Absence of Increased Susceptibility to Acetaminophen-Induced Liver Injury in a Diet-Induced NAFLD Mouse Model.

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease and its influence on drug-induced liver injury (DILI) is not fully understood. We investigated whether NAFLD can influence acetaminophen (APAP [N-acetyl-p-aminophenol])-induced hepatotoxicity in a diet-induced obese (DIO) mouse model of NAFLD. The male C57BL/6NTac DIO mice, fed a high-fat diet for more than 12 weeks, developed obesity, hyperinsulinemia, impaired glucose tolerance, and hepatomegaly with hepatic steatosis, similar to human NAFLD. In the acute toxicity study after a single dose of APAP (150 mg/kg), compared with control lean mice, the DIO mice had decreased serum transaminase levels and less severe hepatocellular injury. The DIO mice also had altered expression of genes related to APAP metabolism. Chronic APAP exposure for 26 weeks did not predispose the DIO mice with NAFLD to more severe hepatotoxicity compared with the lean mice. These results suggested that the C57BL/6NTac DIO mouse model appears to be more tolerant to APAP-induced hepatotoxicity than lean mice, potentially related to altered xenobiotic metabolizing capacity in the fatty liver. Further mechanistic studies with APAP and other drugs in NAFLD animal models are necessary to investigate the mechanism of altered susceptibility to intrinsic DILI in some human NAFLD patients.

[Discovery of miRNA and target signal molecules involved in inhibition of chlorogenic acid on N-acetyl-p-aminophenol-induced hepatotoxicity based on microRNA array].

This study aims to observe the effect of chlorogenic acid(CGA) on microRNA(miRNA) in the process of protecting against N-acetyl-p-aminophenol(APAP)-induced liver injury. Eighteen C57BL/6 mice were randomly assigned into a normal group, a model group(APAP, 300 mg·kg~(-1)), and a CGA(40 mg·kg~(-1)) group. Hepatotoxicity of mice was induced by intragastric administration of APAP(300 mg·kg~(-1)). The mice in the CGA group were administrated with CGA(40 mg·kg~(-1)) by gavage 1 h after APAP administration. The mice were sacrificed 6 h after APAP administration, and plasma and liver tissue samples were collected for the determination of serum alanine/aspartate aminotransferase(ALT/AST) level and observation of liver histopathology, respectively. MiRNA array combined with real-time PCR was employed to discover important miRNAs. The target genes of miRNAs were predicted via miRWalk and TargetScan 7.2, verified by real-time PCR, and then subjected to functional annotation and signaling pathway enrichment. The results showed that CGA administration lowered the serum ALT/AST level elevated by APAP and alleviate the liver injury. Nine potential miRNAs were screened out from the microarray. The expression of miR-2137 and miR-451a in the liver tissue was verified by real-time PCR. The expression of miR-2137 and miR-451a was significantly up-regulated after APAP administration, and such up-regulated expression was significantly down-regulated after CGA administration, consistent with the array results. The target genes of miR-2137 and miR-451a were predicted and verified. Eleven target genes were involved in the process of CGA protecting against APAP-induced liver injury. Gene Ontology(GO) annotation and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment with DAVID and R language showed that the 11 target genes were enriched in Rho protein-related signal transduction, vascular patterning-related biological processes, binding to transcription factors, and Rho guanyl-nucleotide exchange factor activity. The results indicated that miR-2137 and miR-451a played an important role in the inhibition of CGA on APAP-induced hepatotoxicity.

Design, synthesis, and biological evaluation of novel FXR agonists based on auraptene.

Farnesoid X receptor (FXR) has been considered as an attractive target for metabolic disorder and liver injury, while many current FXR agonists suffer from undesirable side effects, such as pruritus. Therefore, it is urgent to develop new structure types different from current FXR agonists. In this study, a series of structural optimizations were introduced to displace the unstable coumarin and geraniol scaffolds of auraptene (AUR), a novel and safe FXR agonist. All of these efforts led to the identification of compound 14, a potent FXR agonist with nearly fourfold higher activity than AUR. Molecular modeling study suggested that compound 14 fitted well with binding pocket, and formed the key ionic bond with His291 and Arg328. In acetaminophen-induced acute liver injury model, compound 14 exerts better therapeutic effect than that of AUR, which highlighting its pharmacological potential in the treatment of drug-induced liver injury.

Comparative metabonomic analysis of hepatotoxicity induced by acetaminophen and its less toxic meta-isomer.

The leading cause of drug-induced liver injury in the developed world is overdose with N-acetyl-p-aminophenol (APAP). A comparative metabonomic approach was applied to the study of both xenobiotic and endogenous metabolic profiles reflective of in vivo exposure to APAP (300 mg/kg) and its structural isomer N-acetyl-m-aminophenol (AMAP; 300 mg/kg) in C57BL/6J mice, which was anchored with histopathology. Liver and urine samples were collected at 1 h, 3 h and 6 h post-treatment and analyzed by 1H nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass spectrometry (liver only). Histopathology revealed the presence of centrilobular necrosis from 3 h post-APAP treatment, while an AMAP-mediated necrotic endpoint was not observed within the timescale of this study, yet two of five treated mice showed minimal centrilobular eosinophilia. The 1H-NMR xenobiotic metabolic profile of APAP-treated animals comprised of mercapturate (urine and liver) and glutathionyl (liver) conjugates detected at 1 h post-treatment. This finding corroborated the hepatic endogenous metabolic profile which showed depletion of glutathione from 1 h onwards. In contrast, AMAP glutathionyl conjugates were not detected, nor was AMAP-induced depletion of hepatic glutathione observed. APAP administration induced significant endogenous hepatic metabolic perturbations, primarily linked to oxidative and energetic stress, and perturbation of amino acid metabolism. Early depletion of glutathione was followed by depletion of additional sulfur-containing metabolites, while altered levels of mitochondrial and glycolytic metabolites indicated a disruption of energy homeostasis. In contrast, AMAP administration caused minimal, transient, distinct metabolic perturbations and by 6 h the metabolic profiles of AMAP-treated mice were indistinguishable from those of controls.

Mechanisms of interaction of the N-acetyl-p-aminophenol metabolites in terms of nephrotoxicity.

CONTEXT: Epidemiological studies have demonstrated that chronic use of N-acetyl-p-aminophenol is correlated with the occurrence of renal dysfunction. OBJECTIVE: Aim of this study was to review the literature on the mechanisms of interaction N-acetyl-p-aminophenol metabolites in terms of nephrotoxicity. METHODS: We present a literature review of studies published in English language on the damage effects of N-acetyl-p-aminophenol on the kidneys, accessed through PubMed database. RESULTS: The pathogenesis of drug-induced nephrotoxicity attributed to the action of cytochrome P450 enzymes, prostaglandin endoperoxide synthase (PGES) and N-deacetylase. The metabolism of N-acetyl-p-aminophenol with the participation of PGES more explicit is in the core of kidney, whereas cytochrome P450 enzymes play role in the renal cortex. Due to the action of cytochrome P450 and N-deacetylase, a very reactive N-acetyl-p-benzochinoimine (NAPQI) is formed. The result of the catalytic activity of PGES is p-benzoquinone (PBQI) production. The formation of NAPQI and PBQI is accompanied by the production of free radicals. Metabolites can connect covalently with sulfhydryl groups of renal proteins, what can cause the injury of proximal tubules. N-acetyl-p-aminophenol may initiate the apoptosis process involving activation of caspase-9 and caspase-3, but also caspase-12 as a result of generation of free radicals. CONCLUSIONS: The process of NAPQI and PBQI formation can increase oxidative stress that promotes the kidneys damage. The ability of metabolites to produce covalent bonds with sulfhydryl groups of proteins can increase the nephrotoxicity. It was assumed that the induction of apoptosis in renal tubular epithelial cells, and not necrosis underlies the nephrotoxic potential of N-acetyl-p-aminophenol.

CHOP is a critical regulator of acetaminophen-induced hepatotoxicity.

BACKGROUND & AIMS: The liver is a major site of drug metabolism and elimination and as such is susceptible to drug toxicity. Drug induced liver injury is a leading cause of acute liver injury, of which acetaminophen (APAP) is the most frequent causative agent. APAP toxicity is initiated by its toxic metabolite NAPQI. However, downstream mechanisms underlying APAP induced cell death are still unclear. Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) have recently emerged as major regulators of metabolic homeostasis. UPR regulation of the transcription repressor CHOP promotes cell death. We analyzed the role of UPR and CHOP in mediating APAP hepatotoxicity. METHODS: A toxic dose of APAP was orally administered to wild type (wt) and CHOP knockout (KO) mice and damage mechanisms were assessed. RESULTS: CHOP KO mice were protected from APAP induced damage and exhibited decreased liver necrosis and increased survival. APAP metabolism in CHOP KO mice was undisturbed and glutathione was depleted at similar kinetics to wt. ER stress and UPR activation were overtly seen 12h following APAP administration, a time that coincided with strong upregulation of CHOP. Remarkably, CHOP KO but not wt mice exhibited hepatocyte proliferation at sites of necrosis. In vitro, large T immortalized CHOP KO hepatocytes were protected from APAP toxicity in comparison to wt control cells. CONCLUSIONS: CHOP upregulation during APAP induced liver injury compromises hepatocyte survival in various mechanisms, in part by curtailing the regeneration phase following liver damage. Thus, CHOP plays a pro-damage role in response to APAP intoxication.

Use of comparative genomics approaches to characterize interspecies differences in response to environmental chemicals: challenges, opportunities, and research needs.

A critical challenge for environmental chemical risk assessment is the characterization and reduction of uncertainties introduced when extrapolating inferences from one species to another. The purpose of this article is to explore the challenges, opportunities, and research needs surrounding the issue of how genomics data and computational and systems level approaches can be applied to inform differences in response to environmental chemical exposure across species. We propose that the data, tools, and evolutionary framework of comparative genomics be adapted to inform interspecies differences in chemical mechanisms of action. We compare and contrast existing approaches, from disciplines as varied as evolutionary biology, systems biology, mathematics, and computer science, that can be used, modified, and combined in new ways to discover and characterize interspecies differences in chemical mechanism of action which, in turn, can be explored for application to risk assessment. We consider how genetic, protein, pathway, and network information can be interrogated from an evolutionary biology perspective to effectively characterize variations in biological processes of toxicological relevance among organisms. We conclude that comparative genomics approaches show promise for characterizing interspecies differences in mechanisms of action, and further, for improving our understanding of the uncertainties inherent in extrapolating inferences across species in both ecological and human health risk assessment. To achieve long-term relevance and consistent use in environmental chemical risk assessment, improved bioinformatics tools, computational methods robust to data gaps, and quantitative approaches for conducting extrapolations across species are critically needed. Specific areas ripe for research to address these needs are recommended.

Methodological considerations of the acetaminophen Detection Kit®: Involvement of molecular oxygen (O2) in an indophenol reaction.

The Acetaminophen Detection Kit® (Kanto Chemical Company Co. Inc., Tokyo, Japan) is a colorimetric test based on an indophenol reaction. The test involves three reactions: deproteination of the sample, hydrolysis of acetaminophen to yield p-aminophenol, and coupling p-aminophenol with a derivative of phenol in alkali conditions to form a blue-colored indophenol dye. The kit was devised to accomplish these three reactions with only two reagents, allowing the prompt diagnosis of acetaminophen overdose in emergency medicine. In the user instructions included with the kit and in reports introducing the kit, the chemical composition of the two reagents was not disclosed. Details about the composition can be found in the Safety Data Sheet from the manufacturer; however, there is little explanation about the principle (mechanism) of the coupling reaction. This lack of information appears to have hampered the use of this kit in forensic medicine. In this report, we conducted the coupling reaction by successively adding the two reagents to a p-aminophenol (intermediate molecule) solution with the reaction vessel open to the air and under an anaerobic condition. Development of the blue color was inhibited in the absence of air but gradually developed when the reaction vessel was opened to air. Thus, the coupling reaction is an oxidation-reduction (redox) reaction that requires molecular oxygen (O2) dissolved from the air to act as an oxidant. This finding corroborates statements in previous reports and will hopefully facilitate the use of the kit for forensic purposes.

Acetaminophen (APAP, Paracetamol) Interferes With the First Trimester Human Fetal Ovary Development in an Ex Vivo Model.

CONTEXT: Acetaminophen (APAP, paracetamol) is widely used by pregnant women. Although long considered safe, growing evidence indicates that APAP is an endocrine disruptor since in utero exposure may be associated with a higher risk of male genital tract abnormalities. In rodents, fetal exposure has long-term effects on the reproductive function of female offspring. Human studies have also suggested harmful APAP exposure effects. OBJECTIVE: Given that disruption of fetal ovarian development may impact women's reproductive health, we investigated the effects of APAP on fetal human ovaries in culture. DESIGN AND SETTING: Human ovarian fragments from 284 fetuses aged 7 to 12 developmental weeks (DW) were cultivated ex vivo for 7 days in the presence of human-relevant concentrations of APAP (10-8 to 10-3 M) or vehicle control. MAIN OUTCOME MEASURES: Outcomes included examination of postculture tissue morphology, cell viability, apoptosis, and quantification of hormones, APAP, and APAP metabolites in conditioned culture media. RESULTS: APAP reduced the total cell number specifically in 10- to 12-DW ovaries, induced cell death, and decreased KI67-positive cell density independently of fetal age. APAP targeted subpopulations of germ cells and disrupted human fetal ovarian steroidogenesis, without affecting prostaglandin or inhibin B production. Human fetal ovaries were able to metabolize APAP. CONCLUSIONS: Our data indicate that APAP can impact first trimester human fetal ovarian development, especially during a 10- to 12-DW window of heightened sensitivity. Overall, APAP behaves as an endocrine disruptor in the fetal human ovary.

Treatment of Drug-Induced Liver Injury.

Current pharmacotherapy options of drug-induced liver injury (DILI) remain under discussion and are now evaluated in this analysis. Needless to say, the use of the offending drug must be stopped as soon as DILI is suspected. Normal dosed drugs may cause idiosyncratic DILI, and drugs taken in overdose commonly lead to intrinsic DILI. Empirically used but not substantiated regarding efficiency by randomized controlled trials (RCTs) is the intravenous antidote treatment with N-acetylcysteine (NAC) in patients with intrinsic DILI by N-acetyl-p-aminophenol (APAP) overdose. Good data recommending pharmacotherapy in idiosyncratic DILI caused by hundreds of different drugs are lacking. Indeed, a recent analysis revealed that just eight RCTs have been published, and in only two out of eight trials were DILI cases evaluated for causality by the worldwide used Roussel Uclaf Causality Assessment Method (RUCAM), representing overall a significant methodology flaw, as results of DILI RCTs lacking RUCAM are misleading since many DILI cases are known to be attributable erroneously to nondrug alternative causes. In line with these major shortcomings and mostly based on anecdotal reports, glucocorticoids (GCs) and other immuno-suppressants may be given empirically in carefully selected patients with idiosyncratic DILI exhibiting autoimmune features or caused by immune checkpoint inhibitors (ICIs), while some patients with cholestatic DILI may benefit from ursodeoxycholic acid use; in other patients with drug-induced hepatic sinusoidal obstruction syndrome (HSOS) and coagulopathy risks, the indication for anticoagulants should be considered. In view of many other mechanistic factors such as the hepatic microsomal cytochrome P450 with a generation of reactive oxygen species (ROS), ferroptosis with toxicity of intracellular iron, and modification of the gut microbiome, additional therapy options may be available in the future. In summation, stopping the offending drug is still the first line of therapy for most instances of acute DILI, while various therapies are applied empirically and not based on good data from RCTs awaiting further trials using the updated RUCAM that asks for strict exclusion and inclusion details like liver injury criteria and provides valid causality rankings of probable and highly probable grades.

Microbial paracetamol degradation involves a high diversity of novel amidase enzyme candidates.

Pharmaceuticals are relatively new to nature and often not completely removed in wastewater treatment plants (WWTPs). Consequently, these micropollutants end up in water bodies all around the world posing a great environmental risk. One exception to this recalcitrant conversion is paracetamol, whose full degradation has been linked to several microorganisms. However, the genes and corresponding proteins involved in microbial paracetamol degradation are still elusive. In order to improve our knowledge of the microbial paracetamol degradation pathway, we inoculated a bioreactor with sludge of a hospital WWTP (Pharmafilter, Delft, NL) and fed it with paracetamol as the sole carbon source. Paracetamol was fully degraded without any lag phase and the enriched microbial community was investigated by metagenomic and metatranscriptomic analyses, which demonstrated that the microbial community was very diverse. Dilution and plating on paracetamol-amended agar plates yielded two Pseudomonas sp. isolates: a fast-growing Pseudomonas sp. that degraded 200 mg/L of paracetamol in approximately 10 h while excreting 4-aminophenol, and a slow-growing Pseudomonas sp. that degraded paracetamol without obvious intermediates in more than 90 days. Each Pseudomonas sp. contained a different highly-expressed amidase (31% identity to each other). These amidase genes were not detected in the bioreactor metagenome suggesting that other as-yet uncharacterized amidases may be responsible for the first biodegradation step of paracetamol. Uncharacterized deaminase genes and genes encoding dioxygenase enzymes involved in the catabolism of aromatic compounds and amino acids were the most likely candidates responsible for the degradation of paracetamol intermediates based on their high expression levels in the bioreactor metagenome and the Pseudomonas spp. genomes. Furthermore, cross-feeding between different community members might have occurred to efficiently degrade paracetamol and its intermediates in the bioreactor. This study increases our knowledge about the ongoing microbial evolution towards biodegradation of pharmaceuticals and points to a large diversity of (amidase) enzymes that are likely involved in paracetamol metabolism in WWTPs.

Hepatoprotective effect of Centella asiatica 50% ethanol extract against acetaminophen-induced acute liver injury in BALB/c mice.

N-acetyl-p-aminophenol (acetaminophen, APAP) is a well-known component of analgesic and antipyretic monotherapy products. However, exceeding the recommended dose can lead to serious injury to the liver. We conducted this study to determine the potential of Centella asiatica as a natural substance to protect against APAP-induced liver injury. When acute hepatotoxicity was induced in mice by APAP overdose, their liver weight decreased significantly (p < 0.05). However, mice treated with C. asiatica 50% ethanol extract (CA-HE50, 200 mg/kg) for a week before induction of hepatotoxicity by APAP had similar liver weights to those of mice in which hepatotoxicity was not induced. In particular, levels of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, which are biomarkers of liver injury, were significantly increased by APAP and dose-dependently decreased by CA-HE50 (p < 0.05). Glutathione and malondialdehyde, indicators of oxidative stress, were significantly changed by APAP and CA-HE50 (p < 0.05). In addition, hepatic necrosis and expression of genes encoding pro-inflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-1ß, and IL-4) induced by APAP were inhibited by CA-HE50, and these results were dose-dependent. Through our in vivo studies, we found that CA-HE50 can help prevent APAP-induced hepatic tissue injury in BALB/c mice. Furthermore, CA-HE50 was effective at protecting RAW 264.7 cells from lipopolysaccharide-induced cytotoxicity and inhibiting the release of nitric oxide from these cells; in particular, asiaticoside was found to be a key component of CA-HE50 responsible for these effects. Therefore, we suggest that CA-HE50 has potential applications in functional health foods and drugs.

Allyl Isothiocyanate Protects Acetaminophen-Induced Liver Injury via NRF2 Activation by Decreasing Spontaneous Degradation in Hepatocyte.

Acetaminophen (APAP) is one of the most frequently prescribed analgesic and anti-pyretic drugs. However, APAP-induced hepatotoxicity is a major cause of acute liver failure globally. While the therapeutic dose is safe, an overdose of APAP produces an excess of the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI), subsequently resulting in hepatotoxicity. Allyl isothiocyanate (AITC), a bioactive molecule in cruciferous plants, is reported to exert various biological effects, including anti-inflammatory, anti-cancer, and anti-microbial effects. Notably, AITC is known for activating nuclear factor erythroid 2-related factor 2 (NRF2), but there is limited evidence supporting the beneficial effects on hepatocytes and liver, where AITC is mainly metabolized. We applied a mouse model in the current study to investigate whether AITC protects the liver against APAP-induced injury, wherein we observed the protective effects of AITC. Furthermore, NRF2 nuclear translocation and the increase of target genes by AITC treatment were confirmed by in vitro experiments. APAP-induced cell damage was attenuated by AITC via an NRF2-dependent manner, and rapid NRF2 activation by AITC was attributed to the elevation of NRF2 stability by decreasing its spontaneous degradation. Moreover, liver tissues from our mouse experiment revealed that AITC increases the expression of heme oxygenase-1 (HO-1), an NRF2 target gene, confirming the potential of AITC as a hepatoprotective agent that induces NRF2 activation. Taken together, our results indicate the potential of AITC as a natural-product-derived NRF2 activator targeting the liver.

Cinnamon oil against acetaminophen-induced acute liver toxicity by attenuating inflammation, oxidative stress and apoptosis.

Acetaminophen (APAP) is used as a primary drug due to its antipyretic and analgesic activity. The mechanism of action of APAP toxicity in the liver is due to the depletion of glutathione which elicited free radicals generation. Therefore, the objective of our work is to investigate the APAP induced liver damage and its repair by free radical scavenging activity of cinnamon oil (CO) in male Wistar rats. To investigate the effects of CO at different doses (50, 100 and 200 mg/kg b.w.), animals were given a single oral dose of CO per day for 14 days between 12:00-1:00 PM. The biochemical changes, imbalance in oxidative markers, interleukins, caspases and histopathological studies were determined for quantifying the hepatoprotective effect of CO. One dose of APAP (2 g/kg b.w.) results in significant hepatotoxicity and marked increase the serum markers alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), bilirubin, albumin, total protein, content of lipid peroxidation (LPO), interleukins (IL-1ß, IL-6), caspase-3, -9 expression, DNA fragmentation and histopathological changes were observed. Significant decrease in the levels of LPO, interleukins IL-1ß, IL-6, caspase-3, -9 expressions, qualitative as well as quantitative determination of DNA fragments and histopathological changes were reversed by the administration of CO dose dependently. Furthermore, it also restores the depleted activity of antioxidative enzymes. Our study shows that an imbalance in the oxidative parameter in the liver by APAP is restored by treating the animals with CO.

Kaurenoic acid extracted from Sphagneticola trilobata reduces acetaminophen-induced hepatotoxicity through inhibition of oxidative stress and pro-inflammatory cytokine production in mice.

Acetaminophen (paracetamol) is a widely used analgesic and antipyretic drug that is safe at therapeutic doses. However, acetaminophen overdose can be fatal. Currently, the only treatment available is the N-acetyl cysteine. The diterpene kaurenoic acid (ent-kaur-16-en-19-oic acid, KA) is the major constituent of Sphagneticola trilobata (L.) Pruski. KA presents anti-inflammatory, anti-nociceptive and antioxidant properties. In this study, we evaluated the efficacy of KA in a model of acetaminophen-induced hepatotoxicity. KA increased, in a dose-dependent manner, the survival rate after acetaminophen overdose. KA reduced acetaminophen-induced hepatic necrosis and ALT and AST levels. KA decreased acetaminophen-induced neutrophil and macrophage recruitment, oxidative stress and the production of IL-33, TNF-α and IL-1ß, alongside with normalisation of IL-10 levels in the liver. Therefore, KA showed preclinical efficacy in acetaminophen-induced hepatotoxicity and lethality.

Autophagy and apoptosis in liver injury.

Apoptosis is a primary characteristic in the pathogenesis of liver disease. Hepatic apoptosis is regulated by autophagic activity. However, mechanisms mediating their interaction remain to be determined. Basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy also is an adaptive response under stressful conditions. Autophagy can control cell fate through different cross-talk signals. A complex interplay between hepatic autophagy and apoptosis determines the degree of hepatic apoptosis and the progression of liver disease as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances on roles of autophagy that plays in pathophysiology of liver. The autophagic pathway can be a novel therapeutic target for liver disease.

Curcumin attenuated paracetamol overdose induced hepatitis.

AIM: To investigate whether curcumin could attenuate hepatitis in mice with paracetamol overdose. METHODS: Male mice were divided into four groups. Group 1 (control, n = 8); was fed with distilled water; Group 2 [N-acetyl-P-aminophenol (APAP), n = 8]; was fed with a single dose of 400 mg/kg APAP dissolved in distilled water; Group 3 [APAP + curcumin (CUR) 200, n = 8], was fed with a single dose of 400 mg/kg APAP and 200 mg/kg CUR; Group 4 (APAP + CUR 600, n = 8), was fed with a single dose of 400 mg/kg APAP and 600 mg/kg CUR. Twenty-four hours later, the liver was removed to examine hepatic glutathione (GSH), hepatic malondialdehyde (MDA), and histopathologically. Then whole blood was withdrawn from heart to determine transaminase (serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase) and inflammatory cytokines [interleukin (IL)-12 and IL-18] levels by enzyme linked immunosorbent assay. RESULTS: Serum transaminase, hepatic MDA, and inflammatory cytokines increased significantly in the APAP compared with the control group. Curcumin supplementation in APAP + CUR 200 and APAP + CUR 600 groups significantly decreased these parameters compared with the APAP group. The level of GSH decreased significantly in the APAP compared with the control group. Curcumin supplementation in APAP + CUR 200 and APAP + CUR 600 groups significantly increased these parameters compared with the APAP group. The histological appearance of the liver in the control group showed normal. In the APAP-treated group, the liver showed extensive hemorrhagic hepatic necrosis at all zones. Curcumin supplementation in APAP + CUR 200 and APAP + CUR 600 groups, caused the liver histopathology to improve. In the APAP + CUR 200 group, the liver showed focal necrosis and but the normal architecture was well preserved in APAP + CUR 600 group. CONCLUSION: APAP overdose can cause liver injury. Results indicate that curcumin prevents APAP-induced hepatitis through the improvement of liver histopathology by decreased oxidative stress, reduced liver inflammation, and restoration of GSH.

Saikosaponin D disrupts platelet-derived growth factor-ß receptor/p38 pathway leading to mitochondrial apoptosis in human LO2 hepatocyte cells: a potential mechanism of hepatotoxicity.

Herbal hepatotoxicity has been increasingly reported in clinical context, but the underlying mechanisms are poorly understood. Saikosaponin D (SSD) is a major component of saikosaponins isolated from Bupleurum falactum, a herb that has been linked to hepatotoxicity. Our current study was to examine the toxic effect of SSD on human hepatocyte LO2 cells and explore the possible mechanism. The results demonstrated that SSD reduced cell viability and led to dramatic morphological alterations in LO2 cells. Hoechst staining and flow cytometry analyses showed that SSD stimulated hepatocyte apoptosis. SSD-treated cells exhibited apparent nuclear condensation and fragmentation, and the apoptotic cells were increased by SSD dose-dependently. Subsequent experiments showed that SSD decreased mitochondrial membrane potential and downregulated Bcl-2 but upregulated Bax. Moreover, caspase-9 and caspase-3 were activated in SSD-treated LO2 cells. These data consistently indicated that SSD stimulated mitochondrial apoptosis in hepatocytes. Mechanistic investigations showed that SSD disrupted p38 signaling and that p38 specific inhibitor SB203580 mimicked the pro-apoptotic effect of SSD. In addition, platelet-derived growth factor-ß receptor (PDGF-ßR) blocker imatinib reduced p38 phosphorylation and also mimicked the pro-apoptotic effect of SSD in LO2 cells. These data collectively indicated that SSD induced apoptosis by interrupting PDGF-ßR/p38 pathway in LO2 hepatocytes.