Metabolic phenotyping applied to pre-clinical and clinical studies of acetaminophen metabolism and hepatotoxicity

Species-specific differences in acetaminophen hepatotoxicity depend on HSP70 expression level

Acetaminophen (N-Acetyl-p-aminophenol: APAP) is one of the most commonly used analgesic/antipyretic drugs with proven safety at therapeutic doses, however, over-dosage causes dose-dependent liver damage, leading to acute liver failure in severe cases. The level of APAP-induced liver injury has been known to vary amongst animal species, and APAP concentrations that induce cell death have been investigated using primary cultured cells. We constructed in vitro model of APAP-induced hepatotoxicity using mouse, rat and human hepatoma cell lines to investigate species differences in the APAP-induced cytotoxicity by monitoring cell death as a marker. The EC50 for each cell line was Hepa1-6 (mouse) < H-4-II-E (rat) < Hep3B (human), whilst the expression of heat shock protein 70 (HSP70), which was a typical molecular chaperone, positively correlated with the EC50 of each cell. Heat shock treatment, which caused activation of heat shock factor 1 (HSF1) followed by significant induction of HSP70, partially suppressed APAP-induced cell death in Hepa1-6 and H-4-II-E. Moreover, HSP70 or HSF1 siRNA treatment in Hep3B enhanced APAP-induced cell death. These results suggest that APAP-induced cell death in hepatoma cell lines may be partly mediated by protein denaturation and that the expression level of HSP70 has an inhibitory effect.

Protective effects and mechanism of Sangyu granule on acetaminophen-induced liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The Sang Yu granule (SY), a traditional Chinese medicine prescription of Xijing Hospital, was developed based on the Guanyin powder in the classical prescription "Hong's Collection of Proven Prescriptions" and the new theory of modern Chinese medicine. It has been proved to have a certain therapeutic effect on drug-induced liver injury (DILI), but the specific mechanism of action is still unclear.

AIM OF STUDY

Aim of the study was to explore the effect of SangYu granule on treating drug-induced liver injury induced by acetaminophen in mice.

MATERIALS AND METHODS

The chemical composition of SY, serum, and liver tissue was analyzed using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry. To assess hepatic function, measurements were taken using kits for total bile acids, as well as serum AST, ALT, and ALP activity. Concentrations of IL-1β and TNF-α in serum were quantified using ELISA kits. Transcriptome Sequencing Analysis and 2bRAD-M microbial diversity analysis were employed to evaluate gene expression variance in liver tissue and fecal microbiota diversity among different groups, respectively. Western blotting was performed to observe differences in the activation levels of FXR, SHP, CYP7A1 and PPARα in the liver, and the levels of FXR and FGF-15 genes and proteins in the ileum of mice. Additionally, fecal microbiota transplantation (FMT) experiments were conducted to investigate the potential therapeutic effect of administering the intestinal microbial suspension from mice treated with SY on drug-induced liver injury.

RESULTS

SY treatment exhibited significant hepatoprotective effects in mice, effectively ameliorating drug-induced liver injury while concurrently restoring intestinal microbial dysbiosis. Furthermore, SY administration demonstrated a reduction in the concentration of total bile acids, the expression of FXR and SHP proteins in the liver was up-regulated, CYP7A1 protein was down-regulated, and the expressions of FXR and FGF-15 proteins in the ileum were up-regulated. However, no notable impact on PPARα was observed. Furthermore, results from FMT experiments indicated that the administration of fecal suspensions derived from mice treated with SY did not yield any therapeutic benefits in the context of drug-induced liver injury.

CONCLUSION

The aforementioned findings strongly suggest that SY exerts a pronounced ameliorative effect on drug-induced liver injury through its ability to modulate the expression of key proteins involved in bile acid secretion, thereby preserving hepato-enteric circulation homeostasis.

Cyclosporine-A induced cytotoxicity within HepG2 cells by inhibiting PXR mediated CYP3A4/CYP3A5/MRP2 pathway

Cyclosporine-A (CsA) is currently used to treat immune rejection after organ transplantation as a commonly used immunosuppressant. Liver injury is one of the most common adverse effects of CsA, whose precise mechanism has not been fully elucidated. Pregnane X receptor (PXR) plays a critical role in mediating drug-induced liver injury as a key regulator of drug and xenobiotic clearance. As a nuclear receptor, PXR transcriptionally upregulates the expression of drug-metabolizing enzymes and drug transporters, including cytochrome P4503A (CPY3A) and multidrug resistance-associated protein 2 (MRP2). Our study established CsA-induced cytotoxic hepatocytes in an in vitro model, demonstrating that CsA dose-dependently increased the aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) level secreted in the HepG2 cell supernatant, as well as viability and oxidative stress of HepG2 cells. CsA also dose-dependently decreased the PXR, CYP3A4, CPY3A5, and MRP2 levels of HepG2 cells. Mechanistically, altering the expression of PXR, CYP3A4, CYP3A5, and MRP2 affected the impact of CsA on AST and LDH levels. Moreover, altering the expression of PXR also changed the level of CYP3A4, CPY3A5, and MRP2 of HepG2 cells treated by CsA. Our presented findings provide experimental evidence that CsA-induced liver injury is PXR tightly related. We suggest that PXR represents an attractive target for therapy of liver injury due to its central role in the regulation of the metabolizing enzymes CYP3A and MRP2-mediated bile acid transport and detoxification.

Hepatoprotective effect of amifostine and WR-1065 on acetaminophen-induced liver toxicity on Wistar rats

PURPOSE

The most important problem with acetaminophen is its hepatotoxicity. N-acetylcysteine (NAC) is used to treat the hepatotoxicity of acetaminophen. Due to the structural similarities of this compound with amifostine, we decided to test the effect of this substance and its metabolite, WR-1065, on the hepatotoxicity of acetaminophen.

METHODS

The single-dose method contained 1. Control; 2. Acetaminophen (1 g/kg, gavage); 3-5. Acetaminophen + amifostine (100, 200, 400 mg/kg, i.p.); 6-8. Acetaminophen + WR-1065 (50, 100, 200 mg/kg, i.p.); and 9. Acetaminophen + NAC (100, 200 mg/kg, i.p.). The multiple-dose method included the same groups: amifostine (50, 100, 200 mg/kg), WR-1065 (25, 50, 100 mg/kg), and NAC (100 mg/kg). Then, animals were sacrificed, and blood samples were collected for measuring ALT, AST, ALP, and T-Bil, liver tissue for histopathological examination, MDA, and GSH amounts.

RESULTS

Acetaminophen increased the levels of MDA, T-Bil, ALT, AST, and ALP, decreased GSH levels, and augmented necrosis, neutrophils, lymphocytes, and macrophages in the port space in single-dose and multiple-dose studies. Amifostine and WR-1065 significantly reduced the levels of MDA, T-Bil, ALT, AST, ALP, increased GSH content, and ameliorated histopathological alterations in a single-dose and multiple-dose method compared to the acetaminophen group. Moreover, NAC caused a significant decrease in the levels of MDA, T-Bil, ALT, AST, and ALP, and reduced GSH amounts in single-dose and multiple-dose studies.

CONCLUSION

Amifostine and WR-1065 as antioxidant and hepatoprotective compounds are effective in reducing acetaminophen-induced hepatotoxicity with a similar effect to NAC and can be administered as an adjunct in the treatment of acetaminophen overdose.

Bifidobacterium adolescentis-derived hypaphorine alleviates acetaminophen hepatotoxicity by promoting hepatic Cry1 expression

Acetaminophen (APAP)-induced liver injury (AILI) is a pressing public health concern. Although evidence suggests that Bifidobacterium adolescentis (B. adolescentis) can be used to treat liver disease, it is unclear if it can prevent AILI. In this report, we prove that B. adolescentis significantly attenuated AILI in mice, as demonstrated through biochemical analysis, histopathology, and enzyme-linked immunosorbent assays. Based on untargeted metabolomics and in vitro cultures, we found that B. adolescentis generates microbial metabolite hypaphorine. Functionally, hypaphorine inhibits the inflammatory response and hepatic oxidative stress to alleviate AILI in mice. Transcriptomic analysis indicates that Cry1 expression is increased in APAP-treated mice after hypaphorine treatment. Overexpression of Cry1 by its stabilizer KL001 effectively mitigates liver damage arising from oxidative stress in APAP-treated mice. Using the gene expression omnibus (GEO) database, we verified that Cry1 gene expression was also decreased in patients with APAP-induced acute liver failure. In conclusion, this study demonstrates that B. adolescentis inhibits APAP-induced liver injury by generating hypaphorine, which subsequently upregulates Cry1 to decrease inflammation and oxidative stress.

Piezo1 alleviates acetaminophen-induced acute liver injury by activating Nrf2 and reducing mitochondrial reactive oxygen species

Acetaminophen (APAP) overdose is the most common cause for acute liver failure (ALF) in the developed countries, with limited treatment options. Piezo1 is a mechanosensitive cation channel. We found that APAP caused upregulation of Piezo1 in both an APAP-induced acute liver injury (ALI) animal model and a mouse hepatocyte cell line AML12. Activation of Piezo1 by its activator Yoda1 reduced APAP-induced hepatotoxicity and ROS level. Mechanistically, activation of Piezo1 led to accumulation of the antioxidant regulator Nrf2 and upregulation of its target genes Nqo1 and Gsta1, while knockdown of Piezo1 downregulated this pathway. Finally, injection of Yoda1 decreased serum AST and ALT levels, reduced cell death and rescued liver injury in the APAP-induced ALI mouse model. Our findings suggested a previously undiscovered protective role of Piezo1 in APAP-induced ALI, which might shed light on a new therapeutic target for this disease.

Kaempferol prevents acetaminophen-induced liver injury by suppressing hepatocyte ferroptosis via Nrf2 pathway activation

Acetaminophen (APAP)-induced liver injury (AILI) has become a growing public health problem. Ferroptosis, an iron-dependent form of cell death associated with lipid peroxide accumulation, has been recently implicated in AILI. The activation of the Nrf2 signaling pathway is a potential therapy for AILI. Kaempferol (KA), a flavonoid widely existing in edible plants, has been reported to exert profound anti-inflammatory and antioxidant activities. This study aimed to investigate whether KA exerts anti-AILI effects via the Nrf2 signaling pathway. Mice were fasted for 22 h and injected intraperitoneally with APAP (250 mg kg^-1) to induce AILI. Mice were pre-injected intragastrically with KA for 2 h followed by APAP injection. The hepatic injury was observed by H&E staining. Biochemical parameters of the serum and liver were measured using kits. KA alleviated hepatic injury and inflammatory response in AILI mice and ameliorated APAP-induced hepatic iron overload and oxidative stress in mice. In addition, the protective effects of KA against APAP-induced hepatotoxicity were examined in L02 cells in vitro. Cell viability was assayed by the CCK8 assay. Mitochondrial reactive oxygen species (ROS) in L02 cells were detected by MitoSox fluorescence. KA reversed the APAP-induced decrease in cell viability and GSH levels and inhibited the accumulation of intracellular ROS. Furthermore, KA activated the Nrf2 pathway and upregulated Gpx4 in mouse livers and L02 cells to inhibit ferroptosis induced by APAP. Finally, molecular docking indicated the potential interaction of KA with Keap1. Taken together, KA ameliorated oxidative stress and ferroptosis-mediated AILI by activating Nrf2 signaling.

Hepatoprotective effect of nicorandil against acetaminophen-induced oxidative stress and hepatotoxicity in mice via modulating NO synthesis

Acetaminophen (APAP) overdose can produce hepatotoxicity and consequently liver damage. This study investigated the hepatoprotective impacts of nicorandil on hepatic damage induced by APAP. Nicorandil was administered orally (100 mg/kg) for seven days before APAP challenge (500 mg/kg, ip). Pretreatment with nicorandil reduced serum levels of aminotransferases, bilirubin, GGT and LDH, and increased serum level of albumin. Moreover, nicorandil inhibited the increase in liver MDA levels and reversed the decline in GSH content and SOD activity. Besides, it notably alleviated APAP-induced necrosis observed in histopathological findings. Additionally, nicorandil alleviated APAP-induced NO overproduction and iNOS expression; however, the protein expression of eNOS was significantly increased. Moreover, nicorandil markedly reduced hepatic TNF-α and NF-κB levels, in addition to decreasing the protein expression of MPO in hepatic tissues. Furthermore, flow cytometry (annexin V-FITC/PI) displayed a significant decline in late apoptotic and necrotic cells, and an increase in viable cells in nicorandil group. Also, nicorandil caused a significant boost in hepatic antiapoptotic marker bcl-2 level. The presented data proposed that the protective effect of nicorandil might be attributed to its antioxidant, its impact on NO homeostasis, and its anti-inflammatory properties. Therefore, nicorandil may be a promising candidate for protection from liver injury induced by APAP.

Naringin regulates mitochondrial dynamics to protect against acetaminophen-induced hepatotoxicity by activating the AMPK/Nrf2 signaling pathway in vitro

Naringin (Nar) has been reported to exert potential hepatoprotective effects against acetaminophen (APAP)-induced injury. Mitochondrial dysfunction plays an important role in APAP-induced liver injury. However, the protective mechanism of Nar against mitochondrial damage has not been elucidated. Therefore, the aim of this study was to investigate the hepatoprotective effects of Nar against APAP and the possible mechanisms of actions. Primary rat hepatocytes and HepG2 cells were utilized to establish an in vitro model of APAP-induced hepatotoxicity. The effect of APAP and Nar on cell viability was evaluated by a CCK8 assay and detection of the concentrations of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase. The cellular concentrations of biomarkers of oxidative stress were measured by ELISA. The mRNA expression levels of APAP-related phase II enzymes were determined by real-time PCR. The protein levels of Nrf2, phospho (p)-AMPK/AMPK, and biomarkers of mitochondrial dynamics were determined by western blot analysis. The mitochondrial membrane potential (MMP) was measured by high-content analysis and confocal microscopy. JC-1 staining was performed to evaluate mitochondrial depolarization. Nar pretreatment notably prevented the marked APAP-induced hepatocyte injury, increases in oxidative stress marker expression, reductions in the expression of phase II enzymes, significant loss of MMP, mitochondrial depolarization, and mitochondrial fission in vitro. In conclusion, Nar alleviated APAP-induced hepatocyte and mitochondrial injury by activating the AMPK/Nrf2 pathway to reduce oxidative stress in vitro. Applying Nar for the treatment of APAP-induced liver injury might be promising.

Causality Evaluation of Drug-Induced Liver Injury in Newborns and Children in the Intensive Care Unit Using the Updated Roussel Uclaf Causality Assessment Method

Purpose: Drug-induced liver injury (DILI) is a common adverse reaction in the clinic; however, there are relatively few reports of DILI in critically ill newborns and children. Making use of the Pediatric Intensive Care database (PIC), this study identifies which drugs are related to DILI in neonates and children in China.

Methods: Using the PIC, we screened for patients whose liver was suspected of being injured by drugs during hospitalization. The medicine they used was then assessed by the Roussel Uclaf Causality Assessment Method (RUCAM). At the same time, we also collated drug combinations that may affect CYP (Cytochrome P) enzyme metabolism, which may cause DILI.

Results: A total of 13,449 patients were assessed, of whom 77 newborns and 261 children were finally included. The main type of liver injury in neonates was mixed (83.1%), while the hepatic injury types of children were mostly distributed between hepatocellular (59.4%) and cholestatic (28.4%). In terms of the RUCAM assessment, the drugs that were most considered to cause or be associated with hepatic injury in newborns were medium and long chain fat emulsions (17%), sodium glycerophosphate (12%), and meropenem (9%); while omeprazole (11%), methylprednisolone sodium succinate (10%), and meropenem (8%) were the primary culprits of DILI in children. Drug combinations frequently seen in neonates that may affect CYP enzyme metabolism are omeprazole + budesonide (16.9%), dexamethasone + midazolam (10.4%), and midazolam + sildenafil (10.4%). In children, the commonly used drug combinations are fentanyl + midazolam (20.7%), ibuprofen + furosemide (18.4%), and diazepam + omeprazole (15.3%).

Conclusions: In this study, medium and long chain fat emulsions and sodium glycerophosphate have been strongly associated with DILI in newborns, while omeprazole and methylprednisolone sodium succinate play an important role in the DILI of children. Also, attention should be paid to the effect on CYP enzymes when using multiple drugs at the same time. In future DILI cases, it is advisable to use the latest RUCAM for prospective study design so that complete case data and high RUCAM scores can be collected.

Relative Risk Analysis of Liver-related Adverse Drug Reactions in Children Based on China's National Spontaneous Reporting System

OBJECTIVE

To compare the risk of liver-related adverse drug reactions (ADRs) in children and adults.

STUDY DESIGN

A case/non-case analysis on spontaneous reports based on the China National Adverse Drug Reactions Monitoring System database were conducted, focusing on events of liver-related ADRs in children younger than 14 years of age. Both the relative risk of liver-related ADRs in children vs entire population and the risk stratification in children were expressed as a measure of disproportionality using the reporting odds ratio (ROR).

RESULTS

There were 1206 cases of pediatric liver-related ADRs identified from 2012 to 2016, accounting for 2.82% of the entire population. The greatest ROR values in children from 0 to 14 years vs the entire population were observed for analgesics (3.97, 95% CI 3.27-4.81), respiratory (2.60, 95% CI 1.04-6.43), antineoplastic (2.29, 95% CI 2.02-2.58), immunomodulatory (1.91, 95% CI 1.44-2.53), and antimicrobial agents (1.47, 95% CI 1.33-1.63). Notably, infants aged 0-1 years showed significantly greater risk (3.14, 95% CI 2.85-3.48) of liver-related ADRs than the other age groups of children. For infants, analgesics (3.21, 95% CI 2.20-4.66) and antimicrobials (3.15, 95% CI 2.50-3.97) agents were found to have the greatest adjusted RORs than other drug categories. The highest RORs were found for meropenem, amoxicillin, fluconazole, vancomycin, cefaclor, and ceftazidime in the antimicrobial agents for infants.

CONCLUSIONS

Children are sensitive to liver-related ADRs caused by several specific drug categories, and infants are the most sensitive.

Protective Effect of Dihydrokaempferol on Acetaminophen-Induced Liver Injury by Activating the SIRT1 Pathway

Acetaminophen (APAP) overdose is the leading cause of acute liver failure (ALF) in the Western world, with limited treatment opportunities. 3,5,7,4[Formula: see text]-Tetrahydroxyflavanone (Dihydrokaempferol, DHK, Aromadendrin) is a flavonoid isolated from Chinese herbs and displays high anti-oxidant and anti-inflammatory capacities. In this study, we investigated the protective effect by DHK against APAP-induced liver injury in vitro and in vivo and the potential mechanism of action. Cell viability assays were used to determine the effects of DHK against APAP-induced liver injury. The levels of reactive oxygen species (ROS), serum alanine/aspartate aminotransferases (ALT/AST), liver myeloperoxidase (MPO), and malondialdehyde (MDA) were measured and analyzed to evaluate the effects of DHK on APAP-induced liver injury. Western blotting, immunofluorescence staining, RT-PCR, and Transmission Electron Microscope were carried out to detect the signaling pathways affected by DHK. Here, we found that DHK owned a protective effect on APAP-induced liver injury with a dose-dependent manner. Meanwhile, Western blotting showed that DHK promoted SIRT1 expression and autophagy, activated the NRF2 pathway, and inhibited the translocation of nuclear p65 (NF-[Formula: see text]B) in the presence of APAP. Furthermore, SIRT1 inhibitor EX-527 aggravated APAP-induced hepatotoxicity when treating with DHK. Molecular docking results suggested potential interaction between DHK and SIRT1. Taken together, our study demonstrates that DHK protects against APAP-induced liver injury by activating the SIRT1 pathway, thereby promoting autophagy, reducing oxidative stress injury, and inhibiting inflammatory responses.

Structure-Based Reactivity Profiles of Reactive Metabolites with Glutathione

Therapeutic agents can be transformed into reactive metabolites under the action of various metabolic enzymes in vivo and then covalently combine with biological macromolecules (such as protein or DNA), resulting in increasing toxicity. The screening of reactive metabolites in drug discovery and development stages and monitoring of biotransformation in post-market drugs has become an important research field. Generally, reactive metabolites are electrophilic and can be captured by small nucleophiles. Glutathione (GSH) is a small peptide composed of three amino acids (i.e., glutamic acid, cysteine, and glycine). It has a thiol group which can react with electrophilic groups of reactive metabolic intermediates (such as benzoquinone, N-acetyl-p-benzoquinoneimine, and Michael acceptor) to form a stable binding conjugate. This paper aims to provide a review on structure-based reactivity profiles of reactive metabolites with GSH. Furthermore, this review also reveals the relationship between drugs' molecular structures and reactive metabolic toxicity from the perspective of metabolism, giving a reference for drug design and development.

The Protective Effect of Sonneratia apetala Fruit Extract on Acetaminophen-Induced Liver Injury in Mice

Acute liver injury is a common consequence of taking overdose of acetaminophen (APAP). The aim of this study was to evaluate the antioxidant activity and hepatoprotective effect of a mangrove plant Sonneratia apetala fruit extract (SAFE) on APAP-induced liver injury in mice. Mice were orally pretreated with SAFE (100, 200, and 400 mg/kg) daily for one week. The control and APAP groups were intragastrically administered with distilled water, and NAC group was treated with N-Acetyl-L-cysteine (NAC) before APAP exposure. The results manifested that SAFE significantly improved survival rates, attenuated hepatic histological damage, and decreased the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in serum in APAP-exposed mice. SAFE treatment also increased glutathione (GSH) level and glutathione peroxidase (GSH-Px) activity, enhanced catalase (CAT), and total antioxidant capacity (T-AOC), as well as reducing malondialdehyde (MDA) level in liver. In addition, the formation of tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and elevation of myeloperoxidase (MPO) in APAP-exposed mice were inhibited after SAFE treatment. And SAFE also displayed high DPPH radical scavenging activity and reducing power in vitro. The main bioactive components of SAFE such as total phenol, flavonoid, condensed tannin, and carbohydrate were determined. The current study proved that SAFE exerted potential protective effect against APAP-induced acute liver injury, which might be associated with the antioxidant and anti-inflammatory activities of SAFE.

Oxidative Stress Parameters after Abdominal Hysterectomy and Their Relationships with Quality of Recovery

Study aimed to investigate relationship between oxidative stress markers and postoperative recovery in woman after abdominal hysterectomy, as well as to test the hypothesis that different analgesics differently influence redox status.

The quality of recovery was evaluated with a QoR-40 questionnaire in fifty-one patients who underwent abdominal hysterectomy, preoperatively and on the 1st, 2nd, 3rd postoperative days (POD1,2,3). Blood samples were collected at baseline (T0), 3 (T1), 24 (T2), 48 (T3) and 72 (T4) hours after surgery. Oxidative stress markers concentrations (TBARS, NO2 −, H2O2, O2 − ) as well as antioxidative enzymes (SOD, CAT, and GSH) were analyzed.

QoR-40 total score significantly declined on POD1 and POD2 and returned to baseline levels on POD3 (p<0.001). H2O2 levels significantly decreased from T0 to T3 and then, increased at T4 (p=0,011). Changes of TBARS and H2O2 from T0 to T3 showed significant and negative correlation (r=−0.303, p=0.046). There was no significant correlation between QoR-40 total score and any parameter of oxidative stress response (p>0.05). Changes in TBARS levels from T0 to T3 were statistically significant between the study subgroups primarily due to increase of the concentrations in patients receiving paracetamol (p=0.031). Patients age, duration of surgery and cigarette smoking status showed significant influcences on and association with some oxidative stress response markers (TBARS, O2 −, CAT) (p<0.05).

Women who underwent hysterectomy had significant changes of H2O2 and TBARS activity however, those changes were not associated with changes of QoR-40 total scores during recovery.

Acetaminophen cytotoxicity in HepG2 cells is associated with a decoupling of glycolysis from the TCA cycle, loss of NADPH production, and suppression of anabolism

Acetaminophen (APAP) is one of the most commonly used analgesics worldwide, and overdoses are associated with lactic acidosis, hepatocyte toxicity, and acute liver failure due to oxidative stress and mitochondrial dysfunction. Hepatoma cell lines typically lack the CYP450 activity to generate the reactive metabolite of APAP observed in vivo, but are still subject to APAP cytotoxicity. In this study, we employed metabolic profiling and isotope labelling approaches to investigate the metabolic impact of acute exposure to cytotoxic doses of APAP on the widely used HepG2 cell model. We found that APAP exposure leads to limited cellular death and substantial growth inhibition. Metabolically, we observed an up-regulation of glycolysis and lactate production with a concomitant reduction in carbon from glucose entering the pentose-phosphate pathway and the TCA cycle. This was accompanied by a depletion of cellular NADPH and a reduction in the de novo synthesis of fatty acids and the amino acids serine and glycine. These events were not associated with lower reduced glutathione levels and no glutathione conjugates were seen in cell extracts. Co-treatment with a specific inhibitor of the lactate/H⁺ transporter MCT1, AZD3965, led to increased apoptosis in APAP-treated cells, suggesting that lactate accumulation could be a cause of cell death in this model. In conclusion, we show that APAP toxicity in HepG2 cells is largely independent of oxidative stress, and is linked instead to a decoupling of glycolysis from the TCA cycle, lactic acidosis, reduced NADPH production, and subsequent suppression of the anabolic pathways required for rapid growth.

Aminophenols increase proliferation of thyroid tumor cells by inducing the transcription factor activity of estrogen receptor α

Aminophenols, which are widely used as components of hair dye and medicine, may function as environmental endocrine disruptors by regulating the proliferation of endocrine-related cancers. Estrogen receptor α (ERα) is a key regulator of breast cancer. Recently, it was found that ERα may also participate in the transformation and progression of thyroid tumors, but its interaction with aminophenols and its function in thyroid tumors is not clear. In this study, the transcription factor activity of ERα in BHP10-3 cells (a thyroid tumor cell line) was examined using luciferase assays. The promoter recruitment of ERα was examined using chromatin co-precipitation (ChIP). Additionally, in an in vivo study, BHP10-3 cells were transplanted into nude mice. Upon administration of aminophenols, the transcription factor activity of ERα was significantly increased in BHP10-3 cells, and the recruitment of ERα to the promoter of its target gene was increased. Aminophenols enhanced the in vitro and in vivo proliferation of BHP10-3 cells. By discovering that aminophenols induce the onco-promoting activity of ERα, our study extends the understanding of the function of aminophenols and suggests that ERα is a potential therapeutic target for the treatment of thyroid tumors.

Plasma metabolic profiling analysis of Strychnos nux-vomica Linn. and Tripterygium wilfordii Hook F-induced renal toxicity using metabolomics coupled with UPLC/Q-TOF-MS

Both Strychnos nux-vomica Linn. (SNV) and Tripterygium wilfordii Hook F (TwHF) have received extensive attention due to their excellent clinical efficacies. However, clinical applications of SNV and TwHF have been limited by their narrow therapeutic windows and severe kidney toxicities. In this paper, based on ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS), endogenous metabolites after administration of SNV and TwHF extracts were detected, and biomarkers were screened successfully. Additionally, the levels of Cr and BUN in serum and pathological findings of kidneys were detected and observed. Finally, both biochemical and pathological tests of the SNV group and TwHF group indicated that kidney damage had occurred. After comparison with the normal saline group, 15 nephrotoxic biomarkers were selected from the SNV group, and 17 nephrotoxic biomarkers were selected from the TwHF group. The experimental results showed that there are some differences in the mechanisms of nephrotoxicity induced by SNV and TwHF, which are significant for revealing the mechanisms of renal injury of different medicines.

Astragaloside IV Attenuates Acetaminophen-Induced Liver Injuries in Mice by Activating the Nrf2 Signaling Pathway

Acetaminophen (APAP) is a well-known antipyretic and analgesic drug. However, the accidental or intentional APAP overdose will induce liver injury and even acute liver failure. Astragaloside IV (AS-IV), a bioactive compound isolated from Astragali Radix, has been reported to have protective effects on the digestive and immune systems because of its anti-oxidant and anti-inflammatory properties. This study aims to observe whether AS-IV pretreatment provides protection against APAP-induced liver failure. The results of serum alanine/aspartate aminotransferases (ALT/AST) analysis, hepatic glutathione (GSH), and malondialdehyde (MDA) amounts, and liver superoxide dismutase (SOD) activity showed that AS-IV protected against APAP-induced hepatotoxicity. Liver histological observation further evidenced this protection provided by AS-IV. AS-IV was found to reverse the APAP-induced increased amounts of pro-inflammatory cytokines, including interleukin 1β (IL-1β), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α). Western-blot analysis showed that AS-IV increased the transcriptional activation of nuclear factor erythroid 2-related factor 2 (Nrf2), and enhanced the expression of heme oxygenase 1 (HO-1) and reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H): quinone oxidoreductase 1 (NQO1) in the presence of APAP. AS-IV also decreased the expression of kelch-like ECH-associated protein-1 (Keap1). In conclusion, we demonstrated that AS-IV exerted a strong protection against APAP-induced hepatotoxicity by activating Nrf2 antioxidant signaling pathways.

The application of a novel high-resolution mass spectrometry-based analytical strategy to rapid metabolite profiling of a dual drug combination in humans

Metabolite profiling of combination drugs in complex matrix is a big challenge. Development of an effective data mining technique for simultaneously extracting metabolites of one parent drug from both background matrix and combined drug-related signals could be a solution. This study presented a novel high resolution mass spectrometry (HRMS)-based data-mining strategy to fast and comprehensive metabolite identification of combination drugs in human. The model drug combination was verapamil-irbesartan (VER-IRB), which is widely used in clinic to treat hypertension. First, mass defect filter (MDF), as a targeted data mining tool, worked effectively except for those metabolites with similar MDF values. Second, the accurate mass-based background subtraction (BS), as an untargeted data-mining tool, was able to recover all relevant metabolites of VER-IRB from the full-scan MS dataset except for trace metabolites buried in the background noise and/or combined drug-related signals. Third, the novel ring double bond (RDB; valence values of elements in structure) filter, could show rich structural information in more sensitive full-scan MS chromatograms; however, it had a low capability to remove background noise and was difficult to differentiate the metabolites with RDB coverage. Fourth, an integrated strategy, i.e., untargeted BS followed by RDB, was effective for metabolite identification of VER and IRB, which have different RDB values. Majority of matrix signals were firstly removed using BS. Metabolite ions for each parent drug were then isolated from remaining background matrix and combined drug-related signals by imposing of preset RDB values/ranges around the parent drug and selected core substructures. In parallel, MDF was used to recover potential metabolites with similar RDB. As a result, a total of 74 metabolites were found for VER-IRB in human plasma and urine, among which ten metabolites have not been previously reported in human. The results demonstrated that the combination of accurate mass-based multiple data-mining techniques, i.e., untargeted background subtraction followed by ring double bond filtering in parallel with targeted mass defect filtering, can be a valuable tool for rapid metabolite profiling of combination drug.

Metabolomics Analysis of Urine Samples from Children after Acetaminophen Overdose

Acetaminophen (APAP), a commonly used over-the-counter analgesic, accounts for approximately fifty percent of the cases of acute liver failure (ALF) in the United States due to overdose, with over half of those unintentional. Current clinical approaches for assessing APAP overdose rely on identifying the precise time of overdose and quantitating acetaminophen alanine aminotransferase (ALT) levels in peripheral blood. Novel specific and sensitive biomarkers may provide additional information regarding patient status post overdose. Previous non-clinical metabolomics studies identified potential urinary biomarkers of APAP-induced hepatotoxicity and metabolites involved pathways of tricarboxylic acid cycle, ketone metabolism, and tryptophan metabolism. In this study, biomarkers identified in the previous non-clinical study were evaluated in urine samples collected from healthy subjects ( N = 6, median age 14.08 years) and overdose patients ( N = 13, median age 13.91 years) as part of an IRB-approved multicenter study of APAP toxicity in children. The clinical results identified metabolites from pathways previously noted, and pathway analysis indicated analogous pathways were significantly altered in both the rats and humans after APAP overdose. The results suggest a metabolomics approach may enable the discovery of specific, translational biomarkers of drug-induced hepatotoxicity that may aid in the assessment of patients.

Drug-Induced Liver Injury in Children: Clinical Observations, Animal Models, and Regulatory Status

Drug-induced liver injury in children (cDILI) accounts for about 1% of all reported adverse drug reactions throughout all age groups, less than 10% of all clinical DILI cases, and around 20% of all acute liver failure cases in children. The overall DILI susceptibility in children has been assumed to be lower than in adults. Nevertheless, controversial evidence is emerging about children's sensitivity to DILI, with children's relative susceptibility to DILI appearing to be highly drug-specific. The culprit drugs in cDILI are similar but not identical to DILI in adults (aDILI). This is demonstrated by recent findings that a drug frequently associated with aDILI (amoxicillin/clavulanate) was rarely associated with cDILI and that the drug basiliximab caused only cDILI but not aDILI. The fatality in reported cDILI studies ranged from 4% to 31%. According to the US Food and Drug Administration-approved drugs labels, valproic acid, dactinomycin, and ampicillin appear more likely to cause cDILI. In contrast, deferasirox, isoniazid, dantrolene, and levofloxacin appear more likely to cause aDILI. Animal models have been explored to mimic children's increased susceptibility to valproic acid hepatotoxicity or decreased susceptibility to acetaminophen or halothane hepatotoxicity. However, for most drugs, animal models are not readily available, and the underlying mechanisms for the differential reactions to DILI between children and adults remain highly hypothetical. Diagnosis tools for cDILI are not yet available. A critical need exists to fill the knowledge gaps in cDILI. This review article provides an overview of cDILI and specific drugs associated with cDILI.

Alleviative effects from boswellic acid on acetaminophen-induced hepatic injury - Corrected and republished from: Biomedicine (Taipei). 2016 Jun; 6 (2): 9. doi: 10.7603/s40681-016-0009-1PMCID: PMC4864770

Protective effects of boswellic acid (BA) against acetaminophen (APAP)-induced hepatotoxicity in Balb/ cA mice were examined. BA, at 0.05 or 0.1%, was supplied for 4 weeks. Acute liver injury was induced by APAP treatment. Results showed that BA intake increased hepatic BA bioavailability. APAP treatment decreased glutathione (GSH) level, increased reactive oxygen species (ROS) and oxidized glutathione (GSSG) production; and lowered activity and protein expression of glutathione reductase (GR) and heme oxygenase (HO)-1 in liver. BA intake at both doses alleviated subsequent APAP-induced oxidative stress by retaining GSH content, decreasing ROS and GSSG formations, reserving activity and expression of GR and HO-1 in liver, and lowering hepatic cytochrome P450 2E1 activity and expression. APAP treatment enhanced hepatic levels of interleukin-6, tumor necrosis factor-alpha and monocyte chemoattractant protein-1. BA pre-intake diminished APAP-induced release of those inflammatory cytokines and chemokines. APAP up-regulated hepatic protein expression of toll-like receptor (TLR)-3, TLR-4, MyD88, nuclear factor kappa B (NF-κB) p50, NF-κB p65 and JNK. BA pre-intake at both doses suppressed the expression of NF-κB p65 and p-JNK, and only at 0.1% down-regulated hepatic TLR-3, TLR-4 and MyD88 expression. APAP led to obvious foci of inflammatory cell infiltration in liver, determined by H&E stain. BA intake at both doses attenuated hepatic inflammatory infiltration. These findings support that boswellic acid is a potent hepato-protective agent.

Immature mice are more susceptible than adult mice to acetaminophen-induced acute liver injury

Acetaminophen (APAP) overdose induces acute liver injury. The aim of the present study was to analyze the difference of susceptibility between immature and adult mice to APAP-induced acute liver injury. Weanling immature and adult mice were injected with APAP (300 mg/kg). As expected, immature mice were more susceptible than adult mice to APAP-induced acute liver injury. APAP-evoked hepatic c-Jun N-terminal kinase phosphorylation was stronger in immature mice than in adult mice. Hepatic receptor-interacting protein (RIP)1 was obviously activated at APAP-exposed immature and adult mice. Interestingly, hepatic RIP3 activation was more obvious in APAP-treated immature mice than adult mice. Although there was no difference on hepatic GSH metabolic enzymes between immature and adult mice, immature mice were more susceptible than adult mice to APAP-induced hepatic GSH depletion. Of interest, immature mice expressed a much higher level of hepatic Cyp2e1 and Cyp3a11 mRNAs than adult mice. Correspondingly, immature mice expressed a higher level of hepatic CYP2E1, the key drug metabolic enzyme that metabolized APAP into the reactive metabolite NAPQI. These results suggest that a higher level of hepatic drug metabolic enzymes in immature mice than adult mice might contribute to the difference of susceptibility to APAP-induced acute liver injury.

Antcin H Protects Against Acute Liver Injury Through Disruption of the Interaction of c-Jun-N-Terminal Kinase with Mitochondria

AIM

Antrodia Camphorate (AC) is a mushroom that is widely used in Asian countries to prevent and treat various diseases, including liver diseases. However, the active ingredients that contribute to the biological functions remain elusive. The purpose of the present study is to test the hepatoprotective effect of Antcin H, a major triterpenoid chemical isolated from AC, in murine models of acute liver injury.

RESULTS

We found that Antcin H pretreatment protected against liver injury in both acetaminophen (APAP) and galactosamine/tumor necrosis factor (TNF)α models. More importantly, Antcin H also offered a significant protection against acetaminophen-induced liver injury when it was given 1 h after acetaminophen. The protection was verified in primary mouse hepatocytes. Antcin H prevented sustained c-Jun-N-terminal kinase (JNK) activation in both models. We excluded an effect of Antcin H on acetaminophen metabolism and TNF receptor signaling and excluded a direct effect as a free radical scavenger or JNK inhibitor. Since the sustained JNK activation through its interaction with mitochondrial Sab, leading to increased mitochondrial reactive oxygen species (ROS), is pivotal in both models, we examined the effect of Antcin H on p-JNK binding to mitochondria and impairment of mitochondrial respiration. Antcin H inhibited the direct effect of p-JNK on isolated mitochondrial function and binding to isolated mitochondria. Innovation and Conclusion: Our study has identified Antcin H as a novel active ingredient that contributes to the hepatoprotective effect of AC, and Antcin H protects against liver injury through disruption of the binding of p-JNK to Sab, which interferes with the ROS-dependent self-sustaining activation of MAPK cascade. Antioxid. Redox Signal. 26, 207-220.

Caffeic acid attenuated acetaminophen-induced hepatotoxicity by inhibiting ERK1/2-mediated early growth response-1 transcriptional activation

Caffeic acid (CA) is a natural compound abundant in fruits, coffee and plants. This study aims to investigate the involved mechanism of the therapeutic detoxification of CA against acetaminophen (APAP)-induced hepatotoxicity. CA (10, 30 mg/kg) was orally given to mice at 1 h after mice were pre-administrated with APAP (300 mg/kg). The therapeutic detoxification of CA against APAP-induced hepatotoxicity was observed by detecting serum aminotransferases, liver malondialdehyde (MDA) amount and liver histological evaluation in vivo. CA reduced APAP-induced increase in the mRNA expression of early growth response 1 (Egr1) in hepatocytes, and inhibited APAP-induced Egr1 transcriptional activation in vitro and in vivo. CA reduced the increased expression of growth arrest and DNA-damage-inducible protein (Gadd45)α induced by APAP in hepatocytes. Moreover, Egr1 siRNA reduced Gadd45α expression and reversed APAP-induced cytotoxicity in hepatocytes. Further results showed that CA blocked APAP-induced activation of extracellular-regulated protein kinase (ERK1/2) signaling cascade in vivo and in vitro. In addition, the application of ERK1/2 inhibitors (PD98059 and U0126) abrogated the nuclear translocation of Egr1 induced by APAP in hepatocytes. In conclusion, this study demonstrated the therapeutic detoxification of CA against APAP-induced liver injury, and the inhibition of CA on ERK1/2-mediated Egr1 transcriptional activation was involved in this process.

Extract from Mulberry (Morus australis) leaf decelerate acetaminophen induced hepatic inflammation involving downregulation of myeloid differentiation factor 88 (MyD88) signals

Acetaminophen (APAP) induced inflammation and oxidative stress can cause cell death to induce liver damage. The antioxidative and anti-inflammatory effect of Mulberry (Morus australis) leaf extract (MLE) was shown in previous studies. In this study, we investigated the modulation of MLE on APAP induced inflammation and oxidative stress in rat liver injury or liver cancer cell (HepG2). Wistar rat was fed orally with MLE (0.5% or 1.0 %) for 1 week, and then, 900 mg/kg of APAP was injected intraperitoneally (i.p.). Pretreatment of MLE decreased obvious foci of inflammatory cell infiltration in liver. It also reduced the expression of inflammatory parameters including cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and nuclear factor kappa B (NF-κB) in liver. Treating with MLE increased the antioxidative enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase. Giving APAP to HepG2 hepatocyte was conducted to elucidate the mechanism of MLE or its functional components. The result showed that APAP upregulated hepatic protein expression of (myeloid differentiation factor 88) MyD88, nuclear factor kappa B (NF-kB), inhibitor of kappa B (IkB), c-Jun N-terminal kinases (JNK), and receptor interacting proteins (RIP1 and RIP3). Pretreatment of MLE, gallic acid (GA), gallocatechin gallate (GCG), or protocatechuic acid (PCA) suppressed the indicated protein expression. These findings confirmed that MLE has the potential to protect liver from APAP-induced inflammation, and the protecting mechanism might involve decreasing oxidative stress and regulating the innate immunity involving MyD88.

An integrated strategy for the rapid extraction and screening of phosphatidylcholines and lysophosphatidylcholines using semi-automatic solid phase extraction and data processing technology

This study attempts to establish a comprehensive strategy for the rapid extraction and screening of phosphatidylcholines (PCs) and lysophosphatidylcholines (LysoPCs) in biological samples using semi-automatic solid phase extraction (SPE) and data processing technology based on ultra-performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS). First, the Ostro sample preparation method (i.e., semi-automatic SPE) was compared with the Bligh-Dyer method in terms of substance coverage, reproducibility and sample preparation time. Meanwhile, the screening method for PCs and LysoPCs was built through mass range screening, mass defect filtering and diagnostic fragments filtering. Then, the Ostro sample preparation method and the aforementioned screening method were combined under optimal conditions to establish a rapid extraction and screening platform. Finally, this developed method was validated and applied to the preparation and data analysis of tissue samples. Through a systematic evaluation, this developed method was shown to provide reliable and high-throughput experimental results and was suitable for the preparation and analysis of tissue samples. Our method provides a novel strategy for the rapid extraction and analysis of functional phospholipids. In addition, this study will promote further study of phospholipids in disease research.

Alleviative effects from boswellic acid on acetaminophen-induced hepatic injury

Protective effects of boswellic acid (BA) against acetaminophen (APAP)-induced hepatotoxicity in Balb/ cA mice were examined. BA, at 0.05 or 0.1%, was supplied for 4 weeks. Acute liver injury was induced by APAP treatment. Results showed that BA intake increased hepatic BA bioavailability. APAP treatment decreased glutathione (GSH) level, increased reactive oxygen species (ROS) and oxidized glutathione (GSSG) production; and lowered activity and protein expression of glutathione reductase (GR) and heme oxygenase (HO)-1 in liver. BA intake at both doses alleviated subsequent APAP-induced oxidative stress by retaining GSH content, decreasing ROS and GSSG formations, reserving activity and expression of GR and HO-1 in liver, and lowering hepatic cytochrome P450 2E1 activity and expression. APAP treatment enhanced hepatic levels of interleukin-6, tumor necrosis factor-alpha and monocyte chemoattractant protein-1. BA pre-intake diminished APAP-induced release of those inflammatory cytokines and chemokines. APAP upregulated hepatic protein expression of toll-like receptor (TLR)-3, TLR-4, MyD88, nuclear factor kappa B (NF-κB) p50, NF-κB p65 and JNK. BA pre-intake at both doses suppressed the expression of NF-κB p65 and p-JNK, and only at 0.1% down-regulated hepatic TLR-3, TLR-4 and MyD88 expression. APAP led to obvious foci of inflammatory cell infiltration in liver, determined by H&E stain. BA intake at both doses attenuated hepatic inflammatory infiltration. These findings support that boswellic acid is a potent hepatoprotective agent.

Emerging applications of metabolomics in drug discovery and precision medicine

Metabolomics is an emerging 'omics' science involving the comprehensive characterization of metabolites and metabolism in biological systems. Recent advances in metabolomics technologies are leading to a growing number of mainstream biomedical applications. In particular, metabolomics is increasingly being used to diagnose disease, understand disease mechanisms, identify novel drug targets, customize drug treatments and monitor therapeutic outcomes. This Review discusses some of the latest technological advances in metabolomics, focusing on the application of metabolomics towards uncovering the underlying causes of complex diseases (such as atherosclerosis, cancer and diabetes), the growing role of metabolomics in drug discovery and its potential effect on precision medicine.

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.

Metabolomic Approaches in Cancer Epidemiology

Metabolomics is the study of low molecular weight molecules or metabolites produced within cells and biological systems. It involves technologies such as mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR) that can measure hundreds of thousands of unique chemical entities (UCEs). The metabolome provides one of the most accurate reflections of cellular activity at the functional level and can be leveraged to discern mechanistic information during normal and disease states. The advantages of metabolomics over other “omics” include its high sensitivity and ability to enable the analysis of relatively few metabolites compared with the number of genes and messenger RNAs (mRNAs). In clinical samples, metabolites are more stable than proteins or RNA. In fact, metabolomic profiling in basic, epidemiologic, clinical, and translational studies has revealed potential new biomarkers of disease and therapeutic outcome and has led to a novel mechanistic understanding of pathogenesis. These potential biomarkers include novel metabolites associated with cancer initiation, regression, and recurrence. Unlike genomics or even proteomics, however, the degree of metabolite complexity and heterogeneity within biological systems presents unique challenges that require specialized skills and resources to overcome. This article discusses epidemiologic studies of altered metabolite profiles in several cancers as well as challenges in the field and potential approaches to overcoming them.

Effect of amlodipine, lisinopril and allopurinol on acetaminophen-induced hepatotoxicity in rats

Background

Exposure to chemotherapeutic agents such as acetaminophen may lead to serious liver injury. Calcium deregulation, angiotensin II production and xanthine oxidase activity are suggested to play mechanistic roles in such injury.

Objective

This study evaluates the possible protective effects of the calcium channel blocker amlodipine, the angiotensin converting enzyme inhibitor lisinopril, and the xanthine oxidase inhibitor allopurinol against experimental acetaminophen-induced hepatotoxicity, aiming to understand its underlying hepatotoxic mechanisms.

Material and methods

Animals were allocated into a normal control group, a acetaminophen hepatotoxicity control group (receiving a single oral dose of acetaminophen; 750 mg/kg/day), and four treatment groups receive N-acetylcysteine (300 mg/kg/day; a reference standard), amlodipine (10 mg/kg/day), lisinopril (20 mg/kg/day) and allopurinol (50 mg/kg/day) orally for 14 consecutive days prior to acetaminophen administration. Evaluation of hepatotoxicity was performed by the assessment of hepatocyte integrity markers (serum transaminases), oxidative stress markers (hepatic malondialdehyde, glutathione and catalase), and inflammatory markers (hepatic myeloperoxidase and nitrate/nitrite), in addition to a histopathological study.

Results

Rats pre-treated with amlodipine, lisinopril or allopurinol showed significantly lower serum transaminases, significantly lower hepatic malondialdehyde, myeloperoxidase and nitrate/nitrite, as well as significantly higher hepatic glutathione and catalase levels, compared with acetaminophen control rats. Serum transaminases were normalized in the lisinopril treatment group, while hepatic myeloperoxidase was normalized in the all treatment groups. Histopathological evaluation strongly supported the results of biochemical estimations.

Conclusion

Amlodipine, lisinopril or allopurinol can protect against acetaminophen-induced hepatotoxicity, showing mechanistic roles of calcium channels, angiotensin converting enzyme and xanthine oxidase enzyme in the pathogenesis of hepatotoxicity induced by acetaminophen.