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HIV-1 infects the brain and, despite antiretroviral therapy, many infected individuals suffer from HIV-1-associated neurocognitive disorders ( HAND). HAND is associated with dendritic simplification and synaptic loss. Prevention of synaptodendritic damage may ameliorate or forestall neurocognitive decline in latent HIV-1 infections. The HIV-1 transactivating protein (Tat) is produced during viral latency in the brain and may cause synaptodendritic damage. This study examined the integrity of the dendritic network after exposure to HIV-1 Tat by labeling filamentous actin (F-actin)-rich structures (puncta) in primary neuronal cultures. After 24 h of treatment, HIV-1 Tat was associated with the dendritic arbor and produced a significant reduction of F-actin-labeled dendritic puncta as well as loss of dendrites. Pre-treatment with either of two plant-derived phytoestrogen compounds (daidzein and liquiritigenin), significantly reduced synaptodendritic damage following HIV-1 Tat treatment. In addition, 6 days after HIV-1 Tat treatment, treatment with either daidzein, or liquiritigenin enhanced recovery, via the estrogen receptor, from HIV-1 Tat-induced synaptodendritic damage. These results suggest that either liquiritigenin or daidzein may not only attenuate acute synaptodendritic injury in HIV-1 but may also promote recovery from synaptodendritic damage. [ABSTRACT FROM AUTHOR]

Highlights: [•] Liquiritigenin (LIQ) was isolated as an active compound from licorice roots. [•] LIQ effectively reduced the early apoptosis in glutamate-treated HT22 cells. [•] Ca2+ influx, ROS production, and lipid peroxidation were inhibited by LIQ. [•] LIQ suppressed the mitochondrial stress and MAPKs phosphorylation. [•] LIQ might be useful for the development of drugs for neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

The detailed mechanisms on licorice-drug interaction remain to be unclear. The aim of the present study is to investigate the inhibition of important UGT isoforms by two important ingredients of licorice, liquiritin, and liquiritigenin. The results showed that liquiritigenin exhibited stronger inhibition towards all the tested UGT isoforms than liquiritin. Data fitting using Dixon and Lineweaver-Burk plots demonstrated the competitive inhibition of liquiritigenin towards UGT1A1 and UGT1A9-mediated 4-MU glucuronidation reaction. The inhibition kinetic parameters (Ki) were calculated to be 9.1 and 3.2 μM for UGT1A1 and UGT1A9, respectively. Substrate-dependent inhibition behaviour was also observed for UGT1A1 in the present study. All these results will be helpful for understanding the deep mechanism of licorice-drug interaction. However, when translating these in vitro parameters into in vivo situations, more complex factors should be considered, such as substrate-dependent inhibition of UGT isoforms, the contribution of UGT1A1 and UGT1A9 towards the metabolism of drugs, and many factors affecting the abundance of ingredients in the licorice. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Highly efficient and green catalytic conversion of 2′-hydroxy and 2′-amino chalcones to flavanones and tetrahydroquinolones is reported herein. 2′-Hydroxy and 2′-amino chalcones can be almost completely converted to flavanones and tetrahydroquinolones in just 2 min in the presence of piperidine and KOH under room temperature. Liquiritigenin is also efficiently synthesized under similar conditions. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a significant Gram-positive bacterium that is associated with a broad spectrum of diseases ranging from minor skin infections to lethal pneumonia, endocarditis, and toxinoses. α-Hemolysin is one of the most important exotoxins that contribute to the pathogenesis of S. aureus infections. Liquiritigenin is one of the most significant active components in licorice. In this study, hemolysis, western blot, and real-time reverse transcription-PCR assays were performed to investigate the impact of liquiritigenin on the production of S. aureus α-hemolysin. The results showed that low concentrations of liquiritigenin remarkably decreased S. aureus α-hemolysin production in a dose-dependent manner. Using live/dead cell staining and lactate dehydrogenase assays, we found that liquiritigenin could protect human lung cells (A549) from α-hemolysin-mediated injury. The data indicated that this compound could potentially be useful in developing drugs aiming at staphylococcal α-hemolysin. [ABSTRACT FROM AUTHOR]

Abstract: A reversed phase chromatographic system, composed of a stationary phase of C18 silica gel (ODS, 20μm) and a mobile phase of ethanol/water, was used to separate liquiritin and liquiritigenin in the raw material of flavonoids. The linear adsorption isotherm and the equilibrium-dispersive model were adopted to approximatively describe the chromatographic separation behaviors of liquiritin and liquiritigenin in the raw material under different column temperatures, ethanol contents and flow rates of the mobile phase, sample concentrations and feeding times. Combined with orthogonal design, the ED model was used to optimize the chromatographic separating conditions, the corresponding experimental result with a good agreement was obtained and the overload separation was realized. [Copyright &y& Elsevier]

Liquiritigenin (Lq) offers cytoprotective effects against various cardiac injuries, but its beneficial effects on myocardial ischemic (MI) injury and the related mechanisms remain unclear. In the in vivo study, an animal model of MI was induced by intraperitoneal injection of isoproterenol (Iso, 85 mg/kg). ECG, heart rate, serum levels of CK and CK-MB, histopathological changes, and reactive oxygen species (ROS) levels were all measured. In vitro, H9c2 cells were divided into four groups and treated for 24 hr with liquiritigenin (30 μmol/L and 100 μmol/L) followed with CoCl 2 (800 μmol/L) for another 24 hr. Cell viability, apoptosis, mitochondrial membrane potential, and intracellular Ca 2+ concentration ([Ca 2+ ] i ) were then assessed. The L-type Ca 2+ current (I Ca-L ) was detected using a patch clamp technique on isolated rat ventricular myocytes. The myocyte contraction and Ca 2+ transients were measured using an IonOptix detection system. The remarkable cardiac injury and generation of intracellular ROS induced by Iso were alleviated via treatment with Lq. CoCl 2 administration induced cell apoptosis, mitochondrial dysfunction, and Ca 2+ overload in H9c2; Lq reduces these deleterious effects of CoCl 2 . Meanwhile, Lq blocked I Ca-L in a dose-dependent manner. The half-maximal inhibitory concentration of Lq was 110.87 μmol/L. Lq reversibly reduced the amplitude of cell contraction as well as the Ca 2+ transients. The results show that Lq protects against MI injury by antioxidation, antiapoptosis, counteraction mitochondrial dysfunction, and inhibition of I Ca-L , thus damping intracellular Ca 2+ ., (© 2022 John Wiley & Sons Ltd.)

The aim of the present research is to find the influence of honey in the metabolism of liquiritin by human intestinal flora to validate the folkloric use of honey-treated licorice (Glycyrrhiza uralensis). The metabolites of liquiritin were analyzed by HPLC-MS/MS and FT-ICR-MS/MS. The immunological effects were investigated by using an in vitro splenocyte proliferation assay. In the presence of honey, liquiritin was metabolized slowly into the main metabolite (liquiritigenin), and the other metabolite (davidigenin) was only found in low abundance. But, in the absence of honey, liquiritin was rapidly transformed into liquiritigenin, and liquiritigenin was further metabolized into davidigenin, making davidigenin the main metabolite. The splenocyte proliferation assay revealed that liquiritigenin shows remarkable immuno-enhancing effects, whereas liquiritin and davidigenin exhibit little or adverse effect on the proliferation of ConA-induced murine splenocytes. The presence of honey can alter the metabolism of liquiritin and, thus, influence the pharmacological effects of the licorice, rendering the honey-treated licorice as a medicine to invigorate the spleen. [ABSTRACT FROM AUTHOR]

Abstract: The adsorption and electro-oxidation of double stranded (ds) DNA on multi-walled carbon nanotubes (MWNTs), which was directly grown on graphite electrode, was investigated through potentiometric stripping analysis (PSA), and the influence factors, such as accumulation time, immersion time and DNA concentration, were examined in detail. By using the MWNTs modified electrode, liquiritigenin (4′,7-dihydroxyflavone), which was synthesized in medium strong acid circumstance, was firstly found to cause dsDNA damage in the presence of Cu(II) by observing a new peak at 0.84V and an increase at 1.06V in the PSA spectrum when liquiritigenin was introduced into the dsDNA and Cu(II) solution. Liquiritigenin exhibited two conflicting effects, i.e., pro-oxidation and anti-oxidation at its different concentrations in the damage system. Biquinoline and catalase were found to inhibit the dsDNA damage, which showed that Cu(I) and H2O2 participated in the damage process. Piezoelectric quartz crystal impedance (PQCI) analysis was also used to further validate the DNA damage, and the frequency shift was found to be mainly due to the change on density–viscosity of the tested solution which was caused by the degradation of the DNA macromolecules. A possible mechanism of oxidative DNA damage induce by liquiritigenin in the presence of Cu(II) on multi-walled carbon nanotubes was proposed. [Copyright &y& Elsevier]

Abstract: Xiao-xu-ming decoction (XXMD) is a traditional Chinese medicine that has been widely used to treat theoplegia and its sequelae. This paper reports the development of three separate assays based on reversed phase high-performance liquid chromatography–mass spectrometry (HPLC–MS) and HPLC–MS/MS for the determination of seven active constituents of XXMD viz oroxylin A-7-O-glucuronide, wogonoside, liquiritigenin, cimifugin, 5-O-methylvisammiol, glycyrrhizic acid and glycyrrhetinic acid in rat plasma. All calibration curves were linear (r >0.99) with lower limits of quantitation (LLOQs)<12.4ng/mL. Intra- and inter-day precisions (as relative standard deviation) were all <10.7% with recoveries in the range of 88.7–113%. In addition, the seven analytes were shown to be stable in rat plasma samples under relevant storage conditions. The validated methods were successfully applied to a pharmacokinetic study in rat after oral administration of XXMD. [Copyright &y& Elsevier]

Ssanghwa-tang is a medicinal formula that is widely prescribed in Korea to decrease fatigue after an illness. Fermented herbal medicines might be made more efficacious than conventional herbal medicines by increasing the absorption and bioavailability of the active compounds. In this study, Ssanghwa-tang was fermented to produce bioconversion compositions using Lactobacillus fermentum, and six peaks were decreased, four peaks were increased and one peak newly appeared in the HPLC-DAD chromatogram. The structures of the newly-appearing compound ( 1) and increased ( 2-5) compounds were identified as follows using NMR and MS: liquiritigenin ( 1), nodakenetin ( 2), cinnamyl alcohol ( 3), decursinol ( 4), and benzoic acid ( 5). The decreased compounds were identified to be paeoniflorin ( 6), liquiritin ( 7), nodakenin ( 8), cinnamaldehyde ( 9), decursin ( 10), and decursinol angelate ( 11) using HPLC-DAD analysis with authentic compounds. The high performance liquid chromatography method was used to quantify the eleven constituents in Ssanghwa-tang and fermented Ssanghwa-tang. All calibration curves of the standard compounds exhibited excellent linearity with a R > 0.9940. [ABSTRACT FROM AUTHOR]

Abstract: Liquiritigenin is one of the flavonoids present in Glycyrrhizae radix. In the present study, the effects of liquiritigenin on the function of osteoblastic MC3T3-E1 cells were studied. Liquiritigenin caused a significant elevation of cell growth, alkaline phosphatase activity, collagen synthesis, mineralization, and glutathione content in the cells (P <0.05). Moreover, liquiritigenin significantly decreased the production of reactive oxygen species (ROS) and osteoclast differentiation inducing factors such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and receptor activator of nuclear factor-κB ligand (RANKL) in the presence of antimycin A, which inhibits mitochondrial electron transport and has been used as a ROS generator. These results demonstrate that liquiritigenin may have positive effects on skeletal structure. [Copyright &y& Elsevier]

Abstract: The present paper is to examine whether liquiritigenin is able to attenuate the Alzheimer''s-like learning and memory deficits in a transgenic (Tg) mouse model that over-expresses amyloid protein precursor (APP), and explores the underlying mechanisms. Consistent with our previous observations, we found that treatment with liquiritigenin improved the behavioral performance of Tg mice and it attenuated the protein expression of oligomeric form of amyloid β-peptide (Aβ). Furthermore, treatment with liquiritigenin inhibited astrocytosis in the hippocampus, and it may through its inhibitory activities on Notch-2, an important molecular regulating neural proliferation and differentiation. These findings provide evidence for beneficial activity of liquiritigenin in a mouse model of Alzheimer''s disease and support the continued investigation of Notch signaling pathway as a target for treatment of Alzheimer''s disease. [Copyright &y& Elsevier]

Liquiritigenin (7,4′-dihydroxyflavone), the primary active component of a traditional Chinese medicine Glycyrrhizae radix, has a wide range of pharmacological activities. Six oxidative metabolites of liquiritigenin (7,3′,4′-trihydroxyflavone, a hydroxyl quinine metabolite, two A-ring dihydroxymetabolites, 7,4′-dihydroxyflavone, and 7-hydroxychromone) have been detected in rat liver microsomes (RLMs), and one CYP3A4-catalyzed metabolite (7,4′-dihydroxyflavone) has been identified in human liver microsomes (HLMs) recently. In this study, a novel mono-hydroxylated metabolite was detected in reaction catalyzed by HLMs, and was identified as 4′,5,7-trihydroxyflavanone by comparing the tandem mass spectra and the chromatographic retention time with that of the standard compound. Significant difference in CLint (9-fold) was found between these two oxidative pathways of liquiritigenin, and C5-hydroxylation pathway was identified as the major oxidative metabolism of liquiritigenin. The study with chemical selective inhibitor, cDNA-expressed human CYPs, correlation assay, and kinetic study demonstrated that CYP1A2 was the specific isozyme responsible for the C5-hydroxylation metabolism of liquiritigenin in HLMs. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the present study was to determine if liquiritigenin, which is a newly discovered estrogen receptor β (ERβ) agonist, can induce differentiation of brain-derived progenitor cells from rats and to investigate the mechanisms involved. Treatment of brain-derived progenitor cell cultures with liquiritigenin increased the number of cells that differentiated into neurons; but the treatment did not alter the growth of astrocytes. Furthermore, treatment with liquiritigenin decreased Notch-2 mRNA and protein expression, which could promote the growth of new neurons. Using RNA interference (RNAi), we determined that inhibition of Notch-2 by liquiritigenin was probably ERβ-dependent. These findings highlight the possible role of liquiritigenin in the repair and regeneration of injured brain tissue of patients with neurodegenerative diseases and support further investigation of the Notch-2 signaling pathway using ERβ agonists. [ABSTRACT FROM AUTHOR]

Abstract: In an attempt to develop potent and selective antitumor agents, a series of liquiritigenin thiosemicarbazone derivatives were designed and synthesized. The cytotoxicities of these compounds were evaluated in vitro against K562, DU-145, SGC-7901, HCT-116 and Hela cell lines. The pharmacological results showed that most of the prepared compounds displayed excellent selective cytotoxicity toward K562 and DU-145 cells. From the structure–activity relationships we may conclude that the introduction of a thiosemicarbazone functional group at the 4-position in the skeleton of liquiritigenin is associated with an increase in cytotoxicity. [Copyright &y& Elsevier]

Abstract: Considerable evidence has emerged supporting the neuroprotective and cognition-preserving effects of estrogen, but these benefits are complicated by the evidence that estrogen increases the risk of certain cancers. Selective estrogen receptor modulators (SERMs) that specifically target the brain while avoiding peripheral organs offer a way to allow the application of estrogen treatment to neurodegenerative diseases with fewer undesirable effects. In an attempt to find such estrogen substitutes, liquiritigenin was discovered as a relatively selective estrogen receptor β (ERβ) agonist. In the present study, we extend our previous findings to investigate the effects of liquiritigenin on the learning and memory deficits and related neuropathology in Aβ(25–35) hippocampal-injected rats. Our results show that liquiritigenin treatment improves the behavioral performance of the model rats and attenuates neuronal loss in the brain. More importantly, liquiritigenin treatment decreases mRNA levels and protein expression of Notch-2, an effect that could promote the generation of new neurons. These findings provide evidence for the beneficial activity of liquiritigenin in a brain-injured rat model and support the continued investigation of SERMs such as liquiritigenin as an alternative to estrogen-based hormone therapy in reducing the risk of neurodegenerative diseases such as Alzheimer''s disease. [Copyright &y& Elsevier]

1. Cytoprotective effects of liquiritigenin (LQ) against liver injuries have been reported, but its pharmacokinetics has not been studied in acute hepatitis. Thus, pharmacokinetics of LQ and its two conjugated glucuronide metabolites: 4'-O-glucuronide (M1) and 7-O-glucuronide (M2), in rats with acute hepatitis induced by d-galactosamine/lipopolysaccharide (GalN/LPS) rats or carbon tetrachloride-treated (CCl4-treated) rats were evaluated. 2. LQ was administered intravenously (20 mg kg-1) and orally (50 mg kg-1) to control GalN/LPS and CCl4-treated rats. Expression of uridine 5'-diphospho-glucuronosyltransferases 1A (UGT1A) and in vitro metabolism of LQ in hepatic and intestinal microsomes were also measured. 3. After intravenous administration of LQ, area under the plasma concentration-time curve (AUC) of LQ in GalN/LPS rats was significantly smaller than that in controls due to faster non-renal clearance, as a result of its greater free fraction in plasma and faster hepatic blood flow rate than the controls. In CCl4-treated rats, the AUCM1, 0-8 h/AUCLQ and AUCM2, 0-8 h/AUCLQ ratios were significantly greater than the controls due to decrease in biliary excretion of M1 and M2. However, no significant pharmacokinetic changes were observed in both acute hepatitis rats after oral administration due to comparable intestinal metabolism of LQ. 4. Modification of oral dosage regimen of LQ may not be necessary in patients with acute hepatitis; but human studies are required. [ABSTRACT FROM AUTHOR]

1. Cytoprotective effects of liquiritigenin (LQ) against liver injuries have been reported, but its pharmacokinetics has not been studied in acute hepatitis. Thus, pharmacokinetics of LQ and its two conjugated glucuronide metabolites: 4'-O-glucuronide (M1) and 7-O-glucuronide (M2), in rats with acute hepatitis induced by d-galactosamine/lipopolysaccharide (GalN/LPS) rats or carbon tetrachloride-treated (CCl4-treated) rats were evaluated. 2. LQ was administered intravenously (20 mg kg-1) and orally (50 mg kg-1) to control GalN/LPS and CCl4-treated rats. Expression of uridine 5'-diphospho-glucuronosyltransferases 1A (UGT1A) and in vitro metabolism of LQ in hepatic and intestinal microsomes were also measured. 3. After intravenous administration of LQ, area under the plasma concentration-time curve (AUC) of LQ in GalN/LPS rats was significantly smaller than that in controls due to faster non-renal clearance, as a result of its greater free fraction in plasma and faster hepatic blood flow rate than the controls. In CCl4-treated rats, the AUCM1, 0-8 h/AUCLQ and AUCM2, 0-8 h/AUCLQ ratios were significantly greater than the controls due to decrease in biliary excretion of M1 and M2. However, no significant pharmacokinetic changes were observed in both acute hepatitis rats after oral administration due to comparable intestinal metabolism of LQ. 4. Modification of oral dosage regimen of LQ may not be necessary in patients with acute hepatitis; but human studies are required. [ABSTRACT FROM AUTHOR]

Abstract: Flavonoids are a very diverse group of plant secondary metabolites with a wide array of activities in plants, as well as in nutrition and health. All flavonoids are derived from a limited number of flavanone intermediates, which serve as substrates for a variety of enzyme activities, enabling the generation of diversity in flavonoid structures. Flavonoids can be characteristic metabolites, like isoflavonoids for legumes. Others, like flavones, occur in nearly all plants. Interestingly, there exist two fundamentally different enzymatic systems able to directly generate flavones from flavanones, flavone synthase (FNS) I and II. We describe an inducible flavone synthase activity from soybean (Glycine max) cell cultures, generating 7,4′-dihydroxyflavone (DHF), which we classified as FNS II. The corresponding full-length cDNA (CYP93B16) was isolated using known FNS II sequences from other plants. Functional expression in yeast allowed the detailed biochemical characterization of the catalytic activity of FNS II. A direct conversion of flavanones such as liquiritigenin, naringenin, and eriodictyol into the corresponding flavones DHF, apigenin and luteolin, respectively, was demonstrated. The enzymatic reaction of FNSII was stereoselective, favouring the (S)- over the (R)-enantiomer. Phylogenetic analyses of the subfamily of plant CYP93B enzymes indicate the evolution of a gene encoding a flavone synthase which originally catalyzed the direct conversion of flavanones into flavones, via early gene duplication into a less efficient enzyme with an altered catalytic mechanism. Ultimately, this allowed the evolution of the legume-specific isoflavonoid synthase activity. [Copyright &y& Elsevier]

Licorice (Glycyrrhiza glabra. L) has been used since ancient times in order to treat gastric ulcers. The major active compounds are saponins and flavonoids. They are responsible for several other properties of the extracts: antibacterial, antiviral, depigmenting. The roots of the plant deposit these complex substances. Radix vegetal products may be easily substituted, making difficult their identification in absence of other vegetative organs such as leaves, flowers or fruits. Glycyrrhiza echinata L. is widerly spread in Romania than the consecrated medicinal species G. glabra. The aim of this study is to determine whether the roots of the two species have similar flavonoid characteristics, using Liquid Chromatography - Mass Spectrometry (LC/MS), a sensitive analysis method. The phytochemistry of licorice roots differs from that of G. echinata roots. The two are not equivalent. G. echinata roots lack the specific compounds correlated to the therapeutic activity of licorice. [ABSTRACT FROM AUTHOR]

Pharmacokinetics of liquiritigenin (LQ) and its two glucuronide metabolites, M1 and M2, in mice, rats, rabbits, and dogs and animal scale-up of the pharmacokinetic parameters of LQ were evaluated. After intravenous administration of LQ, the AUC (AUC0-t) values of LQ, M1, and M2 were proportional to LQ doses in all animals studied. Animal scale-up of some pharmacokinetic parameters of LQ was performed based on the parameters after its intravenous administration (20 mg/kg; in the linear pharmacokinetic range) to the four species. Linear relationships were obtained (r > 0.968) between log CL (or CL/fu) (L/h) and log species body weight (W) (kg) [CL (or CL/fu) = 3.29 (34.0) W0.723 (0.789)] and log Vss (or Vss/fu) (L) and log W (kg) [Vss (or Vss/fu) = 0.340 (3.52) W0.882 (0.948)]. Interspecies scale-up of plasma concentration–time data of LQ using apolysichron (complex Dedrick plots) resulted in similar profiles, and plasma concentration–time profile of humans were predicted using the well-fitted four animal data. Our results indicate that the LQ data obtained from laboratory animals could be utilized to generate preliminary estimates of the pharmacokinetic parameters of LQ in humans. These parameters can serve as guidelines for better planning of clinical studies. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4327–4342, 2009 [ABSTRACT FROM AUTHOR]

AbstractAim:To examine whether liquiritigenin, a newly found agonist of selective estrogen receptor-β, has neuroprotective activity against β-amyloid peptide (Aβ) in rat hippocampal neurons.Methods:Primary cultures of rat hippocampal neurons were pretreated with liquiritigenin (0.02, 0.2, and 2 μmol/L) prior to Aβ25–35 exposure. Following treatment, viability of the cells was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis and by a lactate dehydrogenase activity-based cytotoxicity assay. Intracellular Ca2+ concentration ([Ca2+]i) and levels of reactive oxygen species (ROS), as well as apoptotic rates, were determined. Our studies were extended in tests of whether liquiritigenin treatment could inhibit the secretion of Aβ1–40 as measured using an ELISA method. In order to analyze which genes may be involved, we used a microarray assay to compare gene expression patterns. Finally, the levels of specific proteins related to neurotrophy and neurodenegeration were detected by Western blotting.Results:Pretreated neurons with liquiritigenin in the presence of Aβ25–35 increased cell viability in a concentration-dependent manner. Liquiritigenin treatment also attenuated Aβ25–35-induced increases in [Ca2+]i and ROS level and decreased the apoptotic rate of neurons. Some genes, including B-cell lymphoma/leukemia-2 (Bcl-2), neurotrophin 3 (Ntf-3) and amyloid β (A4) precursor protein-binding, family B, member 1 (Apbb-1) were regulated by liquiritigenin; similar results were shown at the protein level by Western blotting.Conclusion:Our results demonstrate that liquiritigenin exhibits neuroprotective effects against Aβ25-35-induced neurotoxicity and that it can decrease the secretion of Aβ1–40. Therefore, liquiritigenin may be useful for further study as a prodrug for treatment of Alzheimer's disease.Acta Pharmacologica Sinica (2009) 30: 899–906; doi: 10.1038/aps.2009.74 [ABSTRACT FROM AUTHOR]

1. Pharmacokinetics of liquiritigenin, a candidate for inflammatory liver disease, and its two glucuronide conjugates, M1 and M2, were evaluated in rats. The hepatic and gastrointestinal first-pass effects of liquiritigenin were also evaluated in rats. 2. After oral administration of liquiritigenin at a dose of 20 mg kg-1, 1.07% of the dose was not absorbed from the gastrointestinal tract up to 24 h, and the F-value was only 6.68%. In vitro metabolism of liquiritigenin in S9 fractions of rat tissues showed that the liver and intestine were major tissues responsible for glucuronidation of liquiritigenin. The hepatic and gastrointestinal first-pass effects of liquiritigenin were approximately 3.67% and 92.5% of the oral dose, respectively. 3. Although the hepatic first-pass effect of liquiritigenin after absorption into the portal vein was 57.1%, the value was only 3.67% of the oral dose due to extensive gastrointestinal first-pass effect in rats. Therefore, the low F-value of liquiritigenin in rats was primarily attributable to an extensive gastrointestinal first-pass effect although liquiritigenin was well absorbed. Compared with rats, the higher F-value of liquiritigenin could be expected in humans. [ABSTRACT FROM AUTHOR]

Abstract: Licorice (the root of Glycyrrhizae plant) has been used as an oriental herbal medicine for thousands of years. The licorice flavonoid components are reported to possess immunomodulatory activities. In this present study, we investigated the immunomodulatory effects of liquiritigenin (LG) and liquiritin (LQ), licorice flavonoid components, against disseminated candidiasis due to Candida albicans, a dimorphic fungus, that causes severe disease via hematogenous dissemination and local diseases such as vaginitis and thrush. Results showed that direct interaction of LG or LQ with C. albicans yeast cells resulted in no growth-inhibition, in vitro. When tested in a murine model of disseminated candidiasis, mice given LQ intraperitoneally before intravenous challenge with live C. albicans yeast cells had similar mean survival times (MST) as untreated mice groups. On the contrary, mice given LG in the same manner as LQ above had longer MST than the untreated mice groups (P <0.05). In one experiment, 3 out of 5 LG-treated mice survived during the entire period of the 55-day observation. Furthermore, the 3 survivors were cured—shown by a lack of CFU (colony forming unit) in the kidneys. This protection was nulled when mice were pretreated with anti-CD4+ antibody before LG-treatment and challenge with the yeast. However, the protection was transferable by the CD4+ T cells isolated from LG-treated mice not infected with the yeast. In addition, mice given CD4+ T cells that were pre-treated with LG, in vitro were also protected against disseminated candidiasis. ELISA analysis revealed that in LG-treated mice IFNγ and IL-2 were dominantly produced compared to IL-4 and IL-10. When LG-given mice were treated with anti-mouse IFNγ, the protection was again nulled. Combined together, these results indicate that LG protects mice against disseminated candidiasis by the CD4+ Th1 immune response. [Copyright &y& Elsevier]

Abstract: Liquiritigenin is a flavanone existed in Radix glycyrrhizae. The objective of this study is to explore the effects of liquiritigenin on SMMC-7721 cells and its possible mechanism. The viability of liquiritigenin treat cells was decreased in a dose-dependent manner assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylterazolium bromide (MTT), and apoptotic morphological changes also be observed, such as chromatin condensation and nuclear fragmentation. Assessment of apoptotic cells by flow cytometry indicated that cells fell into apoptosis after 0.4mM liquiritigenin treatment. In addition, a concomitant time-dependent increase in caspase-3 activity was also observed. The level of p53 protein increased and Bcl-2 protein decreased time-dependently. Further studies found the induction of apoptosis by liquiritigenin was accompanied with the production of reactive oxygen species (ROS), disruption of mitochondrial membrane potential and depletion of antioxidant enzymes. The significant ROS generation was firstly found at 3h and being time-dependent until 9h. A time-dependent decrease in membrane potential occurred, and significant loss appeared at 9h and 12h. Furthermore, pretreatment of N-acetyl-cysteine (NAC), ROS production and apoptosis induced by liquiritigenin were both suppressed. In sum, this paper indicated the cytotoxicity of liquiritigenin on SMMC-7721 cells may via effect on generation of ROS, later lead to cell apoptosis. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: Random Forest screening of the phytochemical constituents of 240 herbs used in traditional Chinese medicine identified a number of compounds as potential inhibitors of the human aromatase enzyme (CYP19). Molecular modelling/docking studies indicated that three of these compounds (myricetin, liquiritigenin and gossypetin) would be likely to form stable complexes with the enzyme. The results of the virtual screening studies were subsequently confirmed experimentally, by in vitro (fluorimetric) assay of the compounds’ inhibitory activity. The IC-50s for the flavones, myricetin and gossypetin were determined as 10 and 11μM, respectively, whilst the flavanone, liquiritigenin, gave an IC-50 of 0.34μM—showing about a 10-fold increase in potency, therefore, over the first generation aromatase inhibitor, aminoglutethimide. [Copyright &y& Elsevier]

Background and Purpose: Glycyrrhizae radix has been widely used as a cytoprotective, plant-derived medicine. We have identified a flavanoid, liquiritigenin, as an active component in extracts of Glycyrrhizae radix. This research investigated the effects of liquiritigenin on the induction of inducible NOS (iNOS) and proinflammatory cytokines by lipopolysaccharide (LPS) in Raw264.7 cells, and on paw oedema in rats.Experimental Approach: iNOS expression was determined by western blotting, real-time reverse transcription-PCR and reporter gene analyses. Tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta and IL-6 were assayed by ELISA. Gel shift assay and immunoblotting were used to assess NF-kappaB activation. The effect of liquiritigenin on acute inflammation in vivo was evaluated using carrageenan-induced paw oedema.Key Results: Treatment of Raw264.7 cells with liquiritigenin caused inhibition of LPS-induced NF-kappaB DNA binding activity, due to repression of I-kappaBalpha phosphorylation and degradation. Liquiritigenin treatment prevented LPS from increasing the levels of iNOS protein and mRNA in a concentration-dependent manner. Liquiritigenin also suppressed the production of TNF-alpha, IL-1beta and IL-6 from Raw264.7 cells after LPS. In rats, liquiritigenin treatment inhibited formation of paw oedema induced by carrageenan.Conclusion and Implications: These results demonstrate that liquiritigenin exerts anti-inflammatory effects, which results from the inhibition of NF-kappaB activation in macrophages, thereby decreasing production of iNOS and proinflammatory cytokines. Our findings showing inhibition by liquiritigenin of paw oedema as well as inflammatory gene induction will help to understand the pharmacology and mode of action of liquiritigenin, and of the anti-inflammatory use of Glycyrrhizae radix. [ABSTRACT FROM AUTHOR]

Abstract: Glycyrrhizae radix has been used as one of the oldest and most frequently employed botanicals in both western and oriental countries. Previously, we showed that liquiritigenin (LQ), an aglycone of liquiritin in G. radix, exerts cytoprotective effects against heavy metal-induced toxicity in vitro. This study investigated in vivo protective effects of LQ against acute liver injuries induced by acetaminophen (APAP) or APAP plus buthionine sulfoximine (BSO). Liver injuries were assessed by blood biochemistry and histopathology in rats administered with LQ purified from the acid hydrolyates of liquiritin singly (p.o. or i.v., 2–4 days) or in combination with dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxybiphenyl-2,2′-dicarboxylate (DDB), a synthetic derivative of Schisandrin C in Fructus shizandrae, and exposed to APAP or APAP+BSO. LQ treatments (oral) effectively decreased liver injuries induced by a single dose of APAP, as evidenced by decreases in hepatic necrosis and inflammation as well as plasma alanine aminotransferase and lactate dehydrogenase activities. LQ, when intravenously applied, enhanced hepatoprotective effect with a greater potency. APAP+BSO led to severe liver injuries, resulting in lethality. LQ pretreatments significantly reduced the potentiated liver necrosis, decreasing mortality. In spite of the improvement in blood biochemistry, DDB failed to protect the liver from injuries induced by APAP or APAP+BSO. Combined treatments of rats with LQ and DDB showed some additive protective effect. The present study demonstrates that LQ efficaciously protects the liver from acute injuries induced by APAP or from APAP-induced severe injuries during GSH deficiency, indicating that LQ is one of the principal cytoprotective components comprised in G. radix. [Copyright &y& Elsevier]