Isoliquiritigenin from licorice flavonoids attenuates NLRP3-mediated pyroptosis by SIRT6 in vascular endothelial cells.

ETHNOPHARMACOLOGIC RELEVANCE: Licorice is a traditional Chinese medicine that has been used for cardiovascular diseases. Recent studies found that supplementation with licorice extracts attenuated the development of atherosclerosis (AS) in hypercholesterolemic patients. Many studies have shown that licorice flavonoids, the main active components of licorice, have a variety of pharmacological effects, including anti-inflammation, regulation of lipid metabolism, and antioxidation. However, the key active components against AS in licorice flavonoids are still unclear. AIM OF THE STUDY: The aim of this paper is to investigate the active components of licorice flavonoids that exert anti-atherosclerotic effects and the underlying mechanisms. MATERIALS AND METHODS: Network pharmacology was used to screen the active components of licorice flavonoids that have anti-atherosclerotic effects. Combining bioinformatics analysis and in vitro studies, the effects and underlying mechanisms of the active component isoliquiritigenin (ISL) on cell pyroptosis were further investigated in tumor necrosis factor (TNF)-α-treated human umbilical vein endothelial cells (HUVECs). RESULTS: We constructed a compound-target network and screened 3 active components, namely, ISL, glabridin, and naringenin in licorice flavonoids. The half maximal effective concentration values of these 3 components suggested that ISL was the key active component against TNF-α-induced endothelial cell injury. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that ISL could potentially treat AS via the nucleotide-binding and oligomerization domain (NOD)-like receptor signaling pathway. An in vitro study verified that ISL suppressed TNF-α-induced NLRP3 activation and pyroptosis in HUVECs. The molecular docking and cellular thermal shift assay showed good compatibility between ISL and class III histone deacetylase sirtuin 6 (SIRT6). Moreover, we found that ISL upregulated the expression of SIRT6 in TNF-α-treated HUVECs. Further study found that SIRT6 knockdown reduced the inhibitory effect of ISL on pyroptosis, whereas the NLRP3 inhibitor reversed this process in TNF-α-treated HUVECs. CONCLUSIONS: Our results demonstrate that ISL is a key active component of licorice flavonoids. ISL attenuates NLRP3-mediated vascular endothelial cell pyroptosis via SIRT6, and SIRT6 may be a potential target of ISL for the treatment of AS.

Mechanism insight on licorice flavonoids release from Carbopol hydrogels: Role of "release steric hindrance" and drug solubility in the release medium.

The present study was to systematically evaluate different licorice flavonoids (LFs) compounds release behaviors from the single payload hydrogel and LFs extracts hydrogels based on the drug solubility in the release medium (DSRM), intermolecular strength of the hydrogel and the "release steric hindrance" (RSH). Two kinds of LFs (LFs 1: LFs 2 = 5:1, W/W) hydrogels were prepared with Carbopol 940 (CBP) as the thickener, and ten LFs single payload hydrogels were prepared according to the actual content in the LFs 1 extracts. The drug release mechanisms were confirmed by in vitro release experiments and molecular dynamic simulation analysis, and evaluated using novel indicators of ERLFs 1/Sin (the enhancement ratio (ER) of drug release percent of LFs 1-CBP hydrogel to the single payload hydrogel), ERLFs 2/ LFs 1 (ER of drug release percent of LFs 2-CBP hydrogel to LFs 1-CBP hydrogel) and ERrelease medium (ER of drug release percent in different release medium). We found that LFs 1-CBP possessed a significantly higher intermolecular strength and RSH than LFs 2-CBP, resulting in a higher viscosity, which had a positive correlation with the payload content and a negative correlation with the drug release percent. Therefore, the ERLFs 2/ LFs 1 values of ten LFs compounds were all higher than 1. For liquiritigenin and retrochalcone with higher DSRM, they displayed similar ERLFs 1/ Sin, ERLFs 2/ LFs 1 and ERrelease medium values (≈1). For formononetin, licoflavone A and licochalcone A with low DSRM, they exhibited ERLFs 1/Sin values >1. The low DSRM was the decisive factor to restrict their release from the single payload hydrogel. The presence of glycyrrhizin acid (GA) in the LFs could facilitate their release from the LFs extracts hydrogel. For isoliquiritin, isoliquiritigenin and glabridin with a lower content in the LFs extracts, they exhibited ERLFs 1/Sin values <1. The RSH predominantly restricted its release. The study provided guidelines for the reasonable design of LFs extracts hydrogel in pharmaceutical topical formulations.

Preparation and characterization of active oxidized starch films containing licorice residue extracts and its potential against methicillin-resistant S. aureus.

The antibacterial and antioxidant packaging films were fabricated by incorporating licorice residue extracts (LREs) into oxidized starch (OS) films. The bioactive fraction (BF) was firstly obtained from LREs by using bioassay-guided isolation method. The BF showed potent anti-Gram(+) bacteria effects, especially against methicillin-resistant S. aureus (MRSA) with MIC of 32.5 µg/mL. The present results also indicated that the addition of BF could significantly decrease the moisture content, water vapor permeability, light transmittance of OS films. Notably, the antibacterial and antioxidant activities of OS films significantly enhanced with the concentration of BF increasing. Moreover, the films with the highest concentration of BF showed the lowest tensile strength (4.23 MPa) and the highest elongation at break (63.89%). Meanwhile, the bioactive films could release bioactive compounds such as licochalcone A and licochalcone B into the alcoholic and fatty food simulants. Taken together, the active OS films containing LREs have the potential for application in food packaging films, due to its potential against MRSA and antioxidant activity as well as good physicochemical properties.

A Review: The Anti-inflammatory, Anticancer and Antibacterial Properties of Four Kinds of Licorice Flavonoids Isolated from Licorice.

Plants have always been an important source of medicines for humans, and licorice is a very significant herb in the development of humans. As a traditional herb, it is widely cultivated in China, Japan, Russia, Spain and India. With the development of organic chemistry and biochemistry, various chemical ingredients extracted from licorice have been studied and identified. Among them, many chemical components were considered to have strong pharmacological activities, such as anti-inflammatory, anti-ulcer, antibacterial, anticancer and so on. Based on those reports, licorice has attracted the attention of many researchers in recent years, and they are devoted to discovering the active ingredients and mechanism of action of active compounds. Licorice flavonoids are one of the main extracts of licorice root and stem and have many potential biological properties. This paper aims to summarize the four kinds of licorice flavonoids, including liquiritigenin, isoliquiritigenin, licochalcone (including licochalcone A and licochalcone B) and glabridin, about their biological activities of anti-inflammatory, anticancer, antibacterial.

Multi-pathway integrated adjustment mechanism of licorice flavonoids presenting anti-inflammatory activity.

Glycyrrhiza, commonly known as licorice, is a herbal medicine that has been used for thousands of years. Licorice contains multiple flavonoids, which possess a variety of biological activities. On the basis of the anti-inflammatory effects of licorice flavonoids, the potential mechanism of action was investigated via a plasma metabolomics approach. A total of 9 differential endogenous metabolites associated with the therapeutic effect of licorice flavonoids were identified, including linoleic acid, sphingosine, tryptophanamide, corticosterone and leukotriene B4. Besides classical arachidonic acid metabolism, metabolism of sphingolipids, tryptophan and fatty acids, phospholipids synthesis, and other pathways were also involved. The multi-pathway integrated adjustment mechanism of licorice flavonoid action may reduce side effects in patients, along with any anti-inflammatory functions, which provides a foundation for identifying and developing novel, high-potential natural drugs with fewer side effects for clinical application.

Flavonoids Extracted from Licorice Prevents Colitis-Associated Carcinogenesis in AOM/DSS Mouse Model.

Inflammatory bowel disease (IBD) is generally considered as a major risk factor in the progression of colitis-associated carcinogenesis (CAC). Thus, it is well accepted that ameliorating inflammation creates a potential to achieve an inhibitory effect on CAC. Licorice flavonoids (LFs) possess strong anti-inflammatory activity, making it possible to investigate its pharmacologic role in suppressing CAC. The purpose of the present study was to evaluate the anti-tumor potential of LFs, and further explore the underlying mechanisms. Firstly, an azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced mouse model was established and administered with or without LFs for 10 weeks, and then the severity of CAC was examined macroscopically and histologically. Subsequently, the effects of LFs on expression of proteins associated with apoptosis and proliferation, levels of inflammatory cytokine, expression of phosphorylated-Janus kinases 2 (p-Jak2) and phosphorylated-signal transducer and activator of transcription 3 (p-Stat3), and activation of nuclear factor-κB (NFκB) and P53 were assessed. We found that LFs could significantly reduce tumorigenesis induced by AOM/DSS. Further study revealed that LFs treatment substantially reduced activation of NFκB and P53, and subsequently suppressed production of inflammatory cytokines and phosphorylation of Jak2 and Stat3 in AOM/DSS-induced mice. Taken together, LFs treatment alleviated AOM/DSS induced CAC via P53 and NFκB/IL-6/Jak2/Stat3 pathways, highlighting the potential of LFs in preventing CAC.

Multi-objective optimization of purification technology for licorice flavonoids based on entropy-weight method / 中草药

Objective: To multi-objectively optimize the purification process parameters of licorice flavonoids using entropy-weight method, Plackett-Burman design (PBD), and Box-Behnken design (BBD). Methods: On the basis of HPLC fingerprints of licorice, the macroporous resin type was chosen using the recovery rates of six components (liquiritin apioside, liquiritigenin, isoliquiritin apioside, licuraside, isoliquiritin, and neoisoiiquiritin) as detection indexes. Weights of the recovery rates of six components were determined by entropy-weight method, in order to obtain the comprehensive index. The significantly influencing factors were firstly evaluated by PBD, then purification conditions were optimized by BBD. Results: ADS-7 type resin showed a high selectivity for six components. The optimized purification technology was as follows: pH value was 4.5, sample concentration was 0.20 g/mL, ratio of sample to resin was 1.0 g/g, flow rate was 0.6 mL/min, elution dosage was 6.7 BV, ethanol concentration was 83% of eluting agent, and elution rate was 1.0 mL/min. Under the conditions, the recovery rates of six components were 86%-97%, the theoretical and actual comprehensive indexes were 93.32% and 93.05%, respectively, with a relative error of 1.17%. Conclusion: Entropy-weight method combined with PBD and BBD-RSM used to optimize the purification process for the licorice flavonoids in this study is scientific and feasible, providing a new reference to realize the multi-objective optimization of the purification technology for active constituents in Chinese materia medica.

Evaluation of cytotoxiciy and tumor-specificity of licorice flavonoids based on chemical structure.

BACKGROUND: The mechanism of cytotoxicity induction by flavonoids has been studied by many investigators, but their tumor specificity is not clear. To address this point, 10 licorice flavonoids were subjected to quantitative structure-activity relationship (QASR) analysis with cytotoxicity assay with four human oral carcinoma and three normal cell lines. MATERIALS AND METHODS: Cytotoxicity was determined by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide method. Physico-chemical, structural, and quantum-chemical parameters were calculated based on the conformations optimized by the LowModeMD method. RESULTS: Licurazid and isoliquiritigenin had the highest cytotoxicity against tumor cells, and liquiritin, isoliquiritin and licurazid had the highest tumor specificity, suggesting an antitumor potential for licurazid. Chalcones had slightly higher cytotoxicity and tumor specificity than flavanones. The number of sugar units in the molecule was somewhat negatively-correlated with cytotoxicity, but not with tumor specificity. Parameters that reflect the three-dimensional structure, molecular volume and number of phenolic OH groups were significantly correlated with cytotoxicity, but not with tumor specificity. On the other hand, solvation energy was significantly correlated with tumor specificity, but not with cytotoxicity. CONCLUSION: These physicochemical descriptors may be useful to estimate cytotoxicity or tumor specificity of structurally-related compounds to these licorice flavonoids.