The amelioration of N-acetyl-p-benzoquinone imine toxicity by ginsenoside Rg3: the role of Nrf2-mediated detoxification and Mrp1/Mrp3 transports

The pharmacological role of Ginsenoside Rg3 in liver diseases: A review on molecular mechanisms

Liver diseases are a significant global health burden and are among the most common diseases. Ginssennoside Rg3 (Rg3), which is one of the most abundant ginsenosides, has been found to have significant preventive and therapeutic effects against various types of diseases with minimal side effects. Numerous studies have demonstrated the significant preventive and therapeutic effects of Rg3 on various liver diseases such as viral hepatitis, acute liver injury, nonalcoholic liver diseases (NAFLD), liver fibrosis and hepatocellular carcinoma (HCC). The underlying molecular mechanism behind these effects is attributed to apoptosis, autophagy, antioxidant, anti-inflammatory activities, and the regulation of multiple signaling pathways. This review provides a comprehensive description of the potential molecular mechanisms of Rg3 in the development of liver diseases. The article focuses on the regulation of apoptosis, oxidative stress, autophagy, inflammation, and other related factors. Additionally, the review discusses combination therapy and liver targeting strategy, which can accelerate the translation of Rg3 from bench to bedside. Overall, this article serves as a valuable reference for researchers and clinicians alike.

Acetaminophen-induced liver injury: Molecular mechanism and treatments from natural products

Acetaminophen (APAP) is a widely used analgesic and antipyretic over-the-counter medicine worldwide. Hepatotoxicity caused by APAP overdose is one of the leading causes of acute liver failure (ALF) in the US and in some parts of Europe, limiting its clinical application. Excessive APAP metabolism depletes glutathione and increases N-acetyl-p-benzoquinoneimide (NAPQI) levels, leading to oxidative stress, DNA damage, and cell necrosis in the liver, which in turn leads to liver damage. Studies have shown that natural products such as polyphenols, terpenes, anthraquinones, and sulforaphane can activate the hepatocyte antioxidant defense system with Nrf2 as the core player, reduce oxidative stress damage, and protect the liver. As the key enzyme metabolizing APAP into NAPQI, cytochrome P450 enzymes are also considered to be intriguing target for the treatment of APAP-induced liver injury. Here, we systematically review the hepatoprotective activity and molecular mechanisms of the natural products that are found to counteract the hepatotoxicity caused by APAP, providing reference information for future preclinical and clinical trials of such natural products.

Ginsenoside Rg3 Reduces the Toxicity of Graphene Oxide Used for pH-Responsive Delivery of Doxorubicin to Liver and Breast Cancer Cells

Doxorubicin (DOX) is extensively used in chemotherapy, but it has serious side effects and is inefficient against some cancers, e.g., hepatocarcinoma. To ameliorate the delivery of DOX and reduce its side effects, we designed a pH-responsive delivery system based on graphene oxide (GO) that is capable of a targeted drug release in the acidic tumor microenvironment. GO itself disrupted glutathione biosynthesis and induced reactive oxygen species (ROS) accumulation in human cells. It induced IL17-directed JAK-STAT signaling and VEGF gene expression, leading to increased cell proliferation as an unwanted effect. To counter this, GO was conjugated with the antioxidant, ginsenoside Rg3, prior to loading with DOX. The conjugation of Rg3 to GO significantly reduced the toxicity of the GO carrier by abolishing ROS production. Furthermore, treatment of cells with GO-Rg3 did not induce IL17-directed JAK-STAT signaling and VEGF gene expression-nor cell proliferation-suggesting GO-Rg3 as a promising drug carrier. The anticancer activity of GO-Rg3-DOX conjugates was investigated against Huh7 hepatocarcinoma and MDA-MB-231 breast cancer cells. GO-Rg3-DOX conjugates significantly reduced cancer cell viability, primarily via downregulation of transcription regulatory genes and upregulation of apoptosis genes. GO-Rg3 is an effective, biocompatible, and pH responsive DOX carrier with potential to improve chemotherapy-at least against liver and breast cancers.

Mitophagy and endoplasmic reticulum-phagy accelerated by a p62 ZZ ligand alleviates paracetamol-induced hepatotoxicity

BACKGROUND AND PURPOSE

Paracetamol (acetaminophen)-induced hepatotoxicity is the leading cause of drug-induced liver injury worldwide. Autophagy is a degradative process by which various cargoes are collected by the autophagic receptors such as p62/SQSTM1/Sequestosome-1 for lysosomal degradation. Here, we investigated the protective role of p62-dependent autophagy in paracetamol-induced liver injury.

EXPERIMENTAL APPROACH

Paracetamol-induced hepatotoxicity was induced by a single i.p. injection of paracetamol (500 mg·kg^-1 ) in C57/BL6 male mice. YTK-2205 (20 mg·kg^-1 ), a p62 agonist targeting ZZ domain, was co- or post-administered with paracetamol. Western blotting and immunocytochemistry were performed to explore the mechanism.

KEY RESULTS

N-terminal arginylation of the molecular chaperone calreticulin retro-translocated from the endoplasmic reticulum (ER) was induced in the livers undergoing paracetamol-induced hepatotoxicity, and YTK-2205 exhibited notable therapeutic efficacy in acute hepatotoxicity as assessed by the levels of serum alanine aminotransferase and hepatic necrosis. This efficacy was significantly attributed to accelerated degradation of ubiquitin (Ub) conjugates as well as damaged mitochondria (mitophagy) and endoplasmic reticulum (ER-phagy). In primary murine hepatocytes treated with paracetamol, YTK-2205 induced the co-localization of p62⁺ LC3⁺ phagophores to the sites of mitophagy and ER-phagy. A similar activity of YTK-2205 was observed with N-acetyl-p-benzoquinone imine, a putative toxic metabolite of paracetamol in Hep3B cells.

CONCLUSION AND IMPLICATIONS

Our results elucidated that p62-dependent autophagy plays a key role in the removal of cytotoxic materials such as damaged mitochondria in paracetamol-induced hepatotoxicity. Small molecule ligands to p62 may be developed into drugs to treat this pathological condition.

Ginsenoside Rg3 induces apoptosis and inhibits proliferation by down-regulating TIGAR in rats with gastric precancerous lesions

BACKGROUND

Ginsenoside Rg3 (GRg3) is one of the main active ingredients in Chinese ginseng extract and has various biological effects, such as immune-enhancing, antitumour, antiangiogenic, immunomodulatory and anti-inflammatory effects. This study aimed to investigate the therapeutic effect of GRg3 on gastric precancerous lesion (GPL) induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and the potential mechanism of action.

METHODS

The MNNG-ammonia composite modelling method was used to establish a rat model of GPL. Histopathological changes in the rat gastric mucosa were observed by pathological analysis using haematoxylin-eosin staining to assess the success rate of the composite modelling method. Alcian blue-periodic acid Schiff staining was used to observe intestinal metaplasia in the rat gastric mucosa. Apoptosis was detected in rat gastric mucosal cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling staining. The production level of reactive oxygen species (ROS) was determined by the dihydroethidium fluorescent probe method, and that of TP53-induced glycolysis and apoptosis regulator (TIGAR) protein was determined by immunohistochemical staining and western blotting. The production levels of nicotinamide adenine dinucleotide phosphate (NADP) and glucose-6-phosphate dehydrogenase (G6PDH) were determined by an enzyme-linked immunosorbent assay, and that of glutathione (GSH) was determined by microanalysis.

RESULTS

GRg3 significantly alleviated the structural disorganization and cellular heteromorphism in the form of epithelial glands in the gastric mucosa of rats with GPL and retarded the progression of the disease. Overexpression of TIGAR and overproduction of NADP, GSH and G6PDH occurred in the gastric mucosal epithelium of rats with GPL, which in turn led to an increase in the ROS concentration. After treatment with GRg3, the expression of TIGAR and production of NADP, GSH G6PDH decreased, causing a further increase in the concentration of ROS in the gastric mucosal epithelium, which in turn induced apoptosis and played a role in inhibiting the abnormal proliferation and differentiation of gastric mucosal epithelial cells.

CONCLUSION

Grg3 can induce apoptosis and inhibit cell proliferation in MNNG-induced GPL rats. The mechanism may be related to down-regulating the expression levels of TIGAR and production levels of GSH, NADP and G6PD, and up-regulating the concentration of ROS.

Dietary phenolic-type Nrf2-activators: implications in the control of toxin-induced hepatic disorders

Numerous studies have exemplified the importance of nuclear factor erythroid 2-related factor 2 (Nrf2) activation in the alleviation of toxin-induced hepatic disorders primarily through eliminating oxidative stress. Whereafter, increasingly more efforts have been contributed to finding Nrf2-activators, especially from dietary polyphenols. The present review summarized the phenolic-type Nrf2-activators published in the past few decades, analyzed their effectiveness based on their structural characteristics and outlined their related mechanisms. It turns out that flavonoids are the largest group of phenolic-type Nrf2-activators, followed by nonflavonoids and phenolic acids. When counting on subgroups, the top three types are flavonols, flavones, and hydroxycinnamic acids, with curcuminoids having the highest effective doses. Moreover, most polyphenols work through the phosphorylation of Nrf2. Besides, mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt) are the frequent targets of these Nrf2-activators, which indirectly mediate the behavior of Nrf2. However, current data are not sufficient to conclude any structure-activity relationship.

Lupeol ameliorates LPS/D-GalN induced acute hepatic damage by suppressing inflammation and oxidative stress through TGFβ1-Nrf2 signal pathway

Acute hepatic damage is a severe condition characterized by inflammation and oxidative stress, which is a serious threat to people's life and health. But there are few effective treatments for acute liver injury. Therefore, safe and effective therapeutic approaches for preventing acute liver damage are urgently needed. Lupeol is a natural compound, which has significant antioxidant and anti-inflammatory properties in liver disease. However, the protective mechanism of lupeol against acute liver injury remains unclear. Here, zebrafish and mutant mice were utilized to investigate the protective effects of lupeol against lipopolysaccharide (LPS)/ D-galactosamine(D-GalN) -induced liver injury and the underlying mechanisms. We found that pretreatment with lupeol attenuated the LPS/D-GalN-induced liver injury by decreasing the infiltration of inflammatory cells and reducing pro-inflammatory cytokines. We also demonstrated that lupeol could protect injured liver from oxidative stress by downregulating the expression of TGFβ1 and upregulating Nrf2. Notably, our experimental results provided the support that lupeol effectively protected against LPS/D-GalN-induced acute liver injury via suppression of inflammation response and oxidative stress, which were largely dependent on the upregulation of the Nrf2 pathway via downregulating TGFβ1.

Ginsenoside Rg3 ameliorates acetaminophen-induced hepatotoxicity by suppressing inflammation and oxidative stress

OBJECTIVES

Improper usage of acetaminophen (APAP) leads to morbidity and also mortality secondary to liver damage. Ginseng could suppress APAP-induced hepatotoxicity and ginsenoside Rg3 is a kind of major component in ginseng against liver damage. Herein, we intended to estimate the beneficial function and molecular mechanism of Rg3 on APAP-caused hepatotoxicity and identified hepatoprotection.

METHODS

A total of 50 C57BL/6J mice were divided into five random groups, and each contains 10 mice as the control, acetaminophen (350 mg/kg) and Rg3 (5, 10 and 20 mg/kg) + acetaminophen (350 mg/kg) groups. These mice were intragastric administration a single dose of acetaminophen by oral treatment behind pre-administered with several doses of ginsenoside Rg3 for six hours.

KEY FINDINGS

According to our data, the injection of APAP (350 mg/kg) enhanced the basal levels of alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase and lactic dehydrogenase. However, these abnormal added were alleviated by Rg3. Moreover, Rg3 treatment obviously relieved APAP-caused inflammation and oxidant in liver tissues. The depletion of glutathione, glutathione peroxidase, total antioxidant capacity and generation of malondialdehyde induced by APAP treatment were reduced by Rg3. By H&E staining, Rg3 effectively reduced APAP-caused apoptosis and inflammatory infiltration. Moreover, Rg3 attenuated APAP-caused hepatic damage in part by regulating the pro-inflammatory and anti-inflammatory cytokines. Moreover, we found that Rg3 could bind to NLRP3 suggesting the anti-inflammatory effects of Rg3 by molecular docking study.

CONCLUSIONS

In summary, Rg3 showed hepatic protective function in APAP-induced hepatotoxicity as evidenced by a reduction of the oxidant and the inflammatory reply, relieve of hepatocellular damage, showing potential in Rg3 as a potential therapeutic medicine to prevent hepatic injury.

An UPLC-MS/MS Method for Determination of Osimertinib in Rat Plasma: Application to Investigating the Effect of Ginsenoside Rg3 on the Pharmacokinetics of Osimertinib

Osimertinib is a novel oral, potent, and irreversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) for treatment of advanced T790M mutation-positive advanced non-small cell lung cancer, which is commonly combined with ginsenoside Rg3 in clinic to enhance the efficacy and minimize adverse reactions. In the present study, a highly sensitive UPLC-MS/MS method was established and validated for analysis of osimertinib in rat plasma according to US FDA guideline. Separation was performed on a C18 (2.1 × 50 mm, 2.6 μm) column using a gradient elution of ammonium formate (10 mM) with 0.1% formic acid buffer (A) and ACN (B) at a flow rate of 0.2 mL/min. Detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization in the MRM mode. The method was validated over a concentration range of 1-400 ng/mL for osimertinib. The intra- and interday accuracy and precision values were within ±15%. No significant degradation occurred under the experimental conditions in stability assays. There was a further investigation on the effects of multiple doses of ginsenoside Rg3 on the pharmacokinetics of osimertinib in rats for the first time. The results implied that osimertinib exhibited a slow absorption and moderate-rate elimination in rats following oral administration. Coadministeration with ginsenoside Rg3 (5 mg/kg, 7 days, i.g.) may have no effect on the pharmacokinetics of osimertinib in rats. The results provide a reference for the clinical concomitant medications of Rg3 and osimertinib.

Panax ginseng C.A. Meyer (Rg3) Ameliorates Gastric Precancerous Lesions in Atp4a-/- Mice via Inhibition of Glycolysis through PI3K/AKT/miRNA-21 Pathway

Gastric cancer, one of the most common types of cancers, develops over a series of consecutive histopathological stages. As such, the analysis and research of the gastric precancerous lesions (GPLs) play an important role in preventing the occurrence of gastric cancer. Ginsenoside Rg3 (Rg3), an herbal medicine, plays an important role in the prevention and treatment of various cancers. Studies have demonstrated a correlation between glycolysis and gastric cancer progression. Herein, the aim of the present study was to clarify the potential role for glycolysis pathogenesis in Rg3-treated GPL in Atp4a^−/− mice. The GPL mice model showed chronic gastritis, intestinal metaplasia, and more atypical hyperplasia in gastric mucosa. According to the results of HE and AB-PAS staining, it could be confirmed that GPL mice were obviously reversed by Rg3. Additionally, the increased protein levels of PI3K, AKT, mTOR, HIF-1α, LDHA, and HK-II, which are crucial factors for evaluating GPL in the aspect of glycolysis pathogenesis in the model group, were downregulated by Rg3. Meanwhile, the miRNA-21 expression was decreased and upregulated by Rg3. Furthermore, the increased gene levels of Bcl-2 and caspase-3 were attenuated in Rg3-treated GPL mice. In conclusion, the findings of this study imply that abnormal glycolysis in GPL mice was relieved by Rg3 via regulation of the expressions of PI3K, AKT, mTOR, HIF-1α, LDHA, HK-II, and miRNA-21. Rg3 is an effective supplement for GPL treatment and can be harnessed to inhibit proliferation and induce apoptosis of GPL cells.

Montelukast Prevents Mice Against Acetaminophen-Induced Liver Injury

Acetaminophen (APAP) is a widely used over-the-counter antipyretic and analgesic drug. Overdose of APAP is the leading cause of hospital admission for acute liver failure. Montelukast is an antagonist of cysteinyl leukotriene receptor 1 (Cysltr1), which protects from inflammation and oxidative stress. However, the function of montelukast in APAP-induced hepatotoxicity remains unknown. In this study, we examined whether pharmacological inhibition of Cystlr1 could protect mice against APAP-induced hepatic damage. We found that APAP treatment upregulated messenger RNA and protein levels of Cysltr1 both in vitro and in vivo. Pharmacological inhibition of Cysltr1 by montelukast ameliorated APAP-induced acute liver failure. The hepatoprotective effect of montelukast was associated with upregulation of hepatic glutathione/glutathione disulfide level, reduction in c-Jun-NH2-terminal kinase activation and oxidative stress. In mouse primary hepatocytes, inhibition of Cysltr1 by montelukast ameliorated the expression of inflammatory-related genes and APAP-induced cytotoxicity. We conclude that montelukast may be used to treat APAP-induced acute hepatic injury.

Ginsenoside Rg3 Prolongs Survival of the Orthotopic Hepatocellular Carcinoma Model by Inducing Apoptosis and Inhibiting Angiogenesis

Aim

Microvessel density is a marker of tumor angiogenesis activity for development and metastasis. Our preliminary study showed that ginsenoside Rg3 (Rg3) induces apoptosis in hepatocellular carcinoma (HCC) in vitro. The aim of this study was to investigate the cross-link for apoptosis induction and antiangiogenesis effect of Rg3 on orthotopic HCC in vivo.

Methods

The murine HCC cells Hep1-6 were implanted in the liver of mouse. With oral feeding of Rg3 (10 mg/kg once a day for 30 days), the quantitative analysis of apoptosis was performed by using pathology and a transmission electron microscope and microvessel density was quantitatively measured by immunohistochemical staining of the CD105 antibody. The mice treated with Rg3 (n = 10) were compared with the control (n = 10) using Kaplan-Meier analysis. Animal weight and tumor weight were measured to determine the toxicity of Rg3 and antitumor effect on an orthotopic HCC tumor model.

Results

With oral feeding of Rg3 daily in the first 30 days on tumor implantation, Rg3 significantly decreased the orthotopic tumor growth and increased the survival of animals (P < 0.05). Rg3-treated mice showed a longer survival than the control (P < 0.05). Rg3 treatment induced apoptosis and inhibited angiogenesis. They contributed to the tumor shrinkage. Rg3 initialized the tumor apoptotic progress, which then weakened the tumor volume and its capability to produce the vascularized network for further growth of the tumor and remote metastasis.

Conclusion

Rg3 inhibited the activation of microtumor vessel formation in vivo besides its apoptosis induction. Rg3 may be used as an adjuvant agent in the clinical HCC treatment regimen.

Free radicals, antioxidants, nuclear factor-E2-related factor-2 and liver damage

Oxidative/nitrosative stress is proposed to be a critical factor in various diseases, including liver pathologies. Antioxidants derived from medicinal plants have been studied extensively and are relevant to many illnesses, including liver diseases. Several hepatic disorders, such as viral hepatitis and alcoholic or nonalcoholic steatohepatitis, involve free radicals/oxidative stress as agents that cause or at least exacerbate liver injury, which can result in chronic liver diseases, such as liver fibrosis, cirrhosis and end-stage hepatocellular carcinoma. In this scenario, nuclear factor-E2-related factor-2 (Nrf2) appears to be an essential factor to counteract or attenuate oxidative or nitrosative stress in hepatic cells. In fact, a growing body of evidence indicates that Nrf2 plays complex and multicellular roles in hepatic inflammation, fibrosis, hepatocarcinogenesis and regeneration via the induction of its target genes. Inflammation is the most common feature of chronic liver diseases, triggering fibrosis, cirrhosis and hepatocellular carcinoma. Increasing evidence indicates that Nrf2 counteracts the proinflammatory process by modulating the recruitment of inflammatory cells and inducing the endogenous antioxidant response of the cell. In this review, the interactions between antioxidant and inflammatory molecular pathways are analyzed.

Schisandra chinensis acidic polysaccharide partialy reverses acetaminophen-induced liver injury in mice

Schisandra chinensis is a hepatoprotective herb that has been used for centuries in China. Polysaccharide is one of the major active components in S. chinensis, which has been reported to improve liver injuries induced by carbon tetrachloride, alcohol, or high-fat diet. In this study, we observed the effects and corresponding mechanisms of the secondary component of Schisandra polysaccharide (acidic polysaccharide, SCAP) on a murine model of severe acute liver injury induced by acetaminophen (APAP). SCAP significantly decreased the serum alanine aminotransferase (ALT), aspartate aminotransferas (AST), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) levels, and was found to alleviate hepatic pathological alterations in the mouse model. Meanwhile, SCAP revealed a protective effects on the liver injury-related enzymes and factors, such as significantly diminished malondialdehyde (MDA) levels and glutathione (GSH) depletion, reduced ratio of B-cell lymphoma-2 (Bcl-2)-associated X protein (Bax)/Bcl-2, prohibited cleaved caspase-3 expression, and elevated the expression of p-AMPK, p-Akt, p-glycogen synthase kinase 3β (GSK 3β), nuclear factor erythroid 2-derived-like 2 (Nrf 2) and heme oxygenase-1 (HO-1) proteins in the liver tissues of the mouse model. In conclusion, we speculated that the protective activities of SCAP on the APAP-induced mouse model of acute liver injury might be related to its antioxidation, anti-inflammation and anti-apoptosis properties.

Therapeutic Potential of Plants and Plant Derived Phytochemicals against Acetaminophen-Induced Liver Injury

Acetaminophen (APAP), which is also known as paracetamol or N-acetyl-p-aminophenol is a safe and potent drug for fever, pain and inflammation when used at its normal therapeutic doses. It is available as over-the-counter drug and used by all the age groups. The overdose results in acute liver failure that often requires liver transplantation. Current clinical therapy for APAP-induced liver toxicity is the administration of N-acetyl-cysteine (NAC), a sulphydryl compound an approved drug which acts by replenishing cellular glutathione (GSH) stores in the liver. Over the past five decades, several studies indicate that the safety and efficacy of herbal extracts or plant derived compounds that are used either as monotherapy or as an adjunct therapy along with conventional medicines for hepatotoxicity have shown favorable responses. Phytochemicals mitigate necrotic cell death and protect against APAP-induced liver toxicityby restoring cellular antioxidant defense system, limiting oxidative stress and subsequently protecting mitochondrial dysfunction and inflammation. Recent experimental evidences indicat that these phytochemicals also regulate differential gene expression to modulate various cellular pathways that are implicated in cellular protection. Therefore, in this review, we highlight the role of the phytochemicals, which are shown to be efficacious in clinically relevant APAP-induced hepatotoxicity experimental models. In this review, we have made comprehensive attempt to delineate the molecular mechanism and the cellular targets that are modulated by the phytochemicals to mediate the cytoprotective effect against APAP-induced hepatotoxicity. In this review, we have also defined the challenges and scope of phytochemicals to be developed as drugs to target APAP-induced hepatotoxicity.

Saponins (Ginsenosides) from the Leaves of Panax quinquefolius Ameliorated Acetaminophen-Induced Hepatotoxicity in Mice

Acetaminophen (APAP) overdose is one of the most common inducements of drug-induced liver injury (DILI) in the world. The main purpose of this paper was to investigate the liver protection activity of saponins (ginsenosides) from the leaves of Panax quinquefolius (PQS) against APAP-induced hepatotoxicity, and the involved mechanisms were demonstrated for the first time. Mice were pretreated with PQS (150 and 300 mg/kg) by oral gavage for 7 days before being treated with 250 mg/kg APAP. Severe liver injury was exerted at 24 h post-APAP, and hepatotoxicity was assessed. Our results showed that pretreatment with PQS significantly decreased the serum alanine aminotransferase (ALT), aspartate transaminase (AST), tumor necrosis factor (TNF-α), and interleukin-1β (IL-1β) levels in a dose-dependent manner as compared to the APAP administration. Meanwhile, compared with that in the APAP group, PQS decreased hepatic malondialdehyde (MDA) contents and 4-hydroxynonenal (4-HNE) expression and restored reduced glutathione (GSH) content and superoxide dismutase (SOD) activity in livers of mice. PQS inhibited the overexpression of pro-inflammatory factors cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in the liver tissues. Furthermore, Western blotting analysis revealed that PQS pretreatment inhibited the activation of apoptotic signaling pathways via increase of Bcl-2 and decrease of Bax and caspase-3 protein expression levels. Liver histopathological observation provided further evidence that PQS pretreatment significantly inhibited APAP-induced hepatocyte necrosis, inflammatory cell infiltration, and congestion. Biological indicators of nitrative stress such as 3-nitrotyrosine (3-NT) were inhibited after PQS pretreatment, compared to the APAP group. The present study clearly demonstrates that PQS exerts a protective effect against APAP-induced hepatic injury because of its antioxidant, anti-apoptotic, and anti-inflammatory activities. The findings from the present investigation show that PQS might be a promising candidate treatment agent against drug-induced ALI.

Ameliorative Effects and Possible Molecular Mechanism of Action of Black Ginseng (Panax ginseng) on Acetaminophen-Mediated Liver Injury

Background: Frequent overdosing of acetaminophen (APAP) has become the major cause of acute liver injury (ALI). The present study aimed to evaluate the potential hepatoprotective effects of black ginseng (BG) on APAP-induced mice liver injuries and the underlying mechanisms of action were further investigated for the first time. Methods: Mice were treated with BG (300, 600 mg/kg) by oral gavage once a day for seven days. On the 7th day, all mice were treated with 250 mg/kg APAP which caused severe liver injury after 24 h and hepatotoxicity was assessed. Results: Our results showed that pretreatment with BG significantly decreased the levels of serum alanine aminotransferase (ALT) and aspartate transaminase (AST) compared with the APAP group. Meanwhile, hepatic antioxidant including glutathione (GSH) was elevated compared with the APAP group. In contrast, a significant decrease of the levels of the lipid peroxidation product malondialdehyde (MDA) was observed in the BG-treated groups compared with the APAP group. These effects were associated with significant increases of cytochrome P450 E1 (CYP2E1) and 4-hydroxynonenal (4-HNE) levels in liver tissues. Moreover, BG supplementation suppressed activation of apoptotic pathways through increasing Bcl-2 and decreasing Bax protein expression levels according to western blotting analysis. Histopathological examination revealed that BG pretreatment significantly inhibited APAP-induced necrosis and inflammatory infiltration in liver tissues. Biological indicators of nitrative stress like 3-nitrotyrosine (3-NT) were also inhibited after pretreatment with BG, compared with the APAP group. Conclusions: The results clearly suggest that the underlying molecular mechanisms of action of BG-mediated alleviation of APAP-induced hepatotoxicity may involve its anti-oxidant, anti-apoptotic, anti-inflammatory and anti-nitrative effects.

Regeneration of glutathione by α-lipoic acid via Nrf2/ARE signaling pathway alleviates cadmium-induced HepG2 cell toxicity

Alpha-lipoic acid (α-LA) is an important antioxidant that is capable of regenerating other antioxidants, such as glutathione (GSH). However, the underlying molecular mechanism by which α-LA regenerates GSH remains poorly understood. The current study aimed to investigate whether α-LA regenerates GSH by activation of Nrf2 to alleviate cadmium-induced cytotoxicity in HepG2 cells. In the present study, we found that cadmium induced cell death by depletion of GSH through inactivation of Nrf2. Addition of α-LA to cadmium-treated cells reactivated Nrf2 and regenerated GSH through elevating the Nrf2-downstream genes γ-glutamate-cysteine ligase (γ-GCL) and GR, both of which are key enzymes for GSH synthesis. However, blocking Nrf2 with brusatol in the cells co-treated with α-LA and cadmium reduced the mRNA and the protein levels of γ-GCL and GR, thus suppressed GSH regeneration by α-LA. Our results indicated that α-LA activated Nrf2 signaling pathway, which upregulated the transcription of the enzymes for GSH synthesis and therefore GSH contents to alleviate cadmium-induced cytotoxicity in HepG2 cells.

Anticancer effects of ginsenoside Rg3 (Review)

Cancer is a life-threatening disease with an alarmingly increased annual mortality rate globally. Although various therapies are employed for cancer, the final effect is not satisfactory. Chemotherapy is currently the most commonly used treatment option. However, the unsatisfactory efficacy, severe side-effects and drug resistance hinder the therapeutic efficacy of chemotherapeutic drugs. There is increasing evidence indicating that ginsenoside Rg3, a naturally occurring phytochemical, plays an important role in the prevention and treatment of cancer. The suggested mechanisms mainly include the induction of apoptosis, and the inhibition of proliferation, metastasis and angiogenesis, as well as the promotion of immunity. In addition, ginsenoside Rg3 can be used as an adjuvant to conventional cancer therapies, improving the efficacy and/or reducing adverse effects via synergistic activities. Ginsenoside Rg3 may be a widely applied natural medicine against cancer. To date however, there is no systematic summary available of the anticancer effects of ginsenoside Rg3. Therefore, in this review, all available literature over the past 10 years was reviewed and discussed in order to facilitate further research of ginsenoside Rg3.

Naturally Occurring Nrf2 Activators: Potential in Treatment of Liver Injury

Oxidative stress plays a major role in acute and chronic liver injury. In hepatocytes, oxidative stress frequently triggers antioxidant response by activating nuclear erythroid 2-related factor 2 (Nrf2), a transcription factor, which upregulates various cytoprotective genes. Thus, Nrf2 is considered a potential therapeutic target to halt liver injury. Several studies indicate that activation of Nrf2 signaling pathway ameliorates liver injury. The hepatoprotective potential of naturally occurring compounds has been investigated in various models of liver injuries. In this review, we comprehensively appraise various phytochemicals that have been assessed for their potential to halt acute and chronic liver injury by enhancing the activation of Nrf2 and have the potential for use in humans.

Ginseng for Liver Injury: Friend or Foe?

Panax sp., including Panax ginseng Meyer, Panax quiquifolius L., or Panax notoginseng (Burk.) FH Chen, have been used as functional foods or for traditional Chinese medicine for diabetes, inflammation, stress, aging, hepatic injury, and cancer. In recent decades, a number of both in vitro and in vivo experiments as well as human studies have been conducted to investigate the efficacy and safety of various types of ginseng samples and their components. Of these, the hepatoprotective and hepatotoxic effects of ginseng and their ginsenosides and polysaccharides are reviewed and summarized.

Chaetominine reduces MRP1-mediated drug resistance via inhibiting PI3K/Akt/Nrf2 signaling pathway in K562/Adr human leukemia cells

Drug resistance limits leukemia treatment and chaetominine, a cytotoxic alkaloid that promotes apoptosis in a K562 human leukemia cell line via the mitochondrial pathway was studied with respect to chemoresistance in a K562/Adr human resistant leukemia cell line. Cytotoxicity assays indicated that K562/Adr resistance to adriamycin (ADR) did not occur in the presence of chaetominine and that chaetominine increased chemosensitivity of K562/Adr to ADR. Data show that chaetominine enhanced ADR-induced apoptosis and intracellular ADR accumulation in K562/Adr cells. Accordingly, chaetominine induced apoptosis by upregulating ROS, pro-apoptotic Bax and downregulating anti-apoptotic Bcl-2. RT-PCR and western-blot confirmed that chaetominine suppressed highly expressed MRP1 at mRNA and protein levels. But little obvious alternation of another drug transporter MDR1 mRNA was observed. Furthermore, inhibition of MRP1 by chaetominine relied on inhibiting Akt phosphorylation and nuclear Nrf2. In summary, chaetominine strongly reverses drug resistance by interfering with the PI3K/Akt/Nrf2 signaling, resulting in reduction of MRP1-mediated drug efflux and induction of Bax/Bcl-2-dependent apoptosis in an ADR-resistant K562/Adr leukemia cell line.

Schisandrol B protects against acetaminophen-induced acute hepatotoxicity in mice via activation of the NRF2/ARE signaling pathway

AIM

The nuclear factor erythroid 2-related factor 2 (NRF2) acts through the antioxidant response element (ARE) to regulate the expression of many detoxifying and antioxidant genes responsible for cytoprotective processes. We previously reported that Schisandrol B (SolB) isolated from Schisandra sphenanthera produced a protective effect against acetaminophen (APAP)-induced liver injury. In this study we investigated whether the NRF2/ARE signaling pathway was involved in this hepato-protective effect.

METHODS

Male C57BL/6 mice were treated with SolB (200 mg · kg(-1) · d(-1), ig) for 3 d before injection of APAP (400 mg/kg, ip). Serum and liver tissue samples were collected 6 h later. The mRNA and protein expression were measured using qRT-PCR and Western blot assay, respectively. The activation of NRF2 was examined in HepG2 cells using luciferase reporter gene assay.

RESULTS

SolB pretreatment significantly alleviated the hepatic injury (large patchy necrosis and hyperemia of the hepatic sinus), the increase of serum AST, ALT levels and hepatic MDA contents, and the decrease of liver and mitochondrial glutathione levels in APAP-treated mice. Furthermore, SolB pretreatment significantly increased nuclear accumulation of NRF2 and increased hepatic expression of NRF2 downstream proteins, including GCLC, GSR, NQO1, GSTs, MRP2, MRP3 and MRP4 in APAP-treated mice. Moreover, treatment with SolB (2.5-20 μmol/L) dose-dependently increased the activity of NRF2 reporter gene in HepG2 cells.

CONCLUSION

SolB exhibits a remarkable protective effect against APAP-induced hepatotoxicity, partially via activation of the NRF2/ARE pathway and regulation of NRF2 target genes, which induce detoxification and increase antioxidant capacity.

A Distinctive Pattern of Beauveria bassiana-biotransformed Ginsenoside Products Triggers Mitochondria/FasL-mediated Apoptosis in Colon Cancer Cells

Ginseng is one of the most commonly used adaptogens. Transformation into the minor ginsenosides produces compounds with more effective action. Beauveria bassiana, a teleomorph of Cordyceps bassiana, is a highly efficient producer of mammalian steroids and produces large amounts of sugar-utilizing enzymes. However, the fermentation of steroid glycosides in ginseng with B. bassiana has never been studied. Thus, we evaluated the bioconversion of the major ginsenosides in white ginseng by B. bassiana. Interestingly, B. bassiana increased the total amount of protopanaxadiols and hydrolyzed Rb1 into minor ginsenosides, exhibiting high levels of Rd and Rg3, as well as moderate levels of Rb2 and Rc analyzed by high-performance liquid chromatography coupled with evaporative light-scattering detection. The β-glucosidase activity was highly increased, which led to the selective elimination of sugar moiety at the 20-C position of Rb1 to Rd, followed by Rg3. Rb2 and Rc accumulated because of the minimal activities of α-L-arabinopyranosidase and α-L-arabinofuranosidase, respectively. The fermentation product exerted dose-dependent cytotoxicity in HCT-15 cells, which are resistant to ginseng. The product, but not white ginseng, exhibited apoptotic effects via the Fas ligand and caspase 8/9. This study demonstrates for the first time that the B. bassiana-fermented metabolites have potent apoptotic activity in colon cancer cells, linking to a therapeutic use.

Insights in the mechanism underlying the protective effect of α-lipoic acid against acetaminophen-hepatotoxicity

Acetaminophen (APAP) is one of the most widely used analgesic antipyretic drugs and is a major cause of acute liver failure at overdose. The aim of this study is to investigate the possible protective effect of α-lipoic acid (α-LA, 20 or 100 mg/kg administered simultaneously or after 1.5 h) against APAP-induced hepatotoxicity in rats. Administration of APAP (1.5 g/kg i.p.) resulted in elevation of serum ALT and hepatic malondialdehyde (MDA) content, as well as decrease in hepatic glutathione (GSH) content. In addition, elevation in hepatic hemeoxygenase-1 (HO-1) and NADPH oxidase expression was observed accompanied with a significant reduction in glutathione synthase and cystathionine-beta-synthase (CβS) expression. Furthermore, nuclear factor kappa-B (NF-κB) activity was enhanced in APAP-treated rats. Administration of the standard APAP antidote; N-acetylcysteine (NAC, 1200 mg/kg) or α-LA (20 mg/kg), simultaneously or 1.5 h after APAP, ameliorated APAP-induced alterations in liver function, oxidant and inflammatory markers. Importantly, simultaneous administration of NAC or α-LA (20 mg/kg) was more protective than their later administration. However, the beneficial effect of α-LA was lost at higher dose level (100 mg/kg). Taken together, the beneficial effects of α-lipoic acid (20 mg/kg) were comparable to those of NAC which provides a new possible treatment for APAP-induced hepatotoxicity in patients who cannot tolerate NAC. However, careful dose selection is warranted since the beneficial effects of α-LA were lost at higher doses.

Panaxatriol saponins attenuated oxygen-glucose deprivation injury in PC12 cells via activation of PI3K/Akt and Nrf2 signaling pathway

Panaxatriol saponins (PTS), the main components extracted from Panax notoginseng, have been shown to be efficacious in the prevention and treatment of cerebrovascular diseases in China. NF-E2-related factor 2 (Nrf2), a transcription factor regulating antioxidant and cytoprotective responses to oxidative stress, has received particular attention as a molecular target for pharmacological intervention of ischemic diseases. The aim of this study was to characterize the effect of PTS on the activation of Nrf2 signaling pathway and the potential role in its protective effect. We found that PTS induced heme oxygenase-1 (HO-1) expression in PC12 cells via activating Nrf2 signaling pathway. Phosphatidylinositol 3-kinase (PI3K)/Akt kinase was involved in the upstream of this PTS activated pathway. Moreover, combination of the main components in PTS significantly enhanced the expression of Nrf2 mediated phase II enzymes. Importantly, the protective effect of PTS against oxygen-glucose deprivation-reperfusion (OGD-Rep) induced cell death was significantly attenuated by PI3K inhibitor and antioxidant response element (ARE) decoy oligonucleotides, suggesting that both PI3K/Akt and Nrf2 signaling pathway are essential during this protective process. Taken together, our results suggest that PTS may activate endogenous cytoprotective mechanism against OGD-Rep induced oxidative injury via the activation of PI3K/Akt and Nrf2 signaling pathway.

Recent updates on acetaminophen hepatotoxicity: the role of nrf2 in hepatoprotection

Acetaminophen (APAP) known as paracetamol is the main ingredient in Tylenol, which has analgesic and anti-pyretic properties. Inappropriate use of APAP causes major morbidity and mortality secondary to hepatic failure. Overdose of APAP depletes the hepatic glutathione (GSH) rapidly, and the metabolic intermediate leads to hepatocellular death. This article reviews the mechanisms of hepatotoxicity and provides an overview of current research studies. Pharmacokinetics including metabolism (activation and detoxification), subsequent transport (efflux)-facilitating excretion, and some other aspects related to toxicity are discussed. Nuclear factor erythroid 2-related factor 2 (Nrf2)-regulated gene battery plays a critical role in the multiple steps associated with the mitigation of APAP toxicity. The role of Nrf2 as a protective target is described, and potential natural products inhibiting APAP toxicity are outlined. This review provides an update on the mechanism of APAP toxicity and highlights the beneficial role of Nrf2 and specific natural products in hepatoprotection.