced oxidative stress-mediated apoptotic processes and impairment of embryonic development in mouse blastocysts by liquiritigenin

Ochratoxin A (OTA), a mycotoxin constituent of a range of food commodities, including coffee, wine, beer, grains, and spices, exerts toxicological and pathological effects in vivo, such as nephrotoxicity, hepatotoxicity, and immunotoxicity. In a previous report, we highlighted the potential of OTA to induce apoptosis via reactive oxygen species (ROS) generation in mouse blastocysts that led to impaired preimplantation and postimplantation embryo development in vitro and in vivo. Here, we have shown that liquiritigenin (LQ), a type of flavonoid isolated from Glycyrrhiza radix, effectively protects against OTA-mediated apoptosis and inhibition of cell proliferation in mouse blastocysts. Preincubation of blastocysts with LQ clearly prevented OTA-triggered impairment of preimplantation and postimplantation embryonic development and fetal weight loss, both in vitro and in vivo. Detailed investigation of regulatory mechanisms revealed that OTA mediated apoptosis and embryotoxicity through ROS generation, loss of mitochondrial membrane potential (MMP), and activation of caspase-9 and caspase-3, which were effectively prevented by LQ. The embryotoxic effects of OTA were further validated in an animal model in vivo. Intravenous injection of dams with OTA (3 mg/kg/day) led to apoptosis of blastocysts, impairment of embryonic development from zygote to blastocyst stage and decrease in day 18 fetal weight. Notably, preinjection of dams with LQ (5 mg/kg/day) effectively prevented OTA-induced apoptosis and toxic effects on embryo development. Our collective results clearly demonstrate that OTA exposure via injection has the potential to damage preimplantation and postimplantation embryonic development against which LQ has a protective effect.

Natural products in licorice for the therapy of liver diseases: Progress and future opportunities

Liver diseases related complications represent a significant source of morbidity and mortality worldwide, creating a substantial economic burden. Oxidative stress, excessive inflammation, and dysregulated energy metabolism significantly contributed to liver diseases. Therefore, discovery of novel therapeutic drugs for the treatment of liver diseases are urgently required. Licorice is one of the most commonly used herbal drugs in Traditional Chinese Medicine for the treatment of liver diseases and drug-induced liver injury (DILI). Various bioactive components have been isolated and identified from the licorice, including glycyrrhizin, glycyrrhetinic acid, liquiritigenin, Isoliquiritigenin, licochalcone A, and glycycoumarin. Emerging evidence suggested that these natural products relieved liver diseases and prevented DILI through multi-targeting therapeutic mechanisms, including anti-steatosis, anti-oxidative stress, anti-inflammation, immunoregulation, anti-fibrosis, anti-cancer, and drug-drug interactions. In the current review, we summarized the recent progress in the research of hepatoprotective and toxic effects of different licorice-derived bioactive ingredients and also highlighted the potency of these compounds as promising therapeutic options for the treatment of liver diseases and DILI. We also outlined the networks of underlying molecular signaling pathways. Further pharmacology and toxicology research will contribute to the development of natural products in licorice and their derivatives as medicines with alluring prospect in the clinical application.

Liquiritigenin Inhibits Colorectal Cancer Proliferation, Invasion, and Epithelial-to-Mesenchymal Transition by Decreasing Expression of Runt-Related Transcription Factor 2

Inhibition of tumor metastasis is one of the most important purposes in colorectal cancer (CRC) treatment. This study aimed to explore the effects of liquiritigenin, a flavonoid extracted from the roots of Glycyrrhiza uralensis Fisch, on HCT116 cell proliferation, invasion, and epithelial-to-mesenchymal transition (EMT). We found that liquiritigenin significantly inhibited HCT116 cell proliferation, invasion, and the EMT process, but had no influence on cell apoptosis. Moreover, liquiritigenin remarkably reduced the expression of runt-related transcription factor 2 (Runx2) in HCT116 cells. Overexpression of Runx2 obviously reversed the liquiritigenin-induced invasion and EMT inhibition. Furthermore, liquiritigenin inactivated the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway in HCT116 cells. Upregulation of Runx2 reversed the liquiritigenin-induced PI3K/AKT pathway inactivation. In conclusion, our research verified that liquiritigenin exerted significant inhibitory effects on CRC invasion and EMT process by downregulating the expression of Runx2 and inactivating the PI3K/AKT signaling pathway. Liquiritigenin could be an effective therapeutic and preventative medicine for CRC treatment.

Therapeutic Potential of Plants and Plant Derived Phytochemicals against Acetaminophen-Induced Liver Injury

Acetaminophen (APAP), which is also known as paracetamol or N-acetyl-p-aminophenol is a safe and potent drug for fever, pain and inflammation when used at its normal therapeutic doses. It is available as over-the-counter drug and used by all the age groups. The overdose results in acute liver failure that often requires liver transplantation. Current clinical therapy for APAP-induced liver toxicity is the administration of N-acetyl-cysteine (NAC), a sulphydryl compound an approved drug which acts by replenishing cellular glutathione (GSH) stores in the liver. Over the past five decades, several studies indicate that the safety and efficacy of herbal extracts or plant derived compounds that are used either as monotherapy or as an adjunct therapy along with conventional medicines for hepatotoxicity have shown favorable responses. Phytochemicals mitigate necrotic cell death and protect against APAP-induced liver toxicityby restoring cellular antioxidant defense system, limiting oxidative stress and subsequently protecting mitochondrial dysfunction and inflammation. Recent experimental evidences indicat that these phytochemicals also regulate differential gene expression to modulate various cellular pathways that are implicated in cellular protection. Therefore, in this review, we highlight the role of the phytochemicals, which are shown to be efficacious in clinically relevant APAP-induced hepatotoxicity experimental models. In this review, we have made comprehensive attempt to delineate the molecular mechanism and the cellular targets that are modulated by the phytochemicals to mediate the cytoprotective effect against APAP-induced hepatotoxicity. In this review, we have also defined the challenges and scope of phytochemicals to be developed as drugs to target APAP-induced hepatotoxicity.

Phytochemical and Pharmacological Role of Liquiritigenin and Isoliquiritigenin From Radix Glycyrrhizae in Human Health and Disease Models

The increasing lifespan in developed countries results in age-associated chronic diseases. Biological aging is a complex process associated with accumulated cellular damage by environmental or genetic factors with increasing age. Aging results in marked changes in brain structure and function. Age-related neurodegenerative diseases and disorders (NDDs) represent an ever-growing socioeconomic challenge and lead to an overall reduction in quality of life around the world. Alzheimer’s disease (AD) and Parkinson’s disease (PD) are most common degenerative neurological disorders of the central nervous system (CNS) in aging process. The low levels of acetylcholine and dopamine are major neuropathological feature of NDDs in addition to oxidative stress, intracellular calcium ion imbalance, mitochondrial dysfunction, ubiquitin-proteasome system impairment and endoplasmic reticulum stress. Current treatments minimally influence these diseases and are ineffective in curing the multifunctional pathological mechanisms. Synthetic neuroprotective agents sometimes have negative reactions as an adverse effect in humans. Recently, numerous ethnobotanical studies have reported that herbal medicines for the treatment or prevention of NDDs are significantly better than synthetic drug treatment. Medicinal herbs have traditionally been used around the world for centuries. Radix Glycyrrhizae (RG) is the dried roots and rhizomes of Glycyrrhiza uralensis or G. glabra or G. inflata from the Leguminosae/Fabaceae family. It has been used for centuries in traditional medicine as a life enhancer, for the treatment of coughs and influenza, and for detoxification. Diverse chemical constituents from RG have reported including flavanones, chalcones, triterpenoid saponins, coumarines, and other glycosides. Among them, flavanone liquiritigenin (LG) and its precursor and isomer chalcone isoliquiritigenin (ILG) are the main bioactive constituents of RG. In the present review, we summarize evidence in the literature on the structure and phytochemical properties and pharmacological applications of LG and ILG in age-related diseases to establish new therapeutics to improve human health and lifespan.

UPLC-MS/MS Method for the Determination of 14 Compounds in Rat Plasma and Its Application in a Pharmacokinetic Study of Orally Administered Xiaoyao Powder

Xiaoyao Powder (XYP), a common Chinese medicine, comprises eight traditional Chinese herbs and has been widely used clinically to treat liver damage and mental disorders. An ultra-performance liquid chromatography–tandem mass spectrometry method was developed to investigate the pharmacokinetics of 14 compounds (albiflorin, paeoniflorin, ferulic acid, senkyunolide I, quercetin, isoliquiritigenin, atractylenolide III, ligustilide, atractylenolide II, liquiritin, liquiritigenin, saikosaponin c, glycyrrhizic acid, and saikosaponin a) in XYP. Naringenin was used as the internal standard. The compounds were separated using an ACQUITY UPLC^TM BEH C18 column (1.7 μm, 50 × 2.1 mm) with a mobile phase consisting of acetonitrile and 0.1% formic acid in water at a flow rate of 0.3 mL/min. Detection was performed on a triple-quadrupole tandem mass spectrometer using multiple reaction monitoring and an electrospray ionization source in both positive and negative ionization modes. All calibration curves exhibited good linearity (r² > 0.9974) over the measured ranges. The intra- and inter-day precisions were within 12%, and the accuracy ranged from 89.93% to 106.64%. Extraction recovery and matrix effect results were satisfactory. The method was successfully applied in a pharmacokinetic study of the 14 compounds in rat plasma after the oral administration of XYP.

Ginsenoside Rg1 protects against acetaminophen-induced liver injury via activating Nrf2 signaling pathway in vivo and in vitro

Acetaminophen (APAP) is a worldwide used drug for treating fever and pain. However, APAP overdose is the leading cause of drug-induced liver injury. The purpose of the current study is to evaluate the hepatoprotective effect of ginsenoside Rg1 (Rg1), the main pharmacologically active compounds of Panax ginseng, against APAP-induced acute liver injury, and further to elucidate the involvement of Nrf2 signaling pathway by in vivo and in vitro experiments. Male C57BL/6 mice were treated with Rg1 for 3 days before injection of APAP. Serum and liver tissue samples were collected 6 h later. The results indicated that Rg1 significantly attenuated APAP-induced hepatotoxicity and oxidative stress in a dose-dependent manner. Rg1 effectively enhanced antioxidant and detoxification capacity, which is largely dependent on up-regulating Nrf2 nuclear translocation, reducing Keap1 protein expression and up-regulating Nrf2 target genes including GCLC, GCLM, HO-1, NQO1, Ugt1a1, Ugt1a6, Ugt2b1, Sult2a1, Mrp2, Mrp3 and Mrp4. Furthermore, Rg1 repressed the activities of Cyp2e1, Cyp3a11, Cyp1a2, which are important enzymes in the formation of APAP toxic metabolite N-acetyl-p-benzoquinone imine. However, the changes in transporters and enzymes, as well as ameliorative liver histology induced by Rg1 were abrogated by Nrf2 antagonist all-transretinoic acid in vivo and Nrf2 siRNA in vitro. In conclusion, Rg1 produced hepatoprotective effects against APAP-induced acute liver injury via Nrf2 signaling pathway. Rg1 might be an effective approach for the prevention against acute liver injury.

Protective Effects of Liquiritigenin against Citrinin-Triggered, Oxidative-Stress-Mediated Apoptosis and Disruption of Embryonic Development in Mouse Blastocysts

The mycotoxin citrinin (CTN), a natural contaminant in foodstuffs and animal feeds, exerts cytotoxic and genotoxic effects on various mammalian cells and embryos. A previous investigation by our group revealed potentially hazardous effects of CTN on mouse oocyte maturation and pre- and post-implantation embryo development via the induction of apoptosis. The present study showed that CTN induces apoptosis and inhibits cell proliferation in the inner cell mass of mouse blastocysts. Notably, we observed for the first time that both these effects are suppressed by liquiritigenin (LQ). LQ is a type of flavonoid isolated from Glycyrrhiza radix with several biochemical and pharmacological activities, including antioxidant and anti-inflammatory properties. The preincubation of blastocysts with LQ clearly prevented CTN-induced disruption of pre- and post-implantation embryonic development and fetal weight loss, both in vitro and in vivo. CTN-induced damage processes directly promoted reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential (MMP) and activation of caspase-9 and caspase-3, which were effectively blocked by LQ. Moreover, in an animal model, intravenous injection of dams with CTN (3 mg/kg/day) triggered apoptosis of blastocysts, disruption of embryonic development from the zygote to the blastocyst stage and a decrease in fetal weight. Pre-injection with LQ (5 mg/kg/day) effectively reduced apoptosis and impaired the cytotoxic effects of CTN on development. Our in vivo findings further confirm that CTN exposure via injection has the potential to impair pre- and post-implantation development, leading to apoptosis and the suppression of sequent embryonic development, which can be effectively prevented by LQ.

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.

Screening of hepatoprotective compounds from licorice against carbon tetrachloride and acetaminophen induced HepG2 cells injury

BACKGROUND

Licorice and its constituents, especially licorice flavonoids have been reported to possess significant hepatoprotective activities. However, previous studies mainly focus on the extract and major compounds, and few reports are available on other licorice compounds.

PURPOSE

This work aims to evaluate the in vitro hepatoprotective activities of licorice compounds and screen active compounds, and to establish the structure-activity relationship.

METHODS

A compound library consisting of 180 compounds from three medicinal licorice species, Glycyrrhiza uralensis, G. glabra and G. inflata was established. HepG2 cells were incubated with the compounds, together with the treatment of 0.35% CCl₄ for 6 h and 14 mM APAP for 24 h, respectively.

RESULTS

A total of 62 compounds at 10 µM showed protective effects against CCl₄ to improve cell viability from 52.5% to >60%, and compounds 5 (licoflavone A), 104 (3,4-didehydroglabridin), 107 (isoliquiritigenin), 108 (3,4,3',4'-tetrahydroxychalcone), and 111 (licochalcone B) showed the most potent activities, improving cell viability to >80%. And 64 compounds showed protective effects against APAP to improve cell viability from 52.0% to >60%, and compounds 47 (derrone), 76 (xambioona), 77 ((2S)-abyssinone I), 107 (isoliquiritigenin), 118 (licoagrochalcone A), and 144 (2'-O-demethybidwillol B) showed the most potent activities, improving cell viability to >80%. Preliminary structure-activity analysis indicated that free phenolics compounds especially chalcones showed relatively stronger protective activities than other types of compounds.

CONCLUSION

Compounds 5, 76, 104, 107, 111, 118 and 144 possess potent activities against both CCl₄ and APAP, and 5, 76 and 118 were reported for the first time. They could be the major active compounds of licorice for the treatment of liver injury.

Estrogen receptor activation contributes to RNF146 expression and neuroprotection in Parkinson's disease models

RNF146 is an E3 ubiquitin ligase that specifically recognizes and polyubiquitinates poly (ADP-ribose) (PAR)-conjugated substrates for proteasomal degradation. RNF146 has been shown to be neuroprotective against PAR polymerase-1 (PARP1)-induced cell death during stroke. Here we report that RNF146 expression and RNF146 inducers can prevent cell death elicited by Parkinson’s disease (PD)-associated and PARP1-activating stimuli. In SH-SY5Y cells, RNF146 expression conferred resistance to toxic stimuli that lead to PARP1 activation. High-throughput screen using a luciferase construct harboring the RNF146 promoter identified liquiritigenin as an RNF146 inducer. We found that RNF146 expression by liquiritigenin was mediated by estrogen receptor activation and contributed to cytoprotective effect of liquiritigenin. Finally, RNF146 expression by liquiritigenin in mouse brains provided dopaminergic neuroprotection in a 6-hydroxydopamine PD mouse model. Given the presence of PARP1 activity and RNF146 deficits in PD, it could be a potential therapeutic strategy to restore RNF146 expression by natural compounds or estrogen receptor activation.

Poly-pharmacokinetic Study of a Multicomponent Herbal Medicine in Healthy Chinese Volunteers

The advent of mass spectrometry-based analytical technologies coupled with multivariate statistical methods offer tremendous new opportunities for understanding the pharmacokinetics (PKs) of multicomponent herbal medicines (HMs). We recently proposed a poly-PK strategy to characterize the concentration-time profile and the metabolic response profile of multicomponent HMs using an integrated phytochemical and metabolomics approach. Here, we provided the first example of the poly-PK strategy, in which we simultaneously characterized the PK as well as the metabolic response profiles of a Chinese HM, Huangqi decoction (HQD, consisting of Radix Astragali and Radix Glycyrrhizae), in healthy Chinese volunteers. Using the poly-PK approach, we identified 56 HQD-derived compounds and 292 biotransformed HQD metabolites in human plasma. Additionally, we acquired the concentration-time profiles of these plasma HQD metabolites and correlated them with a plasma metabolomics profile consisting of 166 human endogenous metabolites that were significantly altered in response to HQD intervention.

Pharmacological Activities and Phytochemical Constituents

Glycyrrhiza glabra is one of the most popular medicinal plants and it has been used in traditional herbal remedy since ancient times (Blumenthal et al. in Herbal medicine: expanded commission E monographs. Integrative Medicine Communications, Newton, 2000; Parvaiz et al. in Global J Pharmocol 8(1):8–13, 2014; Altay et al. in J Plant Res 129(6):1021–1032, 2016). Many experimental, pharmacological and clinical studies show that liquorice has antimicrobial, antibacterial, antiviral, antifungal, antihepatotoxic, antioxidant, antiulcer, anti-hemorrhoid antihyperglycemic, antidiuretic, antinephritic, anticarcinogenic, antimutagenic, anticytotoxic, anti-inflammatory, and blood stopper activity.

Protective effect of liquiritigenin on depressive-like behavior in mice after lipopolysaccharide administration

Liquiritigenin (Liq), the main active ingredient of traditional Chinese medicine licorice, possesses anti-inflammatory and neuroprotective properties. The current investigation was designed to explore whether liquiritigenin could relieve lipopolysaccharide (LPS)-induced depression-like behavior in mice and the underlying mechanism. Liquiritigenin (7.5mg/kg, 15mg/kg) and fluoxetine (20mg/kg) were pretreated intragastrically once daily for 7 consecutive days. LPS (0.5mg/kg) was injected subcutaneously to establish the depression model 30min after pretreatment on day 7. Interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels in serum and hippocampus were detected by enzyme-linked immunosorbent assay (ELISA). Behavioral assessment was conduct 24h post LPS injection. The expressions of p65NF-κB, IκBα, brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) in hippocampus were determined by western blot. The obtained results showed that liquiritigenin effectively reduced the levels of pro-inflammatory cytokines and the expressions of p-p65NF-κB and p-IκBα. Furthermore, liquiritigenin preconditioning could down-regulate the immobility time in tail suspension test (TST), forced swimming test (FST) and up-regulate BDNF and TrkB contents in hippocampus. Thus, it is assumed that the antidepressant activity of liquiritigenin might be attributed to its anti-inflammatory property and BDNF/TrkB signaling pathway.

Beneficial effects of Glycyrrhizae radix extract in preventing oxidative damage and extending the lifespan of Caenorhabditis elegans

ETHNOPHARMACOLOGICAL RELEVANCE

Glycyrrhizae radix (GR) is a medicinal herb extensively used in traditional Chinese medicine. This study aimed to evaluate the pharmacological effect of GR and the possible mechanisms of GR, to provide a pharmacological basis in traditional medicine.

MATERIALS AND METHODS

In the present study, C. elegans (L1-larvae to young adults) was exposed to 0.12-0.24 g/mL of GR in 12-well sterile tissue culture plates at 20°C in the presence of food. Lethality, growth, lifespan, reproduction, locomotion, metabolism, intestinal autofluorescence, and reactive oxygen species (ROS) production assays were performed to investigate the possible safety profile and beneficial effects of GR in these nematodes. We found that the lifespan of nematodes exposed to 0.18-0.24 g/mL of GR was extended. We then determined the mechanism of the longevity effect of GR using quantitative reverse transcription PCR and oxidative stress resistance assays induced by heat and paraquat.

RESULTS

Prolonged exposure to 0.12-0.24 g/mL of GR did not induce lethality, alter body length, morphology or metabolism, affect brood size, locomotion, the development of D-type GABAergic motor neurons, or induce significant induction of intestinal autofluorescence and intestinal ROS production. In C. elegans, pretreatment with GR suppressed the damage due to heat-stress or oxidative stress induced by paraquat, a ROS generator, on lifespan, and inhibited the induction of intestinal ROS production induced by paraquat. Moreover, prolonged exposure to GR extended lifespan, increased locomotion and decreased intestinal ROS production in adult day-12 nematodes. Furthermore, prolonged exposure to GR significantly altered the expression patterns of genes encoding the insulin-like signaling pathway which had a key role in longevity control. Mutation of daf-16 gene encoding the FOXO transcription factor significantly decreased lifespan, suppressed locomotion, and increased intestinal ROS production in GR exposed adult nematodes.

CONCLUSIONS

GR is relatively safe and has protective effects against the damage caused by both heat-stress and oxidative stress at the examined concentrations. Furthermore, GR is capable of extending the lifespan of nematodes, and the insulin-like signaling pathway may play a crucial role in regulating the lifespan-extending effects of GR.

Glycyrrhiza glabra

Liquorice foliage

AMPK activation by liquiritigenin inhibited oxidative hepatic injury and mitochondrial dysfunction induced by nutrition deprivation as mediated with induction of farnesoid X receptor

PURPOSE

Nutrition is indispensable for cell survival and proliferation. Thus, loss of nutrition caused by serum starvation in cells could induce formation of reactive oxygen species (ROS), resulting in cell death. Liquiritigenin (LQ) is an active flavonoid in licorice and plays a role in the liver as a hepatic protectant.

METHODS

This study investigated the effect of LQ, metformin [an activator of activated AMP-activated protein kinase (AMPK)] and GW4064 [a ligand of farnesoid X receptor (FXR)] on mitochondrial dysfunction and oxidative stress induced by serum deprivation as well as its molecular mechanism, as assessed by immunoblot and flow cytometer assays.

RESULTS

Serum deprivation in HepG2, H4IIE and AML12 cells successfully induced oxidative stress and apoptosis, as indicated by depletion of glutathione, formation of ROS, and altered expression of apoptosis-related proteins such as procaspase-3, poly(ADP-ribose) polymerase, and Bcl-2. However, LQ pretreatment significantly blocked these pathological changes and mitochondrial dysfunction caused by serum deprivation. Moreover, LQ activated AMPK in HepG2 cells and mice liver, as shown by phosphorylation of AMPK and ACC, and this activation was mediated by its upstream kinase (i.e., LKB1). Experiments using a chemical inhibitor of AMPK with LKB1-deficient Hela cells revealed the role of the LKB1-AMPK pathway in cellular protection conferred by LQ. LQ also induced protein and mRNA expression of both FXR as well as small heterodimer partner, which is important since treatment with FXR ligand GW4064 protected hepatocytes against cell death and mitochondrial damage induced by serum deprivation.

CONCLUSION

AMPK activators such as LQ can protect hepatocytes against oxidative hepatic injury and mitochondrial dysfunction induced by serum deprivation, and the beneficial effect might be mediated through the LKB1 pathway as well as FXR induction.

Amelioration of trinitrobenzene sulfonic acid-induced colitis in mice by liquiritigenin

BACKGROUND AND AIM

The anti-inflammatory effects of liquiritigenin, a major flavonoid isolated from Glycyrrhizae uralensis, have been reported in many inflammation models. However, its protective effects have not been reported in a colitis model. This study investigated the anti-inflammatory effect and mechanism of liquiritigenin for trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice.

METHODS

Male mice imprinting control regions (ICR) were randomly divided into five groups: normal, TNBS-induced colitis, colitis treated with liquiritigenin at low dose (10 mg/kg) and high dose (20 mg/kg), or mesalazine (10 mg/kg). TNBS colitis induction was performed except for in the normal group, and they were treated with liquiritigenin or mesalazine except control group. The treatment effect was measured after three days treatment, by body weight, colon length, macroscopic score, histological score, levels of cytokines (tumor necrosis factor-α, interleukin [IL]-1β, IL-6, and IL-10) in colon tissue as well as the nuclear factor kappa-light-chain-enhancer pathway of activated B cells (NF-κB) activation.

RESULTS

Mice treated with high-dose liquiritigenin showed significant body weight gain, inhibition of colon shortening, protective effect on histological damages, and myeloperoxidase activity of colon tissue compared with the control group. Furthermore, mice treated with high-dose liquiritigenin experienced significantly suppressed tumor necrosis factor-α, IL-1β, and IL-6 as well as enhanced IL-10 expression (all P < 0.05). High-dose liquiritigenin treatment group showed significant decreases in TNBS-induced phosphorylation of IKKβ, p65, and IκB-α.

CONCLUSION

Liquiritigenin may ameliorate TNBS-induced colitis in mice by suppressing expression of pro-inflammatory cytokines through NF-κB pathway.

Protective effect of liquiritigenin against methylglyoxal cytotoxicity in osteoblastic MC3T3-E1 cells

Methylglyoxal (MG), a reactive dicarbonyl compound, is a metabolic byproduct of glycolysis and elevated MG levels contribute to diabetic complications. Glycation reactions of MG with amino acids can induce oxidative stress, leading to subsequent cytotoxicity. In the present study, the effect of liquiritigenin on MG-induced cytotoxicity was investigated using osteoblastic MC3T3-E1 cells. Pretreatment of MC3T3-E1 cells with liquiritigenin prevented the MG-induced cell death and production of protein adduct, intracellular reactive oxygen species, mitochondrial superoxide, cardiolipin peroxidation, and TNF-α in osteoblastic MC3T3-E1 cells. In addition, liquiritigenin increased the activity of glyoxalase I inhibited by MG. These findings suggest that liquiritigenin provides a protective action against MG-induced cell damage by reducing oxidative stress and by increasing MG detoxification. Pretreatment with liquiritigenin prior to MG exposure reduced MG-induced mitochondrial dysfunction by preventing mitochondrial membrane potential dissipation and adenosine triphosphate loss. Additionally, the nitric oxide and PGC-1α levels were significantly increased by liquiritigenin, suggesting that liquiritigenin may induce mitochondrial biogenesis. Our findings indicate that liquiritigenin might exert its therapeutic effects via enhancement of glyoxalase I activity and mitochondrial function, and anti-oxidant and anti-inflammatory activities. Taken together, liquiritigenin has potential as a preventive agent against the development of diabetic osteopathy related to MG-induced oxidative stress in diabetes.

Isoliquiritigenin attenuates oxidative hepatic damage induced by carbon tetrachloride with or without buthionine sulfoximine

Glycyrrhizae radix (G. radix) has been demonstrated to have hepatoprotective properties. This study determined the therapeutic effects of isoliquiritigenin (isoLQ) in G. radix, against liver injury induced by CCl4 in rats. CCl4 (0.5 ml/kg/d, twice) or CCl4 plus buthionine sulfoximine exerted severe liver damage assessed by increased plasma levels of alanine aminotransferase and aspartate aminotransferase, in addition to hepatic degeneration and necrosis. These pathological changes were markedly protected by pretreatment with isoLQ (5, 20 mg/kg/d, p.o.) for 3 consecutive days. In addition, pretreatment with isoLQ inhibited CCl4-induced reduction of cytochrome P450 2E1 protein and mRNA expression as well as activity in the liver. Moreover, isoLQ pretreatment reversed the decrease in hepatic antioxidant capacity induced by CCl4 as well as suppressed expression of tumor necrosis factor-alpha and cyclooxigenase-2 in the liver. These results suggest that isoLQ has a protective effect against CCl4-induced liver damage through induction of antioxidant and anti-inflammatory activities.

Glycyrrhizae radix methanol extract attenuates methamphetamine-induced locomotor sensitization and conditioned place preference

Glycyrrhizae Radix modulates the neurochemical and locomotor alterations induced by acute psychostimulants in rodents via GABAb receptors. This study investigated the influence of methanol extract from Glycyrrhizae Radix (MEGR) on repeated methamphetamine- (METH-) induced locomotor sensitization and conditioned place preference (CPP). A cohort of rats was treated with METH (1 mg/kg/day) for 6 consecutive days, subjected to 6 days of withdrawal, and then challenged with the same dose of METH to induce locomotor sensitization; during the withdrawal period, the rats were administered MEGR (60 or 180 mg/kg/day). A separate cohort of rats was treated with either METH or saline every other day for 6 days in METH-paired or saline-paired chambers, respectively, to induce CPP. These rats were also administered MEGR (180 mg/kg) prior to every METH or CPP expression test. Pretreatment with MEGR (60 and 180 mg/kg/day) attenuated the expression of METH-induced locomotor sensitization dose-dependently, and 180 mg/kg MEGR significantly inhibited the development and expression of METH-induced CPP. Furthermore, administration of a selective GABAb receptor antagonist (SCH50911) prior to MEGR treatment effectively blocked the inhibitory effects of MEGR on locomotor sensitization, but not CPP. These results suggest that Glycyrrhizae Radix blocked repeated METH-induced behavioral changes via GABAb receptors.

Bioactive profiles, antioxidant activities, nitrite scavenging capacities and protective effects on H2O2-injured PC12 cells of Glycyrrhiza glabra L. leaf and root extracts

This study compared the total flavonoid content of Glycyrrhiza glabra L. leaf and root extracts. Results suggested that the total flavonoid content in the leaf extract was obviously higher than that in the root extract. Pinocembrin, the main compound in the leaf extract after purification by column chromatography, showed good antioxidant activity and nitrite scavenging capacity, but moderate inhibitory effect on mushroom tyrosinase. Liquiritin was the main compound in root extract and possessed strong inhibitory effect on mushroom tyrosinase. Both compounds exhibited significant protection effect on H₂O₂-injured PC12 cells at a low concentration. These results indicate that Glycyrrhiza glabra L. leaf is potential as an important raw material for functional food.

Effects of the total saponins from Rosa laevigata Michx fruit against acetaminophen-induced liver damage in mice via induction of autophagy and suppression of inflammation and apoptosis

The effect of the total saponins from Rosalaevigata Michx fruit (RLTS) against acetaminophen (APAP)-induced liver damage in mice was evaluated in the present paper. The results showed that RLTS markedly improved the levels of liver SOD, CAT, GSH, GSH-Px, MDA, NO and iNOS, and the activities of serum ALT and AST caused by APAP. Further research confirmed that RLTS prevented fragmentation of DNA and mitochondrial ultrastructural alterations based on TdT-mediated dUTP nick end labeling (TUNEL) and transmission electron microscopy (TEM) assays. In addition, RLTS decreased the gene or protein expressions of cytochrome P450 (CYP2E1), pro-inflammatory mediators (IL-1β, IL-4, IL-6, TNF-α, iNOS, Bax, HMGB-1 and COX-2), pro-inflammatory transcription factors (NF-κB and AP-1), pro-apoptotic proteins (cytochrome C, p53, caspase-3, caspase-9, p-JNK, p-p38 and p-ERK), and increased the protein expressions of Bcl-2 and Bcl-xL. Moreover, the gene expression of IL-10, and the proteins including LC3, Beclin-1 and Atg5 induced by APAP were even more augmented by the extract. These results demonstrate that RLTS has hepatoprotective effects through antioxidative action, induction of autophagy, and suppression of inflammation and apoptosis, and could be developed as a potential candidate to treat APAP-induced liver damage in the future.

Liquiritigenin induces tumor cell death through mitogen-activated protein kinase- (MPAKs-) mediated pathway in hepatocellular carcinoma cells

Liquiritigenin (LQ), separated from Glycyrrhiza radix, possesses anti-inflammatory, antihyperlipidemic, and antiallergic effects. Our present study aims to investigate the antihepatocellular carcinoma effects of LQ both in cell and animal models. LQ strikingly reduced cell viability, enhanced apoptotic rate, induced lactate dehydrogenase over-release, and increased intracellular reactive oxygen species (ROS) level and caspase 3 activity in both PLC/PRL/5 and HepG2 cells. The expression of cleaved PARP, the hall-marker of apoptosis, was enhanced by LQ. LQ treatment resulted in a reduction of the expressions of B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma-extra large (Bcl-xL), and an increase of the phosphorylation of c-Jun N-terminal kinases (JNK) and P38. LQ-mediated cell viability reduction, mitochondrial dysfunction, apoptosis related protein abnormal expressions, and JNK and P38 activation were partially abolished by N-Acetyl-L-cysteine (a ROS inhibitor) pretreatment. Moreover, LQ suppressed the activation of extracellular signaling-regulated kinase (ERKs) and reduced the translocation of phosphor-ERKs from cytoplasm to nucleus. This antitumor activity was further confirmed in PLC/PRL/5-xenografted mice model. All these data indicate that the antihepatocellular carcinoma effects of LQ are related to its modulation of the activations of mitogen-activated protein kinase (MAPKs). The study provides experimental evidence supporting LQ as a potential therapeutic agent for hepatocellular carcinoma treatment.

Bioactivity and potential health benefits of licorice

Licorice is an herbal plant named for its unique sweet flavor. It is widely used in the food and tobacco industries as a sweetener. Licorice is also used in traditional Chinese medicine (TCM) and complementary medicine. Because the use of licorice has long been a part of TCM, the details of its therapeutic applications have been thoroughly established. In modern science, licorice is of interest because of its broad range of applications. Extracts of and compounds isolated from licorice have been well studied and biologically characterized. In this review, we discuss the nutraceutical and functional activities of licorice as well as those of the extracts of and the isolated compounds from licorice, including agents with anti-inflammatory activity, cell-protective abilities, and chemopreventive effects. The side effects of licorice are also enumerated. A comparison of the activities of licorice described by modern science and TCM is also presented, revealing the correspondence of certain characteristics.