The protective role of liquiritin in high fructose-induced myocardial fibrosis via inhibiting NF-κB and MAPK signaling pathway

Diabetic cardiomyopathy has been known as an important complication of diabetes and characterized by persistent diastolic dysfunction, resulting in myocardial fibrosis, which is associated inflammatory response and oxidative stress. Liquiritin is a major constituent of Glycyrrhiza Radix, possessing various pharmacological activities and exhibiting various positive biological effects, including anti-cancer, anti-oxidative and neuroprotective effects. Here, we investigated the anti-inflammatory properties and protective effects of lquiritin in high fructose-induced mice and cardiomyocytes to clarify the potential mechanism. The mice were divided into the control mice, 30% high fructose-induced mice, 10mg/kg liquiritin-treaed mice after fructose feeding and 20mg/kg liquiritin-treaed mice after fructose feeding. Liquiritin effectively reduced the lipid accumulation and insulin resistance induced by fructose feeding. In comparison to high fructose-feeding control mice, liquiritin-treated mice developed less myocardial fibrosis with lower expression of Collagen type I, Collagen type II and alpha smooth muscle-actin (α-SMA). In addition, liquiritin significantly reduced the inflammatory cytokine release and NF-κB phosphorylation through IKKα/IκBα signaling pathway suppression. Further, Mitogen-activated protein kinases (MAPKs), including p38, ERK1/2 and JNK, was up-regulated for fructose stimulation, which was inactivated by liquiritin treatment in vivo and in vitro studies. Our data indicates that liquiritin has a protective effect against high fructose-induced myocardial fibrosis via suppression of NF-κB and MAPKs signaling pathways, and liquiritin may be a promising candidate for diabetes-related myocardial fibrosis treatment.

Liquiritin, a novel inhibitor of TRPV1 and TRPA1, protects against LPS-induced acute lung injury

TRPV1 and TRPA1 are cation channels that play key roles in inflammatory signaling pathways. They are co-expressed on airway C-fibers, where they exert synergistic effects on causing inflammation and cough. Licorice, the root of Glycyrrhiza uralensis, has been widely used in China as an anti-inflammatory and anti-coughing herb. To learn if TRPV1 and TRPA1 might be key targets of the anti-inflammatory and antitussive effects of licorice, we examined liquiritin, the main flavonoid compound and active ingredient of licorice, on agonist-evoked TRPV1 and TRPA1 activation. Liquiritin inhibited capsaicin- and allyl isothiocyanate-evoked TRPV1 and TRPA1 whole-cell currents, respectively, with a similar potency and maximal inhibition. In a mouse acute lung injury (ALI) model induced by the bacterial endotoxin lipopolysaccharide, which involves both TRPV1 and TRPA1, an oral gavage of liquiritin prevented tissue damage and suppressed inflammation and the activation of NF-κB signaling pathway in the lung tissue. Liquiritin also suppressed LPS-induced increase in TRPV1 and TRPA1 protein expression in the lung tissue, as well as TRPV1 and TRPA1 mRNA levels in cells contained in mouse bronchoalveolar lavage fluid. In cultured THP-1 monocytes, liguiritin, or TRPV1 and TRPA1 antagonists capsazepine and HC030031, respectively, diminished not only cytokine-induced upregulation of NF-κB function but also TRPV1 and TRPA1 expression at both protein and mRNA levels. We conclude that the anti-inflammatory and antitussive effects of liquiritin are mediated by the dual inhibition of TRPV1 and TRPA1 channels, which are upregulated in nonneuronal cells through the NF-κB pathway during airway inflammation via a positive feedback mechanism.

Pharmacological activities and pharmacokinetics of liquiritin: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Liquiritin is a flavonoid derived from Radix et Rhizoma Glycyrrhizae, which is a widely used traditional Chinese medicine with the effects of invigorating spleen qi, clearing heat, resolving toxins, and dispelling phlegm to stop coughs.

AIM OF THE STUDY

In this review,the pharmacokinetics and pharmacological activities of liquiritin have been summarized.

MATERIALS AND METHODS

The information on liquiritin up to 2021 was collected from PubMed, Web of Science, Springer Link, and China National Knowledge Infrastructure databases. The key words were "liquiritin", "nerve", "tumor", "cardiac", etc. RESULTS: The absorption mechanism of liquiritin conforms to the passive diffusion and first-order kinetics while with low bioavailability. Liquiritin can penetrate the blood-brain-barrier. Besides, liquiritin displays numerous pharmacological effects including anti-Alzheimer's disease, antidepressant, antitumor, anti-inflammatory, cardiovascular protection, antitussive, hepatoprotection, and skin protective effects. In addition, the novel preparations, new pharmacological effects,and cdusafty of liquiritin are also discussed in this review.

CONCLUSION

This review provides a comprehensive state of knowledge on the pharmacokinetics and pharmacological activities of liquiritin, and makes a forecast for its research directions and applications in clinic.

Production of rubusoside from stevioside by using a thermostable lactase from Thermus thermophilus and solubility enhancement of liquiritin and teniposide

Solubility is an important factor for achieving the desired plasma level of drug for pharmacological response. About 40% of drugs are not soluble in water in practice and therefore are slowly absorbed, which results in insufficient and uneven bioavailability and GI toxicity. Rubusoside (Ru) is a sweetener component in herbal tea and was discovered to enhance the solubility of a number of pharmaceutically and medicinally important compounds, including anticancer compounds. In this study, thirty-one hydrolyzing enzymes were screened for the conversion of stevioside (Ste) to Ru. Recombinant lactase from Thermus thermophiles which was expressed in Escherichia coli converted stevioside to rubusoside as a main product. Immobilized lactase was prepared and used for the production of rubusoside; twelve reaction cycles were repeated with 95.4% of Ste hydrolysis and 49 g L(-1) of Ru was produced. The optimum rubusoside synthesis yield was 86% at 200 g L(-1), 1200 U lactase. The purified 10% rubusoside solution showed increased water solubility of liquiritin from 0.98 mg mL(-1) to 4.70±0.12 mg mL(-1) and 0 mg mL(-1) to 3.42±0.11 mg mL(-1) in the case of teniposide.

Neuroprotective effects of liquiritin on cognitive deficits induced by soluble amyloid-β1-42 oligomers injected into the hippocampus

This study assessed the modulating effects of liquiritin against cognitive deficits, oxidative damage, and neuronal apoptosis induced by subsequent bilateral intrahippocampal injections of aggregated amyloid-β_1-42 (Aβ_1-42). This study also explored the molecular mechanisms underlying the above phenomena. Liquiritin was orally administered to rats with Aβ_1-42-induced cognitive deficits for 2 weeks. The protective effects of liquiritin on the learning and memory impairment induced by Aβ_1-42 were examined in vivo by using Morris water maze. The rats were then euthanized for further studies. The antioxidant activities of liquiritin in the hippocampus of the rats were investigated by biochemical and immunohistochemical methods. The apoptosis of the neurons was assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling assay. Liquiritin at doses of 50-100 mg/kg significantly improved the cognitive ability, restored the abnormal activities of glutathione peroxidase and superoxide dismutase, and decreased the levels of malondialdehyde，8-hydroxy-2'-deoxyguanosine and protein carbonyl in the hippocampus of rats with Alzheimer's disease. Moreover, neural apoptosis in the hippocampus of Aβ_1-42-treated rats was reversed by liquiritin. Liquiritin can significantly ameliorate Aβ_1-42-induced spatial learning and memory impairment by inhibiting oxidative stress and neural apoptosis.

Liquiritigenin and liquiritin alleviated monocrotaline-induced hepatic sinusoidal obstruction syndrome via inhibiting HSP60-induced inflammatory injury

Hepatic sinusoidal obstruction syndrome (HSOS) is a life-threatening liver disease caused by the damage to liver sinusoidal endothelial cells (LSECs). Liquiritigenin and liquiritin are two main compounds in Glycyrrhizae Radix et Rhizoma (Gan-cao). Our previous study has shown that both liquiritigenin and liquiritin alleviated monocrotaline (MCT)-induced HSOS in rats via inducing the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant signaling pathway. This study aims to further investigate whether inhibiting liver inflammatory injury also contributed to the liquiritigenin and liquiritin-provided alleviation on MCT-induced HSOS. The results of serum alanine/aspartate aminotransferases (ALT/AST) activities and total bilirubin (TBil) amount, liver histological evaluation, scanning electron microscope observation and hepatic metalloproteinase-9 (MMP9) expression showed that liquiritigenin and liquiritin both alleviated MCT-induced HSOS in rats. Liquiritigenin and liquiritin reduced the increased liver myeloperoxidase (MPO) activity, mRNA expression of pro-inflammatory factors, hepatic infiltration of immune cells, hepatic toll-like receptor 4 (TLR4) expression and nuclear factor κB (NFκB) nuclear accumulation induced by MCT in rats. Furthermore, liquiritigenin and liquiritin attenuated MCT-induced liver mitochondrial injury, increased the decreased Lon protein expression and reduced the release of heat shock protein 60 (HSP60). Moreover, liquiritigenin and liquiritin also reduced NFκB nuclear accumulation and decreased the elevated cellular mRNA expression of NFκB-downstream pro-inflammatory cytokines induced by HSP60 in macrophage RAW264.7 cells. In conclusion, our study revealed that both liquiritigenin and liquiritin alleviated MCT-induced HSOS by inhibiting hepatic inflammatory responses triggered by HSP60.

Liquiritin inhibits proliferation and induces apoptosis in HepG2 hepatocellular carcinoma cells via the ROS-mediated MAPK/AKT/NF-κB signaling pathway

Liquiritin (LIQ), a major constituent of Glycyrrhiza Radix, exhibits various pharmacological activities. In this study, to explore the potential anti-cancer effects and its underlying molecular mechanisms of LIQ in hepatocellular carcinoma (HCC) cells. LIQ significantly decreased viability and induced apoptosis in HepG2 cells by decreasing mitochondrial membrane potential and regulating Bcl-2 family proteins, cytochrome c, cle-caspase-3, and cle-PARP. The cell cycle analysis and western blot analysis revealed that LIQ induced G2/M phase arrest through increased expression of p21 and decreased levels of p27, cyclin B, and CDK1/2. The flow cytometry and western blot analysis also suggested that LIQ promoted the accumulation of ROS in HepG2 cells and up-regulated the phosphorylation expression levels of p38 kinase, c-Jun N-terminal kinase (JNK), and inhibitor of NF-κB (IκB-α); the phosphorylation levels of extracellular signal-regulated kinase (ERK), protein kinase B (AKT), signal transducer activator of transcription 3 (STAT3), and nuclear factor kappa B (NF-κB) were down-regulated. However, these effects were reversed by N-acetyl-L-cysteine (NAC), MAPK, and AKT inhibitors. The findings demonstrated that LIQ induced cell cycle arrest and apoptosis via the ROS-mediated MAPK/AKT/NF-κB signaling pathway in HepG2 cells, and the LIQ may serve as a potential therapeutic agent for the treatment of human HCC.

A novel concept for detoxification: complexation between aconitine and liquiritin in a Chinese herbal formula ('Sini Tang')

ETHNOPHARMACOLOGICAL RELEVANCE

Sini Tang (SNT) is a traditional Chinese herbal formulation consisting of three different herbs: Aconitum carmichaelii (Fuzi), Zingiber officinale (Ganjiang), and Glycyrrhiza uralensis (Gancao). For this study, we modified this mixture by adding the bark of Cinnamomum cassia (Rougui, ). Aconitum carmichaelii contains aconitine and its derivatives, all of which are highly toxic alkaloids. These compounds are commonly detoxified with pyrolytic and hydrolytic pretreatments, such as Heishunpian, which requires repeated soaking in salt water, boiling until the roots turn black, and drying in the oven. We now demonstrate that Glycyrrhiza uralensis, which is often used in Traditional Chinese Medicine for detoxification, reduces the concentration of free aconitine in decoctions by forming a complex between liquiritin and aconitine.

MATERIALS AND METHODS

Aqueous extracts of SNT, each individual herb or herbal mixture, and methanolic extracts of individual herbs were tested for free aconitine by HPLC coupled with a diode array detector. A detected complex was investigated by NMR and UV/vis spectroscopy. The continuous variations method and (1)H-NMR titrations provided the complex stoichiometry and binding constant. A 2D-ROESY experiment was performed to obtain the structural details of the formed complex.

RESULTS

A fast and simple HPLC method was developed to determine the amounts of aconitine and its derivatives found in herbal extracts. The Heishunpian pretreatment led to nearly complete pyrolysis and hydrolysis of the toxic compounds. However, in some batches, considerable amounts of aconitine remained. The addition of Glycyrrhiza uralensis to Aconitum carmichaelii, or liquiritin to free aconitine, led to a complexation with aconitine. The complex possessed a 1:1 stoichiometry and a binding constant of ca. 3000 L/mol to 4000 L/mol in mixtures of aqueous methanol.

CONCLUSIONS

A new HPLC based method allows the concentration of toxic aconitine and other diester diterpene alkaloids in herbal extracts to be rapidly determined. This method provides a starting point for the development of routine quality control procedures. The complexation of free aconitine by adding an excess of Glycyrrhiza uralensis or free liquiritin to SNT formulations will make these formulations safer.

Combining TRAIL and liquiritin exerts synergistic effects against human gastric cancer cells and xenograft in nude mice through potentiating apoptosis and ROS generation

Gastric cancer is one of the most factors, leading to cancer-related death worldwide. However, the therapies to prevent gastric cancer are still limited and the emergence of drug resistance leads to development of new anti-cancer drugs and combinational chemotherapy regimens. Our study was aimed to explore the anti-gastric cancer effects of liquiritin (LIQ), a major constituent of Glycyrrhiza Radix, which possesses a variety of pharmacological activities. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) preferentially inhibited tumor cells over other normal cells, when used in alone or in combination. The results indicated that LIQ, when applied in single, was moderately effective to suppress proliferation, and migration, as well as to induce apoptosis and reactive oxygen species (ROS) generation of human gastric cancer cell lines, AGS and SNU-216, which are TRAIL-resistant. Significantly, when used in combination, the two drugs functioned synergistically to impede the progression and growth of human gastric cancer cells in vitro and gastric cancer cell xenograft nude mice in vivo. Both intrinsic and extrinsic apoptosis were induced by the two in combination via activating Caspases. And c-Jun N-terminal kinase (JNK) activity was dramatically induced by TRAIL/LIQ. Importantly, TRAIL/LIQ-triggered apoptosis and JNK were dependent on ROS production. The data indicated that application of TRAIL/LIQ in combination had a potential value for clinical use to synergistically prevent human gastric cancer development.

Liquiritin protects PC12 cells from corticosterone-induced neurotoxicity via regulation of metabolic disorders, attenuation ERK1/2-NF-κB pathway, activation Nrf2-Keap1 pathway, and inhibition mitochondrial apoptosis pathway

Liquiritin, a flavone derived from the medicine food homology plant liquorice, possesses neuroprotective. However, the neuroprotective mechanism is not clear. In this study, metabolomics based LC-MS was performed to discover the metabolite changes in PC12 cells treated with corticosterone-induced neurotoxicity after liquiritin treatment. A total of 30 metabolites were identified as differential metabolites. Among them, 11 metabolites were regulated by liquiritin, and involved in the D-glutamine and D-glutamate metabolism, and glutathione metabolism, etc. Based on the results of metabolomics, three cell signaling pathways related to these metabolic pathways were verified. The results showed that the ERK1/2-NF-κB pathway related to the D-glutamine and D-glutamate metabolism was attenuated by liquiritin via down-regulation phospho-ERK1/2, phospho-IκBα, phospho-NF-κB protein expression levels. Furthermore, the Nrf2-Keap1 pathway related to glutathione metabolism was activated by liquiritin via up-regulation Nrf2, Keap1, HO-1, NQO1 protein expression levels, and increased SOD, CAT, GSH-PX enzyme activity, thus exerting antioxidant activity. Additionally, liquiritin inhibited the mitochondrial apoptosis by decreasing the Ca²⁺ concentration, improving MMP, up-regulating Bcl-2, and down-regulating Bax, cytochrome C, cleaved-Caspase-3 expression levels. These results suggest that the neuroprotective mechanisms of liquiritin are connected to the regulation of metabolic disorders, activation Nrf2/Keap1 pathway, attenuation ERK1/2/NF-κB pathway, and inhibition mitochondrial apoptosis pathway.

Soil potassium is correlated with root secondary metabolites and root-associated core bacteria in licorice of different ages

AIMS

Licorice (Glycyrrhiza uralensis Fisch.) is a crucial medicinal herb as it accumulates glycyrrhizin and liquiritin in roots. Licorice root-associated bacterial communities shaped by soil characteristics are supposed to regulate the accumulation of root secondary metabolites.

METHODS

The soil characteristics, root secondary metabolites, and root-associated bacterial communities were analyzed in licorice plants of different ages to explore their temporal dynamics and interaction mechanisms.

RESULTS

Temporal variation in soil characteristics and root secondary metabolites was distinct. The alpha-diversity of root-associated bacterial communities decreased with root proximity, and the community composition was clustered in the rhizosphere. Different taxa that were core-enriched from the dominant taxa in the bulk soil, rhizosphere soil, and root endosphere displayed varied time-decay relationships. Soil total potassium (TK) as a key factor regulated the temporal variation in some individual taxa in the bulk and rhizosphere soils; these taxa were associated with the adjustment of root secondary metabolites across different TK levels.

CONCLUSIONS

Licorice specifically selects root-associated core bacteria over the course of plant development, and TK is correlated with root secondary metabolites and individual core-enriched taxa in the bulk and rhizosphere soils, which may have implications for practical licorice cultivation.

Metabolic profiling of mice plasma, bile, urine and feces after oral administration of two licorice flavonones

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is an ancient food and medicinal plant. Liquiritigenin and liquiritin, two kinds of major flavonoes in licorice, are effective substances used as antioxidant, anti-inflammatory and tumor-suppressive food, cosmetics or medicines. However, their in vivo metabolites have not been fully explored.

AIM OF STUDY

To clarify the metabolism of liquiritigenin and liquiritin in mice.

MATERIALS AND METHODS

In this study, we developed a liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry approach to determine the metabolites in mice plasma, bile, urine and feces after oral administration of liquiritigenin or liquiritin. The structures of those metabolites were tentatively identified according to their fragment pathways, accurate masses, characteristic product ions, metabolism laws or reference standard matching.

RESULTS

A total of 26 and 24 metabolites of liquiritigenin or liquiritin were respectively identified. The products related with apigenin, luteolin or quercetin were the major metabolites of liquiritigenin or liquiritin in mice. Seven main metabolic pathways including (de)hydrogenation, (de)hydroxylation, (de)glycosylation, (de)methoxylation, acetylation, glucuronidation and sulfation were summarized to tentatively explain their biotransformation.

CONCLUSION

This study not only can provide the evidence for in vivo metabolites and pharmacokinetic mechanism of liquiritigenin and liquiritin, but also may lay the foundation for further development and utilization of liquiritigenin, liquiritin and then licorice.

REDUCING TOXICITY AND INCREASING EFFICIENCY: ACONITINE WITH LIQUIRITIN AND GLYCYRRHETINIC ACID REGULATE CALCIUM REGULATORY PROTEINS IN RAT MYOCARDIAL CELL

BACKGROUND

Compatibility of Radix Aconiti Carmichaeli and Liquorice is known to treat heart diseases such as heart failure and cardiac arrhythmias. This work answers the question that whether the active components (Aconitine, Liquiritin and Glycyrrhetinic Acid) of Radix Aconiti Carmichaeli and Liquorice could result in regulating intracellular calcium homeostasis and calcium cycling, and thereby verifies the therapeutic material basis.

MATERIALS AND METHODS

The myocardial cells were divided into twelve groups randomly as control group, Aconitine group, nine different dose groups that orthogonal combined with Aconitine, Liquiritin and Glycyrrhetinic Acid, and Verapamil group. The myocardial cellular survival rate and morphology were assessed. The expression of calcium regulation protein(RyR2, NCX1, DHPR-a1) in the myocardial cell by Western-blotting.

RESULTS

The results exhibited that Aconitine (120 uM) significantly damaged on myocardial cell, decreased the survival rate and expression of Na⁺/Ca²⁺ exchangers (NCX1) and dihydropteridine reducta-α1 (DHPR-a1), and increased the expression of ryanodine receptor type2 (RyR2) obviously. The compatibility groups (Aconitine, Liquiritin and Glycyrrhetinic Acid) all could against the damage on the myocardial cell by Aconitine at different levels.

CONCLUSION

Aconitine with Liquiritin and Glycyrrhetinic Acid may regulate the expression of calcium-regulated proteins to protect myocardial cells from damage.

De novo biosynthesis of liquiritin in Saccharomyces cerevisiae

Liquiritigenin (LG), isoliquiritigenin (Iso-LG), together with their respective glycoside derivatives liquiritin (LN) and isoliquiritin (Iso-LN), are the main active flavonoids of Glycyrrhiza uralensis, which is arguably the most widely used medicinal plant with enormous demand on the market, including Chinese medicine prescriptions, preparations, health care products and even food. Pharmacological studies have shown that these ingredients have broad medicinal value, including anti-cancer and anti-inflammatory effects. Although the biosynthetic pathway of glycyrrhizin, a triterpenoid component from G. uralensis, has been fully analyzed, little attention has been paid to the biosynthesis of the flavonoids of this plant. To obtain the enzyme-coding genes responsible for the biosynthesis of LN, analysis and screening were carried out by combining genome and comparative transcriptome database searches of G. uralensis and homologous genes of known flavonoid biosynthesis pathways. The catalytic functions of candidate genes were determined by in vitro or in vivo characterization. This work characterized the complete biosynthetic pathway of LN and achieved the de novo biosynthesis of liquiritin in Saccharomyces cerevisiae using endogenous yeast metabolites as precursors and cofactors for the first time, which provides a possibility for the economical and sustainable production and application of G. uralensis flavonoids through synthetic biology.

Liquiritin reduces lipopolysaccharide-aroused HaCaT cell inflammation damage via regulation of microRNA-31/MyD88

BACKGROUND

Pressure ulcers are a common issue for people who have limited mobility. This study tested the impact of liquiritin on human keratinocyte HaCaT cell inflammatory damage aroused by lipopolysaccharide (LPS).

METHODS

HaCaT cells were underwent LPS and/or liquiritin incubation. Cell viability, apoptosis and inflammatory molecules interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and cyclooxygenase-2 (Cox-2) expressions, along with nuclear factor kappa B (NF-κB) and c-Jun N-terminal kinase (JNK) pathways activities were tested by MTT assay, Guava Nexin assay, ELISA and western blotting, respectively. qRT-PCR was done for measuring microRNA-31 (miR-31) expression. miR-31 inhibitor was transfected to silence miR-31. Animal pressure ulcers was established on the dorsal skin of adult rats. The effects of liquiritin on wound healing were analyzed by measuring wound closure rates.

RESULTS

LPS aroused HaCaT cell inflammatory damage, as evidenced by the decrease of cell viability, increase of cell apoptosis and enhanced expressions of IL-6, TNF-α and Cox-2. Liquiritin protected HaCaT cells against LPS-aroused inflammatory damage through increasing cell viability, decreasing cell apoptosis, and reducing IL-6, TNF-α and Cox-2 expressions. Liquiritin attenuated the LPS-aroused NF-κB and JNK pathways activation in HaCaT cells. Rat pressure ulcers model also confirmed that liquiritin promoted wound healing. In mechanism, miR-31 expression was boosted by liquiritin in HaCaT cells. Silencing miR-31 weakened the impacts of liquiritin on LPS-irritated HaCaT cells. Myeloid differentiation factor 88 (MyD88) was a target of miR-31 in HaCaT cells.

CONCLUSION

This research affirmed the beneficial impact of liquiritin on pressure ulcers. Liquiritin reduced LPS-aroused HaCaT cell inflammatory damage might be implemented via raising miR-31 expression, lowering MyD88 expression, and repressing NF-κB and JNK pathways.

A green and efficient pseudotargeted lipidomics method for the study of depression based on ultra-high performance supercritical fluid chromatography-tandem mass spectrometry

The pseudotargeted lipidomics method integrates the advantages of untargeted andtargeted lipidomics methods as a novel emerging approach. In this study, a green andefficient pseudotargeted lipidomics method based on ultra-high performancesupercritical fluid chromatography-tandem mass spectrometry (UHPSFC-MS/MS) wasdeveloped. The tandem mass spectra of the analytes were obtained by using UHPSFCwith quadrupole-time of flight MS (Q-TOF MS) in MS E mode and the multiplereaction monitoring (MRM) transitions of the lipidome were defined. Then, thecandidate MRM transitions were verified by UHPSFC with triple quadrupole massspectrometry (QqQ MS) in the scheduled MRM mode. In total, 758 potential lipidscorresponding to 509 and 249 MRM transitions were detected within 8 min in positiveand negative modes, respectively. The established pseudotargeted lipidomics methodwas validated to have excellent analytical characteristics. Compared with thepseudotargeted method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), the UHPSFC-MS/MS-basedpseudotargeted method not only reduced the analytical time by half but also improvedthe sensitivity and resolution for most analytes, especially had better separation forlipid isomers. Besides, the UHPSFC-MS/MS-based pseudotargeted method showedhigher sensitivity and better repeatability for most analytes than the UHPSFC-MS/MS-based untargeted method. The established method was finally applied to investigatingthe lipid profiles of the plasma from the depressed rats and 33 differential variableswere screened, which related to three metabolic pathways. The results indicated thatthe UHPSFC-MS/MS-based pseudotargeted method is reliable and efficient and couldbe used in the lipidomics studies.

The effects of Glycyrrhizae uralenis and its major bioactive components on pharmacokinetics of daphnetin in Cortex daphnes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Glycyrrhizae uralenis (GU) is often prescribed together with Cortex daphnes (CD) in traditional Chinese medicinal practice to increase the efficacy of CD on the treatment of rheumatoid arthritis (RA), but the reasons were still unknown. In order to clarify the rationality of herbaceous compatibility between CD and GU, the comparative evaluations on pharmacokinetic behaviors of daphnetin (a predominantly active ingredient in CD) after intragastric administration of CD and CD-GU (combination of CD and GU) extract were studied. In addition, the effects of glycyrrhizin and liquiritin, active ingredients of Glycyrrhiza triterpenes and Glycyrrhiza flavones respectively, on the pharmacokinetics of daphnetin were also investigated.

MATERIALS AND METHODS

Five groups of rats were orally administered with CD extract, CD-GU extract, pure daphnetin, co-administration of daphnetin and glycyrrhizin as well as co-administration of daphnetin and liquiritin at the same single dose of daphnetin (20 mg/kg). The rat plasma concentrations of daphnetin were determined by our developed UPLC-MS/MS method. The pharmacokinetics of daphnetin in above groups were investigated and compared.

RESULTS

Comparing with oral administration of CD extract, AUC and Tmax of daphnetin significantly increased after giving CD-GU (p<0.05). In addition, in comparison to daphnetin alone, co-administration of daphnetin with liquiritin significantly increased the AUC and Cmax of daphnetin for ~1.5-fold, while co-administered with glycyrrhizin showed limited impact on the pharmacokinetics of daphnetin.

CONCLUSIONS

In this study, it was found that liquiritin, one of the major components of GU, significantly enhanced the bioavailability of the main component daphnetin in CD. In addition, the bioavailability of daphnetin in the CD-GU prescription was also significantly higher than that in CD alone, which could be due to liquiritin. Such results explained the mechanism of the increased efficacy in treating RA with the combined use of CD and GU.

Protective effects of liquiritin on UVB-induced skin damage in SD rats

Overexposure to ultraviolet B (UVB) rays can cause damage to the skin. Liquiritin has a variety of pharmacological effects, such as anti-inflammatory and antioxidant. In the present study, the effect of liquiritin on UVB irradiated rat skin was investigated. Results showed that UVB irradiation caused erythema and wrinkles on the skin surface, as well as thickening and loss of elasticity of the epidermis and a significant increase in the level of ROS in the skin tissue. At the same time, western blot detected an increase in nuclear factor kappa-B (NF-κB) and matrix metalloproteinases (MMPs) and Elisa also detected an increase in pro-inflammatory factors. Therefore, we hypothesized that UVB irradiation-induced damage is associated with inflammation. Interestingly, application of liquiritin to exposed skin of rats reduced the increase in ROS, pro-inflammatory factors, and MMPs caused by UVB irradiation and increased the levels of Sirtuin3 (SIRT3) and Collagen α1. In addition, after intraperitoneal injection of the SIRT3 inhibitor 3-TYP in rats, the protective effect of liquiritin against UVB damage was found to be diminished. These results suggested that promotion of SIRT3 with liquiritin inhibits UVB-induced production of pro-inflammatory mediators, possibly acting through the SIRT3/ROS/NF-κB pathway. In conclusion, this study suggests that liquiritin is an effective drug candidate for the prevention of UVB damage.

Antifungal activity of liquiritin in Phytophthora capsici comprises not only membrane-damage-mediated autophagy, apoptosis, and Ca2+ reduction but also an induced defense responses in pepper

Phytophthora capsici causes a severe soil-borne disease in a wide variety of vegetables; to date, no effective strategies to control P. capsici have been developed. Liquiritin (LQ) is a natural flavonoid found in licorice (Glycyrrhiza spp.) root, and it is used in pharmaceuticals. However, the antifungal activity of LQ against P. capsici remains unknown. In the present study, we demonstrated that LQ inhibits P. capsici mycelial growth and sporangial development. In addition, the EC₅₀ of LQ was 658.4 mg/L and LQ caused P. capsici sporangia to shrink and collapse. Next, LQ severely damaged the cell membrane integrity, leading to a 2.0-2.5-fold increase in relative electrical conductivity and malondialdehyde concentration, and a 65-70% decrease in sugar content. Additionally, the H₂O₂ content was increased about 2.0-2.5 fold, but the total antioxidant activity, catalase activity and laccase activity were attenuated by 40-45%, 30-35% and 70-75%. LQ also induced autophagy, apoptosis, and reduction of intracellular Ca²⁺ content. Furthermore, LQ inhibited P. capsici pathogenicity by reducing the expression of virulence genes PcCRN4 and Pc76RTF, and stimulating the plant defense (including the activated transcriptional expression of defense-related genes CaPR1, CaDEF1, and CaSAR82, and the increased antioxidant enzyme activity). Our results not only elucidate the antifungal mechanism of LQ but also suggest a promising alternative to commercial fungicides or a key compound in the development of new fungicides for the control of the Phytophthora disease.

Phytotoxic mechanism of allelochemical liquiritin on root growth of lettuce seedlings

As the main active ingredient of the traditional Chinese medicine Glycyrrhiza uralensis Fisch, liquiritin has multiple biological activities, including anti-inflammatory, antihepatotoxicity, immune regulation, anti-virus and anti-cancer. In addition, liquiritin has been recognized as an allelochemical that displays markedly inhibitory effects on the growth of target plants, G. uralensis and lettuce. However, its phytotoxic mechanism remains unknown. In the present study, the mode of action of liquiritin against root growth of lettuce seedling was researched. After treatments with liquiritin, the cell division in root tips of lettuce seedlings was partly arrested, and the cell viability and root vitality were obviously lost. At the same time, overproduction of reactive oxygen species (ROS), malondialdehyde (MDA) and proline (Pro) in lettuce seedlings were induced by liquiritin. The results indicated that the phytotoxic effects of liquiritin was probably dependent on the induction of ROS overproduction, resulting in membrane lipids peroxidation following with cell death and mitosis process disorder.

Mixed micelles for enhanced oral bioavailability and hypolipidemic effect of liquiritin: preparation, in vitro and in vivo evaluation

OBJECTIVES

Liquiritin, as one of the main flavonoids in Glycyrrhiza, exhibits extensive pharmacological effects, such as the anti-oxidant, anti-inflammatory, anti-tumor and so on. Herein, the aqueous solubility and oral bioavailability of liquiritin was purposely enhanced via the preparation of the mixed micelles.

METHODS

The liquiritin-loaded micelles (LLM) were fabricated via thin-film dispersion method. The optimal LLM formulation was evaluated through physical properties including particle size (PS), encapsulation efficiency (EE) and drug loading (DL). In vitro accumulate release as well as in vivo pharmacokinetics were also evaluated. Moreover, the hypolipidemic activity of LLM was observed in the hyperlipidemia mice model.

RESULTS

The LLM exhibited a homogenous spherical shape with small mean PS, good stability and high encapsulation efficiency. The accumulate release rates in vitro of the LLM were obviously higher than free liquiritin. The oral bioavailability of the formulation was heightened by 3.98 times in comparison with the free liquiritin. More importantly, LLM increased the hypolipidemic and effect of alleviating lipid metabolism disorder in hepatocytes of liquiritin in hyperlipidemia mice model.

CONCLUSIONS

Collectively, the improved solubility of liquiritin in water coupled with its enhanced oral bioavailability and concomitant hypolipidemic activity could be attributed to the incorporation of the drug into the mixed micelles.

Liquiritin exhibits anti-acute lung injury activities through suppressing the JNK/Nur77/c-Jun pathway

BACKGROUND

Licorice (Glycyrrhiza uralensis Fisch.), a well-known traditional medicine, is traditionally used for the treatment of respiratory disorders, such as cough, sore throat, asthma and bronchitis. We aim to investigate the effects of liquiritin (LQ), the main bioactive compound in licorice against acute lung injury (ALI) and explore the potential mechanism.

METHODS

Lipopolysaccharide (LPS) was used to induce inflammation in RAW264.7 cells and zebrafish. Intratracheal instillation of 3 mg/kg of LPS was used for induction an ALI mice model. The concentrations of IL-6 and TNF-α were tested using the enzyme linked immunosorbent assay. Western blot analysis was used to detect the expression of JNK/Nur77/c-Jun related proteins. Protein levels in bronchoalveolar lavage fluid (BALF) was measured by BCA protein assay. The effect of JNK on Nur77 transcriptional activity was determined by luciferase reporter assay, while electrophoretic mobility shift assay was used to examine the c-Jun DNA binding activity.

RESULTS

LQ has significant anti-inflammatory effects in zebrafish and RAW264.7 cells. LQ inhibited the expression levels of p-JNK (Thr183/Tyr185), p-Nur77 (Ser351) and p-c-Jun (Ser63), while elevated the Nur77 expression level. Inhibition of JNK by a specific inhibitor or small interfering RNA enhanced the regulatory effect of LQ on Nur77/c-Jun, while JNK agonist abrogated LQ-mediated effects. Moreover, Nur77-luciferase reporter activity was suppressed after JNK overexpression. The effects of LQ on the expression level of c-Jun and the binding activity of c-Jun with DNA were attenuated after Nur77 siRNA treatment. LQ significantly ameliorated LPS-induced ALI with the reduction of lung water content and BALF protein content, the downregulation of TNF-α and IL-6 levels in lung BALF and the suppression of JNK/Nur77/c-Jun signaling, which can be reversed by a specific JNK agonist.

CONCLUSION

Our results indicated that LQ exerts significant protective effects against LPS-induced inflammation both in vivo and in vitro via suppressing the activation of JNK, and consequently inhibiting the Nur77/c-Jun signaling pathway. Our study suggests that LQ may be a potential therapeutic candidate for ALI and inflammatory disorders.

Protective effect of liquiritin on coronary heart disease through regulating the proliferation of human vascular smooth muscle cells via upregulation of sirtuin1

This study aimed to explore whether liquiritin affects the development of coronary heart disease by regulating the proliferation and migration of human vascular smooth muscle cells (hVSMCs). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) release detection were performed to measure the toxic effects of liquiritin on hVSMCs. An in vitro atherosclerosis model in hVSMCs was established using oxidized low-density lipoprotein (ox-LDL), and cell proliferation and apoptosis were detected using an MTT assay and flow cytometry analysis. Western blotting and reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) were used to detect protein and mRNA expressions, respectively. Caspase3 activity and cell migration were measured using an activity detection kit and Transwell assay, respectively. The results indicated that liquiritin at doses <160 μM had no significant effect on cell viability and LDH release in hVSMCs. Ox-LDL significantly induced cell proliferation and migration, and inhibited hVSMCs apoptosis. Liquiritin significantly inhibited cell proliferation and migration, and enhanced cell apoptosis in ox-LDL induced hVSMCs. Sirtuin1 (SIRT1) was lowly expressed in atherosclerotic plaque tissues in coronary heart disease patients and in ox-LDL-induced hVSMCs. Liquiritin improved SIRT1 expression in ox-LDL-induced hVSMCs, whereas the improvement was inhibited by Selisistat (EX 527, an effective SIRT1 inhibitor) treatment. EX 527 reversed the effects of liquiritin on cell proliferation, migration, and apoptosis in ox-LDL-induced hVSMCs In conclusion, liquiritin plays a protective role in coronary heart disease by regulating the proliferation and migration of hVSMCs by increasing SIRT1 expression.

A comprehensive profiling and identification of liquiritin metabolites in rats using ultra-high-performance liquid chromatography coupled with linear ion trap-orbitrap mass spectrometer

Liquiritin (LQ), a main component of liquorice, exerts various biological activities. However, insufficient attentions have been paid to the metabolism study on this natural compound until now. Our present study was conducted to investigate the LQ metabolites in rats urine, faeces and plasma using UHPLC-LTQ-Orbitrap mass spectrometer in both positive and negative ion modes. Meanwhile, post-acquisition data-mining methods including high-resolution extracted ion chromatogram (HREIC), multiple mass defect filters (MMDFs), neutral loss fragments (NLFs) and diagnostic product ions (DPIs) were utilised to screen and identify LQ metabolites from HR-ESI-MS to ESI-MSⁿ stage. As a result, a total of 49 metabolites were detected and characterised unambiguously or tentatively. These metabolites were presumed to generate through glucuronidation, sulfation, deglucosylation, dehydrogenation, methylation, hydrogenation, hydroxylation, ring cleavage and their composite reactions. Our results not only provided novel and useful data to better understand the biological activities of LQ, but also indicated that the proposed strategy was reliable for a rapid discovery and identification drug-related constituents in vivo.

A high coverage pseudotargeted lipidomics method based on three-phase liquid extraction and segment data-dependent acquisition using UHPLC-MS/MS with application to a study of depression rats

Pseudotargeted analysis combines the advantages of untargeted and targeted lipidomics methods based on chromatography-mass spectrometry (MS). This study proposed a comprehensive pseudotargeted lipidomics method based on three-phase liquid extraction (3PLE) and segment data-dependent acquisition (SDDA). We used a 3PLE method to extract the lipids with extensive coverage from biological matrixes. 3PLE was composed of one aqueous and two organic phases. The upper and middle organic phases enriched neutral lipids and glycerophospholipids, respectively, combined and detected together. Besides, the SDDA strategy improved the detection of co-elution ions in the lipidomics analysis. A total of 554 potential lipids were detected by the developed approach in both positive and negative modes using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Compared with the conventional liquid-liquid extraction (LLE) approaches, including methyl tert-butyl ether (MTBE) and Bligh-Dyer (BD) methods, 3PLE combined with SDDA significantly increased the lipid coverage 87.2% and 89.7%, respectively. Also, the proposed pseudotargeted lipidomics approach exhibited higher sensitivity and better repeatability than the untargeted approach. Finally, we applied the established pseudotargeted method to the plasma lipid profiling from the depressed rats and screened 61 differential variables. The results demonstrated that the pseudotargeted method based on 3PLE and SDDA broadened lipid coverage and improved the detection of co-elution ions with excellent sensitivity and precision, indicating significant potential for the lipidomics analysis.