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

Liquiritin as a Tumor Suppressor Prevents the Development of Breast Cancer via the Epidermal Growth Factor Receptor/Mitogen-Activated Protein Kinase 8 Signaling Pathway

Liquiritin, a key component extracted from Glycyrrhiza radix, exhibits a variety of physiological effects. This study investigates the role of liquiritin in the progression of breast cancer. This investigation conducted experiments using two breast cancer cell lines treated with varying concentrations of liquiritin, further validating our findings in vivo. Bioinformatics analysis was used to identify the pathways potentially regulated by liquiritin in breast cancer. The results indicated that the epidermal growth factor receptor (EGFR) and mitogen-activated protein kinase 8 (MAPK8) are potential downstream factors regulated by liquiritin in breast cancer. Our findings demonstrated that liquiritin significantly suppressed cell proliferation and induced cell cycle arrest in a dose-dependent manner. In addition, liquiritin triggered apoptosis by inhibiting the phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B signaling pathway. Liquiritin also reduced mitochondrial membrane potential, leading to mitochondrial dysfunction and promoting excessive reactive oxygen species (ROS) production by suppressing the EGFR/MAPK8 signaling pathway. Furthermore, liquiritin treatment resulted in a notable decrease in tumor size in breast cancer models through inhibiting cell proliferation and promoting apoptosis. In conclusion, liquiritin serves as an effective tumor suppressor, suppressing the proliferation and cell cycle progression of breast cancer cells, while inducing apoptosis by regulating mitochondrial function and ROS generation via the EGFR/MAPK8 signaling pathway.

Liquiritin exerts psoriasis therapy and prevention by regulating the YY1/RBP3 axis

BACKGROUND

Psoriasis (PSO) poses a global health threat. The current research challenge in PSO is relapse. Liquiritin (LIQ), a major active compound from Glycyrrhiza inflata Batalin, has multiple pharmacological properties, including anti-inflammatory and anti-proliferative. Nonetheless, the precise mechanisms underlying LIQ's therapeutic actions in PSO and prevention abilities remain elusive.

PURPOSE

The present study aimed to delve into the potential to treat and prevent PSO and the mechanism of LIQ.

METHODS

The anti-inflammatory and anti-proliferative effects of LIQ were studied in vitro with the HaCaT cell line. Then, Transcriptional analysis and bioinformatic analysis were used to determine the internal associations of the target set. Subsequently, functional experiment, luciferase report assay, ChIP-PCR, and immunohistochemical validation of clinical samples were performed to investigate the mechanism of LIQ. Finally, the anti-psoriatic effects and prevention abilities of LIQ were verified in vivo with imiquimod (IMQ)-induced PSO-like mouse models.

RESULTS

Here, we identified differentially expressed genes in LIQ-stimulated HaCaT cells and Retinol-Binding Protein 3 (RBP3) as the core target, whereas YY1 was a predicted upstream transcription factor of RBP3. The YY1/RBP3 axis was obviously altered after administering LIQ at optimal doses of 20 μM in vitro and 100 µg/ml in vivo. LIQ can significantly inhibit the progression of PSO in vivo. Notably, LIQ also prevented the relapse of psoriatic lesions induced by the second round of low-dose IMQ. Mechanistically, we observed that LIQ could increase the promotion of YY1 for RBP3 by enhancing the binding affinity between them.

CONCLUSION

These findings revealed that the YY1/RBP3 axis is a potential psoriatic target, and LIQ is a promising and innovative therapeutic candidate for the treatment and prevention of PSO.

Curcumin suppresses colorectal tumorigenesis through restoring the gut microbiota and metabolites

BACKGROUND

Curcumin has been reported to have activity for prevention and therapy of CRC, yet its underlying mechanisms remain largely unknown. Recently, emerging evidence suggests that the gut microbiota and its metabolites contribute to the causation and progression of Colorectal cancer (CRC). In this study, we aimed to investigate if curcumin affects the tumorigenesis of CRC by modulating gut microbiota and its metabolites.

METHODS

Forty male C57BL/6JGpt mice were randomly divided into four groups: negative control (NC), curcumin control, CRC model, and curcumin treatment (CRC-Cur) groups. CRC mouse model was induced by using azoxymethane (AOM) and dextran sodium sulfate (DSS), and the mice in CRC model and curcumin treatment groups received oral PBS or curcumin (150 mg/kg/day), respectively. Additionally, fecal samples were collected. 16 S rRNA sequencing and Liquid Chromatography Mass Spectrometry (LC-MS)-based untargeted metabolomics were used to observe the changes of intestinal flora and intestinal metabolites.

RESULTS

Curcumin treatment restored colon length and structural morphology, and significantly inhibited tumor formation in AOM/DSS-induced CRC model mice. The 16S rRNA sequencing analysis indicated that the diversity and richness of core and total species of intestinal microflora in the CRC group were significantly lower than those in the NC group, which were substantially restored in the curcumin treatment group. Curcumin reduced harmful bacteria, including Ileibacterium, Monoglobus and Desulfovibrio, which were elevated in CRC model mice. Moreover, curcumin increased the abundance of Clostridia_UCG-014, Bifidobacterium and Lactobacillus, which were decreased in CRC model mice. In addition, 13 different metabolites were identified. Compared to the NC group, ethosuximide, xanthosine, and 17-beta-estradiol 3-sulfate-17-(beta-D-glucuronide) were elevated in the CRC model group, whereas curcumin treatment significantly reduced their levels. Conversely, glutamylleucine, gamma-Glutamylleucine, liquiritin, ubenimex, 5'-deoxy-5'-fluorouridine, 7,8-Dihydropteroic acid, neobyakangelicol, libenzapril, xenognosin A, and 7,4'-dihydroxy-8-methylflavan were decreased in the CRC group but notably upregulated by curcumin. Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis revealed enrichment in seven pathways, including folate biosynthesis (P < 0.05).

CONCLUSIONS

The gut microecological balance was disrupted in AOM/DSS-induced CRC mice, accompanied by metabolite dysbiosis. Curcumin restored the equilibrium of the microbiota and regulated metabolites, highly indicating that curcumin may alleviate the development of AOM/DSS induced colorectal cancer in mice by regulating intestinal flora homeostasis and intestinal metabolites.

Liquiritin ameliorates painful diabetic neuropathy in SD rats by inhibiting NLRP3-MMP-9-mediated reversal of aquaporin-4 polarity in the glymphatic system

Background

Despite advancements in diabetes treatment, the management of Painful Diabetic Neuropathy (PDN) remains challenging. Our previous research indicated a significant correlation between the expression and distribution of Aquaporin-4 (AQP4) in the spinal glymphatic system and PDN. However, the potential role and mechanism of liquiritin in PDN treatment remain uncertain.

Methods

This study established a rat model of PDN using a combination of low-dose Streptozotocin (STZ) and a high-fat, high-sugar diet. Rats were treated with liquiritin and MCC950 (an NLRP3 inhibitor). We monitored fasting blood glucose, body weight, and mechanical allodynia periodically. The glymphatic system's clearance function was evaluated using Magnetic Resonance Imaging (MRI), and changes in proteins including NLRP3, MMP-9, and AQP4 were detected through immunofluorescence and Western blot techniques.

Results

The rats with painful diabetic neuropathy (PDN) demonstrated several physiological changes, including heightened mechanical allodynia, compromised clearance function within the spinal glymphatic system, altered distribution of AQP4, increased count of activated astrocytes, elevated expression levels of NLRP3 and MMP-9, and decreased expression of AQP4. However, following treatment with liquiritin and MCC950, these rats exhibited notable improvements.

Conclusion

Liquiritin may promote the restoration of AQP4 polarity by inhibiting NLRP3 and MMP-9, thereby enhancing the clearance functions of the spinal cord glymphatic system in PDN rats, alleviating the progression of PDN.

Liquiritin Alleviates Inflammation in Lipopolysaccharide-Induced Human Corneal Epithelial Cells

PURPOSE

This research was designed to elucidate the anti-inflammatory impacts of liquiritin on lipopolysaccharide (LPS)-activated human corneal epithelial cells (HCECs).

METHODS

The Cell Counting kit-8 (CCK-8) assay was adopted to assess cell viability. The enzyme-linked immunosorbent assay (ELISA) was used to detect the secretion levels of the proinflammatory cytokines IL-6, IL-8, and TNF-α. Transcriptome analysis was conducted to identify the genes that exhibited differential expression between different treatment. The model group included cells treated with LPS (10 µg/mL), the treatment group comprised cells treated with liquiritin (80 µM) and LPS (10 µg/mL), and the control group consisted of untreated cells. To further validate the expression levels of the selected genes, including CSF2, CXCL1, CXCL2, CXCL8, IL1A, IL1B, IL24, IL6, and LTB, quantitative real-time PCR was performed. The expression of proteins related to the Akt/NF-κB signaling pathway was assessed through western blot analysis. NF-κB nuclear translocation was evaluated through immunofluorescence staining.

RESULTS

The secretion of IL-6, IL-8, and TNF-α in LPS-induced HCECs was significantly downregulated by liquiritin. Based on the transcriptome analysis, the mRNA expression of pro-inflammatory cytokines, namely IL-6, IL-8, IL-1β, IL-24, TNF-α, and IL-1α was overproduced by LPS stimulation, and suppressed after liquiritin treatment. Furthermore, the Western blot results revealed a remarkable reduction in the phosphorylation degrees of NF-κB p65, IκB, and Akt upon treatment with liquiritin. Additionally, immunofluorescence analysis confirmed liquiritin's inhibition of LPS-induced p65 nuclear translocation.

CONCLUSIONS

Collectively, these findings imply that liquiritin suppresses the expression of proinflammatory cytokines, and the anti-inflammatory impacts of liquiritin may be caused by its repression of the Akt/NF-κB signaling pathway in LPS-induced HCECs. These data indicate that liquiritin could provide a potential therapeutic application for inflammation-associated corneal diseases.

The implications of lipid mobility, drug-enhancers (surfactants)-skin interaction, and TRPV1 activation on licorice flavonoid permeability

Licorice flavonoids (LFs) are derived from perennial herb licorice and have been attaining a considerable interest in cosmetic and skin ailment treatments. However, some LFs compounds exhibited poor permeation and retention capability, which restricted their application. In this paper, we systematically investigated and compared the enhancement efficacy and mechanisms of different penetration enhancers (surfactants) with distinct lipophilicity or "heat and cool" characteristics on ten LFs compounds. Herein, the aim was to unveil how seven different enhancers modified the stratum corneum (SC) surface and influence the drug-enhancers-skin interaction, and to relate these effects to permeation enhancing effects of ten LFs compounds. The enhancing efficacy was evaluated by enhancement ratio (ER)permeation, ERretention, and ERcom, which was conducted on the porcine skin. It was summarized that heat capsaicin (CaP) and lipophilic Plurol® Oleique CC 497 (POCC) caused the most significance of SC lipid fluidity, SC water loss, and surface structure alterations, thereby resulting in a higher permeation enhancing effects than other enhancers. CaP could completely occupied drug-skin interaction sites in the SC, while POCC only occupied most drug-skin interactions. Moreover, the enhancing efficacy of both POCC and CaP was dependent on the log P values of LFs. For impervious LFs with low drug solubility, enhancing their drug solubility could help them permeate into the SC. For high-permeation LFs, their permeation was inhibited ascribed to the strong drug-enhancer-skin strength in the SC. More importantly, drug-surfactant-skin energy possessed a good negative correlation with the LFs permeation amount for most LFs molecules. Additionally, the activation of transient receptor potential vanilloid 1 (TRPV1) could enhance LFs permeation by CaP. The study provided novel insights for drug permeation enhancement from the viewpoint of molecular pharmaceutics, as well as the scientific utilization of different enhancers in topical or transdermal formulations.

A Novel Approach for Dermal Application of Pranoprofen-Loaded Lipid Nanoparticles for the Treatment of Post-Tattoo Inflammatory Reactions

Recently, the number of people acquiring tattoos has increased, with tattoos gaining significant popularity in people between 20 and 40 years old. Inflammation is a common reaction associated with tattooing. The purpose of this study was to evaluate a nanostructured lipid carrier loading pranoprofen (PRA-NLC) as a tattoo aftercare formulation to reduce the inflammation associated with tattooing. In this context, the in vitro drug release and the ex vivo permeation-through-human-skin tests using Franz cells were appraised. The tolerance of our formulation on the skin was evaluated by studying the skin's biomechanical properties. In addition, an in vivo anti-inflammatory study was conducted on mice skin to evaluate the efficacy of the formulation applied topically after tattooing the animals. PRA-NLC showed a sustained release up to 72 h, and the amount of pranoprofen retained in the skin was found to be 33.48 µg/g/cm2. The formulation proved to be well tolerated; it increased stratum corneum hydration, and no signs of skin irritation were observed. Furthermore, it was demonstrated to be non-cytotoxic since the cell viability was greater than 80%. Based on these results, we concluded that PRA-NLC represents a suitable drug delivery carrier for the transdermal delivery of pranoprofen to alleviate the local skin inflammation associated with tattooing.

Recombinant p40 Protein Promotes Expression of Occludin in HaCaT Keratinocytes: A Brief Communication

The ability of epithelial barriers to perform as the first defense line against external damage derives from tight junctions, protein complexes that block microorganisms through the paracellular space. Indeed, disturbances of barrier permeability caused by bacterial metabolites and other inflammatory stimuli are the consequence of changes in protein expression in these complexes. Postbiotics, molecules derived from bacteria with beneficial effects on the host, improve barrier function through the activation of survival pathways in epithelial cells. Lacticaseibacillus rhamnosus GG secretes the muramidase p40, which protects intestinal barriers through an EGFR-dependent pathway. In this work, we cloned, expressed, and purified the recombinant p40 protein from L. rhamnosus GR-1 to evaluate its effect on cell viability, cell cytotoxicity, TEER, and protein levels of tight junctions, as well as EGFR activation via Western blot on HaCaT keratinocytes subjected to LPS. We found a novel mutation at residue 368 that does not change the structure of p40. Our protein also reduces the LPS-induced increase in cell cytotoxicity when it is added prior to this stimulus. Furthermore, although LPS did not cause changes in barrier function, p40 increased TEER and occludin expression in HaCaT, but unlike previous work with p40 from LGG, we found that recombinant p40 did not activate EGFR. This suggests that recombinant p40 enhances epithelial barrier function through distinct signaling pathways.

The PI3K-Akt-mTOR and Associated Signaling Pathways as Molecular Drivers of Immune-Mediated Inflammatory Skin Diseases: Update on Therapeutic Strategy Using Natural and Synthetic Compounds

The dysregulated phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway has been implicated in various immune-mediated inflammatory and hyperproliferative dermatoses such as acne, atopic dermatitis, alopecia, psoriasis, wounds, and vitiligo, and is associated with poor treatment outcomes. Improved comprehension of the consequences of the dysregulated PI3K/Akt/mTOR pathway in patients with inflammatory dermatoses has resulted in the development of novel therapeutic approaches. Nonetheless, more studies are necessary to validate the regulatory role of this pathway and to create more effective preventive and treatment methods for a wide range of inflammatory skin diseases. Several studies have revealed that certain natural products and synthetic compounds can obstruct the expression/activity of PI3K/Akt/mTOR, underscoring their potential in managing common and persistent skin inflammatory disorders. This review summarizes recent advances in understanding the role of the activated PI3K/Akt/mTOR pathway and associated components in immune-mediated inflammatory dermatoses and discusses the potential of bioactive natural products, synthetic scaffolds, and biologic agents in their prevention and treatment. However, further research is necessary to validate the regulatory role of this pathway and develop more effective therapies for inflammatory skin disorders.

Identification of chemical constituents of Qingjin Yiqi granules and comparative study on pharmacokinetics of 23 main bioactive components in normal and Lung-Qi deficiency rats by UPLC-MS/MS method

Qingjin Yiqi granules (QJYQ granules) are hospital preparations derived from ancient prescriptions under the guidance of academician Zhang Boli; they have the effect of invigorating qi and nourishing yin, strengthening the spleen and harmonizing the middle, clearing heat, and drying dampness, and are mainly used for patients with coronavirus disease 2019 (COVID-19) during the recovery period. However, their chemical constituents and pharmacokinetic characteristics in vivo have not been systematically investigated. In this study, 110 chemical constituents of QJYQ granules were identified using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), and a fast and sensitive ultra-high-performance liquid chromatography-mass spectrometry method was developed and validated for the target analytes. A rat model of lung-qi deficiency was established by subjecting mice to passive smoking combined with cold baths, and 23 main bioactive components of QJYQ granules were analyzed in normal and model rats after oral administration. The results showed that, compared to the normal group, there were significant differences in the pharmacokinetics of baicalin, schisandrin, ginsenoside Rb1, naringin, hesperidin, liquiritin, liquiritigenin, glycyrrhizic acid, and hastatoside in the model rats (P < 0.05), indicating that the in vivo processes of the above components changed under pathological conditions, suggesting that they may have pharmacological effects as active components. This study has helped identify QJYQ particulate substances and further supports their clinical application..

4'-OH as the Action Site of Lipids and MRP1 for Enhanced Transdermal Delivery of Flavonoids

To date, the transdermal delivery study mainly focused on the drug delivery systems' design and efficacy evaluation. Few studies reported the structure-affinity relationship of the drug with the skin, further revealing the action sites of the drugs for enhanced permeation. Flavonoids attained a considerable interest in transdermal administration. The aim is to develop a systematic approach to evaluate the substructures that were favorable for flavonoid delivery into the skin and understand how these action sites interacted with lipids and bound to multidrug resistance protein 1 (MRP1) for enhanced transdermal delivery. First, we investigated the permeation properties of various flavonoids on the porcine skin or rat skin. We found that 4'-OH (hydroxyl group on the carbon 4' position) rather than 7-OH on the flavonoids was the key group for flavonoid permeation and retention, while 4'-OCH₃ and -CH₂═CH₂-CH-(CH₃)₂ were unfavorable for drug delivery. 4'-OH could decrease flavonoids' lipophilicity to an appropriate log P and polarizability for better transdermal drug delivery. In the stratum corneum, flavonoids used 4'-OH as a hand to specifically grab the C═O group of the ceramide NS (Cer), which increased the miscibility of flavonoids and Cer and then disturbed the lipid arrangement of Cer, thereby facilitating their penetration. Subsequently, we constructed overexpressed MRP1 HaCaT/MRP1 cells by permanent transfection of human MRP1 cDNA in wild HaCaT cells. In the dermis, we observed that 4'-OH, 7-OH, and 6-OCH₃ substructures were involved in H-bond formation within MRP1, which increased the flavonoid affinity with MRP1 and flavonoid efflux transport. Moreover, the expression of MRP1 was significantly enhanced after the treatment of flavonoids on the rat skin. Collectively, 4'-OH served as the action site for increased lipid disruption and enhanced affinity for MRP1, which facilitate the transdermal delivery of flavonoids, providing valuable guidelines for molecular modification and drug design of flavonoids.

Liquiritin inhibits MRGPRX2-mediated pseudo-allergy through the PI3K/AKT and PLCγ signaling pathways

Liquiritin is a natural flavone with a variety of pharmacological effects derived from the medicinal food homology plant Glycyrrhiza uralensis Fisch. As a kind of lethal allergic reactions, pseudo-allergic reactions (PARs) arise from the Mas-related G protein coupled receptor X2 (MRGPRX2)-triggered fast degranulation of mast cells (MCs). In the current work, the anti-pseudo-allergy action and potential mechanisms of liquiritin were explored in vivo and in vitro. Liquiritin suppressed the calcium influx and degranulation elicited by Compound 48/80 (C48/80) in mouse peritoneal mast cells (MPMCs). In mice, liquiritin also inhibited the C48/80-elicited hind paw extravasation, as well as the elevations in TNF-α and histamine levels. Molecular docking combined with detection of HEK293T cells expressing human MRGPRX2 showed that liquiritin was a potential MRGPRX2 antagonist and inhibited PARs through the PI3K/AKT and PLCγ signaling pathways downstream of MRGPRX2. The present work opens a new avenue for the PARs management.

Experimental study on the effect of luteolin on the proliferation, apoptosis and expression of inflammation-related mediators in lipopolysaccharide-induced keratinocytes

OBJECTIVE

This study aimed at exploring the effects of luteolin on psoriasis-like cell model proliferation, apoptosis regulation and the expression of inflammation-related mediators.

METHODS

A Cell Counting Kit-8 (CCK-8) assay was used to determine the survival rate of human immortalized keratinocytes (HaCaT cells) and normal human epidermal keratinocytes (NHEK cells) following stimulation with luteolin and lipopolysaccharide (LPS). Western blot and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis were used to detect the protein and mRNA expressions of nuclear factor (NF)-κB p65 and interleukin (IL)-6 after LPS stimulation. Then a luteolin stimulation protocol (10 μmol/L, 24 h) was determined and a reasonable LPS stimulation concentration (20 μg/mL, 24 h) was chosen to establish the psoriasis cell model. Keratinocytes in luteolin pre-treatment and control groups were stimulated with 20 μg/mL LPS for 24 h, and the expressions of NF-κB p65 and IL-6 were detected by western blot and RT-qPCR. The apoptosis of HaCaT cells was detected by flow cytometry, and the enzyme-linked immunosorbent assay (ELISA) was used to detect the expression of psoriasis-related inflammatory factors.

RESULTS

CCK-8 assay indicated that luteolin inhibited the proliferation of keratinocytes. LPS stimulated the proliferation of keratinocytes and upregulated the expression of NF-κB p65 and IL-6 in a concentration-dependent manner, and induced psoriasis-like changes. Furthermore, the protein and mRNA expression levels of NF-κB p65 and IL-6 were decreased in the luteolin pre-stimulation group (p < 0.05). Treatment with luteolin downregulated the expression of the LPS-induced inflammatory mediators in keratinocytes (p < 0.05). The flow cytometry results showed that luteolin induced HaCaT cells apoptosis. Finally, ELISA results demonstrated that luteolin inhibited the release of the IL-17, IL-23 and tumor necrosis factor α (TNF-α) in the pre-stimulation group (p < 0.05).

CONCLUSION

This study confirmed that luteolin can effectively relieve inflammatory mediators in LPS-induced keratinocyte models of psoriasis, which suggested the potential of luteolin in treating psoriasis.

Development and Validation of a UPLC-MS/MS Method for the Quantification of Components in the Ancient Classical Chinese Medicine Formula of Guyinjian

Guyinjian (GYJ) is an ancient classic formula of traditional Chinese medicine used for the treatment of liver and kidney yin deficiency; it was derived from the book "Jing Yue Quan Shu" in the Ming Dynasty. Modern clinical observation experiments have shown that GYJ has a definite therapeutic effect on the treatment of gynecological diseases such as kidney deficiency type oligomenorrhea, climacteric syndrome, intermenstrual bleeding, pubertal metrorrhagia, etc. However, the lack of GYJ quality control studies has greatly limited the development of its wider clinical application. In this study, a validated UPLC-MS/MS method was developed successfully for the first time and used to quantify fourteen compounds in GYJ samples with good specificity, linearity (r = 0.9960-0.9999), precision (RSD% ≤ 3.18%), stability (RSD% ≤ 2.22%) and accuracy (recovery test within 88.64-107.43%, RSD% at 2.82-6.22%). Simultaneously, the determination results of 15 batches of GYJ samples were analyzed by multivariate statistical methods, and it was found that the compounds have a greater influence on batch-to-batch stability, mainly Rehmannioside D, Loganin, Morroniside, Ginsenoside Re, and 3',6-Disinapoylsucrose. The proposed new method has the advantages of high sensitivity, high selectivity, and rapid analysis, which provides a reference for the GYJ quality control study.

Liquiritin Alleviates Depression-Like Behavior in CUMS Mice by Inhibiting Oxidative Stress and NLRP3 Inflammasome in Hippocampus

Objective

Central inflammation is generally accepted to be involved in the pathology of depression. We investigated whether liquiritin exerts antidepressant effects by inhibiting central NLRP3 inflammasomes.

Results

The behavioral despair model and chronic unpredictable mild stress (CUMS) model in mice were established to evaluate the antidepressant action of liquiritin. In the despair model study, liquiritin (40 mg/kg) administration reduced immobility time in tail suspension test (TST) and forced swimming test (FST) without affecting locomotion activity. In CUMS model study, liquiritin (40 mg/kg, once daily for 4 weeks) significantly increased sucrose consumption and body weight of CUMS mice. The behavioral experiment results showed that liquiritin reduced the immobile time of CUMS mice in TST and FST, respectively, and increased the time spent and open arm entries in the elevated plus-maze (EPM) test. Further, the hippocampal superoxide dismutase (SOD) activity was increased in liquiritin-treated group, while malonaldehyde (MDA) decreased. Additionally, the hippocampal cytokines interleukin-18 (IL-18) and interleukin-1 beta (IL-1β) contents were reduced in the liquiritin-treated group. Further, liquiritin downregulated the expression of NLRP3 in the hippocampus of CUMS mice rather than TLR4. Besides, NLRP3 inflammasome-associated proteins caspase-1 and ASC were also downregulated. However, liquiritin did not alter the thermal stability of NLRP3 in the cellular thermal shift assay (CETSA), suggesting that its inhibition of NLPR3 was not by direct targeting of NLRP3 protein.

Conclusions

Liquiritin attenuates depression-like behavior of CUMS mice and inhibited cytokines levels triggered by NLRP3 inflammasome, suggesting the antidepressant action is, at least partially, associated with antioxidant stress and inhibition of NLRP3 inflammasome activation.