Dihydroquercetin (DHQ) ameliorated concanavalin A-induced mouse experimental fulminant hepatitis and enhanced HO-1 expression through MAPK/Nrf2 antioxidant pathway in RAW cells

Mechanism of Action of Dihydroquercetin in the Prevention and Therapy of Experimental Liver Injury

Liver disease is a global health problem that affects the well-being of tens of thousands of people. Dihydroquercetin (DHQ) is a flavonoid compound derived from various plants. Furthermore, DHQ has shown excellent activity in the prevention and treatment of liver injury, such as the inhibition of hepatocellular carcinoma cell proliferation after administration, the normalization of oxidative indices (like SOD, GSH) in this tissue, and the down-regulation of pro-inflammatory molecules (such as IL-6 and TNF-α). DHQ also exerts its therapeutic effects by affecting molecular pathways such as NF-κB and Nrf2. This paper discusses the latest research progress of DHQ in the treatment of various liver diseases (including viral liver injury, drug liver injury, alcoholic liver injury, non-alcoholic liver injury, fatty liver injury, and immune liver injury). It explores how to optimize the application of DHQ to improve its effectiveness in treating liver diseases, which is valuable for preparing potential therapeutic drugs for human liver diseases in conjunction with DHQ.

Taxifolin inhibits NETosis through activation of Nrf2 and provides protective effects in models of lupus and antiphospholipid syndrome

OBJECTIVES

Taxifolin (dihydroquercetin) is a bioactive plant flavonoid that exhibits anti-inflammatory and anti-oxidative properties. We hypothesized that taxifolin might be an effective dietary supplement to ameliorate symptoms arising from thrombo-inflammatory diseases such as lupus and APS.

METHODS

We used in vitro assays and a mouse model to determine mechanisms by which taxifolin inhibits neutrophil extracellular trap (NET) formation (i.e. NETosis) and venous thrombosis in lupus and APS.

RESULTS

At doses ranging from 0.1 to 1 µg/ml, taxifolin inhibited NETosis from control neutrophils stimulated with autoantibodies isolated from lupus and APS patients, and its suppressive effects were mitigated by blocking the antioxidant transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2). Furthermore, taxifolin at a dose as low as 20 mg/kg/day reduced in vivo NETosis in thrombo-inflammatory mouse models of lupus and APS while also significantly attenuating autoantibody formation, inflammatory cytokine production and large-vein thrombosis.

CONCLUSION

Our study is the first to demonstrate the protective effects of taxifolin in the context of lupus and APS. Importantly, our study also suggests a therapeutic potential to neutralize neutrophil hyperactivity and NETosis that could have relevance to a variety of thrombo-inflammatory diseases.

Purple sweet potato polysaccharide ameliorates concanavalin A-induced hepatic injury by inhibiting inflammation and oxidative stress

BACKGROUND

Autoimmune hepatitis (AIH) is a prevalent liver disease that can potentially lead to hepatic fibrosis and cirrhosis. The prolonged administration of immunosuppressive medications carries significant risks for patients. Purple sweet potato polysaccharide (PSPP), a macromolecule stored in root tubers, exhibits anti-inflammatory, antioxidant, immune-enhancing, and intestinal flora-regulating properties. Nevertheless, investigation into the role and potential mechanisms of PSPP in AIH remains notably scarce.

PURPOSE

Our aim was to explore the possible protective impacts of PSPP against concanavalin A (Con A)-induced liver injury in mice.

METHODS

Polysaccharide was isolated from purple sweet potato tubers using water extraction and alcohol precipitation, followed by purification through DEAE-52 cellulose column chromatography and Sephadex G-100 column chromatography. A highly purified component was obtained, and its monosaccharide composition was characterized by high performance liquid chromatography (HPLC). Mouse and cellular models induced by Con A were set up to investigate the impacts of PSPP on hepatic histopathology, apoptosis, as well as inflammation- and oxidative stress-related proteins in response to PSPP treatment.

RESULTS

The administration of PSPP significantly reduced hepatic pathological damage, suppressed elevation of ALT and AST levels, and attenuated hepatic apoptosis in Con A-exposed mice. PSPP was found to mitigate Con A-induced inflammation by suppressing the TLR4-P2X7R/NLRP3 signaling pathway in mice. Furthermore, PSPP alleviated Con A-induced oxidative stress by activating the PI3K/AKT/mTOR signaling pathway in mice. Additionally, PSPP demonstrated the ability to reduce inflammation and oxidative stress in RAW264.7 cells induced by Con A in vitro.

CONCLUSION

PSPP has the potential to ameliorate hepatic inflammation via the TLR4-P2X7R/NLRP3 pathway and inhibit hepatic oxidative stress through the PI3K/AKT/mTOR pathway during the progression of Con A-induced hepatic injury. The results of this study have unveiled the potential hepatoprotective properties of purple sweet potato and its medicinal value for humans. Moreover, this study serves as a valuable reference, highlighting the potential of PSPP-1 as a drug candidate for the treatment of immune liver injury.

Efficacy of Rhamnus utilis Decne. Aqueous extract in mice with acute alcoholic liver injury and metabolomic study

Rhamnus utilis Decne. (Family Rhamnaceae Juss.) leaf is commonly prepared as a anti-inflammatory herbal medicine and used for tea production. To investigate the mechanism of Rhamnus utilis Decne. aqueous extract (RDAE) against acute alcoholic liver disease (ALD) in mice. The ALD mouse (Male ICR) model was induced via intragastric administration of 52 % alcohol. Mice in each group were treated by gavage once daily with the RDAE (1.12, 2.25, 4.500 g/kg). The expression of proteins involved in the MAPKs/NF-κB/COX-2-iNOS pathway was measured by western blotting. Non-targeted metabolomics was used to determine metabolic profiles and critical pathways, while targeted metabolomics validated key amino acid metabolites. After administration of RDAE, the body mass of mice was significantly increased. The liver index was significantly decreased. Meanwhile, the serum levels of AST, ALT, TG, TC, MDA, TNF-α, IL-1β and IL-6 were significantly decreased (P < 0.05, P < 0.01), but GSH level was inversely increased (P < 0.05). Metabolomic analysis revealed nine major pathways involved in the therapeutic effect of RDAE, including fructose and mannose metabolism. The levels of 7 amino acids including leucine, proline and alanine/sarcosine were significantly upregulated. Additionally, protein levels of p-NF-κB (p65)/NF-κB (p65), p-ERK1/2/ERK1/2, p-JNK/JNK, p-p38/p38, COX-2 and iNOS were significantly decreased (P < 0.01, P < 0.05). RDAE is used to treat acute ALD by improving lipid metabolism, inhibiting the expression of pro-inflammatory cytokines and regulating MAPKs/NF-κB/COX-2-iNOS signalling pathway. These findings provide valuable insights for acute ALD therapy based on traditional Chinese medicine (TCM).

Antioxidative and anti-inflammatory effects of taxifolin in H2O2-induced oxidative stress in HTR-8/SVneo trophoblast cell line

Oxidative stress has been implicated in numerous pregnancy-related disorders. Biologically active plant secondary metabolites, which are present in everyday diet, could prove effective therapeutic agents in preventing these disorders. This study evaluated effects of taxifolin (dihydroquercetin) on ROS production, markers of oxidative damage to lipids and proteins, activity of antioxidant enzymes and production of pro-inflammatory cytokines in H2O2-induced oxidative stress in trophoblast HTR-8/SVneo cells. Taxifolin in 10 µM and 100 µM concentrations attenuated oxidative damage to lipids and proteins, as evidenced by a decrease in MDA content, extracellular LDH activity, carbonyl groups and nitrite contents. A reduction in the activity of antioxidant enzymes SOD, CAT and GPx in cells pre-treated with taxifolin, prior to H2O2 exposure, was also observed, along with a reduction in intracellular ROS production. Both evaluated concentrations of taxifolin showed anti-inflammatory activity in trophoblast cells, by reducing production of pro-inflammatory cytokines IL-1β and IL-6. In this model of H2O2-induced oxidative stress, taxifolin showed marked antioxidative and anti-inflammatory activities in trophoblast cells, adding further evidence of its protective effects and showing potential as a therapeutic agent in preventing adverse pregnancy outcomes.

Dihydroquercetin improves experimental acute liver failure by targeting ferroptosis and mitochondria-mediated apoptosis through the SIRT1/p53 axis

BACKGROUND

Ferroptosis and mitochondria-mediated apoptosis are both involved in the pathogenesis of acute liver failure (ALF). Ferroptosis-produced reactive oxygen species (ROS) trigger the chain oxidation of polyunsaturated phospholipids and promote mitochondrial apoptosis. Dihydroquercetin (DHQ) also plays an important protective role against liver injury.

PURPOSE

Here, we aimed to investigate the protective effects of DHQ on ALF. We also explored the underlying mechanism.

METHODS

We established a Lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced ALF mouse model and tumor necrosis factor-α (TNF-α)/D-Gal-induced ALF LO2 cell model. 2',7'-Dichlorofluorescein diacetate (DCFH-DA) and Dihydroethidium (DHE) were used to detect total ROS levels. Lipid ROS was assessed using C11-BODIPY flow cytometry. Lipid peroxidative products levels were detected using MDA ELISA assay and 4-hydroxynonenal (4-HNE) immunohistochemistry. QRT-PCR and western blots were used to test mRNA and protein expression levels, respectively. Cell viability was evaluated with CCK8 assay, and apoptosis was analyzed using flow cytometry.

RESULTS

DHQ treatment improved LPS/D-Gal-induced ALF, as well as TNF-α/D-Gal-induced reductions in LO2 viability and increased sirtuin 1 (SIRT1) expression. DHQ pretreatment also reduced the accumulation of ROS, reduced lipid peroxidation, elevated mitochondrial membrane potentials (ΔΨm), and decreased liver cell apoptosis both in vivo and in vitro. Additionally, the knockdown of SIRT1 and p53 activator (Tenovin-6) treatment reversed DHQ's inhibitory effects on ferroptosis and mitochondria-mediated apoptosis in vitro. DHQ enhanced p53 deacetylation by both up-regulating SIRT1 expression and directly bonding to SIRT1. We also found that Tenovin-6's stimulatory effects on ferroptosis and mitochondria-mediated apoptosis in the DHQ-treated LO2 ALF cell model were partially attenuated by overexpression of solute carrier family 7member 11 (SLC7A11), as well as by apoptotic protease activating factor 1 (Apaf-1) knockdown.

CONCLUSION

Our results suggest that DHQ alleviated ALF by inhibiting both ferroptosis and mitochondria-mediated apoptosis by regulating the SIRT1/p53 axis. Thus, DHQ may serve as a novel therapy for ALF.

Guizhi Fuling Wan ameliorates concanavalin A-induced autoimmune hepatitis in mice

BACKGROUND

Autoimmune hepatitis (AIH) is an immune-mediated hepatic disease associated with intense complications. AIH is more common in females and needs effective drugs to treat. Guizhi Fuling Wan (GZFLW) is a traditional Chinese herbal formula used to treat various gynecologic diseases. In this study, we aim to extend the new use of GZFLW for AIH.

METHODS

The tandem MS-based analysis was used to identify secondary metabolites in GZFLW. Therapeutic effects of GZFLW were tested in a concanavalin A (Con A)-induced AIH model in mice. Ethnopharmacological mechanisms underlying the antiapoptotic, antioxidant, and immunomodulatory protective effects were determined.

RESULTS

Oral administration of GZFLW attenuates AIH in a Con A-induced hepatotoxic model in vivo. The tandem MS-based analysis identified 15 secondary metabolites in GZFLW. The Con A-induced AIH syndromes, including hepatic apoptosis, inflammation, reactive oxygen species accumulation, function failure, and mortality, were significantly alleviated by GZFLW in mice. Mechanistically, GZFLW restrained the caspase-dependent apoptosis, restored the antioxidant system, and decreased pro-inflammatory cytokine production in the livers of Con A-treated mice. Besides, GZFLW repressed the Con A-induced hepatic infiltration of inflammatory cells, splenic T cell activation, and splenomegaly in mice.

CONCLUSIONS

Our findings demonstrate the applicable potential of GZFLW in treating AIH. It prompts further investigation of GZFLW as a treatment option for AIH and possibly other hepatic diseases.

The Alleviating Effect of Taxifolin on Deoxynivalenol-Induced Damage in Porcine Intestinal Epithelial Cells

Deoxynivalenol (DON) contamination in feed is a global concern that severely threatens the health of animals and humans. Taxifolin (TA) is a natural flavonoid, a member of the polyphenols, that possesses robust antioxidant properties. This study aimed to investigate the effect of TA on DON-induced damage in porcine intestinal epithelial cells (IPEC-J2). The cells were pre-incubated with a series of concentrations of TA for 24 h and exposed to DON (0.5 μg/mL) for another 24 h. The results showed that pretreatment with TA (150 μM) significantly inhibited the DON-induced decline in cell viability (p < 0.05) and cell proliferation (p < 0.01). Additionally, 150 μM TA also alleviated DON-induced apoptosis (p < 0.01). Moreover, TA decreased the production of reactive oxygen species (ROS) induced by DON (p < 0.01). In addition, TA attenuated DON-induced cell junction damage (p < 0.05). Further experiments showed that TA reversed the DON-induced reduction in antioxidant capacity in the IPEC-J2 cells, probably via activating the Nrf2 signaling pathway (p < 0.05). Collectively, these findings suggest that 150 μM TA can protect against 0.5 μg/mL DON-induced damage to IPEC-J2 cells, potentially via the activation of the Nrf2 signaling pathway. This study provides insight into TA's potential to act as a green feed additive in the pig farming industry and its efficacy in counteracting DON-induced intestinal damage.

Ingestion of taxifolin-rich foods affects brain activity, mental fatigue, and the whole blood transcriptome in healthy young adults: a randomized, double-blind, placebo-controlled, crossover study

The antioxidant properties of polyphenols, which are found in most plants, have been shown to be useful for maintaining health, including enhancing brain function and alleviating stress. We aimed to investigate the effect of a single intake of taxifolin-containing foods on cognitive task performance and whole blood gene expression in healthy young adults. This study was a randomized, placebo-controlled, double-blind, crossover trial in which healthy young adults were administered a single dose of either a placebo or food containing taxifolin. Cognitive tests (serial 3s, serial 7s, and rapid visual information processing) to examine brain activity and visual analog scale questionnaires to analyze mental fatigue were applied. The set of tests was repeated four times. The findings showed that taxifolin intake improved calculation abilities and reduced mental fatigue. An analysis of whole blood gene expression before and after the test revealed that the expression of foreign substance removal-related genes increased following the ingestion of taxifolin and that most differentially expressed genes were enriched in granulocytes. Taxifolin intake was shown to affect the brain activity of healthy young adults and demonstrated an antifatigue effect, thereby reducing subjective fatigue. A single intake of taxifolin may enhance the removal of foreign substances by strengthening the innate immune system and suppressing the occurrence of injury.

Novel Therapeutic Potentials of Taxifolin for Obesity-Induced Hepatic Steatosis, Fibrogenesis, and Tumorigenesis

The molecular pathogenesis of nonalcoholic steatohepatitis (NASH) includes a complex interaction of metabolic stress and inflammatory stimuli. Considering the therapeutic goals of NASH, it is important to determine whether the treatment can prevent the progression from NASH to hepatocellular carcinoma. Taxifolin, also known as dihydroquercetin, is a natural bioactive flavonoid with antioxidant and anti-inflammatory properties commonly found in various foods and health supplement products. In this study, we demonstrated that Taxifolin treatment markedly prevented the development of hepatic steatosis, chronic inflammation, and liver fibrosis in a murine model of NASH. Its mechanisms include a direct action on hepatocytes to inhibit lipid accumulation. Taxifolin also increased brown adipose tissue activity and suppressed body weight gain through at least two distinct pathways: direct action on brown adipocytes and indirect action via fibroblast growth factor 21 production in the liver. Notably, the Taxifolin treatment after NASH development could effectively prevent the development of liver tumors. Collectively, this study provides evidence that Taxifolin shows pleiotropic effects for the treatment of the NASH continuum. Our data also provide insight into the novel mechanisms of action of Taxifolin, which has been widely used as a health supplement with high safety.

Dietary Polyphenols Alleviate Autoimmune Liver Disease by Mediating the Intestinal Microenvironment: Challenges and Hopes

Autoimmune liver disease is a chronic liver disease caused by an overactive immune response in the liver that imposes a significant health and economic cost on society. Due to the side effects of existing medicinal medications, there is a trend toward seeking natural bioactive compounds as dietary supplements. Currently, dietary polyphenols have been proven to have the ability to mediate gut-liver immunity and control autoimmune liver disease through modulating the intestinal microenvironment. Based on the preceding, this Review covers the many forms of autoimmune liver illnesses, their pathophysiology, and the modulatory effects of polyphenols on immune disorders. Finally, we focus on how polyphenols interact with the intestinal milieu to improve autoimmune liver disease. In conclusion, we suggest that dietary polyphenols have the potential as gut-targeted modulators for the prevention and treatment of autoimmune liver disease and highlight new perspectives and critical issues for future pharmacological applications.

Cucurbitacin E glucoside alleviates concanavalin A-induced hepatitis through enhancing SIRT1/Nrf2/HO-1 and inhibiting NF-ĸB/NLRP3 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Cucurbitacins are highly oxygenated tetracyclic triterpenoids, that represent the major metabolites reported from C. colocynthis (L.) Schrad.. Cucurbitacin E glucoside (CuE) is a tetracyclic triterpene glycoside separated from Cucurbitaceae plants. CuE has potent anti-inflammatory, immunomodulatory, and anti-tumor properties.

AIM OF THE STUDY

The current study aimed at examining the hepatoprotective effect of CuE against concanavalin A (Con A)-produced hepatitis.

MATERIALS AND METHODS

Mice were intravenously administered Con A (15 mg/kg) to induce AIH. CuE was orally administered at two different doses for five days preceding Con A injection.

RESULTS

The results revealed that CuE pretreatment markedly attenuated the serum indices of hepatotoxicity and the severity of hepatic lesions. CuE depressed Con A-provoked increment in CD4⁺ T-cells in hepatic tissue. The antioxidant activity of CuE was evident through its ability to decrease markers of Con A-induced oxidative stress (malondialdehyde, 4-hydroxyenonanal, and protein carbonyl) and intensified the antioxidants in the hepatic tissue (SOD, GSH, and TAC). CuE increased mRNA expression of SIRT1 and Nrf2 as well as its binding capacity. Subsequently, CuE augmented mRNA expression of Nrf2 targeted genes as NQO1, GCL, and HO-1 and recovered its normal level. CuE inhibited the activation of NF-κB/downstream pro-inflammatory mediators signaling. Furthermore, CuE attenuated the mRNA expression of NLRP3 and its associated genes.

CONCLUSION

Collectively, these results demonstrated the remarkable hepatoprotective potential of CuE towards Con A-induced AIH which was mediated via suppression of oxidative stress, enhancing SIRT1/Nrf2/HO-1, and prohibition of the NF-κB/NLRP3 signaling. CuE could be a candidate for hepatitis patients.

Modeling of the Structure and Forecasting Properties of Dihydroquercetin Derivatives

AIMS

To study new chemical compounds with the potential cure proper, and to develop modifications of the preferred structure of dihydroquercetin.

BACKGROUND

Producing of the new drugs needs the study of the cure properties of the chemical composes first of all, and computer modeling can make this process more informative and easily.

OBJECTIVE

Computer projection of the chemical compounds potential cure properties.

METHODS

The reactivity of the studied models was evaluated by comparing the energies of the boundary molecular orbitals (HOMO and LUMO), as well as the difference in their values. The reaction center of the model molecules was determined via the analysis of the charge characteristics on atoms in each of them.

RESULTS

A theoretical model of new chemical compounds with the potential properties of drugs was substantiated and modifications of the preferred structure of dihydroquercetin have been developed. The concept of new compounds has been expanded and opportunities for the modification of compounds with high pharmacological activity have been discussed. Using the AM1, PM3, RM1 methods spatial characteristics were calculated. The results of quantum-chemical studies of model derivatives of dihydroquercetin via the RM1 method were carried out.

CONCLUSIONS

Calculation of the enthalpies of formation of model molecules allowed evaluating their thermodynamic stability. An analysis of the electric dipole moments made a possibility determining the preferred (polar) nature of the solvents for the studied model molecular systems.

Ameliorative effect of taxifolin on gentamicin-induced ototoxicity via down-regulation of apoptotic pathways in mouse cochlear UB/OC-2 cells

BACKGROUND

Taxifolin is a flavanonol with efficacious cytoprotective properties, such as anti-inflammatory, antioxidant, anticancer, hepatoprotective, and nephroprotective effects. However, the potential protective effects of taxifolin against gentamicin-induced ototoxicity have not been confirmed. In this study, the possible mechanisms underlying the effects of taxifolin on gentamicin-induced death of UB/OC-2 cochlear cells were investigated.

METHODS

Mouse cochlear UB/OC-2 cells with or without taxifolin pretreatment were exposed to gentamicin, and the effects on cytotoxicity, reactive oxygen species (ROS) production, mitochondrial permeability transition, and apoptotic marker expression were examined using biochemical techniques, flow cytometry, western blotting, and fluorescent staining.

RESULTS

Little or no apparent effect of taxifolin on cell viability was observed at concentrations less than 40 μM. Further investigations showed that gentamicin significantly inhibited cell viability in a concentration-dependent manner. Pretreatment with taxifolin attenuated gentamicin-induced lactate dehydrogenase release, as well as cellular cytotoxicity. In addition, taxifolin significantly prevented gentamicin-induced cell damage by decreasing ROS production, stabilizing mitochondrial membrane potential, and downregulating the mitochondrial pathway of apoptosis.

CONCLUSION

In summary, pretreatment with taxifolin is effective for mitigating gentamicin-induced apoptotic cell death mediated by the mitochondrial pathway. Our data suggest that taxifolin provides a new approach to combat gentamicin-induced ototoxicity.

The Nrf2 Pathway in Liver Diseases

Oxidative stress is the leading cause of most liver diseases, such as drug-induced liver injury, viral hepatitis, and alcoholic hepatitis caused by drugs, viruses, and ethanol. The Kelch-like ECH-associated protein 1-NFE2-related factor 2 (Keap1-Nrf2) system is a critical defense mechanism of cells and organisms in response to oxidative stress. Accelerating studies have clarified that the Keap1-Nrf2 axis are involved in the prevention and attenuation of liver injury. Nrf2 up-regulation could alleviate drug-induced liver injury in mice. Moreover, many natural Nrf2 activators can regulate lipid metabolism and oxidative stress of liver cells to alleviate fatty liver disease in mice. In virus hepatitis, the increased Nrf2 can inhibit hepatitis C viral replication by up-regulating hemeoxygenase-1. In autoimmune liver diseases, the increased Nrf2 is essential for mice to resist liver injury. In liver cirrhosis, the enhanced Nrf2 reduces the activation of hepatic stellate cells by reducing reactive oxygen species levels to prevent liver fibrosis. Nrf2 plays a dual function in liver cancer progression. At present, a Nrf2 agonist has received clinical approval. Therefore, activating the Nrf2 pathway to induce the expression of cytoprotective genes is a potential option for treating liver diseases. In this review, we comprehensively summarized the relationships between oxidative stress and liver injury, and the critical role of the Nrf2 pathway in multiple liver diseases.

Dihydroquercetin ameliorates LPS-induced neuroinflammation and memory deficit

Dihydroquercetin (DHQ) is a pentahydroxyflavanone that has been used as an important suppliment against oxidative stress related inflammation and neuroinflammation. Neuroinflammation, which is the activation of the defense mechanism of the central nervous system, upon exposure to stimuli like amyloid β, Lewy bodies, lipopolysaccharide (LPS) and reactive oxygen species. It is an important pathophysiological mediator of a number of neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis and others. The objective of the present study is to evaluate the neuroprotective effect of DHQ, a potent antioxidant molecule, against LPS induced neuroinflammation. On the first day of the experiment (day-1), neuroinflammation was induced through intracerebroventricular injection of LPS (5 ​μg/5 μl) into each lateral ventricle in the rats. DHQ-0.5, 1 and 2 ​μg/kg was injected into the tail vein in respective groups from day-2 to day-10. Behavioral studies showed that DHQ attenuated the LPS-induced loss in long-term memory and working memory as evaluated by elevated plus maze and Y-maze test, respectively.

Further, the biochemical estimations revealed that DHQ dose-dependently attenuated the LPS-induced decrease in acetylcholine level and increased in the acetylcholine-esterase activity in the hippocampal region. DHQ also increased the catalase activity and decreased nitric oxide and lipid peroxidation altered by LPS injection. DHQ also attenuated interleukin-6 in the brain, which has elevated upon LPS induction. The decrease in IL-6 is attributed to its antioxidant activity. Hence, DHQ could be a potential therapeutic candidate in the management of neuroinflammation and related neurodegenerative disorders.

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Dihydroquercetin (DHQ) improves LPS induced loss in working memory and long-term memory.

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DHQ attenuates LPS –induced decrease in cholinergic activity.

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DHQ shows anti-oxidant properties.

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DHQ shows anti-neuroinflammatory effect.

Anti-fibrotic activity of sitagliptin against concanavalin A-induced hepatic fibrosis. Role of Nrf2 activation/NF-κB inhibition

Sitagliptin is known for its anti-diabetic activity though it has other pleiotropic pharmacological actions. Its effect against concanavalin A (Con A)-induced hepatic fibrosis has not been investigated yet. Our target was to test whether sitagliptin can suppress the development of Con A-induced hepatic fibrosis and if so, what are the mechanisms involved? Con A (6 mg/kg) was injected once weekly to male Swiss albino mice for four weeks. Sitagliptin was daily administered concurrently with Con A. Results have shown the potent hepatoprotective activity of sitagliptin against Con A-induced hepatitis and fibrosis. That was evident through the amelioration of hepatotoxicity serum parameters (ALT, AST, ALP, and LDH) and the increase in the level of serum albumin in sitagliptin treated mice. Simultaneously, there was amendment of the Con A-induced hepatic lesions and repression of fibrosis in sitagliptin-treated animals. Hydroxyproline, collagen content and the immuno-expression of the fibrotic markers, TGF-β and α-SMA were depressed upon sitagliptin treatment. Sitagliptin suppressed Con A-induced oxidative stress and increased antioxidants. RT-PCR analysis showed enhancement of mRNA expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its target genes (GCLc, GCLm, NQO-1, HO-1) by sitagliptin. Furthermore, sitagliptin ameliorated the level and immuno-expression of nuclear factor kappa-B (NF-κB) alongside the immuno-expression of the inflammatory cytokine, TNF-α. Taken together, this study demonstrates the hepatoprotective activity of sitagliptin which may be in part related to enhancement of Nrf2 signaling pathway and inhibition of NF-κB which interact inflammatory response in liver. Sitagliptin might be a new candidate to suppress hepatitis-associated fibrosis.

Summary of Natural Products Ameliorate Concanavalin A-Induced Liver Injury: Structures, Sources, Pharmacological Effects, and Mechanisms of Action

Liver diseases represent a threat to human health and are a significant cause of mortality and morbidity worldwide. Autoimmune hepatitis (AIH) is a progressive and chronic hepatic inflammatory disease, which may lead to severe complications. Concanavalin A (Con A)-induced hepatic injury is regarded as an appropriate experimental model for investigating the pathology and mechanisms involved in liver injury mediated by immune cells as well as T cell-related liver disease. Despite the advances in modern medicine, the only available strategies to treat AIH, include the use of steroids either solely or with immunosuppressant drugs. Unfortunately, this currently available treatment is associated with significant side-effects. Therefore, there is an urgent need for safe and effective drugs to replace and/or supplement those in current use. Natural products have been utilized for treating liver disorders and have become a promising therapy for various liver disorders. In this review, the natural compounds and herbal formulations as well as extracts and/or fractions with protection against liver injury caused by Con A and the underlying possible mechanism(s) of action are reviewed. A total of 53 compounds from different structural classes are discussed and over 97 references are cited. The goal of this review is to attract the interest of pharmacologists, natural product researchers, and synthetic chemists for discovering novel drug candidates for treating immune-mediated liver injury.

Dissecting Efficacy and Metabolic Characteristic Mechanism of Taxifolin on Renal Fibrosis by Multivariate Approach and Ultra-Performance Liquid Chromatography Coupled With Mass Spectrometry-Based Metabolomics Strategy

Taxifolin (TFN) is an important natural compound with antifibrotic activity; however, its pharmacological mechanism is not clear. In this study, our aim is to gain insight into the effects of TFN and its potential mechanisms in unilateral ureteral obstruction (UUO) animal model using metabolomics approach to identify the metabolic biomarkers and perturbed pathways. Serum metabolomics analysis by UPLC-Q-TOF/MS was carried out to discover the changes in the metabolic profile. It showed that TFN has a significant protective effect on UUO-induced renal fibrosis and a total of 32 potential biomarkers were identified and related to RF progression. Of note, 27 biomarkers were regulated by TFN treatment, which participate in eight metabolic pathways, including phenylalanine, tyrosine and tryptophan biosynthesis, and phenylalanine metabolism. It also showed that metabolomics was a promising strategy to better dissect metabolic characteristics and pharmacological mechanisms of natural compounds by multivariate approach and ultra-performance liquid chromatography coupled with mass spectrometry.

Taxifolin ameliorate high-fat-diet feeding plus acute ethanol binge-induced steatohepatitis through inhibiting inflammatory caspase-1-dependent pyroptosis

Excessive alcohol drinking and a high-fat diet (HFD) promote steatohepatitis in the comorbidity of NAFLD and AFLD. Taxifolin (TAX) is a rich dihydroxyflavone compound found in onions, milk thistle and Douglas fir. We aimed to explore the intervention mechanism of TAX on chronic steatohepatitis induced by HFD feeding plus acute ethanol binge. We established an in vivo model by HFD feeding plus a single dose of ethanol binge, and established an in vitro model by oleic acid or palmitic acid on HepG2 cells to induce lipid accumulation. TAX regulated lipid synthesis by inhibiting the expression of SREBP1 and upregulating the PPARγ level. In addition, TAX inhibited the expression of P2X7R, IL-1β, and caspase-1. Moreover, TAX reduced the expression of caspase-1 activation; thereby inhibiting the recruitment of macrophages and neutrophils. TAX also improved the inflammatory response caused by caspase-1 activation in steatotic hepatocytes. TAX exhibited an inhibitory effect on lipid accumulation and caspase-1-related pyroptosis. Collectively, TAX has therapeutic potential as an intervention of steatohepatitis induced by alcohol combined with HFD and for preventing non-alcoholic fatty liver degeneration targeting caspase-1-dependent pyroptosis.

Induction of HO-1 by 5, 8-Dihydroxy-4',7-Dimethoxyflavone via Activation of ROS/p38 MAPK/Nrf2 Attenuates Thrombin-Induced Connective Tissue Growth Factor Expression in Human Cardiac Fibroblasts

Heme oxygenase-1 (HO-1) has been shown to exert as an antioxidant and anti-inflammatory enzyme in cardiovascular inflammatory diseases. Flavonoids have been demonstrated to display anti-inflammatory and antioxidant effects through the induction of HO-1. 5,8-Dihydroxy-4',7-dimethoxyflavone (DDF), one of the flavonoid compounds, is isolated from Reevesia formosana. Whether DDF induced HO-1 expression on human cardiac fibroblasts (HCFs) remained unknown. Here, we found that DDF time- and concentration-dependently induced HO-1 protein and mRNA expression, which was attenuated by pretreatment with reactive oxygen species (ROS) scavenger N-acetyl cysteine (NAC) in HCFs. DDF-enhanced ROS generation was attenuated by NAC, but not by either diphenyleneiodonium chloride (DPI, Nox inhibitor) or MitoTempol (mitochondrial ROS scavenger). Interestingly, pretreatment with glutathione (GSH) inhibited DDF-induced HO-1 expression. The ratio of GSH/GSSG was time-dependently decreased in DDF-treated HCFs. DDF-induced HO-1 expression was attenuated by an inhibitor of p38 MAPK (p38i VIII) or siRNA, but not by MEK1/2 (PD98059) or JNK1/2 (SP600125). DDF-stimulated p38 MAPK phosphorylation was inhibited by GSH or p38i VIII. Moreover, DDF-induced HO-1 expression was mediated through Nrf2 phosphorylation and translocation into the nucleus which was attenuated by NAC or p38 siRNA. DDF also stimulated antioxidant response element (ARE) promoter activity which was inhibited by NAC, GSH, or p38i VIII. Interaction between Nrf2 and the ARE-binding sites on the HO-1 promoter was revealed by chromatin immunoprecipitation assay, which was attenuated by NAC, GSH, or p38i VIII. We further evaluated the functional effect of HO-1 expression on the thrombin-induced fibrotic responses. Our result indicated that the induction of HO-1 by DDF can attenuate the thrombin-induced connective tissue growth factor expression. These results suggested that DDF-induced HO-1 expression is, at least, mediated through the activation of the ROS-dependent p38 MAPK/Nrf2 signaling pathway in HCFs. Thus, the upregulation of HO-1 by DDF could be a candidate for the treatment of heart fibrosis.

Dihydroquercetin Activates AMPK/Nrf2/HO-1 Signaling in Macrophages and Attenuates Inflammation in LPS-Induced Endotoxemic Mice

Dihydroquercetin (DHQ) is a flavonoid compound known for its anti-oxidant effects. Oxidative stress plays a dominant role in regulating the pathways associated with systemic inflammatory immune activation during endotoxemia. Whether and how DHQ regulates inflammatory responses in endotoxemia remains elusive. Here we show DHQ pretreatment effectively reduced the Ten-day mortality in bacterial endotoxin lipopolyssacharide (LPS)-challenged mice, suppressing LPS-induced inflammatory responses reflected by impaired production of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) in the serum of mice. In Raw 264.7 cells, DHQ pretreatment significantly inhibited the transcriptional upregulation of TNF-α, interferon-γ (IFN-γ), interleukin-10 (IL-10) and toll-like receptor 4 (TLR-4) after LPS stimulation. Additionally, knockdown of heme oxygenase-1 (HO-1), one of the most important DHQ induced antioxidant genes, cancelled the inhibition of DHQ treatment on LPS induced TNF-α, IFN-γ production. Nuclear factor erythroid 2-related factor 2 (Nrf2) expression and AMP-activated protein kinase (AMPK) phosphorylation were both enhanced by DHQ in Raw 264.7 cells, indicating a DHQ induced AMPK/Nrf2/HO-1 signal axis. In conclusion, DHQ pretreatment could protect mice against the inflammation and mortality associated with endotoxemia.

Taxifolin Shows Anticataractogenesis and Attenuates Diabetic Retinopathy in STZ-Diabetic Rats via Suppression of Aldose Reductase, Oxidative Stress, and MAPK Signaling Pathway

Background:

Due to the increased prevalence of diabetes-associated complications of the eye like diabetic retinopathy and cataract, the need for a novel therapeutic agent is urgent. Due to the advantages that the polyphenolic compounds enjoy in diabetes and associated complications, we postulated that Taxifolin (TXF), a poly-phenolic flavanol, could show anti-retinopathic and anti-cataract effect in diabetes-induced rats.

Methods:

TXF at a dose of 10, 25, and 50 mg/kg was given by oral route to STZ mediated diabetic rats for a time period of 10 weeks. The opacity of lens was studied after every 7 days of treatment till 10 weeks; evaluation of the severity of cataract and changes in the histology of lens as well as retina was done. Tissue homogenates of lens isolated after the end of the study were evaluated for markers of oxidative stress, levels of aldose reductase, p38MAPK, VEGF, and ERK1/2.

Results:

Outcomes suggested that TXF improved retinopathy and cataract in diabetes-induced rats. The treatment of TXF also improved the status of oxidative stress and inhibited the levels of p38MAPK, VEGF, and ERK1/2. The treatment also improved the lens opacity in diabetic rats. The results suggest that the protective effect of TXF against cataract and retinopathy may be due to the anti-oxidative potential of TXF and its inhibiting effect on VEGF, ERK1/2, p38MAPK, and aldose reductase.

Conclusion:

The study confirms that TXF is a potential candidate showing a protective effect against diabetic induced retinopathy and cataract..

Dihydroquercetin protects against renal fibrosis by activating the Nrf2 pathway

BACKGROUND

Dihydroquercetin (DHQ) is an antifibrotic agent. However, whether DHQ can prevent renal fibrosis remains unknown.

PURPOSE

This study aimed to investigate the effects of DHQ on tubulointerstitial fibrosis and its underlying mechanisms in unilateral ureteral obstruction (UUO) mice in vivo and NRK-49F cells in vitro.

METHODS

In vivo, UUO mice received vehicle or DHQ treatment. In vitro, NRK-49F cells were pretreated with DHQ and exposed to transforming growth factor-β1 (TGF-β1). Changes in fibroblast activation, collagen synthesis, oxidative stress, and related signaling pathways were assessed by immunohistochemical staining, Western blot analysis, real-time reverse transcription-PCR, and fluorescence microscopy.

RESULTS

UUO induced tubular atrophy, inflammation, fibroblast differentiation into myofibroblast, and collagen deposition, whereas DHQ ameliorated these effects. UUO also resulted in decreased levels of nuclear factor-erythroid-2-related factor 2 (Nrf2), catalase, and heme oxygenase-1, but increased H₂O₂ and malondialdehyde levels. DHQ treatment corrected these changes. In vitro, the intracellular Nrf2 level of NRK-49F exposed to TGF-β1 decreased. However, DHQ rescued intracellular Nrf2 level and promoted nuclear translocation of Nrf2. DHQ scavenged TGF-β1-induced accumulation of reactive oxygen species, inhibited TGF-β1-induced Smad3 phosphorylation, and prevented TGF-β1-induced fibroblast activation and collagen synthesis in NRK-49F. Nrf2 knockdown could suppress the DHQ-mediated inhibitory effects on oxidative stress, Smad3 phosphorylation, fibroblast activation, and collagen deposition. Furthermore, DHQ ameliorated established renal fibrosis in UUO mice.

CONCLUSIONS

DHQ posed remarkable preventive and therapeutic effects on UUO-induced renal fibrosis and suppressed fibroblast activation by reducing oxidative stress and Smad3 phosphorylation via Nrf2 signaling. This study provided a mechanistic basis for the clinical application of DHQ in renal fibrosis treatment.

Antioxidant Capacity and Hepatoprotective Role of Chitosan-Stabilized Selenium Nanoparticles in Concanavalin A-Induced Liver Injury in Mice

Selenium nanoparticles (SeNPs) have attracted wide attention for their use in nutritional supplements and nanomedicine applications. However, their potential to protect against autoimmune hepatitis has not been fully investigated, and the role of their antioxidant capacity in hepatoprotection is uncertain. In this study, chitosan-stabilized SeNPs (CS-SeNPs) were prepared by means of rapid ultra-filtration, and then their antioxidant ability and free-radical scavenging capacity were evaluated. The hepatoprotective potential of a spray-dried CS-SeNPs powder against autoimmune liver disease was also studied in the concanavalin A (Con A)-induced liver injury mouse model. CS-SeNPs with size of around 60 nm exhibited acceptable oxygen radical absorbance capacity and were able to scavenge DPPH, superoxide anion, and hydroxyl radicals. The CS-SeNPs powder alleviated Con A-caused hepatocyte necrosis and reduced the elevated levels of serum alanine transaminase, aspartate transaminase, and lactic dehydrogenase in Con A-treated mice. These results suggest that the CS-SeNPs powder protected the mice from Con-A-induced oxidative stress in the liver by retarding lipid oxidation and by boosting the activities of superoxide dismutase, glutathione peroxidase, and catalase, partly because of its ability to improve Se retention. In conclusion, SeNPs present potent hepatoprotective potential against Con A-induced liver damage by enhancing the redox state in the liver; therefore, they deserve further development.

Mangiferin Attenuates LPS/D-GalN-Induced Acute Liver Injury by Promoting HO-1 in Kupffer Cells

Acute liver injury and its terminal phase, hepatic failure, trigger a series of complications, including hepatic encephalopathy, systematic inflammatory response syndrome, and multiorgan failure, with relatively high morbidity and mortality. Liver transplantation is the ultimate intervention, but the shortage of donor organs has limited clinical success. Mangiferin (MF), a xanthone glucoside, has been reported to have excellent anti-inflammatory efficacy. Here, a lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver injury mouse model was established to investigate the protective role of MF and the underlying mechanisms of action. Pretreatment with MF improved survival, decreased serum aminotransferase activities, and inhibited hepatic TNF-α production in LPS/D-GalN-challenged mice. Through Kupffer cell (KC) deletion by GdCl₃ and KC adoptive transfer, KCs were confirmed to be involved in these beneficial effects of MF. MF reduced LPS-mediated TNF-α production via the suppression of the TLR4/NF-κB signaling pathway in vitro. MF promoted HO-1 expression, but the knockdown of HO-1 prevented TNF-α inhibition, suggesting that the damage-resistance effects of HO-1 occurred via the suppression of TNF-α synthesis. When HO-1-silenced KCs were transferred to the liver with KC deletion, the protective effect of MF against LPS/D-GalN-induced acute liver injury was reduced, illustrating the role of KC-derived HO-1 in the anti-injury effects of MF. Collectively, MF attenuated acute liver injury induced by LPS/D-GalN via the inhibition of TNF-α production by promoting KCs to upregulate HO-1 expression.

Mycophenolate mofetil attenuates concanavalin A-induced acute liver injury through modulation of TLR4/NF-κB and Nrf2/HO-1 pathways

BACKGROUND

Acute liver injury (ALI) is a serious health condition associated with rising morbidity and sudden progression. This study was designed to investigate the possible hepatocurative potential of two dose levels (30 and 60 mg/kg) of Mycophenolate mofetil (MMF), an immune-suppressant agent, against Concanavalin A (Con A)-induced ALI in mice.

METHOD

A single dose of Con A (20 mg/kg, IV) was used to induce ALI in mice. MMF (30 mg/kg and 60 mg/kg) was administered orally for 4 days post Con A injection.

RESULTS

MMF (30 mg/kg) failed to cause significant amelioration in Con A-induced ALI while MMF (60 mg/kg) significantly alleviated Con A-induced ALI. Administration of MMF (60 mg/kg) significantly decreased Con A-induced increase in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Additionally, MMF significantly restored the disrupted oxidant/antioxidants status induced by Con A. MMF caused marked increase in hepatic nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) levels. Moreover, MMF significantly reduced Con A-induced increase in the expression of hepatic toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ) and interleukin-1β (Il-1β). Also, MMF administration significantly decreased Con A-induced increase in the immune-expression of pro-apoptotic Bcl-2-associated X protein (Bax) and markedly increased Con A-induced decrease in the anti-apoptotic B-cell lymphoma 2 protein (Bcl2).

CONCLUSION

The observed ameliorative effect of MMF against Con A-induce ALI may be contributed to its anti-inflammatory, anti-oxidant and anti-apoptotic potentials taking into consideration that TLR4/NF-κB and Nrf2/HO-1 are the main implicated pathways. Schematic diagram summarizing the possible mechanisms underlying the ameliorative potential of Mycophenolate Mofetil against Con A-induced acute liver injury. Bax Bcl-2-associated X protein, Bcl2 B-cell lymphoma 2, MMF Mycophenolate mofetil, Con A Concanavalin A, GSH reduced glutathione, HO-1 Heme oxygenase-1, IL-1β Interleukin-1β, IFN-γ Interferon-γ, MDA Malondialdehyde, NF-κB Nuclear Factor Kappa B, Nrf2 Nuclear factor erythroid 2-related factor 2, NO Nitric Oxide, SOD Superoxide Dismutase, TLR4 Toll-like receptor 4, TNF-α tumor necrosis factor-α.

Comparative Pharmacokinetic Study of Taxifolin after Oral Administration of Fructus Polygoni Orientalis Extract in Normal and Fibrotic Rats by UPLC-MS/MS

Fructus polygoni orientalis (FPO) is widely used in clinical practice in China, especially in treatment of liver diseases including viral hepatitis, liver fibrosis, and liver cirrhosis. However, its pharmacokinetic (PK) alterations in liver fibrotic rats have rarely been reported. To study whether taxifolin, one of the main flavonoids in FPO can be absorbed into blood after oral administration of FPO extract and to compare the differences in pharmacokinetic parameters of taxifolin to normal and liver fibrotic rats induced by porcine serum (PS), a UPLC-MS/MS method was developed and validated for determination of taxifolin in rat plasma using puerarin as the internal standard (IS). All validation parameters met the acceptance criteria according to regulatory guidelines. The results indicated that after treatment of rats with PS alone for 12 weeks, the liver fibrotic model group was built successfully. The taxifolin can be absorbed into the blood after oral administration of the FPO extract. The C _max of taxifolin was 1940 ± 502.2 ng/mL and 2648 ± 208.5 ng/mL (p < 0.05), the AUC_0∼t of taxifolin was 4949.7 ± 764.89 h·ng/mL and 6679.9 ± 734.26 h·ng/mL (p < 0.05), the AUC_0∼∞ of taxifolin was 5049.4 ± 760.7 and 7095.2 ± 962.3 h·ng/mL (p < 0.05), and the mean residence time (MRT) of taxifolin was 2.46 ± 0.412 h and 3.17 ± 0.039 h (p < 0.05) in the normal and fibrotic model groups, respectively. These results confirmed that the pharmacokinetic parameters of taxifolin are altered in liver fibrosis, manifested as C _max, AUC_0∼t , AUC_0∼∞, and the mean residence time (MRT). It suggested that it is essential to consider the characteristics of pharmacokinetics after oral administration of FPO in liver disease patients.

Nrf2 in liver toxicology

Liver plays essential roles in the metabolism of many endogenous chemicals and exogenous toxicants. Mechanistic studies in liver have been at the forefront of efforts to probe the roles of bioactivation and detoxication of environmental toxins and toxicants in hepatotoxicity. Moreover, idiosyncratic hepatoxicity remains a key barrier in the clinical development of drugs. The now vast Nrf2 field emerged in part from biochemical and molecular studies on chemical inducers of hepatic detoxication enzymes and subsequent characterization of the modulation of drug/toxicant induced hepatotoxicities in mice through disruption of either Nrf2 or Keap1 genes. In general, loss of Nrf2 increases the sensitivity to such toxic chemicals, highlighting a central role of this transcription factor and its downstream target genes as a modifier to chemical stress. In this review, we summarize the impact of Nrf2 on the toxicology of multiple hepatotoxicants, and discuss efforts to utilize the Nrf2 response in predictive toxicology.

Hepatoprotective Effect of the Ethanol Extract of Illicium henryi against Acute Liver Injury in Mice Induced by Lipopolysaccharide

The root bark of Illicium henryi has been used in traditional Chinese medicine to treat lumbar muscle strain and rheumatic pain. Its ethanol extract (EEIH) has been previously reported to attenuate lipopolysaccharide (LPS)-induced acute kidney injury in mice. The present study aimed to evaluate the in vitro antioxidant activities and in vivo protective effects of EEIH against LPS-induced acute liver injury (ALI) in mice as well as explore its molecular mechanisms. The mice were injected intraperitoneally (i.p.) with EEIH at the doses of 1.25, 2.5, and 5.0 mg/kg every day for 5 days. One hour after the last administration, the mice were administered i.p. with LPS (8 mg/kg). After fasting for 12 h, blood and liver tissues were collected to histopathological observation, biochemical assay, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analyses. EEIH possessed 2,2-diphenyl-1-picrylhydrazil (DPPH) and 2,2'-azino-bis-(3-ethylbenzothiozoline-6-sulfonic acid) disodium salt (ABTS) radical scavenging activities and ferric-reducing antioxidant capacity in vitro. The histopathological examination, serum biochemical analysis, and liver myeloperoxidase (MPO) activity showed that EEIH pretreatment alleviated LPS-induced liver injury in mice. EEIH significantly dose-dependently decreased the mRNA and protein expression levels of inflammatory factors TNF-α, IL-1β, IL-6, and COX-2 in liver tissue of LPS-induced ALI mice via downregulating the mRNA and protein expressions of toll-like receptor 4 (TLR4) and inhibiting the phosphorylation of nuclear factor-κB (NF-κB) p65. Furthermore, EEIH markedly ameliorated liver oxidative and nitrosative stress burden in LPS-treated mice through reducing the content of thiobarbituric acid reactive substances (TBARS), inducible nitric oxide synthase (iNOS), and nitric oxide (NO) levels, restoring the decreased superoxide dismutase (SOD) and reduced glutathione (GSH) levels, and up-regulating nuclear factor erythroid 2 related factor 2 (Nrf2). These results demonstrate that EEIH has protective effects against ALI in mice via alleviating inflammatory response, oxidative and nitrosative stress burden through activating the Nrf2 and suppressing the TLR4/NF-κB signaling pathways. The hepatoprotective activity of EEIH might be attributed to the flavonoid compounds such as catechin (1), 3',4',7-trihydroxyflavone (2), and taxifolin (7) that most possibly act synergistically.

Cardioprotective effects of dihydroquercetin against ischemia reperfusion injury by inhibiting oxidative stress and endoplasmic reticulum stress-induced apoptosis via the PI3K/Akt pathway

Dihydroquercetin (DHQ), a dihydroxyflavone, possesses potent antioxidant properties and is proposed to be useful in the prevention and treatment of cardiovascular disease. In this study, we aimed to investigate whether DHQ has protective effects against MIRI and to elucidate the mechanism of attenuation of oxidative stress-and ERS-induced apoptosis via the PI3K/Akt pathway. Isolated rat hearts and H9c2 cardiomyocytes were treated with or without DHQ, and then subjected to I/R and H/R, respectively. Our results showed that DHQ pretreatment markedly alleviated cardiac dysfunction, scavenged free radicals, reduced lipid peroxidation, and increased the activity of antioxidant enzymes ex vivo and in vitro. The result of western blot analysis showed that DHQ inhibited the apoptotic pathway and the expression of pro-apoptotic proteins CHOP, Caspase-12, and p-JNK. In addition, DHQ delayed the onset of ERs by reducing GRP78, p-PERK, and p-eif2α expression levels and by increasing HO-1 expression and Nrf2 binding to antioxidant response elements. These cardioprotective effects of DHQ were partially counteracted by the PI3K/Akt inhibitor LY294002. The protective effects of DHQ on the inhibition of MIRI may be mediated by activating the PI3K/Akt pathway to reduce oxidative stress-and ERS-induced apoptosis.

Exposure to tris(1,3-dichloro-2-propyl) phosphate (TDCPP) induces vascular toxicity through Nrf2-VEGF pathway in zebrafish and human umbilical vein endothelial cells

The growing production and extensive use of organophosphate flame retardants (OPFRs) have led to an increase in their environmental distribution and human exposure. Developmental toxicity is a major concern of OPFRs' adverse health effects. However, the impact of OPFRs exposure on vascular development and the toxicity pathway for developmental defects are poorly understood. In this study, we investigated the effects of exposure to tris(1,3-dichloro-2-propyl) phosphate (TDCPP), a frequently detected OPFR, on early vascular development, and the possible role of nuclear factor erythroid 2-related factor (Nrf2)-dependent angiogenic pathway in TDCPP's vascular toxicity. TDCPP exposure at 300 and 500 μg/L impeded the growth of intersegmental vessels (ISV), a type of microvessels, as early as 30 hpf. Consistently, a similar pattern of decreased extension and remodeling of common cardinal vein (CCV), a typical macrovessel, was observed in zebrafish at 48 hpf and 72 hpf. Developing vasculature in zebrafish was more sensitive than general developmental parameters to TDCPP exposure. The expression of genes related to VEGF signaling pathway dose-dependently decreased in TDCPP-treated larvae. In in vitro experiments using human umbilical vein endothelial cells (HUVECs), the increased cell proliferation induced by VEGF was suppressed by TDCPP exposure in a dose-dependent fashion. In addition, we found a repression of Nrf2 expression and activity in TDCPP-treated larvae and HUVECs. Strikingly, the application of CDDO-Im, a potent Nrf2 activator, enhanced VEGF and protected against defective vascular development in zebrafish. Our results reveal that vascular impairment is a sensitive index for early exposure to TDCPP, which could be considered in the environmental risk assessment of OPFRs. The identification of Nrf2-mediating VEGF pathway provides new insight into the adverse outcome pathway (AOP) of OPFRs.

Effects of Taxifolin on Osteoclastogenesis in vitro and in vivo

Osteoporosis is a highly prevalent disease which has been a major public health problem and considered to be associated with chronic low-grade systemic inflammation and oxidative damage. Taxifolin is a natural flavonoid and possesses many pharmacological activities including antioxidant and anti-inflammatory. Because flavonoids have been confirmed to fight osteoporosis and promote bone health, the aim of this study was to investigate the effects of taxifolin on the formation and function of osteoclast. In this study, we examined the effects of taxifolin on osteoclast using both in vitro and in vivo studies. Taxifolin suppressed the activation of nuclear factor-κB, C-Fos and mitogen-activated protein kinase, and also decreased osteoclast-specific genes expression, including Trap, Mmp-9, Cathepsin K, C-Fos, Nfatc1, and Rank. Taxifolin also prevented reactive oxygen species (ROS) production following RANKL stimulation. In addition, taxifolin alleviated ovariectomized-induced bone loss by repressing osteoclast activity and decreasing serum levels of tumor necrosis factor-α, interleukin-1β, interleukin-6 and receptor activator of nuclear factor-κB ligand (RANKL) in vivo. Our results indicated that taxifolin inhibits osteoclastogenesis via regulation of modulation of several RANKL signaling pathways. Therefore, taxifolin may be considered as a potential alternative therapeutic agent for treating osteoclast-related diseases.

Simultaneous determination of bioactive flavonoids of Hoveniae Semen in rat plasma by LC-MS/MS: Application to a comparative pharmacokinetic study

A selective, sensitive and fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for the determination of dihydromyricetin, dihydroquercetin, myricetin and quercetin in rat plasma after intragastric administration of Hoveniae Semen total flavonoids. Baicalin was selected as the internal standard. Analytes were extracted from the rat plasma by protein precipitation with acetonitrile and separated on a C18 chromatographic column (Agilent ZORBAX Eclipse Plus, 4.6 mm × 100 mm, 3.5 μm) using the mobile phase containing acetonitrile (A) and 0.1% formic acid-water (B) by gradient elution at 0.5 mL/min flow rate. A tandem mass spectrometer equipped with an electrospray ionization (ESI) source was used to detect analytes. The analytes were measured by multiple reaction monitoring (MRM) in the negative ionization mode. The lower limit of quantification of dihydromyricetin, dihydroquercetin, myricetin and quercetin were 0.70, 8.16, 1.62 and 0.56 ng/mL, respectively. The accuracy, intra-day and inter-day precision and recovery were all satisfactory and the compounds were stable in rat plasma under all tested conditions. The approach was successfully applied to study pharmacokinetic characteristics of the four bioactive flavonoids in plasma after administering Hoveniae Semen total flavonoids intragastrically to rat. Further investigation was carried out to assess pharmacokinetic comparability of the four bioactive flavonoids after intragastric administration of Hoveniae Semen total flavonoids to mixture of flavonoids.

Protective effects of protopanaxatriol on acute liver injury induced by concanavalin A

The purpose of this study was to explore the protective effect of protopanaxatriol (PPT) on acute liver injury induced by concanavalin A (ConA). In this study, mice were randomly separated into four groups. The first group received PBS (i.v.). The second group was given PPT (50 mg/kg body weight, i.p.) for 3 days before PBS (i.v.) injection. The third group received ConA (15 mg/kg body weight, i.v.). The fourth group was administered PPT (50 mg/kg body weight, i.p.) for 3 days before ConA (i.v.) injection. The serum levels of ALT and AST were detected after 20 h of ConA injection. The pathological changes of liver were observed by H/E staining. The expression of inflammatory factors was measured by ELISA and qRTPCR, and the changes of the signaling pathway were detected by western blot. Histopathological changes and blood transaminase elevation indicated significant liver injury after ConA injection. However, PPT pretreatment obviously reversed these changes. The ELISA and qRT-PCR results indicated that PPT preconditioning significantly inhibited the production of inflammatory factors. In addition, this inhibitory effect of PPT was mainly mediated by regulation of the nuclear factor-κB (NF-κB) signaling pathway. The active ingredient of ginseng, PPT, exerts an obvious protective effect on acute liver injury caused by ConA through inhibiting the inflammatory response.

ATP/P2X7 receptor signaling as a potential anti-inflammatory target of natural polyphenols

Innate immune cells, such as macrophages, respond to pathogen-associated molecular patterns, such as a lipopolysaccharide (LPS), to secrete various inflammatory mediators. Recent studies have suggested that damage-associated molecular patterns (DAMPs), released extracellularly from damaged or immune cells, also play a role in the activation of inflammatory responses. In this study, to prevent excess inflammation, we focused on DAMPs-mediated signaling that promotes LPS-stimulated inflammatory responses, especially adenosine 5’-triphosphate (ATP)-triggered signaling through the ionotropic purinergic receptor 7 (P2X7R), as a potential new anti-inflammatory target of natural polyphenols. We focused on the phenomenon that ATP accelerates the production of inflammatory mediators, such as nitric oxide, in LPS-stimulated J774.1 mouse macrophages. Using an siRNA-mediated knockdown and specific antagonist, it was found that the ATP-induced enhanced inflammatory responses were mediated through P2X7R. We then screened 42 polyphenols for inhibiting the ATP/P2X7R-induced calcium influx, and found that several polyphenols exhibited significant inhibitory effects. Especially, a flavonoid baicalein significantly inhibited ATP-induced inflammation, including interleukin-1β secretion, through inhibition of the ATP/P2X7R signaling. These findings suggest that ATP/P2X7R signaling plays an important role in excess inflammatory responses and could be a potential anti-inflammatory target of natural polyphenolic compounds.

Flavonoids, Sterols and Lignans from Cochlospermum vitifolium and Their Relationship with Its Liver Activity

The sterols β-sitostenone (1), stigmast-4,6,8(14),22-tetraen-3-one (2), β-sitosterol (3) and stigmasterol (4), the aromatic derivatives antiarol (5) and gentisic acid (6), the phenylpropanes coniferyl alcohol (7), epoxyconiferyl alcohol (8) and ferulic acid (9), the apocarotenoid vomifoliol (10), the flavonoids naringenin (11), 7,4′-dimethoxytaxifolin (7,4′-dimethoxydihydroquercetin, 12), aromadendrin (13), kaempferol (14), taxifolin (dihydroquercetin, 15), prunin (naringenin-7-O-β-d-glucoside, 16), populnin (kaempferol-7-O-β-d-glucoside, 17) and senecin (aromadendrin-7-O-β-d-glucoside, 18) and the lignans kobusin (19) and pinoresinol (20), were isolated from the dried bark of Cochlospermum vitifolium Spreng (Cochlospermaceae), a Mexican medicinal plant used to treat jaundice, liver ailments and hepatitis C. Fourteen of these compounds were isolated for the first time from this plant and from the Cochlospermum genus. Compounds 3–4, 6–7, 9–11, 13–17 and 20 have previously exhibited diverse beneficial liver activities. The presence of these compounds in C. vitifolium correlates with the use of this Mexican medicinal plant.

Involvement of the Nrf2/HO-1/CO axis and therapeutic intervention with the CO-releasing molecule CORM-A1, in a murine model of autoimmune hepatitis

Concanavalin A (ConA)-induced hepatitis is an experimental model of human autoimmune hepatitis induced in rodents by i.v. injection of Con A. The disease is characterized by increase in serum levels of transaminases and massive immune infiltration of the livers. Type 1, type 2, and type 17 cytokines play a pathogenic role in the development of ConA-induced hepatitis. To understand further the immunoregulatory mechanisms operating in the development and regulation of ConA-induced hepatitis, we have evaluated the role of the anti-inflammatory pathway Nrf2/HO-1/CO (Nuclear Factor E2-related Factor 2/Heme Oxygenase-1/Carbon Monoxide) in this condition and determined whether the in vivo administration of CO via the CO-releasing molecule (CORM) CORM-A1, influences serological and histological development of Con-A-induced hepatitis. We have firstly evaluated in silico the genes belonging to the Nrf2/HO-1/CO pathway that are involved in the pathogenesis of autoimmune hepatitis (AIH). The data obtained from the in silico study demonstrate that a significant number of genes modulated in the liver of ConA-challenged mice belong to the Nrf2 pathway; on the other hand, the administration of CORM-A1 determines an improvement in several sero-immunological and histological parameters, and it is able to modulate genes identified by the in silico analysis. Collectively, our data indicate that the Nrf2/HO-1/CO pathway is fundamental for the regulation of the immune responses, and that therapeutic intervention aimed at its modulation by CORM-A1 may represent a valuable strategy to be considered for the treatment of autoimmune hepatitis in humans.

Pristimerin as a Novel Hepatoprotective Agent Against Experimental Autoimmune Hepatitis

Pristimerin (Pris) is bioactive natural quinonoid triterpene that has anti-inflammatory and anti-cancer activities. Meanwhile, its effect against hepatitis needs to be elucidated. This investigation aimed to evaluate the ability of Pris to protect against autoimmune hepatitis (AIH). A mouse model of AIH was established using single concanavalin A (Con A) intravenous injection. Mice were treated with Pris at two different doses (0.4 and 0.8 mg/kg) for 5 days prior to Con A challenge. Markers of hepatic injury, oxidative, inflammatory, and apoptotic damage were estimated. Results have revealed that Pris pretreatment ameliorated Con A-induced hepatic damage. There was decrease in the elevated serum indices of hepatic damage (ALT, AST, ALP, and LDH) and improvement of the histopathological picture of the liver. Pris effectively decreased Con A-induced neutrophil infiltration into the hepatic tissue as presented by amelioration of the level and immuno-expression of myeloperoxidase (MPO). Additionally, Pris attenuated Con A-induced increase in CD4+ T-cells in hepatic tissue. Lipid peroxidation was significantly depressed simultaneously with enhancement of the antioxidant capacity in Pris pretreated animals. Pris also enhanced nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA expression and its binding capacity. In addition, Pris increased mRNA expression of heme-oxygenase-1 (HO-1) and restored its normal level. Furthermore, Pris decreased the level and immuno-expression of nuclear factor kappa-B (NF-κB) as well as the downstream inflammatory cascade (TNF-α, IL-6, and IL-1β). Finally, Pris showed inhibitory effect on Con A-induced apoptotic alteration in liver as it decreased the mRNA expression and levels the apoptotic markers (Bax and caspase-3) and increased mRNA expression and level of the anti-apoptotic protein (Bcl2). In conclusion, this study demonstrates the potent hepatoprotective efficacy of Pris against Con A-induced hepatitis which may be related to anti-oxidative, anti-inflammatory, and anti-apoptotic pathways. Pris could serve as a new candidate for the management of hepatitis.

Pretreatment with dihydroquercetin, a dietary flavonoid, protected against concanavalin A-induced immunological hepatic injury in mice and TNF-α/ActD-induced apoptosis in HepG2 cells

We have previously demonstrated the hepatoprotective effect of dihydroquercetin (DHQ) against concanavalin A (Con A)-induced immunological hepatic injury in mice.

Taxifolin Activates the Nrf2 Anti-Oxidative Stress Pathway in Mouse Skin Epidermal JB6 P+ Cells through Epigenetic Modifications

Nuclear factor erythroid-2 related factor 2 (Nrf2) is a vital transcription factor that regulates the anti-oxidative defense system. Previous reports suggested that the expression of the Nrf2 gene can be regulated by epigenetic modifications. The potential epigenetic effect of taxifolin (TAX), a potent cancer chemopreventive agent, in skin cancer chemoprotection is unknown. In this study, we investigated how Nrf2 is epigenetically regulated by TAX in JB6 P+ cells. TAX was found to inhibit the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced colony formation of JB6 P+ cells. TAX induced antioxidant response element (ARE)-luciferase activity in HepG2-C8 cells and up-regulated mRNA and protein levels of Nrf2 and its downstream genes heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1), in JB6 P+ cells. Furthermore, bisulfite genomic sequencing revealed that TAX treatment reduces the methylation level of the first 15 CpGs sites in the Nrf2 promoter. Western blotting showed that TAX inhibits the expression levels of DNA methyltransferase (DNMT) and histone deacetylase (HDAC) proteins. In summary, our results revealed that TAX can induce expression of Nrf2 and its downstream target genes in JB6 P+ cells by CpG demethylation. These finding suggest that TAX may exhibit a skin cancer preventive effect by activating Nrf2 via an epigenetic pathway.

Mesenchymal stem cells improve mouse non-heart-beating liver graft survival by inhibiting Kupffer cell apoptosis via TLR4-ERK1/2-Fas/FasL-caspase3 pathway regulation

Background

Liver transplantation is the optimal treatment option for end-stage liver disease, but organ shortages dramatically restrict its application. Donation after cardiac death (DCD) is an alternative approach that may expand the donor pool, but it faces challenges such as graft dysfunction, early graft loss, and cholangiopathy. Moreover, DCD liver grafts are no longer eligible for transplantation after their warm ischaemic time exceeds 30 min. Mesenchymal stem cells (MSCs) have been proposed as a promising therapy for treatment of certain liver diseases, but the role of MSCs in DCD liver graft function remains elusive.

Methods

In this study, we established an arterialized mouse non-heart-beating (NHB) liver transplantation model, and compared survival rates, cytokine and chemokine expression, histology, and the results of in vitro co-culture experiments in animals with or without MSC infusion.

Results

MSCs markedly ameliorated NHB liver graft injury and improved survival post-transplantation. Additionally, MSCs suppressed Kupffer cell apoptosis, Th1/Th17 immune responses, chemokine expression, and inflammatory cell infiltration. In vitro, PGE2 secreted by MSCs inhibited Kupffer cell apoptosis via TLR4-ERK1/2-caspase3 pathway regulation.

Conclusion

Our study uncovers a protective role for MSCs and elucidates the underlying immunomodulatory mechanism in an NHB liver transplantation model. Our results suggest that MSCs are uniquely positioned for use in future clinical studies owing to their ability to protect DCD liver grafts, particularly in patients for whom DCD organs are not an option according to current criteria.

Mesenchymal stem cells improve mouse non-heart-beating liver graft survival by inhibiting Kupffer cell apoptosis via TLR4-ERK1/2-Fas/FasL-caspase3 pathway regulation

BACKGROUND

Liver transplantation is the optimal treatment option for end-stage liver disease, but organ shortages dramatically restrict its application. Donation after cardiac death (DCD) is an alternative approach that may expand the donor pool, but it faces challenges such as graft dysfunction, early graft loss, and cholangiopathy. Moreover, DCD liver grafts are no longer eligible for transplantation after their warm ischaemic time exceeds 30 min. Mesenchymal stem cells (MSCs) have been proposed as a promising therapy for treatment of certain liver diseases, but the role of MSCs in DCD liver graft function remains elusive.

METHODS

In this study, we established an arterialized mouse non-heart-beating (NHB) liver transplantation model, and compared survival rates, cytokine and chemokine expression, histology, and the results of in vitro co-culture experiments in animals with or without MSC infusion.

RESULTS

MSCs markedly ameliorated NHB liver graft injury and improved survival post-transplantation. Additionally, MSCs suppressed Kupffer cell apoptosis, Th1/Th17 immune responses, chemokine expression, and inflammatory cell infiltration. In vitro, PGE2 secreted by MSCs inhibited Kupffer cell apoptosis via TLR4-ERK1/2-caspase3 pathway regulation.

CONCLUSION

Our study uncovers a protective role for MSCs and elucidates the underlying immunomodulatory mechanism in an NHB liver transplantation model. Our results suggest that MSCs are uniquely positioned for use in future clinical studies owing to their ability to protect DCD liver grafts, particularly in patients for whom DCD organs are not an option according to current criteria.