Beneficial effect of quercetin on cholestatic liver injury

Quercetin, a natural flavonoid, protects against hepatic ischemia-reperfusion injury via inhibiting Caspase-8/ASC dependent macrophage pyroptosis

INTRODUCTION

Hepatic ischemia-reperfusion injury (IRI) is an inevitable adverse event following liver surgery, leading to liver damage and potential organ failure. Despite advancements, effective interventions for hepatic IRI remain elusive, posing a significant clinical challenge. The innate immune response significantly contributes to the pathogenesis of hepatic IRI by promoting an inflammatory cytotoxic cycle. We have reported that blocking GSDMD-induced pyroptosis in innate immunity cells protected hepatic IRI from inflammatory injury. However, the search for effective pyroptosis inhibitors continues.

OBJECTIVES

This study aims to evaluate whether quercetin, a natural flavonoid, can inhibit GSDMD-induced pyroptosis and mitigate hepatic IRI.

METHODS

We established the hepatic IRI murine model and cellular pyroptosis model to evaluate the efficacy of quercetin.

RESULTS

Quercetin effectively alleviated hepatic IRI-induced tissue necrosis and inflammation. We found that during hepatic IRI, the cleavage of GSDMD occurred in hepatic macrophages, but not in other non-parenchymal cells. Quercetin inhibited the cleavage of GSDMD in macrophages. Moreover, we found that quercetin blocked the ASC assembly to inhibit the formation of NLRP3 inflammasomes and AIM2 inflammasomes, suppressing macrophage pyroptosis. Co-immunoprecipitation experiments confirmed that quercetin inhibited the interaction between ASC and Caspase-8, which is the mechanism of ASC complex and inflammasome formation. Overexpression of Caspase-8 abolished the anti-pyroptosis effect of quercetin in NLRP3 and AIM2 inflammasome signaling. Furthermore, we found that the hepatoprotective activity of quercetin was reduced in myelocytic GSDMD-deficient mice.

CONCLUSION

Our findings suggest that quercetin has beneficial effects on hepatic IRI. Quercetin could attenuate hepatic IRI and target inhibition of macrophage pyroptosis via blocking Caspase-8/ASC interaction. We recommend that quercetin might serve as a targeted approach for the prevention and personalized treatment of hepatic IRI in perioperative patients.

Exploring the therapeutic potential of quercetin: A focus on its sirtuin-mediated benefits

As the global population ages, preventing lifestyle- and aging-related diseases is increasing, necessitating the search for safe and affordable therapeutic interventions. Among nutraceuticals, quercetin, a flavonoid ubiquitously present in various plants, has garnered considerable interest. This review aimed to collate and analyze existing literature on the therapeutic potentials of quercetin, especially its interactions with SIRTs and its clinical applicability based on its bioavailability and safety. This narrative review was based on a literature survey spanning from 2015 to 2023 using PUBMED. The keywords and MeSH terms used were: "quercetin" AND "bioavailability" OR "metabolism" OR "metabolites" as well as "quercetin" AND "SIRTuin" OR "SIRT*" AND "cellular effects" OR "pathway" OR "signaling" OR "neuroprotective" OR "cardioprotective" OR "nephroprotective" OR "antiatherosclerosis" OR "diabetes" OR "antidiabetic" OR "dyslipidemia" AND "mice" OR "rats". Quercetin demonstrates multiple therapeutic activities, including neuroprotective, cardioprotective, and anti-atherosclerotic effects. Its antioxidant, anti-inflammatory, antiviral, and immunomodulatory properties are well-established. At a molecular level, it majorly interacts with SIRTs, particularly SIRT1 and SIRT6, and modulates numerous signaling pathways, contributing to its therapeutic effects. These pathways play roles in reducing oxidative stress, inflammation, autophagy regulation, mitochondrial biogenesis, glucose utilization, fatty acid oxidation, and genome stability. However, clinical trials on quercetin's effectiveness in humans are scarce. Quercetin exhibits a wide range of SIRT-mediated therapeutic effects. Despite the compelling preclinical data, more standardized clinical trials are needed to fully understand its therapeutic potential. Future research should focus on addressing its bioavailability and safety concerns.

Ginkgo biloba extract alleviates CCl4-induced acute liver injury by regulating PI3K/AKT signaling pathway

Acute liver injury (ALI) is a global health problem associated with high mortality and has attracted clinical attention. Ginkgo biloba extract (GBE) is an extract from dried Ginkgo leaves that has many pharmacological effects because of its various ingredients and has been shown to be hepatoprotective. We investigated the hepatoprotective effect of GBE on carbon tetrachloride (CCl4)-induced acute liver injury in vitro. The components of Ginkgo biloba extract are analyzed by LC-MS, and the key targets of "liver injury-Ginkgo biloba" are identified based on bioinformatics analysis. The signaling pathways such as PI3K/AKT are mainly enriched with high correlation in KEGG. The results of in vitro experiments showed that compared with the Model group, except that the ALT activity level and MDA content in EGB-L group were not significantly decreased (P > 0.05), the activity of ALT, AST and MDA content in other EGB groups were significantly decreased (P < 0.05), and the activities of SOD and CAT were significantly increased (P < 0.05). The expression of inflammatory factors IL-1β, IL-6 and TNF-α were also detected. The results showed that compared with the Model group, the contents of IL-6 in EGB-L group were not significantly decreased (P > 0.05), while the contents of IL-1β, IL-6 and TNF-α in other EGB groups were significantly decreased (P < 0.05), indicating that EGB could reduce the level of cell inflammation. Western blot assay detected the protein expression levels of GF, RTK, PI3K, AKT and p-AKT in cells. The results showed that compared with the Model group, the protein expression levels of GF, RTK, PI3K, AKT and P-AKT were significantly increased after EGB treatment (P < 0.05), and the protein expression level of the EGB-H group was higher than the EGB-L group. Ginkgo biloba extract can inhibit the expression of downstream related genes by activating PI3K/AKT signaling pathway, and at the same time alleviate the inflammatory response of cells, reduce the level of inflammation, and protect the cell damage caused by CCl4.

Biflavonoid quercetin protects against cyclophosphamide-induced organ toxicities via modulation of inflammatory cytokines, brain neurotransmitters, and astrocyte immunoreactivity

BACKGROUND

Cyclophosphamide use has been associated with increased oxidative stress in cells and tissues. Quercetin's antioxidative properties make it of potential benefit in such conditions of oxidative stress.

OBJECTIVE

To assess quercetin's ability to mitigate cyclophosphamide-induced organ toxicities in rats.

METHODS

Sixty rats were assigned into six groups. Groups A and D served as normal and cyclophosphamide control and were fed standard rat chow, groups B and E were fed quercetin supplemented diet (100 mg/kg of feed), while those in groups C and F were fed quercetin at 200 mg/kg of feed. Groups A-C received intraperitoneal (ip) normal saline on days 1 and 2, while D-F received ip cyclophosphamide (150 mg/kg/day on days 1 and 2). On day 21, behavioural tests were carried out, animals were sacrificed and blood samples taken. Organs were processed for histological study.

RESULTS

Quercetin reversed cyclophosphamide-induced decrease in body weight, food intake and total antioxidant capacity, and increase in lipid peroxidation (p = 0.001), It also reversed derangement in levels of liver transaminase, urea, creatinine and proinflammatory cytokines (p = 0.001). Improvement in working-memory and anxiety-related behaviours were also observed. Finally, quercetin reversed alterations in levels of acetylcholine, dopamine and brain-derived neurotropic factor (p = 0.021); while reducing serotonin levels and astrocyte immunoreactivity.

CONCLUSION

Quercetin shows significant ability to protect against cyclophosphamide-induced changes in rats.

A review of edible plant-derived natural compounds for the therapy of liver fibrosis

Liver fibrosis has a high incidence worldwide and is the common pathological basis of many chronic liver diseases. Liver fibrosis is caused by the excessive deposition of extracellular matrix and concomitant collagen accumulation in livers and can lead to the development of liver cirrhosis and even liver cancer. A large number of studies have provided evidence that liver fibrosis can be blocked or even reversed by appropriate medical interventions. However, the antifibrosis drugs with ideal clinical efficacy are still insufficient. The edible plant-derived natural compounds have been reported to exert effective antifibrotic effects with few side-effects, representing a kind of promising source for the treatment of liver fibrosis. In this article, we reviewed the current progress of the natural compounds derived from dietary plants in the treatment of liver fibrosis, including phenolic compounds (capsaicin, chlorogenic acid, curcumin, ellagic acid, epigallocatechin-3-gallate, resveratrol, sinapic acid, syringic acid, vanillic acid and vitamin E), flavonoid compounds (genistein, hesperidin, hesperetin, naringenin, naringin and quercetin), sulfur-containing compounds (S-allylcysteine, ergothioneine, lipoic acid and sulforaphane) and other compounds (betaine, caffeine, cucurbitacin B, lycopene, α-mangostin, γ-mangostin, ursolic acid, vitamin C and yangonin). The pharmacological effects and related mechanisms of these compounds in in-vivo and in-vitro models of liver fibrosis are focused.

Quercetin potentiates the hepatoprotective effect of sildenafil and/or pentoxifylline against intrahepatic cholestasis: Role of Nrf2/ARE, TLR4/NF-κB, and NLRP3/IL-1β signaling pathways

AIM

Intrahepatic cholestasis is a common pathological condition of several types of liver disorders. In this study, we aimed to investigate the regulatory effects of quercetin (QU) on selected phosphodiesterase inhibitors against alpha-naphthyl isothiocyanate (ANIT)-induced acute intrahepatic cholestasis.

METHODS

Cholestasis was induced in Wistar albino rats by ANIT as a single dose (60 mg/kg; P·O.). QU (50 mg/kg, daily, P·O.), sildenafil (Sild; 10 mg/kg, twice daily, P·O.), and pentoxifylline (PTX; 50 mg/kg, daily, P.O.) were evaluated either alone or in combinations for 10 days for their antioxidant, anti-inflammatory, and anti-pyroptotic effects.

RESULTS

ANIT produced a prominent intrahepatic cholestasis as evidenced by a significant alteration in liver functions, histological structure, inflammatory response, and oxidative stress biomarkers. Furthermore, up-regulation of NF-κB-p65, TLR4, NLRP3, cleaved caspase-1, IKK-β, and IL-1β concurrently with down-regulation of Nrf-2, HO-1, and PPAR-γ expressions were observed after ANIT. QU, Sild, or PTX treatment significantly alleviated the disturbance induced by ANIT. These findings were further supported by the improvement in histopathological features. Additionally, co-administration of QU with Sild or PTX significantly improved liver defects due to ANIT as compared to the individual drugs.

SIGNIFICANCE

Combined QU with Sild or PTX exhibited promising hepatoprotective effects and anti-cholestatic properties through modulation of Nrf2/ARE, TLR4/NF- κB, and NLRP3/IL-1β signaling pathways.

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.

The construction of preclinical evidence for the treatment of liver fibrosis with quercetin: A systematic review and meta-analysis

Quercetin (3,3',4',5,7-pentahydroxyflavone), a flavonoid, is widely found in fruits and vegetables and exerts broad-spectrum pharmacological effects in the liver. Many studies have explored the bioactivity of quercetin in the treatment of liver fibrosis. Hence, through a systematic review and biological mechanism evaluation, this study aimed to construct a body of preclinical evidence for the treatment of liver fibrosis using quercetin. The literature used in this study was mainly obtained from four databases, and the SYRCLE list (10 items) was used to evaluate the quality of the included literature. A meta-analysis of HA, LN, and other indicators was performed via STATA 15.0 software. Subgroup analyses based on animal species and model protocol were performed to further obtain detailed results. Moreover, the therapeutic mechanism of quercetin was summarized in a directed network form based on a comprehensive search of the literature. After screening, a total of 14 articles (comprising 15 studies) involving 254 animals were included. The results from the analysis showed that the corresponding liver function indexes, such as the levels of HA and LN, were significantly improved in the quercetin group compared with the model group, and liver function, such as the levels of AST and ALT, were also improved in the quercetin group. The species- and model-based subgroup analyses of AST and ALT revealed that quercetin exerts a significant effect. The therapeutic mechanism of quercetin was shown to be related to multiple pathways involving anti-inflammatory and antioxidant activities and lipid accumulation, including regulation of the TGF-β, α-SMA, ROS, and P-AMPK pathways. The results showed that quercetin exerts an obvious effect on liver fibrosis, and more prominent improvement effects on liver function and liver fibrosis indicators were obtained with a dose of 5-200 mg during a treatment course ranging from 4 to 8 weeks. Quercetin might be a promising therapeutic for liver fibrosis.

18β-Glycyrrhetinic Acid Protects against Cholestatic Liver Injury in Bile Duct-Ligated Rats

18β-Glycyrrhetinic acid is a nutraceutical agent with promising hepatoprotective effects. Its protective mechanisms against cholestatic liver injury were further investigated in a rodent model of extrahepatic cholestasis caused by Bile Duct Ligation (BDL) in rats. The daily oral administration of 18β-Glycyrrhetinic acid improved liver histology, serum biochemicals, ductular reaction, oxidative stress, inflammation, apoptosis, impaired autophagy, and fibrosis. 18β-Glycyrrhetinic acid alleviated the BDL-induced hepatic and systemic retention of bile acids, matrix-producing cell activation, hepatic collagen deposition, Transforming Growth Factor beta-1/Smad activation, malondialdehyde elevation, glutathione reduction, High Mobility Group Box-1/Toll-Like Receptor-4 activation, NF-κB activation, inflammatory cell infiltration/accumulation, Interleukin-1β expression, Signal Transducer and Activator of Transcription-1 activation, Endoplasmic Reticulum stress, impairment autophagy, and caspase 3 activation. Conversely, the protein expression of Sirt1, Farnesoid X Receptor, nuclear NF-E2-Related Factor-2, Transcription Factor EB, bile acid efflux transporters, and LC3-II, as well as the protein phosphorylation of AMP-Activated Protein Kinase, was promoted in 18β-Glycyrrhetinic acid-treated BDL rats. The hepatoprotective effects of 18β-Glycyrrhetinic acid in the present investigation correlated well with co-activation and possible interactions among Sirt, FXR, and Nrf2. The concurrent or concomitant activation of Sirt1, FXR, and Nrf2 not only restored the homeostatic regulation of bile acid metabolism, but also alleviated oxidative stress, inflammation, apoptosis, impaired autophagy, and fibrosis.

Extraction and Identification of Two Flavonoids in Phlomoides hyoscyamoides as an Endemic Plant of Iran: The Role of Quercetin in the Activation of the Glutathione Peroxidase, the Improvement of the Hydroxyproline and Protein Oxidation in Bile Duct-Ligated Rats

BACKGROUND

Cholestatic liver disease, a serious chronic condition that develops progressive hepatic degeneration through free radicals.

OBJECTIVE

The present study was designed to extract and identify two flavonoids in Phlomoides hyoscyamoides plant, native to Iran and evaluate the role of quercetin identified on the liver injury among bile ductligated rats.

METHODS

This study was conducted on 25 male Wistar rats within three groups of sham control, mere bile duct-ligated, and bile duct-ligated with quercetin. The bile duct-ligated animals received quercetin at a dose of 50 mg/kg/day for 10 days, followed by biochemical tests, oxidative stress markers, activity of antioxidant enzymes and hematoxylin and eosin staining. Molecular docking was used to explore the interactive behavior of quercetin with glutathione peroxidase.

RESULTS

According to analyses of the obtained extract, two main active ingredients of P. hyoscyamoides were rutin and quercetin. Bile duct-ligated group showed a significant liver necrosis, a clear increase in plasma and tissue oxidative stress parameters, and a decrease in glutathione peroxidase activity as compared to sham control group. Quercetin injection in bile duct-ligated rats resulted in significant decrease in hydroxyproline, protein carbonyl and histopathologic indexes and significant increase in glutathione peroxidase activity (P-value≤0.05). Based on the molecular docking, the quercetin was able to regulate the glutathione peroxidase activity.

CONCLUSION

The quercetin acts as an enzyme inducer by renewing the glutathione peroxidase activity and inhibiting the oxidation of proteins and hence decreases the oxidative stress. These results could be a sign of confirming the positive role of quercetin in attenuating the liver damage and degeneration.

Changes in Glutathione Content in Liver Diseases: An Update

Glutathione (GSH), a tripeptide particularly concentrated in the liver, is the most important thiol reducing agent involved in the modulation of redox processes. It has also been demonstrated that GSH cannot be considered only as a mere free radical scavenger but that it takes part in the network governing the choice between survival, necrosis and apoptosis as well as in altering the function of signal transduction and transcription factor molecules. The purpose of the present review is to provide an overview on the molecular biology of the GSH system; therefore, GSH synthesis, metabolism and regulation will be reviewed. The multiple GSH functions will be described, as well as the importance of GSH compartmentalization into distinct subcellular pools and inter-organ transfer. Furthermore, we will highlight the close relationship existing between GSH content and the pathogenesis of liver disease, such as non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), chronic cholestatic injury, ischemia/reperfusion damage, hepatitis C virus (HCV), hepatitis B virus (HBV) and hepatocellular carcinoma. Finally, the potential therapeutic benefits of GSH and GSH-related medications, will be described for each liver disorder taken into account.

Curcumin exerts hepatoprotection via overexpression of Paraoxonase-1 and its regulatory genes in rats undergone bile duct ligation

OBJECTIVES

Curcumin is described as an antioxidant, hepato-protective and antifibrotic in liver fibrosis, although its mechanism is still not known. One of the models of the chronic liver disease stemming from oxidative stress and the generation of free radical has been considered to be bile duct ligation (BDL). Paraoxonase 1 (PON1) is a prominent antioxidant enzyme. Therefore, the objective of the present research is to assess the effects of curcumin on upregulation of PON1 in BDL rats.

METHODS

As predicted, the rats have been divided into the four groups of Sham, Sham + Cur (curcumin), BDL and BDL + Cur. We evaluated the efficacy of curcumin (100 mg/kg/day) on protein and gene expression of PON1 and regulatory genes contributed to the gene expression PON1 such as Sp1, PKCα, SREBP-2, AhR, JNK and regulation PON1 activity gene expression of Apo A1.

RESULTS

Curcumin attenuated alterations in liver histology, hepatic enzymes and the mRNA expression of fibrotic markers (p<0.05). In addition, curcumin increased significantly mRNA, protein expression of PON1 and mRNA of the genes that are contributed to the expression of PON1 such as Sp1, PKCα, SREBP-2, AhR, JNK and increased PON1 activity through upregulation of Apo A1 (p<0.05).

CONCLUSIONS

Cirrhosis progression may be inhibited by treatment with curcumin through the increased influence the expression and activity of PON1.

Effects of Inclusion of Different Doses of Persicaria odorata Leaf Meal (POLM) in Broiler Chicken Feed on Biochemical and Haematological Blood Indicators and Liver Histomorphological Changes

Simple Summary

The frequent use of antimicrobial growth promoters (AGPs) in poultry feed leads to antimicrobial resistance, resulting in a ban on their subtherapeutic use in food-producing animals. In this context, there is a dire need to find safe and potential alternatives. Recently, phytobiotics, especially herbs, have gained attention and have been studied extensively for their possible use as alternative poultry feed additives. Persicaria odorata is a herb (phytobiotic) that is reported to possess antioxidant, antimicrobial, immunomodulatory, and hepatoprotective properties. This study is the first of its kind to assess the effects of different doses of supplementation of Persicaria odorata leaf meal (POLM) on haematological blood indicators, serum biochemistry, organ parameters, and histomorphology of the liver in broiler chickens. The results revealed that the dietary supplementation of POLM enhanced the growth performance, positively improved the haematological indices and serum biochemistry profile with no deleterious effects on internal organs, and ameliorated the histomorphology of the liver, even at dietary supplementation of 8 g/kg. Thus, POLM would be safe at an inclusion rate of 8 g/kg as an alternative phytogenic feed additive in broiler chickens.

Abstract

This research was conducted to estimate the effects of Persicaria odorata leaf meal (POLM) on haematological indices, serum biochemical attributes, and internal organs parameters, including histomorphological features of the liver, in broiler chickens. A total of 120 one-day-old male broiler chicks (Cobb-500) were randomly allocated into four experimental groups. The dietary treatments were basal diet (BD), which served as the control (C), along with BD + 2 g/kg POLM (Po2), BD + 4 g/kg POLM (Po4), BD + 8 g/kg POLM (Po8), which were the supplemented groups. The body weight gain (BWG) showed a linear increase and feed conversion ratio (FCR) showed a linear decrease with increasing POLM dosage at day 42 (p ˂ 0.05) and for the overall growth performance period (p ˂ 0.01). On day 21 and day 42, the values of red blood cells (RBCs), white blood cells (WBCs), haemoglobin (Hb), and packed cell volume (PCV) showed linear increases (p ˂0.05) as the dosage of POLM increased in the diet. On day 21, dietary supplementation of POLM linearly decreased (p ˂ 0.05) the serum activity of alkaline phosphatase (ALP), aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), and serum levels of urea and creatinine. On the other hand, serum levels of total protein (TP), albumin, and globulin showed a linear increase (p ˂ 0.05) as the POLM dosage increased. On day 42, the serum activity of AST and ALT and serum levels of glucose, cholesterol, triglycerides, urea, and creatinine showed linear decreases (p ˂ 0.05) with increased levels of POLM in the diet. However, POLM supplementation linearly increased (p ˂ 0.05) the serum levels of TP and globulin. Dietary inclusion of POLM did not influence the organ parameters and showed no adverse effects on the liver histomorphology. In conclusion, supplementation of POLM increased the growth performance, improving haematological indices and serum biochemistry profiles of broiler chickens without any deleterious effects on the liver histomorphology. The results of the present study provide evidence that POLM can be safely used at a dose rate of 8 g/kg of feed as an alternative to conventional antimicrobial growth promoters (AGPs).

Protective effect of Nasturtium officinale R. Br and quercetin against cyclophosphamide-induced hepatotoxicity in rats

Cyclophosphamide (CPA) is used in the management of autoimmune conditions and malignant illnesses. However, its therapeutic use is limited because of its severe side effects, especially hepatotoxicity attributed to oxidative stress. Nasturtium officinale R. Br (watercress or WC) has pharmacological properties, such as anti-inflammation, and antioxidant activities. Therefore, the present study was design to assess effects of WC or its active ingredient, quercetin (QE), against CPA-induced hepatotoxicity. For this study, 49 male Wistar rats (200-250 g) were randomly selected and categorized into seven equal groups. The animals were pre- and post-treated with both hydroalcoholic extract of WC (500 mg/kg) and quercetin (75 mg/kg) for 10 consecutive days, and intraperitoneal administration of CPA (200 mg/kg) was performed on only day 10, one hour before the last dose of WC or quercetin. On day 11, all the animals were sacrificed, and their blood and liver were gathered for evaluation of the liver enzyme, hepatic oxidative stress markers, antioxidant enzymes activity, and hematoxylin and eosin staining. CPA significantly increased malondialdehyde (MDA), protein carbonyl (PCO) and nitric oxide (NO) levels and liver biomarkers. Otherwise, hepatic catalase (CAT), reduced glutathione (GSH), total thiol content (tSH), and ferric reducing antioxidant power (FRAP) were considerably lower than the control group. Results showed that WC has the ability to reduce the changes (MDA, PCO, FRAP, CAT, ALT and AST) and QE (MDA, PCO, AST) induced by CPA (p < 0.05). Histopathological finding confirmed the indicated results. These findings propose that WC and QE have protective effect against the CPA-induced hepatotoxicity by decreasing oxidative stress.

Quercetin protects against cerebral ischemia/reperfusion and oxygen glucose deprivation/reoxygenation neurotoxicity

Beyond nutrition effect, quercetin is applied as a complement or an alternative for promoting human health and treating diseases. However, its complicated neuroprotective mechanisms have not yet been fully elucidated. This study provides evidence of an alternative target for quercetin, and sheds light on the mechanisms of its neuroprotection against cerebral ischemia/reperfusion (I/R) injury in Sprague-Dawley rats. Oral pretreatment using quercetin has alleviated cerebral I/R-induced neurological deficits, brain infarction, blood-brain barrier disruption, oxidative stress, TNF-α and IL-1β mRNA expression, along with apoptotic caspase 3 activity. The neuroprotective, anti-oxidative, anti-inflammatory, and anti-apoptotic effects of quercetin were replicated in rat hippocampal slice cultures and neuron/glia cultures which suffered from oxygen-glucose deprivation and reoxygenation (OGDR). Biochemical studies revealed a reduction of extracellular signal-regulated kinase (ERK) and Akt phosphorylation, along with an increase in protein tyrosine and serine/threonine phosphatase activity in cerebral I/R rat cortical tissues and OGDR hippocampal slice and neuron/glia cultures. Quercetin alleviated the changes in ERK/Akt phosphorylation and protein phosphatase activities. Inhibition of ERK or Akt alone was enough to cause apoptotic cell death and cytotoxicity in hippocampal slice cultures and neuron/glia cultures, while activators of ERK or Akt alleviated OGDR-induced cytotoxicity. Taken together, our results demonstrate that quercetin alleviated the increment of protein tyrosine and serine/threonine phosphatase activity, along with the reduction of ERK and Akt phosphorylation, which may play pivotal roles in the expansion of brain injury after cerebral I/R.

Natural products for the prevention and treatment of cholestasis: A review

Cholestasis is a common manifestation of decreased bile flow in various liver diseases. It results in fibrosis and even cirrhosis without proper treatment. It is believed that a wide range of factors, including transporter dysfunction, oxidative stress, inflammatory damage, and immune disruption, can cause cholestasis. In recent years, natural products have drawn much attention for specific multiple-target activities in diseases. Many attempts have been made to investigate the anticholestatic effects of natural products with advanced technology. This review summarizes recent studies on the biological activities and mechanisms of recognized compounds for cholestasis treatment. Natural products, including various flavonoids, phenols, acids, quinones, saponins, alkaloids, glycosides, and so on, function as comprehensive regulators via ameliorating oxidative stress, inflammation, and apoptosis, restoring bile acid balance with hepatic transporters, and adjusting immune disruption. Moreover, in this progress, nuclear factor erythroid 2-related factor 2, reactive oxygen species production, heme oxygenase-1, NF-κB, cholesterol 7 alpha-hydroxylase, and farnesoid X receptors are thought as main targets for the activity of natural products. Therefore, this review presents the detailed mechanisms that include multiple targets and diverse signalling pathways. Natural products are the valuable when seeking novel therapeutic agents to treat cholestatic liver diseases.

Lactobionic Acid Conjugated Quercetin Loaded Organically Modified Silica Nanoparticles Mitigates Cyclophosphamide Induced Hepatocytotoxicity

Objective

The study was designed to investigate the therapeutic potential of lactobionic acid (LA) conjugated quercetin (Q) loaded organically modified silica nanoparticles (LA-Q-ORMOSIL) with bulk quercetin to mitigate cyclophosphamide (CP) induced liver injury.

Methodology

Q-ORMOSIL nanoparticles were synthesized and characterized using UV-Vis spectroscopy, TEM, Zeta sizer, FTIR and EDX. Further, encapsulation efficiency and in vitro release kinetic study was done. Q-ORMOSIL nanoparticles surface were modified with lactobionic acid, a ligand for the asialoglycoprotein receptor on the hepatocyte surface. The hepatoprotective effects of Q-ORMOSIL and LA-Q-ORMOSIL nanoparticles were evaluated in vivo. Cyclophosphamide (20 mg/kg/day, i.p) was co-administered for seven days with bulk quercetin (50mg/kg/day) and quercetin nanoparticles (50µg/kg/day). After seven days, the number of biomarkers for liver function test and oxidative stress were determined in liver homogenate. Histopathological changes were also analyzed in control and treated liver tissues.

Results

Physiochemical characterization of LA-Q-ORMOSIL nanoparticles depicts that the particles formed were of approx. 80 nm, spherical, monodispersed in nature and showed sustain drug release in in vitro study. Our results further suggested that Q-ORMOSIL and LA-Q-ORMOSIL nanoparticles significantly decreased tissue TBARS, ROS levels and ALT, AST, and ALP activities compared to CP induced group. On the other hand, tissue antioxidant levels (GSH, GST, and catalase) showed a significant increase in LA-Q-ORMOSIL treated group compared to the CP treated group confirming its high therapeutic efficacy during liver injury.

Conclusion

Targeted nanoquercetin demonstrated a significant hepatoprotective effect compared to bulk quercetin against CP-induced hepatotoxicity and it considerably reduced bulk quercetin dose level to many folds. Bulk quercetin has low bioavailability and thus, from obtained data we suggest that LA-Q-ORMOSIL nanoparticles provide high therapeutic value in protecting experimental animals against CP-induced liver injury. We also propose multifunctional dye-doped LA-modified ORMOSIL nanoparticles for future studies in facilitating nanoparticles uptake to hepatocytes for liver diagnosis and treatment.

A systematic review on hepatoprotective activity of quercetin against various drugs and toxic agents: Evidence from preclinical studies

Quercetin is one of the most abundant flavonoids in human diet that has been reported to exhibit a wide range of pharmacological properties. The biochemical and molecular mechanisms involved in the hepatoprotective activity of quercetin were discussed in this review. Quercetin exhibited hepatoprotective activity against 2-butoxyethanol, acrylamide, acrylonitrile, aflatoxin B1, aroclor-1254, arsenic, sodium arsenite, azathioprine, cadmium chloride, carbon tetrachloride, chlorpyrifos, cyclosporine A, diazinon, dimethylnitrosamine, doxorubicin, epirubicin, ethanol, fenvalerate, isoniazide, rifampicin, lead acetate, lindane, D-galactosamine, methotrexate, methylmercury, nickel sulfate, paracetamol, perfluorooctanoic acid, polychlorinated biphenyls, pyrrolizidine alkaloid clivorine, rotenone, sodium fluoride, streptazotocin, tert-butyl hydroperoxide, thioacetamide, titanium dioxide, tumor necrosis factor-α, tripterygium glycoside, triptolide, ultraviolet A light, concavalin A, bisphenol, and ischemia-induced hepatotoxicity in various animal models due to its antioxidant, free radical-scavenging,anti-inflammatory, antiapoptotic, and cytochrome P450 2E1 (CYP2E1) inhibitory activities. In this review, we provide an overview of the possible mechanisms by which quercetin reduced the hepatotoxicity of different hepatotoxicants. This will help the toxicologists, pharmacologists, and chemists to develop new safer pharmaceutical products with quercetin and other hepatotoxicants.

Slit2 signaling contributes to cholestatic fibrosis in mice by activation of hepatic stellate cells

Liver Cholestasis is a widespread disease of broad etiologies and ultimately results in fibrosis, which is still lacking effective therapeutic strategies. Activation of hepatic stellate cells (HSCs) is the key event of liver fibrosis. Here, we aimed to investigate the effect and mechanism of the Slit2 signaling in cholestasis-induced liver fibrosis. Our findings revealed that the serum levels and hepatic expression of Slit2 were significantly increased in patients with primary biliary cirrhosis (PBC). Additionally, Slit2-Tg mice were much more vulnerable to BDL-induced liver injury and fibrosis compared to WT control. Slit2 up-regulation by Slit2 recombinant protein induced proliferation, and inhibited apoptosis of human HSCs cell line LX-2 via p38 and ERK signaling pathway, resulting in the activation of HSCs. In contrast, Slit2 down-regulation by siRNA silencing inhibit the activation of HSCs. In conclusion, Slit2 is involved in the activation of HSCs and liver fibrogenesis, highlighting Slit2 as a potential therapeutic target for liver fibrosis.

Hepatoprotective effects of rosmarinic acid: Insight into its mechanisms of action

Liver diseases such as hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma are one of the major health challenges in the world and many conditions such as inadequate nutrition, viral infection, ethanol and drug abuse, xenobiotic exposure, and metabolic diseases have been implicated in the development and progression of liver diseases. Several factors including lipid peroxidation, production of reactive oxygen species (ROS), peroxynitrite formation, complement factors and proinflammatory mediators, such as cytokines and chemokines, are involved in hepatic diseases. Rosmarinic acid (RA) is a natural phenolic compound found mainly in the family Lamiaceae consisting of several medicinal plants, herbs and spices. Several biological activities have been reported for RA and these include antioxidant properties as a ROS scavenger and lipid peroxidation inhibitor, anti-inflammatory, neuroprotective and antiangiogenic among others. This review is aimed at discussing the effects of RA on the liver, highlighting its hepatoprotective potential and the underlying mechanisms.

Analysis of Flavonoids Bioactivity for Cholestatic Liver Disease: Systematic Literature Search and Experimental Approaches

Flavonoids are naturally occurring compounds that show health benefits on the liver. However, there is little investigation about identification and evaluation of new flavonoid-containing drugs for cholestatic liver disease, one of the most common liver illnesses. We aimed to a systematic search regarding efficacy of flavonoids for treatment of cholestatic liver disease, and then evaluate naringenin (NG) as representative flavonoid in an obstructive cholestasis model. We searched for information of experimental and clinical studies in four major databases without time and language limits. Intervention was defined as any flavonoid derivate compared with other flavonoid, placebo, or without comparator. In addition, we evaluated NG on a bile duct-ligated model in order to contribute evidence of its actions. Eleven experimental reports that support the efficacy of flavonoids in cholestatic liver disease were identified. However, there was no homogeneity in efficacy endpoints evaluated and methodology. On the other hand, NG showed beneficial effects by improving specific metabolic (cholesterol and lipoproteins) and liver damage (bilirubin and alkaline phosphatase) biomarkers. The review lacks homogeneous evidence about efficacy of flavonoids in experimental settings, and is susceptible to risk for bias. NG only showed improvements in specific disease biomarkers. More investigation is still needed to determine its potential for drug development.

Anti-inflammatory, anti-oxidative stress and novel therapeutic targets for cholestatic liver injury

Cholestasis is a pathological process in which bile drainage is poor for a variety of reasons. Many studies have shown that cholestatic liver injury is a neutrophil-mediated inflammatory response, and oxidative stress induced by neutrophils is the main mechanism of liver cell death. The literature summarizes the bile acid signaling pathway, the neutrophil chemotaxis recruitment process during cholestasis, and the oxidative stress damage produced by neutrophil activation, summarizes the latest research progress. Sphingosine-1-phosphate receptor (S1PR) is a potential therapeutic target for cholestasis that reduces neutrophil aggregation without inhibiting systemic immune status. Early growth response factor 1 (Egr-1) may play a central role in the inflammation induced by cholestasis, and it is also a potential therapeutic target to inhibit the inflammation induced by cholestasis. Strengthening the antioxidant system of hepatocytes to cope with oxidative stress of neutrophils is a feasible treatment for cholestatic liver injury.

Protective effect of free phenolics from Lycopus lucidus Turcz. root on carbon tetrachloride-induced liver injury in vivo and in vitro

Protective effect of free phenolics from Lycopus lucidus Turcz. root (FPLR) on CCl₄-induced hepatotoxicity in vivo and in vitro was first evaluated. Oral administration of FPLR (100 mg/kg bw) to mice significantly reduced the CCl₄-induced elevation of serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, triacylglycerols, total cholesterol, and total bilirubin. FPLR also increased the hepatic GSH contents and antioxidant enzyme activities of SOD and CAT and decreased the hepatic MDA level. Histopathological examinations further confirmed that the FPLR could protect the liver from CCl₄-induced damage. Further research indicated that FPLR prevented the DNA fragmentation caused by CCl₄ based on TUNEL assay. Moreover, immunohistochemistry staining demonstrated that pretreatment with FPLR significantly inhibited the elevation of hepatic TNF-α, IL-6, IL-8, iNOS, COX-2, and Caspase-3 in CCl₄-treated mice. In vitro experiments showed that FPLR remarkably reduced BRL hepatocyte apoptosis and damage caused by CCl₄ treatment. These findings indicate that FPLR could be developed as a functional food or medication for therapeutic purpose and prevention of hepatic injury.

The effects of quercetin on oxidative stress and fibrosis markers in chronic kidney disease rat model

Background: Oxidative stress may play a role in the pathogenesis of (CKD), Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor involved in cell defense mechanism against oxidative stress. In this study, we examined the effect of quercetin, a polyphenplic antioxidant anti fibrosis compund in fruits and vegetables, on the 5/6 nephrectomy-induced CKD progression model rats through modulation of Nrf2 expression.Methods: Male Sprague-Dawley rats were randomly divided into normal control group (C), untreated 5/6 nephrectomy (Nx), quercetin-treated 5/6 nephrectomy (100 mg/kgBW/day orally) (NxQ), and captopril-treated 5/6 nephrectomy (10 mg/kgBW/day orally) (NxK) for 8 weeks. At the end of study, all animals were sacrified. Urine, blood, and kidney tissues were taken for examination of proteinuria, plasma creatinine, urea, malondialdehyde (MDA), glutathione peroxidase (GPx) activity, Nrf2, Keap1, heme oxygenase-1 (HO-1) expressions, and renal fibrosis.Results: Quercetin administration did not affect the level of protein in urine, plasma creatinine, and urea. However, it tended to reduce the level of MDA, increase GPx activity, Nrf2, Keap1, and HO-1 expression as well as the degree of fibrosis.Conclusion: In 5/6 nephrectomized rats, quercetin tended to ameliorate the level of MDA, GPx activity, Nrf2, Keap1, and HO-1 expression. In addition, quercetin tended to decrease the degree of fibrosis in the remnant kidney.

Hepatoprotective effect of quercetin via TRAF6/JNK pathway in acute hepatitis

Quercetin, as a member of the flavonoids family, has many beneficial properties. The aim of our study was to evaluate the protective effect of quercetin in ConA-induced hepatitis in mice, and to clarify its mechanism of action. Hepatitis was induced by using ConA (25 mg/kg), and quercetin was administered intragastrically at the dose of 100 mg/kg or 200 mg/kg for 5 days before ConA injection. The serum levels of liver enzymes, inflammatory cytokines and other marker proteins were determined at 2 h, 8 h and 24 h after ConA injection. Following ConA injection, serum levels of liver enzymes and inflammatory cytokines were significantly increased. Quercetin ameliorated liver damage and histopathological changes, and suppressed the release of inflammatory cytokines. The expression of Bax, Bcl-2, Beclin-1, LC3, P62 and caspase 9 were markedly affected by quercetin pretreatment. The expression of TRAF6 and p-JNK were decreased in the quercetin groups. Quercetin attenuated apoptosis and autophagy in ConA-induced autoimmune hepatitis by inhibiting TRAF6/JNK pathway.

Quercetin Pretreatment Attenuates Hepatic Ischemia Reperfusion-Induced Apoptosis and Autophagy by Inhibiting ERK/NF-κB Pathway

Background

Hepatic ischemia reperfusion (IR) injury is a common phenomenon in transplantation or trauma. The aim of the present study was to determine the protective effect of quercetin (QE) on hepatic IR injury via the ERK/NF-κB pathway.

Methods

Mice were randomized into the sham, IR, QE100 + IR, and QE200 + IR groups. Quercetin was administered intragastrically daily at two doses (100 mg/kg and 200 mg/kg) for 5 days prior to IR injury. The expression levels of liver enzymes, inflammatory cytokines, and other marker proteins were determined at 2, 8, and 24 hours after IR. And they were compared among these groups.

Results

Compared with the IR group, the treatment of QE reduced the release of cytokines, leading to inhibition of apoptosis and autophagy via downregulation of the ERK/NF-κB pathway in this model of hepatic IR injury.

Conclusion

Apoptosis and autophagy caused by hepatic IR injury were inhibited by QE following a reduction in the release of inflammatory cytokines, and the relationship between the two may be associated with inactivation of the ERK/NF-κB pathway.

Hepatoprotective activities of rosmarinic acid against extrahepatic cholestasis in rats

Though rosmarinic acid possesses nutritional, pharmaceutical, and toxic properties and shows therapeutic potential on liver diseases, its therapeutic effects against cholestatic liver diseases have not been proven. Using an extrahepatic cholestasis rat model by bile-duct ligation (BDL), daily oral administration of rosmarinic acid showed improvement effects on liver histology, serum biochemicals, ductular reaction, oxidative stress, inflammation, and fibrosis. Rosmarinic acid alleviated BDL-induced transforming growth factor beta-1 (TGF-β1) production and hepatic collagen deposition, and the anti-fibrotic effects were accompanied by reductions in matrix-producing cells and Smad2/3. BDL rats showed increased hepatic NF-κB/AP-1 activities, inflammatory cell infiltration/accumulation, and cytokine production, and these signs of hepatic inflammation were ameliorated by rosmarinic acid. Mechanistic study revealed an inhibitory effect of rosmarinic acid on the axis of the high mobility group box-1 (HMGB1)/toll-like receptor-4 (TLR4) in BDL rats. Results of cultured hepatic stellate cells further showed the impacts of rosmarinic acid which attenuated TGF-β1-induced stellate cell mitogenic and fibrogenic activation. Our findings support the concept that rosmarinic acid could serve as a hepatoprotective agent, and dietary rosmarinic acid supplementation may be beneficial in terms of improving cholestasis-related liver injury via mechanisms involving resolution of oxidative burden and down-regulation of HMGB1/TLR4, NF-κB, AP-1, and TGF-β1/Smad signaling.

Sildenafil protects against bile duct ligation induced hepatic fibrosis in rats: Potential role for silent information regulator 1 (SIRT1)

Hepatic fibrosis is a potential health problem that may end with life-threatening cirrhosis and primary liver cancer. Recent studies point out to the protective effects of silent information regulator1 (SIRT1), against different models of organs fibrosis. This work aimed to investigate the possible protective effect of sildenafil (SIRT1 activator) against hepatic fibrosis induced by bile duct ligation (BDL). Firstly, three different doses of sildenafil (5, 10, 20mg/kg/day) were investigated; to detect the most protective one against BDL induced liver dysfunction and hepatic fibrosis. The most protective dose is then used; to study its effect on BDL induced SIRT1 downregulation, imbalance of oxidant/antioxidant status, increased inflammatory cytokines and fibrosis. Sildenafil (20mg/kg/day) was the most protective one, it caused upregulation of SIRT1, reduction of hepatic malondialdehyde (MDA) content, increase in expression of nuclear factor erythroid 2-related factor 2 (Nrf2), hemeoxygenease (HO)-1, reduced glutathione (GSH) content and superoxide dismutase (SOD) activity. Hepatic content of tumor necrosis factor-α (TNF-α) and nuclear factor κB (NFκB) expression & content displayed significant reductions with sildenafil treatment, Furthermore, sildenafil caused marked reductions of transforming growth factor (TGF)-β content, expression of plasminogen activator inhibitor-1 (PAI-1), matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), α-smooth muscle actin (α-SMA), fibronectin, collagen I (α1) and hydroxyproline content. However, sildenafil protective effects were significantly reduced by co-administration of EX527 (SIRT1 inhibitor). Our work showed, for the first time that, sildenafil has promising protective effects against BDL induced liver dysfunction and hepatic fibrosis. These effects may be, in part, mediated by up regulation of SIRT1.

Induction of chronic cholestasis without liver cirrhosis - Creation of an animal model

AIM

To analyze time intervals of inflammation and regeneration in a cholestatic rat liver model.

METHODS

In 36 Lewis rats, divided into six groups of 6 animals (postoperative observation periods: 1, 2, 3, 4, 6, 8 wk), the main bile duct was ligated with two ligatures and observed for the periods mentioned above. For laboratory evaluation, cholestasis parameters (bilirubin, γ-GT), liver cell parameters (ASAT, ALAT) and liver synthesis parameters (quick, albumin) were determined. For histological analysis, HE, EvG, ASDCL and HMGB-1 stainings were performed. Furthermore, we used the mRNA of IL-33, GADD45a and p-21 for analyzing cellular stress and regeneration in cholestatic rats.

RESULTS

In chemical laboratory and histological evaluation, a distinction between acute and chronic cholestatic liver injury with identification of inflammation and regeneration could be demonstrated by an increase in cholestasis (bilirubin: 1-wk group, 156.83 ± 34.12 μmol/L, P = 0.004) and liver cell parameters (ASAT: 2-wk group, 2.1 ± 2.19 μmol/L.s, P = 0.03; ALAT: 2-wk group, 1.03 ± 0.38 μmol/L.s, P = 0.03) after bile duct ligation (BDL). Histological evaluation showed an increase of bile ducts per portal field (3-wk group, 48 ± 6.13, P = 0.004) during the first four weeks after bile duct ligation. In addition to inflammation, which is an expression of acute cholestasis, there was an increase of necrotic areas in the histological sections (2-wk group, 1.38% ± 2.28% per slide, P = 0.002). Furthermore, the inflammation could be verified by ASDCL (4-wk group, 22 ± 5.93 positive cells per portal field, P = 0.041) and HMGB-1 [2-wk group, 13 ± 8.18 positive cells per field of view (FoV), P = 0.065] staining. Therefore, in summary of the laboratory evaluation and histological studies, acute cholestasis could be found during the first four weeks after bile duct ligation. Subsequently, the described parameters declined so that chronic cholestasis could be assumed. For quantification of secondary biliary cirrhosis, eosin staining was performed, which did not reveal any signs of liver remodeling, thus precluding the development of a chronic cholestasis model. Additionally, to establish the chronic cholestasis model, we evaluated liver regeneration capacity through measurements of IL-33, p-21 and GADD45a mRNA.

CONCLUSION

We created a chronic cholestasis model. The point of inflammatory and regenerative balance was reached after four weeks. This finding should be used for experimental approaches dealing with chronic cholestatic liver damage.

Glechoma hederacea extracts attenuate cholestatic liver injury in a bile duct-ligated rat model

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, Glechoma hederacea is frequently prescribed to patients with cholelithiasis, dropsy, abscess, diabetes, inflammation, and jaundice. Polyphenolic compounds are main bioactive components of Glechoma hederacea.

AIM OF THE STUDY

This study was aimed to investigate the hepatoprotective potential of hot water extract of Glechoma hederacea against cholestatic liver injury in rats.

MATERIALS AND METHODS

Cholestatic liver injury was produced by ligating common bile ducts in Sprague-Dawley rats. Saline and hot water extract of Glechoma hederacea were orally administrated using gastric gavages. Liver tissues and bloods were collected and subjected to evaluation using histological, molecular, and biochemical approaches.

RESULTS

Using a rat model of cholestasis caused by bile duct ligation (BDL), daily oral administration of Glechoma hederacea hot water extracts showed protective effects against cholestatic liver injury, as evidenced by the improvement of serum biochemicals, ductular reaction, oxidative stress, inflammation, and fibrosis. Glechoma hederacea extracts alleviated BDL-induced transforming growth factor beta-1 (TGF-β1), connective tissue growth factor, and collagen expression, and the anti-fibrotic effects were accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad2/3 activity. Glechoma hederacea extracts attenuated BDL-induced inflammatory cell infiltration/accumulation, NF-κB and AP-1 activation, and inflammatory cytokine production. Further studies demonstrated an inhibitory effect of Glechoma hederacea extracts on the axis of high mobility group box-1 (HMGB1)/toll-like receptor-4 (TLR4) intracellular signaling pathways.

CONCLUSIONS

The hepatoprotective, anti-oxidative, anti-inflammatory, and anti-fibrotic effects of Glechoma hederacea extracts seem to be multifactorial. The beneficial effects of daily Glechoma hederacea extracts supplementation were associated with anti-oxidative, anti-inflammatory, and anti-fibrotic potential, as well as down-regulation of NF-κB, AP-1, and TGF-β/Smad signaling, probably via interference with the HMGB1/TLR4 axis.

Therapeutic Role of Functional Components in Alliums for Preventive Chronic Disease in Human Being

Objectives. Functional components in alliums have long been maintained to play a key role in modifying the major risk factors for chronic disease. To obtain a better understanding of alliums for chronic disease prevention, we conducted a systematic review for risk factors and prevention strategies for chronic disease of functional components in alliums, based on a comprehensive English literature search that was conducted using various electronic search databases, especially the PubMed, ISI Web of Science, and CNKI for the period 2007-2016. Allium genus especially garlic, onion, and Chinese chive is rich in organosulfur compounds, quercetin, flavonoids, saponins, and others, which have anticancer, preventive cardiovascular and heart diseases, anti-inflammation, antiobesity, antidiabetes, antioxidants, antimicrobial activity, neuroprotective and immunological effects, and so on. These results support Allium genus; garlic and onion especially may be the promising dietotherapeutic vegetables and organopolysulfides as well as quercetin mechanism in the treatment of chronic diseases. This review may be used as scientific basis for the development of functional food, nutraceuticals, and alternative drugs to improve the chronic diseases.

Quercetin protects liver injury induced by bile duct ligation via attenuation of Rac1 and NADPH oxidase1 expression in rats

BACKGROUND

Bile duct ligation (BDL) and subsequent cholestasis are correlated with oxidative stress, hepatocellular injury and fibrosis. Quercetin is a flavonoid with antifibrotic, and hepatoprotective properties. However, the molecular mechanism underlying quercetin-mediated hepatoprotection is not fully understood. The current study was to evaluate mechanisms of hepatoprotective effect of quercetin in BDL rat model.

METHODS

We divided male Wistar rats into 4 groups (n=8 for each): sham, sham+quercetin (30 mg/kg per day), BDL, and BDL+quercetin (30 mg/kg per day). Four weeks later, the rats were sacrificed, the blood was collected for liver enzyme measurements and liver for the measurement of Rac1, Rac1-GTP and NOX1 mRNA and protein levels by quantitative PCR and Western blotting, respectively.

RESULTS

Quercetin significantly alleviated liver injury in BDL rats as evidenced by histology and reduced liver enzymes. Furthermore, the mRNA and protein expression of Rac1, Rac1-GTP and NOX1 were significantly increased in BDL rats compared with those in the sham group (P<0.05); quercetin treatment reversed these variables back toward normal (P<0.05). Another interesting finding was that the antioxidant markers e.g. superoxide dismutase and catalase were elevated in quercetin-treated BDL rats compared to BDL rats (P<0.05).

CONCLUSION

Quercetin demonstrated hepatoprotective activity against BDL-induced liver injury through increasing antioxidant capacity of the liver tissue, while preventing the production of Rac1, Rac1-GTP and NOX1 proteins.

MicroRNAs regulate hepatic fibrosis via TGF-β/Smad pathway

Studies have shown that transforming growth factor-β (TGF-β) is one of the most important factors to promote hepatic fibrosis (HF), and the TGF-β/Smad pathway is a major signaling pathway involved in HF. Abnormal expression of microRNAs (miRNAs) has a key role in the development of HF. In recent years, studies suggest that regulating miRNAs may affect the TGF-β/Smad pathway. This paper discusses the TGF-β/Smad pathway and the related miRNAs that are associated with HF.

Quercetin Improves Glucose and Lipid Metabolism of Diabetic Rats: Involvement of Akt Signaling and SIRT1

Glucose and lipid metabolism disorder in diabetes mellitus often causes damage to multiple tissues and organs. Diabetes mellitus is beneficially affected by quercetin. However, its concrete mechanisms are yet to be fully elucidated. In our study, diabetes was induced in Sprague-Dawley rats by STZ injection. The rats were randomly divided into normal control, diabetic model, low-dose quercetin treatment, high-dose quercetin treatment, and pioglitazone treatment groups. Fasting blood glucose was collected to evaluate diabetes. Immunohistochemistry and fluorometric assay were performed to explore SIRT1. Akt levels were measured through immunoprecipitation and Western blot. After 12 weeks of quercetin treatment, the biochemical parameters of glucose and lipid metabolism improved to varying degrees. Hepatic histomorphological injury was alleviated, and hepatic glycogen content was increased. The expression and activity of hepatic SIRT1 were enhanced, and Akt was activated by phosphorylation and deacetylation. These results suggested that the beneficial effects of quercetin on glucose and lipid metabolism disorder are probably associated with the upregulated activity and protein level of SIRT1 and its influence on Akt signaling pathway. Hence, quercetin shows potential for the treatment of glucose and lipid metabolism disorder in diabetes mellitus.

Quercetin and derivatives: useful tools in inflammation and pain management

Inflammation represents a very frequent condition in humans; it is often underestimated, making the problem an increasingly alarming phenomenon. For these reasons, conventional therapies are losing their effectiveness, leaving room for innovative therapies. In this field, natural products showed their efficacy in various diseases; and flavonoids, in particular quercetin, is known for its broad range of activities. In this review, we have highlighted its efficacy in various models of inflammation, focusing also on the activity of its semisynthetic derivatives, and those naturally present in plant extracts. Finally, the analgesic property of quercetin, intrinsically linked to its anti-inflammatory action, has been also evaluated, to investigate about an innovative approach to this interesting natural compound, such as analgesic remedial.

AP-1 Inhibition by SR 11302 Protects Human Hepatoma HepG2 Cells from Bile Acid-Induced Cytotoxicity by Restoring the NOS-3 Expression

The harmful effects of bile acid accumulation occurring during cholestatic liver diseases have been associated with oxidative stress increase and endothelial nitric oxide synthase (NOS-3) expression decrease in liver cells. We have previously reported that glycochenodeoxycholic acid (GCDCA) down-regulates gene expression by increasing SP1 binding to the NOS-3 promoter in an oxidative stress dependent manner. In the present study, we aimed to investigate the role of transcription factor (TF) AP-1 on the NOS-3 deregulation during GCDCA-induced cholestasis. The cytotoxic response to GCDCA was characterized by 1) the increased expression and activation of TFs cJun and c-Fos; 2) a higher binding capability of these at position -666 of the NOS-3 promoter; 3) a decrease of the transcriptional activity of the promoter and the expression and activity of NOS-3; and 4) the expression increase of cyclin D1. Specific inhibition of AP-1 by the retinoid SR 11302 counteracted the cytotoxic effects induced by GCDCA while promoting NOS-3 expression recovery and cyclin D1 reduction. NOS activity inhibition by L-NAME inhibited the protective effect of SR 11302. Inducible NOS isoform was no detected in this experimental model of cholestasis. Our data provide direct evidence for the involvement of AP-1 in the NOS-3 expression regulation during cholestasis and define a critical role for NOS-3 in regulating the expression of cyclin D1 during the cell damage induced by bile acids. AP-1 appears as a potential therapeutic target in cholestatic liver diseases given its role as a transcriptional repressor of NOS-3.

Naringenin prevents TGF-β1 secretion from breast cancer and suppresses pulmonary metastasis by inhibiting PKC activation

BACKGROUND

Targeting the TGF-β1 pathway for breast cancer metastasis therapy has become an attractive strategy. We have previously demonstrated that naringenin significantly reduced TGF-β1 levels in bleomycin-induced lung fibrosis and effectively prevented pulmonary metastases of tumors. This raised the question of whether naringenin can block TGF-β1 secretion from breast cancer cells and inhibit their pulmonary metastasis.

METHODS

We transduced a lentiviral vector encoding the mouse Tgf-β1 gene into mouse breast carcinoma (4T1-Luc2) cells and inoculated the transformant cells (4T1/TGF-β1) into the fourth primary fat pat of Balb/c mice. Pulmonary metastases derived from the primary tumors were monitored using bioluminescent imaging. Spleens, lungs and serum (n = 18-20 per treatment group) were analyzed for immune cell activity and TGF-β1 level. The mechanism whereby naringenin decreases TGF-β1 secretion from breast cancer cells was investigated at different levels, including Tgf-β1 transcription, mRNA stability, translation, and extracellular release.

RESULTS

In contrast to the null-vector control (4T1/RFP) tumors, extensive pulmonary metastases derived from 4T1/TGF-β1 tumors were observed. Administration of the TGF-β1 blocking antibody 1D11 or naringenin showed an inhibition of pulmonary metastasis for both 4T1/TGF-β1 tumors and 4T1/RFP tumors, resulting in increased survival of the mice. Compared with 4T1/RFP bearing mice, systemic immunosuppression in 4T1/TGF-β1 bearing mice was observed, represented by a higher proportion of regulatory T cells and myeloid-derived suppressor cells and a lower proportion of activated T cells and INFγ expression in CD8(+) T cells. These metrics were improved by administration of 1D11 or naringenin. However, compared with 1D11, which neutralized secreted TGF-β1 but did not affect intracellular TGF-β1 levels, naringenin reduced the secretion of TGF-β1 from the cells, leading to an accumulation of intracellular TGF-β1. Further experiments revealed that naringenin had no effect on Tgf-β1 transcription, mRNA decay or protein translation, but prevented TGF-β1 transport from the trans-Golgi network by inhibiting PKC activity.

CONCLUSIONS

Naringenin blocks TGF-β1 trafficking from the trans-Golgi network by suppressing PKC activity, resulting in a reduction of TGF-β1 secretion from breast cancer cells. This finding suggests that naringenin may be an attractive therapeutic candidate for TGF-β1 related diseases.

Paeonol and danshensu combination attenuates apoptosis in myocardial infarcted rats by inhibiting oxidative stress: Roles of Nrf2/HO-1 and PI3K/Akt pathway

Paeonol and danshensu is the representative active ingredient of traditional Chinese medicinal herbs Cortex Moutan and Radix Salviae Milthiorrhizae, respectively. Paeonol and danshensu combination (PDSS) has putative cardioprotective effects in treating ischemic heart disease (IHD). However, the evidence for the protective effect is scarce and the pharmacological mechanisms of the combination remain unclear. The present study was designed to investigate the protective effect of PDSS on isoproterenol (ISO)-induced myocardial infarction in rats and to elucidate the potential mechanism. Assays of creatine kinase-MB, cardiac troponin I and T and histopathological analysis revealed PDSS significantly prevented myocardial injury induced by ISO. The ISO-induced profound elevation of oxidative stress was also suppressed by PDSS. TUNEL and caspase-3 activity assay showed that PDSS significantly inhibited apoptosis in myocardia. In exploring the underlying mechanisms of PDSS, we found PDSS enhanced the nuclear translocation of Nrf2 in myocardial injured rats. Furthermore, PDSS increased phosphorylated PI3K and Akt, which may in turn activate antioxidative and antiapoptotic signaling events in rat. These present findings demonstrated that PDSS exerts significant cardioprotective effects against ISO-induced myocardial infarction in rats. The protective effect is, at least partly, via activation of Nrf2/HO-1 signaling and involvement of the PI3K/Akt cell survival signaling pathway.

EXOCRINE FUNCTION OF THE LIVER IN RATS WITH EXPOSURE TO CОRVITIN

In acute experiments on rats with cannulated bile duct we studied the effect of Corvitin, water-soluble analogue of quercetin, on secretion of bile. Intraportal administration of the test compound at doses of 2,5; 5 and 10 mg/kg resulted in a significant increase in the volume of secreted bile by 20,9, 31,2 and 20,4%, respectively, as compared with the control. Using the method of thin layer chromatography it was established the mild stimulating effect of Corvitin on the processes of bile acids conjugation with taurine and glycine, especially when administered at a dose of 5 mg/kg. This flavonoid did not affect the concentration of glycocholic acid, however increased the content of glycochenodeoxycholic and glycodeoxycholic acids in the mixture between 15 to 35,1%. Regarding free bile acids, the concentration of cholic acid, chenodeoxycholic and deoxycholic acids in the mixture was increased significantly relative to control only after Corvitin application at dose 10 mg/ kg. In the first case – from 17,9 to 29,8%, in the second – from 25 to 65,4%. At the dose of 5 mg/kg, Corvitin significantly increased the ratio of bile cholates conjugation (maximum by 23,2%), whereas 10 mg/kg of the drug decreased this index by 27,0%. After administration of Corvitin, the hydroxylation ratio in all experimental groups differed little from the control: at the dose of 5 and 10 mg/kg this parameter decreased by 14%. Thus, Corvitin modulates exocrine function of the liver, causing an increase in bile secretion and concentration of different cholates, dose-dependently increasing or decreasing the effectiveness of multienzyme systems providing processes of bile acids conjugation in rats.