Glabridin, an isoflavan from licorice root, downregulates iNOS expression and activity under high-glucose stress and inflammation

Paraoxonase-2 agonist vutiglabridin promotes autophagy activation and mitochondrial function to alleviate non-alcoholic steatohepatitis

BACKGROUND AND PURPOSE

Only limited therapeutic agents have been developed for non-alcoholic steatohepatitis (NASH). Glabridin, a promising anti-obesity candidate, has only limited druggability due to its low in vivo chemical stability and bioavailability. Therefore, we developed vutiglabridin (VUTI), which is based on a glabridin backbone, and investigated its mechanism of action in treating NASH in animal models.

EXPERIMENTAL APPROACH

Anti-NASH effects of VUTI were determined in in vitro fatty liver models, spheroids of primary human hepatocytes and L02 normal liver cell lines. To identify VUTI possible cellular target/s, biotin-labelled VUTI was synthesized and underwent chemical proteomic analysis. Further, the evaluation of VUTI therapeutic efficacy was carried out using an amylin-NASH and high-fat (HF) diet-induced obese (DIO) mouse models. This was carried out using transcriptomic, lipidomic and proteomic analyses of the livers from the amylin-NASH mouse model.

KEY RESULTS

VUTI treatment markedly reduces hepatic steatosis, fibrosis and inflammation by promoting lipid catabolism, activating autophagy and improving mitochondrial dysfunction, all of which are hallmarks of effective NASH treatment. The cellular target of VUTI was identified as paraoxonase 2 (PON2), a newly proposed protein target for the treatment of NASH, VUTI enhanced PON2 activity. The results using PON2 knockdown cells demonstrated that PON2 is important for VUTI- activation of autophagy, promoting mitochondrial function, decreasing oxidative stress and alleviating lipid accumulation under lipotoxic condition.

CONCLUSION AND IMPLICATIONS

Our data demonstrated that VUTI is a promising therapeutic for NASH. Targeting PON2 may be important for improving liver function in various immune-metabolic diseases including NASH.

Glabridin reduces neuroinflammation by modulating inflammatory signals in LPS-induced in vitro and in vivo models

OBJECTIVES

Chronic neuroinflammation has become one of the important causes of common neurodegeneration disease. Therefore, the target of this study was to explore the protective action of glabridin on lipopolysaccharide (LPS)-induced neuroinflammation in vivo and in vitro and its mechanism.

METHODS

The neuroinflammation model was established by LPS-induced BV2 cells. The cell viability with various concentrations of glabridin was determined by MTT assay, and the content of NO in each group was detected. A neuroinflammatory model was established in male C57BL/6J mice for a water maze test. Subsequently, NF-κB and SOD indices were measured by ELISA, GFAP and IBA-1 indices were measured by immunofluorescence, and Nissl staining was used to explore the Nissl bodies in the hippocampus of mice.

RESULTS

In vitro experiments, our results expressed that glabridin could markedly increase the cell activity of LPS-induced BV2 cells and reduce the NO expression in cells. It indicated that glabridin had a remarkable impact on the neuroinflammation of LPS-induced BV2 cell protection. In vivo neuroinflammation experiments, mice treated with different doses of glabridin showed significantly improved ability of memory compared with the LPS group in the Morris water maze test. The levels of NF-κB, GFAP, and the number of positive cells in Nissl staining were decreased. High-dose glabridin significantly increased the SOD content in the brain tissue and decreased the IBA-1 levels.

CONCLUSION

Glabridin can significantly reduce or even reverse LPS-induced neuroinflammation, which may be related to the fact that glabridin can reduce the NO expression, NF-κB, IBA-1, GFAP, and other inflammatory mediators, upregulate the expression of SOD to relieve oxidative stress of brain and inhibit the activation of gliocyte in brain tissue.

Immunomodulatory effect of glabridin in ovalbumin induced allergic asthma and its comparison with methylprednisolone in a preclinical rodent model

Glabridin, a polyphenolic flavonoid derived from Glycyrrhiza glabra (licorice) roots, has shown anti-inflammatory and antioxidant properties. The current study sought to investigate glabridin's immunomodulatory effect in ovalbumin induced allergic asthma. Healthy male Wistar rats were divided into five groups. Group I served as a control group. Asthma was induced in groups II- IV. Groups III and IV were treated with glabridin (40 mg/kg) and methylprednisolone (15 mg/kg), respectively. Inflammatory cells counts were determined in blood and bronchoalveolar lavage fluid (BALF). Serum IgE levels and levels of catalase, superoxide dismutase and glutathione peroxidase in lung homogenate were measured. The levels of mRNA expression of pro-inflammatory, anti-inflammatory and oxidative stress markers were analysed. Delayed type hypersensitivity (DTH) and acute toxicity of glabridin were also checked. Glabridin significantly decreased inflammatory cells in the blood and BALF. It increased the concentration of antioxidant enzymes catalase, superoxide dismutase and glutathione peroxidase. Glabridin markedly decreased serum IgE levels and DTH when compared to asthmatic rats. It significantly alleviated the expression of TNF-α, IL-4, IL-5, CXCL1, iNOS, and NF-κB. Administering 10 times the therapeutic dose of glabridin did not show any signs of acute toxicity. Findings suggest that glabridin has the potential to ameliorate allergic asthma and its effects are comparable to those of methylprednisolone. The immunomodulatory effect of glabridin might be contributed by the suppression of pro-inflammatory cytokines, oxidative stress markers, IgE antibodies, and elevation of antioxidant enzymes, suggesting future study and clinical trials to propose it as a candidate to treat allergic asthma.

Honokiol reduces fungal burden and ameliorate inflammation lesions of Aspergillus fumigatus keratitis via Dectin-2 down-regulation

PURPOSE

To screen and identify the mechanism of honokiol on anti-fungi and anti-inflammation in fungal keratitis (FK) through bioinformatic analysis and biological experiments.

METHODS

Transcriptome profile demonstrated differential expression genes (DEGs) of Aspergillus fumigatus keratitis between PBS-treated and honokiol-treated groups via bioinformatics analyses. Inflammatory substances were quantified by qRT-PCR, Western blot and ELISA, and macrophage polarization was examined by flow cytometry. Periodic acid Schiff staining and morphological interference assay were used to detect hyphal distribution in vivo and fungal germination in vitro, respectively. Electron microscopy was to illustrate hyphal microstructure.

RESULTS

Illumina sequencing demonstrated that compared with the honokiol group, 1175 up-regulated and 383 down-regulated genes were induced in C57BL/6 mice Aspergillus fumigatus keratitis with PBS treatment. Through GO analysis, some differential expression proteins (DEPs) played major roles in biological processes, especially fungal defense and immune activation. KEGG analysis provided fungus-related signaling pathways. PPI analysis demonstrated that DEPs from multiple pathways form a close-knit network, providing a broader context for FK treatment. In biological experiments, Dectin-2, NLRP3 and IL-1β were upregulated by Aspergillus fumigatus to evaluate immune response. Honokiol could reverse the trend, comparable to Dectin-2 siRNA interference. Meanwhile, honokiol could also play an anti-inflammatory role via promoting M2 phenotype polarization. Moreover, honokiol reduced hyphal distribution in the stroma, delayed germination, and destroyed the hyphal cell membrane in-vitro.

CONCLUSIONS

Honokiol possesses anti-fungal and anti-inflammatory effects in Aspergillus fumigatus keratitis and may develop a potential and safe therapeutic modality for FK.

Glabridin Inhibits Aspergillus fumigatus Growth and Alleviate Inflammation Mediated by Dectin-2 and NLRP3 Inflammasome

PURPOSE

The research was used to uncover the mechanism of glabridin in Aspergillus fumigatus keratitis in anti-fungus and anti-inflammation.

METHODS

In vitro, RAW 264.7 cells were infected with A. fumigatus with incubation of glabridin in different concentrations. Real-time quantitative polymerase chain reaction (RT‑qPCR), Western blot, and enzyme-linked immunosorbent assay (ELISA) were used to assess the inflammatory severe and alternation with the intervention of Dectin-2 siRNA and glabridin. In vivo, A. fumigatus keratitis mouse models were established by spore intra-stromal injection and treated with glabridin or PBS. And disease scores, inflammatory mediators, and periodic acid-schiff (PAS) staining were exhibited to demonstrate the therapeutic efficiency of glabridin in vivo. Morphological interference assay monitored fungal germination. Scanning and transmission electron microscopy were used to observe the growth of fungi.

RESULTS

In RAW 264.7 cells and mouse keratitis models, noncytotoxic 16 μg/mL glabridin showed significant inhibition in the expression of Dectin-2, NLRP3, Caspase-1, IL-1β, and TNF-α after A. fumigatus infection, almost similar to the intervention of Dectin-2 siRNA. PAS staining illustrated the reduced hyphal distribution in cornea stroma with glabridin treatment. Glabridin remarkably inhibited A. fumigatus growth through delaying germination and disrupting the integrity of the hyphae membrane.

CONCLUSION

Glabridin plays an anti-inflammatory role in A. fumigatus challenge via suppression of the Dectin-2 and NLRP3 inflammasome, and plays an anti-fungal role through delaying germination and changing the hyphal integrity.KEY MESSAGESGlabridin plays an anti-inflammatory role in A. fumigatus infection of RAW264.7 cells in a concentration-dependent manner and through Dectin-2 mediation.Glabridin decreases fungal distribution and inflammation in mouse A. fumigatus keratitis.Glabridin inhibits A. fumigatus growth by delaying germination and disrupting cellular structure in vitro.

Review on the Diverse Biological Effects of Glabridin

Glabridin is a prenylated isoflavan from the roots of Glycyrrhiza glabra Linne and has posed great impact on the areas of drug development and medicine, due to various biological properties such as anti-inflammation, anti-oxidation, anti-tumor, anti-microorganism, bone protection, cardiovascular protection, neuroprotection, hepatoprotection, anti-obesity, and anti-diabetes. Many signaling pathways, including NF-κB, MAPK, Wnt/β-catenin, ERα/SRC-1, PI3K/AKT, and AMPK, have been implicated in the regulatory activities of glabridin. Interestingly, glabridin has been considered as an inhibitor of tyrosinase, P-glycoprotein (P-gp), and CYP2E1 and an activator of peroxisome proliferator-activated receptor γ (PPARγ), although their molecular regulating mechanisms still need further investigation. However, poor water solubility and low bioavailability have greatly limited the clinical applications of glabridin. Hopefully, several effective strategies, such as nanoemulsions, microneedles, and smartPearls formulation, have been developed for improvement.

Antioxidant Phytochemicals as Potential Therapy for Diabetic Complications

The global prevalence of diabetes continues to increase partly due to rapid urbanization and an increase in the aging population. Consequently, this is associated with a parallel increase in the prevalence of diabetic vascular complications which significantly worsen the burden of diabetes. For these diabetic vascular complications, there is still an unmet need for safe and effective alternative/adjuvant therapeutic interventions. There is also an increasing urge for therapeutic options to come from natural products such as plants. Hyperglycemia-induced oxidative stress is central to the development of diabetes and diabetic complications. Furthermore, oxidative stress-induced inflammation and insulin resistance are central to endothelial damage and the progression of diabetic complications. Human and animal studies have shown that polyphenols could reduce oxidative stress, hyperglycemia, and prevent diabetic complications including diabetic retinopathy, diabetic nephropathy, and diabetic peripheral neuropathy. Part of the therapeutic effects of polyphenols is attributed to their modulatory effect on endogenous antioxidant systems. This review attempts to summarize the established effects of polyphenols on endogenous antioxidant systems from the literature. Moreover, potential therapeutic strategies for harnessing the potential benefits of polyphenols for diabetic vascular complications are also discussed.

Glabridin Plays Dual Action to Augment the Efficacy and Attenuate the Hepatotoxicity of Methotrexate in Arthritic Rats

Glabridin is chemically an isoflavane class of natural phenols and is found mainly in the roots of Glycyrrhiza glabra. It has several beneficial pharmacological actions for the management of inflammatory disorders as well as can counteract drug-induced toxic effects. On the other hand, methotrexate (MTX) is the first-line disease-modifying antirheumatic drug for the treatment of rheumatoid arthritis. However, its treatment is associated with major side effects like hepatotoxicity. In the quest to explore a suitable combination therapy that can improve the efficacy and reduce the hepatotoxicity of MTX, we hypothesized that glabridin might serve the purpose for which there is no literature precedent to date. We explored the antiarthritic efficacy of MTX in the presence or the absence of glabridin using Mycobacterium-induced arthritic model in rats. The results of reduction in paw swelling, inhibition of serum cytokines (TNF-α, IL-6, and IL-1β), and improvement in the bone joints from radiological and histopathological findings suggest that glabridin can substantially augment the antiarthritic efficacy of MTX. Further, results of concomitant glabridin treatment with MTX in the experimental time frame demonstrate that glabridin could considerably prevent the MTX-induced hepatic alteration in serum biochemical markers (SGPT and SGOT) and oxidative stress markers (malondialdehyde (MDA) and glutathione reduced (GSH)). Moreover, glabridin showed a marked effect in impeding the regulation of NF-κB/IκBα and Nrf2/Keap1 pathways in the hepatic tissues. The results of simultaneous administration of glabridin with MTX in the rat model indicate that glabridin had no pronounced effect of causing severe alteration in the pharmacokinetic behavior of MTX. In summary, glabridin can significantly potentiate the antiarthritic efficacy of MTX and can also minimize its hepatotoxicity via the inhibition of inflammation and oxidative stress. Further research should be performed to develop glabridin as a phytotherapeutics for the improved efficacy and better tolerability of MTX at the reduced dose level of MTX.

Pharmacological Effects and Underlying Mechanisms of Licorice-Derived Flavonoids

Glycyrrhizae Radix et Rhizoma is the most frequently prescribed natural medicine in China and has been used for more than 2,000 years. The flavonoids of licorice have garnered considerable attention in recent decades due to their structural diversity and myriad pharmacological effects, especially as novel therapeutic agents against inflammation and cancer. Although many articles have been published to summarize different pharmacological activities of licorice in recent years, the systematic summary for flavonoid components is not comprehensive. Therefore, in this review, we summarized the pharmacological and mechanistic data from recent researches on licorice flavonoids and their bioactive components.

Glabridin Liposome Ameliorating UVB-Induced Erythema and Lethery Skin by Suppressing Inflammatory Cytokine Production

Glabridin, a compound of the flavonoid, has shown outstanding skin-whitening and anti-aging properties, but its water insolubility limits its wide application. Therefore, glabridin liposome (GL) has been developed to improve its poor bioavailability, while there are few studies to evaluate its amelioration of UVB- induced photoaging. This study is performed to investigate the amelioration of GL against UVB- induced cutaneous photoaging. The prepared GL has a spheroidal morphology with an average diameter of 200 nm. The GL shows lower cytotoxicity than glabridin, but it has a more effective role in inhibition of melanin. Moreover, the application of GL can effectively relieve UV radiation induced erythema and leathery skin, associated with the down-regulated expression of inflammatory cytokines (TNF-α, IL-6 and IL-10). Taken together, these results demonstrate that GL has potentials as topical therapeutic agents against UVB radiation induced skin damage through inhibiting inflammation.

Strategic ventilation reduces non-ventilated contralateral lung injury induced by one-lung ventilation in rabbits

ABSTRACT One lung ventilation (OLV) often results in trauma to the unventilated contralateral lung. This study aims to evaluate the effects of different OLV regimens on the injury of the unventilated contralateral lung to identify the best conditions for OLV. Forty rabbits were divided into five groups: a sham group, OLV group I (fraction of inspired oxygen (FIO2) 1.0, tidal volume (VT) 8mL/kg, respiratory rate (R) 40 breaths/min and inspiratory/expiratory ratio (I:E) 1:2), OLV group II (FIO2=1.0, VT 8mL/kg, R 40 breaths/min, I:E 1:2, and positive end-expiratory pressure (PEEP) 5 cm H2O), OLV group III (FIO2 1.0, VT 6mL/kg, R 40 breaths/min, I:E 1:2 and PEEP 5 cm H2O) and OLV group IV (FIO2 0.8, VT 6mL/kg, R 40 breaths/min, I:E 1:2 and PEEP 5 cm H2O). Animals from all OLV groups received two-lung ventilation (TLV) to establish a baseline, followed by one of the indicated OLV regimens. The rabbits in the sham group were intubated through trachea and ventilated with fresh air. Arterial blood gas samples were collected, lung injury parameters were evaluated, and the concentrations of TNF-α and IL-8 in bronchoalveolar lavage fluid (BALF) and pulmonary surfactant protein A (SPA) in the unventilated lung were also measured. In OLV group I, the unventilated left lung had higher TNF-α, IL-8 and lung injury score but lower SPA than the ventilated right lung. In OLV groups I to III, the concentrations of TNF-α, IL-8 and lung injury score in the left lung decreased but SPA increased. No differences in these parameters between OLV groups III and IV were observed. Strategic ventilation designed for OLV groups III and IV reduced OLV-induced injury of the non-ventilated contralateral lung in rabbits.

The anti-diabetic activity of licorice, a widely used Chinese herb

ETHNOPHARMACOLOGICAL RELEVANCE

A great deal of valuable experience has been accumulated in the traditional Chinese medicine (TCM) system for the treatment of "Xiaoke" disease which is known as diabetes mellitus now. As the most-commonly used Chinese herb, licorice has been used in TCM for more than two thousand years. It is often used in combination with other herbs to treat metabolic disorders, especially diabetes mellitus.

AIM OF THE STUDY

To summarize the characteristics, mechanisms, and clinical use of licorice and its active components for treating diabetes mellitus.

METHODS

PubMed, Web of Science, Research Gate, Science Direct, Google Scholar, and Academic Journals were used as information sources by the inclusion of the search terms 'diabetes', 'licorice', 'licorice extracts', 'flavonoids', 'triterpenoids', and their combinations, mainly from 2005 to 2019.

RESULTS

Licorice extracts, five flavonoids and three triterpenoids isolated from licorice possess great antidiabetic activities in vivo and in vitro. This was done by several mechanisms such as increasing the appetency and sensitivity of insulin receptor site to insulin, enhancing the use of glucose in different tissues and organs, clearing away the free radicals and resist peroxidation, correcting the metabolic disorder of lipid and protein, and improving microcirculation in the body. Multiple signaling pathways, including the PI3K/Akt, AMPK, AGE-RAGE, MAPK, NF-кB, and NLRP3 signaling pathways, are targets of the licorice compounds.

CONCLUSION

Licorice and its metabolites have a great therapeutic potential for the treatment of diabetes mellitus. However, a better understanding of their pharmacological mechanisms is needed for evaluating its efficacy and safety.

Preparation and Characterization of Licorice-Chitosan Coatings for Postharvest Treatment of Fresh Strawberries

Several plant extracts are being investigated to produce edible coatings, mainly due to their antioxidant and antimicrobial activities. In this study, licorice root extracts were produced by ultrasound-assisted extraction and were combined with chitosan to elaborate edible coatings. Different solvents and temperatures were used in the extraction process, and the antioxidant and antimicrobial activity of the extracts were assessed. The most bioactive extracts were selected for the development of the edible coatings. The rheological properties of the coatings were studied, and they were applied on strawberry to evaluate their physicochemical and microbiological properties. The addition of licorice extract to chitosan resulted in positive effects on the rheological properties of the coatings: the incorporation of phytochemicals to chitosan decreased the shear stress and improved the restructuring ability of the coating solutions. The films presented a reduction of the Burger model parameter, indicating a reduction of rigidity. Furthermore, the strawberry coated with chitosan and licorice extract maintained good quality parameters during storage and showed the best microbiological preservation in comparison with controls. Hence, the use of chitosan with licorice extract is a potential strategy to produce edible coating for improving the postharvest quality of fruits.

Beta-lactoglobulin-nutrition allergen and nanotransporter of different nature ligands therapy with therapeutic action

β-lactoglobulin is one of the nutrition allergens present in the milk of many mammals, with the exception of human. This protein belongs to the family of lipocalins, consisting of nine antiparallel β-strands (β-A to β-I) and one α-helix. This structure allows it to serve as a nanotransporter of various nature ligands in a pH dependent manner, which allows us to confidently consider it as a reliable carrier of drugs directly into the intestine, bypassing the destructive acidic environment of the stomach. Based on the latest data, this review describes the currently known methods of reducing the allergenicity of beta-lactoglobulin, as well as the mechanisms and methods of forming complexes of this protein with ligands, which emphasizes its importance and versatility and explains the growing interest in studying its properties in recent decades, and also opens up prospects for its practical application in medicine and pharmaceuticals.

Targeting Inflammation by Flavonoids: Novel Therapeutic Strategy for Metabolic Disorders

A balanced metabolic profile is essential for normal human physiological activities. Disproportions in nutrition give rise to imbalances in metabolism that are associated with aberrant immune function and an elevated risk for inflammatory-associated disorders. Inflammation is a complex process, and numerous mediators affect inflammation-mediated disorders. The available clinical modalities do not effectively address the underlying diseases but rather relieve the symptoms. Therefore, novel targeted agents have the potential to normalize the metabolic system and, thus, provide meaningful therapy to the underlying disorder. In this connection, polyphenols, the well-known and extensively studied phytochemical moieties, were evaluated for their effective role in the restoration of metabolism via various mechanistic signaling pathways. The various flavonoids that we observed in this comprehensive review interfere with the metabolic events that induce inflammation. The mechanisms via which the polyphenols, in particular flavonoids, act provide a promising treatment option for inflammatory disorders. However, detailed clinical studies of such molecules are required to decide their clinical fate.

Quality evaluation of health foods containing licorice in the Japanese Market

Focusing on licorice, a highly used raw material in health foods, quantitative analysis of functional/medicinal components and a safety and functional evaluation was carried out for herbal medicines, health food ingredients, and so-called health foods. A functional component, glabridin, was detected in herbal medicines from Glycyrrhiza glabra and G. inflata, health food ingredients, and in commercially available health foods that contain licorice. Likewise, glycyrrhizin, a medicinal component, was detected in these sources, except in licorice oil extract. Estrogen activity in vitro was detected in some of the herbal medicines, health food ingredients, and in health foods containing licorice. In the in vivo study, liver weight in ovariectomized (OVX) mice treated with licorice oil extract was significantly higher than that in OVX and sham mice in a dose dependent manner. These results suggest that excessive intake of licorice oil extract from health foods should be avoided, even though these ingredients might be beneficial for medical use in order to maintain bone health in postmenopausal women. Measurement of hepatic cytochrome P-450 (CYP) activity, reproductive organ weight, and fat and bone mass in OVX mice was considered useful for evaluating the safety and efficacy of estrogenic health food ingredients derived from herbal medicines.

Effects of phytochemicals against diabetes

Diabetes mellitus, a chronic metabolic disease, characterized by elevated levels of blood glucose and insufficiency in production and action of insulin is the seventh leading cause of death worldwide. Numerous studies have shown that diabetes mellitus is associated with increased formation of free radicals and decrease in antioxidant potential. In the patients with diabetes mellitus, the levels of antioxidant parameters are found to decrease, hence in many studies phytochemicals which can exert antioxidant and free radical scavenging activities, are suggested to improve the insulin sensitivity. Several phytoactive compounds such as flavonoids, lignans, prophenylphenols, are also found to combat the complications of diabetes. This chapter mainly focuses on the relationship between diabetes mellitus and preventive roles of various phytochemicals on diabetes via their antioxidant properties.

Glabridin Prevents Doxorubicin-Induced Cardiotoxicity Through Gut Microbiota Modulation and Colonic Macrophage Polarization in Mice

The chemotherapeutic drug doxorubicin (DOX) provokes a dose-related cardiotoxicity. Thus, there is an urgent need to identify the underlying mechanisms and develop strategies to overcome them. Here we demonstrated that glabridin (GLA), an isoflavone from licorice root, prevents DOX-induced cardiotoxicity through gut microbiota modulation and colonic macrophage polarization in mice. GLA reduced DOX-induced leakage of myocardial enzymes including aminotransferase, creatine kinase, lactate dehydrogenase, and creatine kinase-MB. GLA downregulated pro-apoptotic proteins (Bax, cleaved-caspase 9 and cleaved-caspase 3) and upregulated anti-apoptotic proteins (HAX-1 and Bcl-2) in the cardiac tissues. In addition, GLA modulated DOX-induced dysbiosis of gut microbiota and thereby decreased the ratio of M1/M2 colonic macrophage, accompanied by the downregulated lipopolysaccharide (LPS) and upregulated butyrate in the feces and peripheral blood. The leakage of myocardial enzymes induced by the DOX was decreased by antibiotics treatment, but not altered by co-treatment with the GLA and antibiotics. The ratio of M1/M2 colonic macrophage and leakage of myocardial enzymes reduced by the GLA were greatly increased by the Desulfovibrio vulgaris or LPS but decreased by the butyrate. Depletion of the macrophage attenuated DOX-induced cardiotoxicity but failed to further affect the effects of GLA. Importantly, GLA decreased production of M1 cytokines (IL-1β and TNF-α) but increased production of M2 cytokines (IL-10 and TGF-β) in the colonic macrophage with the downregulation of NF-κB and the upregulation of STAT6. In summary, GLA prevents DOX-induced cardiotoxicity through gut microbiota modulation and colonic macrophage polarization, and may serve as a potential therapeutic strategy for the DOX-induced cardiotoxicity.

β-Lactoglobulin as a Nanotransporter for Glabridin: Exploring the Binding Properties and Bioactivity Influences

Based on the fact that β-lactoglobulin (β-lg) can solubilize readily in water and bind many small hydrophobic molecules, a novel nanocomplexed glabridin with β-lg was developed by an antisolvent precipitation method. After binding to β-lg, the solubility of glabridin in aqueous solution was enhanced 21 times. Fluorescence spectroscopy of β-lg revealed that the interaction of glabridin with β-lg made the environment of Trp and Tyr residues on β-lg more hydrophilic. The morphology and crystal form of the nanocomplexed glabridin with β-lg was characterized and the changes in β-lg conformation was also been investigated. In combination with molecular docking modeling, the results revealed that glabridin was bound to β-lg by hydrophobic forces and hydrogen-bond interactions. Furthermore, the nanocomplexed glabridin with β-lg had a better 2,2-diphenyl-1-picrylhydrazyl radical-scavenging capacity and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid radical-scavenging capacity compared to free glabridin at the same concentration during in vitro tests. Thus, nanocomplexing with β-lg, by virtue of its ability to enhance the solubility of glabridin in aqueous systems, provides a suitable opportunity as a nanocarrier molecule.

Glabridin inhibits osteosarcoma migration and invasion via blocking the p38- and JNK-mediated CREB-AP1 complexes formation

Osteosarcoma is the most common bone malignancy, and it seriously affects the quality of life of affected children and adolescents. Glabridin (GLA), a major component of licorice root extract, has been reported to exert antitumor effects against a variety of tumor types; however, its effects on osteosarcoma have not been elucidated. In the current study, we investigate the effects and potential antimetastatic mechanisms of GLA on osteosarcoma in vitro and in vivo. Flow cytometry showed that GLA induced G2/M cell cycle phase arrest and promoted cell apoptosis. Transwell and wound-healing assays showed that GLA significantly decreased the migration and invasion of osteosarcoma cells. Further western blotting and quantitative real-time polymerase chain reaction showed that the expression of matrix metalloproteinase (MMP)-2 and MMP-9 in MG63 and HOS cells were reduced after GLA treatment. Moreover, western blotting demonstrated that GLA downregulated the phosphorylation of p38 mitogen-activated protein kinases and c-Jun N-terminal kinase. A coimmunoprecipitation assay illustrated that formation of cAMP response element-binding protein (CREB)-activating protein 1 (AP1) complexes and the DNA binding activities of CREB and AP1 in MG63 and HOS cells were impaired following treatment with GLA. Finally, GLA inhibited tumor growth and suppressed osteosarcoma cell metastasis in vivo. Overall, our findings highlight the potential of GLA as a therapeutic agent for the prevention and treatment of tumor metastasis.

Glabridin inhibits the activation of myofibroblasts in human fibrotic buccal mucosal fibroblasts through TGF-β/smad signaling

Oral submucous fibrosis (OSF) has been recognized as one of the oral potentially malignant disorders. Areca nut chewing is implicated in this pathological fibrosis, and it causes chronic inflammation and persistent activation of myofibroblasts. As yet, existing treatments only provide temporary symptomatic relief and there is a lack of an effective intervention to cure OSF. Therefore, development of approaches to ameliorate myofibroblast activities becomes a crucial objective to prevent the malignant progression of OSF. In this study, we examined the inhibitory effect of glabridin, an isoflavane extracted from licorice root, on the myofibroblast characteristics in human fibrotic buccal mucosal fibroblasts (fBMFs). Our results showed that myofibroblast activities, including collagen gel contractility, migration, invasion and wound healing abilities were reduced after exposure of glabridin in a dose-dependent manner. Most importantly, we demonstrated that the arecoline-induced myofiroblast activities were abolished by glabridin treatment. Additionally, the expression of the myofibroblast marker α-smooth muscle actin and other fibrogenic marker, type I collagen, in fBMFs were dose-dependently downregulated. Moreover, we showed that the production of TGF-β was suppressed by glabridin in fBMFs and the protein expression of phospho-Smad2 was decreased as well. In summary, our data suggested that glabridin repressed the myofibroblast features in fBMFs via TGF-β/Smad2 signaling pathway. Glabridin also prevented the arecoline-increased myofibroblast activities, and could serve as a natural anti-fibrosis compound for OSF.

The anti-inflammatory activity of licorice, a widely used Chinese herb

CONTEXT

Increasing incidence and impact of inflammatory diseases have encouraged the search of new pharmacological strategies to face them. Licorice has been used to treat inflammatory diseases since ancient times in China.

OBJECTIVE

To summarize the current knowledge on anti-inflammatory properties and mechanisms of compounds isolated from licorice, to introduce the traditional use, modern clinical trials and officially approved drugs, to evaluate the safety and to obtain new insights for further research of licorice.

METHODS

PubMed, Web of Science, Science Direct and ResearchGate were information sources for the search terms 'licorice', 'licorice metabolites', 'anti-inflammatory', 'triterpenoids', 'flavonoids' and their combinations, mainly from year 2010 to 2016 without language restriction. Studies were selected from Science Citation Index journals, in vitro studies with Jadad score less than 2 points and in vivo and clinical studies with experimental flaws were excluded.

RESULTS

Two hundred and ninety-five papers were searched and 93 papers were reviewed. Licorice extract, 3 triterpenes and 13 flavonoids exhibit evident anti-inflammatory properties mainly by decreasing TNF, MMPs, PGE2 and free radicals, which also explained its traditional applications in stimulating digestive system functions, eliminating phlegm, relieving coughing, nourishing qi and alleviating pain in TCM. Five hundred and fifty-four drugs containing licorice have been approved by CFDA. The side effect may due to the cortical hormone like action.

CONCLUSION

Licorice and its natural compounds have demonstrated anti-inflammatory activities. More pharmacokinetic studies using different models with different dosages should be carried out, and the maximum tolerated dose is also critical for clinical use of licorice extract and purified compounds.

Glabridin attenuates lipopolysaccharide-induced acute lung injury by inhibiting p38MAPK/ERK signaling pathway

Background

Acute respiratory distress syndrome (ARDS) is a complication caused by pulmonary and/or external factors. In this study, we investigated the protective mechanisms of glabridin in lipopolysaccharide (LPS) induced ARDS in rats.

Results

GLA treatment at dose of 30 mg/kg decreased LPS-induced lung W/D ratio and alleviated evident lung histopathological changes. Expressions of TNF-α and IL-18 were suppressed by GLA in plasma. The levels of SPA, MDA and NO in lung were down-regulated significantly in groups administrated with GLA. While the SOD level increased after GLA administration. Additionally, the attenuation of inflammatory responses by GLA was closely associated with p38MAPK/ERK pathway, and the expressions of protein p-p38MAPK and pERK were inhibited by GLA in LPS-induced ARDS rats.

Materials and Methods

Sixty-four Wistar rats were randomly assigned into control group, Glabridin (GLA) alone group, LPS groups (6 h, 12 h, 24 h), GLA with LPS groups (6 h, 12 h, 24 h). ARDS was induced in rats by intraperitoneal administration of LPS (10 mg/kg). The degree of lung edema was evaluated by calculating the wet/dry weight ratio. The levels of inflammatory mediators, tumor necrosis factor-α (TNF-α) and interleukin-18 (IL-18) were assayed by enzyme-linked immunosorbent assay (ELISA). Surfactant protein A (SPA), malondialdehyde (MDA), nitric oxide (NO) and superoxide dismutase (SOD) were analyzed. Pathological changes of lung tissues were observed by H&E staining. The protein expression of p38MAPK and ERK was detected using immunohistochemical techniques. Lung phosphorylated p38MAPK (p-p38MAPK) and pERK protein expression changes were detected by Western blotting.

Conclusions

Glabridin significantly ameliorated the lung injury induced by LPS in rats via the inhibition of p38MAPK and ERK signaling pathway, antioxidant effect and reducing inflammation.

Downregulation of iNOS and elevation of cAMP mediate the anti-inflammatory effect of glabridin in rats with ulcerative colitis

BACKGROUND

Alternative medicine is widely accepted by public and becoming an attractive approach for treatment of various diseases. Glabridin (Gla), a major flavonoid present in licorice root, was reported to have antioxidant and anti-inflammatory properties.

OBJECTIVE

The study aimed to investigate the possible protective role of Gla against dextran sulphate sodium (DSS)-induced ulcerative colitis (UC) in rats and to clarify the molecular mechanisms underlying Gla function.

METHODS

Forty male Wistar rats were divided into control, colitis group (rats received 5% DSS in drinking water for 7 days), Gla group (50 mg/kg, orally, once daily), and sulfasalazine (SLZ) group (500 mg/kg, orally, once daily). Each of Gla and SLZ was administered 1 week ahead of DSS and parallel with its administration.

RESULTS

Gla ameliorated the inflammatory alterations induced by DSS. Gla group showed a reduction in colon concentration of tumor necrosis factor-alpha (TNF-α) and a decreased colon myeloperoxidase activity (MPO). Gla treatment downregulated inducible nitric oxide synthase (iNOS) gene expression in rat colon with a decreased content of nitric oxide (NO). Gla also increased cyclic AMP (cAMP) concentration in rat colon compared to colitis group. Such findings were comparable to or even better than those obtained by SLZ treatment. The histological features of UC such as ulceration and inflammatory cell infiltrations were improved in rat group treated by Gla.

CONCLUSION

Gla proved a potent anti-inflammatory role in UC through different mechanisms and, being a natural product, it could be safely used as a protective measure in inflammatory bowel diseases.

Nitric oxide synthesis-promoting effects of valsartan in human umbilical vein endothelial cells via the Akt/adenosine monophosphate-activated protein kinase/endothelial nitric oxide synthase pathway

Valsartan (VAL), an antagonist of angiotensin II receptor type 1, has antihypertensive and multiple cardiovascular protective effects. The pleiotropic functions of VAL are related to the increased synthesis and biological activity of intravascular nitric oxide (NO). In this study, the role and mechanisms of VAL in the synthesis of NO were examined in human umbilical vein endothelial cells (HUVECs). Ten µmol/L of VAL was used to treat EA.hy926 cells for 30 minutes, 1, 3, 6, 12, and 24 hours, and three concentrations of VAL (i.e., 10, 1, and 0.1 µmol/L) were used to treat EA.hy926 cells for 24 hours. The cells were divided into five groups: control, VAL, VAL + Compound C (adenosine monophosphate-activated protein kinase [AMPK] inhibitor, 1 µmol/L), VAL + LY294002 (Akt [protein kinase B] inhibitor, 10 µmol/L), and VAL + L-nitro-arginine methyl ester (L-NAME, endothelial NO synthase [eNOS] inhibitor, 500 µmol/L) groups. The NO content in the VAL-treated HUVEC line (EA.hy926) was detected using the nitrate reductase method, and western blot was used to detect the phosphorylation of Akt, AMPK, and eNOS, as well as the changes in total protein levels. VAL increased NO synthesis in EA.hy926 cells in time- and dose-dependent manners (p < 0.05) and the intracellular phosphorylation levels of Akt, AMPK, and eNOS at the corresponding time points. LY294002, Compound C, and L-NAME could inhibit the VAL-promoted NO synthesis. VAL activated Akt, AMPK, and eNOS, thus promoting NO synthesis and playing a protective role in endothelial cells. These results partially explained the mechanisms underlying the cardiovascular protective effects of VAL.

The repressive effect of miR-148a on Wnt/β-catenin signaling involved in Glabridin-induced anti-angiogenesis in human breast cancer cells

Background

Glabridin (GLA), a major component extracted from licorice root, has anti-inflammatory and antioxidant activities, but few studies report its mechanism of inhibition of angiogenesis. This study was an extension of our previous work, which demonstrated that GLA suppressed angiogenesis in human breast cancer (MDA-MB-231 and Hs-578T) cells. Breast cancer is one of the most common malignant diseases in females worldwide, and the major cause of mortality is metastasis that is primarily attributed to angiogenesis. Thus, anti-angiogenesis has become a strategy for the treatment of breast cancer.

Methods

Cell viability of different concentration treatment groups were detected by Cell Counting Kit-8 assay. The expression of several related genes in the Wnt1 signaling pathway in MDA-MB-231 and Hs-578T cells treated with GLA were measured at both the transcription and translation levels using quantitative real-time PCR analyses and western blotting. Immunofluorescence assay analyzed the nuclear translocation of β-catenin. The microRNA-inhibitor was used to knockdown microRNA-148a (miR-148a) expression. Angiogenic potentials of breast cancer cells were analyzed by enzyme-linked immunosorbent assay (ELISA) and tube formation in vitro.

Results

GLA attenuated angiogenesis by the suppression of miR-148a-mediated Wnt/β-catenin signaling pathway in two human breast cancer cell lines (MDA-MB-231 and Hs-578T). GLA also upregulated the expression of miR-148a in a dose-dependent manner, miR-148a, which could directly target Wnt-3′-untranslated regions (UTRs), and decreased the expression of Wnt1, leading to β-catenin accumulation in the membranes from the cytoplasm and nucleus. Downregulation of miR-148a contributed to the reduction of GLA-induced suppression of the Wnt/β-catenin signaling pathway, the angiogenesis and vascular endothelial grow factor (VEGF) secretion.

Conclusions

Our study identified a molecular mechanism of the GLA inhibition of angiogenesis through the Wnt/β-catenin signaling pathway via miR-148a, suggesting that GLA could serve as an adjuvant chemotherapeutic agent for breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3298-1) contains supplementary material, which is available to authorized users.

New Approach in Translational Medicine: Effects of Electrolyzed Reduced Water (ERW) on NF-κB/iNOS Pathway in U937 Cell Line under Altered Redox State

It is known that increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) can exert harmful effects, altering the cellular redox state. Electrolyzed Reduced Water (ERW) produced near the cathode during water electrolysis exhibits high pH, high concentration of dissolved hydrogen and an extremely negative redox potential. Several findings indicate that ERW had the ability of a scavenger free radical, which results from hydrogen molecules with a high reducing ability and may participate in the redox regulation of cellular function. We investigated the effect of ERW on H₂O₂-induced U937 damage by evaluating the modulation of redox cellular state. Western blotting and spectrophotometrical analysis showed that ERW inhibited oxidative stress by restoring the antioxidant capacity of superoxide dismutase, catalase and glutathione peroxidase. Consequently, ERW restores the ability of the glutathione reductase to supply the cell of an important endogenous antioxidant, such as GSH, reversing the inhibitory effect of H₂O₂ on redox balance of U937 cells. Therefore, this means a reduction of cytotoxicity induced by peroxynitrite via a downregulation of the NF-κB/iNOS pathway and could be used as an antioxidant for preventive and therapeutic application. In conclusion, ERW can protect the cellular redox balance, reducing the risk of several diseases with altered cellular homeostasis such as inflammation.

Glabridin induces apoptosis and autophagy through JNK1/2 pathway in human hepatoma cells

BACKGROUND

Extensive research results support the use of herbal medicine or natural food to augment therapy for various cancers. Studies have associated glabridin with numerous biological activities, such as regulating energy metabolism and estrogenic, neuroprotective, antiosteoporotic, and skin-whitening activities.

HYPOTHESIS/PURPOSE

However, how glabridin affects tumor cell autophagy has not been clearly determined.

METHODS

Autophagy is a lysosomal degradation pathway essential for cell survival and tissue homeostasis. In this study, the roles of autophagy and related signaling pathways during glabridin-induced autophagy in human liver cancer cells were investigated. Additionally, the molecular mechanism of the anticancer effects of glabridin in human hepatoma cells was investigated.

RESULTS

The results revealed that glabridin significantly inhibited cell proliferation in human hepatoma cells. Glabridin induced apoptosis dose-dependently in Huh7 cells through caspase-3, -8, and -9 activation and PARP cleavage. Furthermore, autophagy was detected as early as 12h after exposure to a low dose of glabridin, as indicated by the up-regulated expression of LC3-II and beclin-1 proteins. The inhibition of JNK1/2 and p38 MAPK by specific inhibitors significantly reduced glabridin-induced activation of caspases-3, -8, and -9. Blocking autophagy sensitize the Huh7 cells to apoptosis.

CONCLUSION

This study demonstrated for the first time that autophagy occurs earlier than apoptosis does during glabridin-induced apoptosis in human liver cancer cell lines. Glabridin induces Huh7 cell death through apoptosis through the p38 MAPK and JNK1/2 pathways and is a potential chemopreventive agent against human hepatoma.

Glabridin arrests cell cycle and inhibits proliferation of hepatocellular carcinoma by suppressing braf/MEK signaling pathway

Glabridin, an isoflavone isolated from licorice, owns a variety of pharmacological effects. Several reports have demonstrated that glabridin could regulate multiple cellular signaling pathways to inhibit the progression of cancer. However, the target proteins have not been elucidated yet. We used shape screening and induced fit docking to screen the protein data bank against glabridin. Braf and MEK1/2, important intermediate molecules of the braf/MEK cascade, were identified as the potential targets of glabridin. The experimental data showed that glabridin could inhibit the phosphorylation of MEK1/2 and the phosphorylation levels of downstream molecules including ERK1/2 and transcription factors ATF1 and CREB, but had no effect on the phosphorylation of braf. In particular, the in vitro pull-down assay indicated that glabridin selectively bound to braf and MEK1/2. What is more, exposure to glabridin significantly suppressed the proliferation of hepatocellular carcinoma HepG2 cell line. In addition, glabridin might arrest cell cycle in G1 through downregulation of cyclinD3, CDK2, and CDK4. In conclusion, glabridin is a potential multi-molecule-targeting inhibitor in the field of clinical prevention or treatment of cancer.