Near-infrared molecular sensor for visualizing and tracking ONOO- during the process of anti-tuberculosis drug-induced liver damage.

Isoniazid (INH) and pyrazinamide (PZA) are both the first-line anti-tuberculosis drugs in clinical treatment. It is notable that there are serious side effects of the drugs along with upregulation of reactive nitrogen species, mainly including peripheral neuritis, gastrointestinal reactions, and acute drug-induced liver injury (DILI). Among them, DILI is the most common clinical symptom as well as the basic reason of treatment interruption, protocol change, and drug resistance. As vital reactive nitrogen species (RNS), peroxynitrite (ONOO-) has been demonstrated as a biomarker for evaluation and pre-diagnosis of drug-induced liver injury (DILI). In this work, we developed a red-emitting D-π-A type fluorescence probe DIC-NP which was based on 4'-hydroxy-4-biphenylcarbonitrile modified with dicyanoisophorone as a fluorescent reporter and diphenyl phosphinic chloride group as the reaction site for highly selective and sensitive sensing ONOO-. Probe DIC-NP displayed a low detection limit (14.9 nM) and 60-fold fluorescent enhancement at 669 nm in the sensing of ONOO-. Probe DIC-NP was successfully applied to monitor exogenous and endogenous ONOO- in living HeLa cells and zebrafish. Furthermore, we verified the toxicity of isoniazid (INH) and pyrazinamide (PZA) by taking the oxidative stress induced by APAP as a reference, and successfully imaged anti-tuberculosis drug-induced endogenous ONOO- in HepG2 cells. More importantly, we developed a series of mice models of liver injury and investigated the hepatotoxicity caused by the treatment of anti-tuberculosis drugs. At the same time, H&E of mice organs (heart, liver, spleen, lung, kidney) further confirmed the competence of probe DIC-NP for estimating the degree of drug-induced liver injury, which laid a solid foundation for medical research.

The role of the farnesoid X receptor in quadruple anti-tuberculosis drug-induced liver injury.

Anti-tuberculosis drugs-induced liver injury may be associated with the hepatic farnesoid X receptor (FXR). However, the relationship between isoniazid, rifampicin, pyrazinamide and ethambutol (HRZE) coadministration-induced liver injury and FXR has not been clarified. The purpose of this study was to clarify the role of FXR in HRZE-induced liver injury. To measure indices of liver injury, blood samples were collected from clinical tuberculosis patients who had taken HRZE for approximately two months; in these patients serum total bile acids were increased, while other hepatic biochemical indexes showed no significant changes. When Wistar rats were orally administered isoniazid (30 or 60 mg/kg) + rifampicin (45 or 90 mg/kg) + pyrazinamide (150 or 300 mg/kg) + ethambutol (75 or 150 mg/kg) in combination for 15 days, the expression and function of FXR was up-regulated, and hepatic bile acids were decreased. However, following 30 days of HRZE treatment the expression and function of FXR was down-regulated and bile acids accumulated in the liver, suggestive of hepatotoxicity. Treatment of HepaRG cells with HRZE lead to time- and dose- dependent cytotoxicity, with the expression of FXR up-regulated in early stage, but down-regulated with prolonged HRZE treatment, consistent with the results of animal experiments. In summary, HRZE may upregulate FXR with short-term administration, but more prolonged treatment appears to suppress FXR function, resulting in hepatic bile acid accumulation.

Neurodevelopmental toxicity of pyrazinamide to larval zebrafish and the restoration after intoxication withdrawal.

To investigate the neurotoxicity of pyrazinamide (PZA) to larval zebrafish, the PZA effects were assessed followed by its mechanism being explored. Same as isoniazid (INH), this compound is a first-line anti-tuberculosis drug and is suggested to be a risk that inducing nerve injury with long-term intoxication. Our findings indicated that zebrafish larvae obtained severe nerve damage secondary to constant immersion in various concentrations of PZA (i.e., 0.5, 1.0, and 1.5 mM) from 4 hpf (hours post fertilization) onwards until 120 hpf. The damage presented as dramatically decrease of locomotor capacity and dopaminergic neuron (DAN)-rich region length in addition to defect of brain blood vessels (BBVs). Moreover, PZA-administrated zebrafish showed a decreased dopamine (DA) level and downregulated expression of neurodevelopment-related genes, such as shha, mbp, neurog1, and gfap. However, secondary to 48-h restoration in fish medium (i.e., at 168 hpf), the neurotoxicity described above was prominently ameliorated. The results showed that PZA at the concentrations we tested was notably neurotoxic to larval zebrafish, and this nerve injury was restorable after PZA withdrawing. Therefore, this finding will probably provide a reference for clinical medication.

Evidence of drug-induced hepatotoxicity in the Maghrebian population.

Drug-induced hepatotoxicity is one of the most challenging hepatic diseases faced nowadays due to a large number of drugs currently used in clinical practice, the enormous dietary supplements which are potentially hepatotoxic, as well as the ability to appear with different clinical symptoms and the absence of specific markers. The current research survey was conducted to investigate drug-induced hepatotoxicity and demographic characteristics of patients with liver damage in the general Maghrebian population between 1992 and 2018. To achieve this goal a questionnaire was adopted to report details on the undesirable effects of drugs and demographic characteristics of affected patients. The results obtained in the current survey showed that 1001 in 25 093 cases of drug-induced toxicity were registered with drug-induced liver damage between 1992 and 2018. Regarding demographic characteristics of affected patients, the most affected age group was 18 to 44-years-old with a percentage of 45.70% followed by the age group 45 to 64-year-old with a percentage of 27.20%. Females were the most frequently affected by the hepatic side effects of drugs vs. males. Paracetamol, isoniazid, rifampicin, and pyrazinamide were the main responsible drugs for liver damage in the study population. Alteration of biological parameters and subclinical phenomena were used as clinical manifestations of liver damage in the study population. The outcome of the present study suggests paying more attention to drugs used for medication and the involvement of rigorous clinical monitoring to prevent or to minimize the side effects of drugs.

Metabolism and Hepatotoxicity of Pyrazinamide, an Antituberculosis Drug.

Pyrazinamide (PZA) is an important component of a standard combination therapy against tuberculosis. However, PZA is hepatotoxic, and the underlying mechanisms are poorly understood. Biotransformation of PZA in the liver was primarily suggested behind its hepatoxicity. This review summarizes the knowledge of the key enzymes involved in PZA metabolism and discusses their contributions to PZA hepatotoxicity. SIGNIFICANCE STATEMENT: This review outlines the current understanding of PZA metabolism and hepatotoxicity. This work also highlights the gaps in this field, which can be used to guide the future studies on PZA-induced liver injury.

Dry powder inhalation formulation of chitosan nanoparticles for co-administration of isoniazid and pyrazinamide.

Co-loaded isoniazid and pyrazinamide chitosan nanoparticles were formulated using the ionic gelation method. The formulations were adjusted to five mass ratios of tripolyphosphate (TPP) and chitosan at three TPP concentrations. Particle size, polydispersity index, zeta potential, and encapsulation efficiency were used to evaluate all formulations. The results revealed that the ratio of TPP to chitosan had the highest impact in generating chitosan nanoparticles. The selected nanoparticle formulations were freeze-dried, and the obtained dry powders were characterized using scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectroscopy to confirm the interaction of loaded drug and formulation excipients. The aerosolized performance of dry powders was also evaluated using the Andersen cascade impactor. A mass median aerodynamic diameter of 3.3-3.5 µm, % fine particle fraction of 30-44%, and 92-95% emitted dose were obtained from all formulations. The dry powder formulations were not toxic to the respiratory tract cell lines. Furthermore, they did not provoke alveolar macrophages into producing inflammatory cytokines or nitric oxides, indicating that the formulations are safe and could potentially be used to deliver to respiratory tract for tuberculosis treatment.

Immunological detection of pyrazine-2-carboxylic acid for the detection of pyrazinamide resistance in Mycobacterium tuberculosis.

Pyrazinamide (PZA) susceptibility testing in Mycobacterium tuberculosis (Mtb) is a current area of development and PZA-resistant strains are increasingly prevalent. Previous studies have demonstrated that the detection of pyrazinoic acid (POA), the metabolite produced by the deamidation of PZA, is a good predictor for PZA resistance since a resistant strain would not convert PZA into POA at a critical required rate, whereas a susceptible strain will do, expelling POA to the extracellular environment at a certain rate, and allowing for quantification of this accumulated analyte. In order to quantify POA, an indirect competitive ELISA (icELISA) test using hyperimmune polyclonal rabbit serum against POA was developed: for this purpose, pure POA was first covalently linked to the highly immunogenic Keyhole Limpet Hemocyanine, and inoculated in rabbits. A construct made of bovine serum albumin (BSA) linked to pure POA and fixed at the bottom of wells was used as a competitor against spiked samples and liquid Mtb culture supernatants. When spiked samples (commercial POA alone) were analyzed, the half maximal inhibitory concentration (IC50) was 1.16 mg/mL, the limit of detection 200 µg/mL and the assay was specific (it did not detect PZA, IC50 > 20 mg/mL). However, culture supernatants (7H9-OADC-PANTA medium) disrupted the competition and a proper icELISA curve was not obtainable. We consider that, although we have shown that it is feasible to induce antibodies against POA, matrix effects could damage its analytical usefulness; multiple, upcoming ways to solve this obstacle are suggested.

An Evaluation of the In Vitro Roles and Mechanisms of Silibinin in Reducing Pyrazinamide- and Isoniazid-Induced Hepatocellular Damage.

Tuberculosis remains a significant infectious lung disease that affects millions of patients worldwide. Despite numerous existing drug regimens for tuberculosis, drug-induced liver injury is a major challenge that limits the effectiveness of these therapeutics. Two drugs that form the backbone of the commonly administered quadruple antitubercular regimen, that is, pyrazinamide (PZA) and isoniazid (INH), are associated with such hepatotoxicity. Yet, we lack safe and effective alternatives to the antitubercular regimen. Consequently, current research largely focuses on exploiting the hepatoprotective effect of nutraceutical compounds as complementary therapy. Silibinin, a herbal product widely believed to protect against various liver diseases, potentially provides a useful solution given its hepatoprotective mechanisms. In our study, we identified silibinin's role in mitigating PZA- and INH-induced hepatotoxicity and elucidated a deeper mechanistic understanding of silibinin's hepatoprotective ability. Silibinin preserved the viability of human foetal hepatocyte line LO2 when co-administered with 80 mM INH and decreased apoptosis induced by a combination of 40 mM INH and 10 mM PZA by reducing oxidative damage to mitochondria, proteins, and lipids. Taken together, this proof-of-concept forms the rational basis for the further investigation of silibinin's hepatoprotective effect in subsequent preclinical studies and clinical trials.

Bile acids, lipid and purine metabolism involved in hepatotoxicity of first-line anti-tuberculosis drugs.

OBJECTIVES: Rifampin (RIF), isoniazid (INH) and pyrazinamide (PZA) are essential components of the short-term first-line anti-tuberculosis (anti-TB) chemotherapy regimen and can cause hepatotoxicity. However, the mechanism of anti-TB drug-induced hepatotoxicity (ATDH) is currently unclear. We investigate the relevant contributions to liver injury and the pathway of the above-mentioned drugs administered alone or in combination. METHODS: UPLC-Q-TOF/MS-based metabolomics, bile acids (BAs) analysis and FXR/SHP detection were used to evaluate the toxicity of these drugs and clarify the underlying metabolism-related pathway. RESULTS: In C57BL/6 mice administered the corrected clinical doses, RIF, INH and PZA could induced hepatotoxicity; with less toxicity in the combination therapy than RIF. The pathological biochemistry, BAs concentration and metabolically regulated FXR/SHP gene expression analyzes in mice were consistent with the metabolomics results. FXR played a role in the hepatotoxicity of anti-tuberculosis drugs in the obeticholic acid treated and FXR-/- mice. Additionally, the purine and lipid metabolic pathways were involved in ATDH. CONCLUSION: ATDH was involved in bile acids and lipid and purine metabolism. The BAs metabolic pathway involvement in mice was validated in TB patients. The noninvasive metabolomics approach is more systemic than routine toxicity evaluation and can be used to assess compound toxicity and the underlying mechanism.

Cytochemical Evaluation of the Toxic Effects of Combined Antituberculosis Substances on Metabolic State of Blood Lymphocytes.

Combined antituberculosis substances induced a dose-dependent changes in activity of dehydrogenases and hydrolases in rat lymphocytes. The main toxic effect of the substances was related to inhibition of mitochondrial dehydrogenases (succinate dehydrogenase and α-glycerol phosphate dehydrogenase) usually followed by suppression of activity of hydrolytic enzymes (acid phosphatase and non-specific esterase). Opposite changes in lactate dehydrogenase activity reflected specific features of intoxication.

Exposure to first line anti-tuberculosis drugs in prepubertal age reduces the quality and functional competence of spermatozoa and oocytes in Swiss albino mice.

Prepubertal Swiss albino mice of both sex were administered with first-line anti-tuberculosis drugs (ATDs) viz; rifampicin, isoniazid, pyrazinamide, streptomycin and ethambutol intraperitoneally, for 4 weeks. Two weeks after the completion of treatment, male mice were sacrificed to collect caudal spermatozoa and female mice were superovulated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) to collect metaphase II (MII) oocytes from oviduct. Administration of ATDs not only decreased the count, motility and, nuclear maturity and also, increased the head abnormalities, mitochondrial damage and DNA damage in epididymal spermatozoa. Reduction in number of ovulated oocytes, increased degeneration rate and altered distribution pattern of cytoplasmic organelles was observed in oocytes of female mice. Presence of ATDs in in vitro maturation (IVM) medium increased abnormalities in meiotic resulted in abnormal spindle organization (except ethambutol) without affecting nuclear maturation. In conclusion, the result of this study indicates that ATDs have considerable adverse effects on the functional competence of male and female gametes, however, with varied degree of toxicity.

Metabolomics approach discriminates toxicity index of pyrazinamide and its metabolic products, pyrazinoic acid and 5-hydroxy pyrazinoic acid.

Pyrazinamide (PYZ)-an essential component of primary drug regimen used for the treatment and management of multidrug resistant or latent tuberculosis-is well known for its hepatoxicity. However, the mechanism of PYZ-induced hepatotoxicity is still unknown to researchers. Studies have shown that the drug is metabolized in the liver to pyrazinoic acid (PA) and 5-hydroxy pyrazinoic acid (5-OHPA) which individually may cause different degrees of hepatotoxicity. To evaluate this hypothesis, PYZ, PA, and 5-OHPA were administered to albino Wistar rats orally (respectively, at 250, 125, and 125 mg kg-1 for 28 days). Compared to normal rats, PYZ and its metabolic products decreased the weights of dosed rats and induced liver injury and a status of oxidative stress as assessed by combined histopathological and biochemical analysis. Compared to normal controls, the biochemical and morphological changes were more aberrant in PA- and 5-OHPA-dosed rats with respect to those dosed with PYZ. Finally, the serum metabolic profiles of rats dosed with PYZ, PA, and 5-OHPA were measured and compared with those of normal control rats. With respect to normal control rats, the rats dosed with PYZ and 5-OHPA showed most aberrant metabolic perturbations in their sera as compared to those dosed with PA. Altogether, the study suggests that PYZ-induced hepatotoxicity might be associated with its metabolized products, where 5-OHPA contributes to a higher degree in its overall toxicity than PA.

Deleterious effects of 28-day oral co-administration of first-line anti-TB drugs on spleen, blood and bone marrow chromosomes in normal rat.

CONTEXT: Isoniazid, rifampicin and pyrazinamide are most reliable and cost-effective remedy for tuberculosis treatment and prophylaxis among first-line anti-tuberculosis (TB) drugs and have a pronounced tendency to cause adverse drug reactions. Hepatotoxicity is well-studied side effect of these drugs but their effects on other organs like spleen and blood are still needed to be explored. OBJECTIVE: To explore the probable outcome of co-administration these three major antitubercular drugs (ATDs), rifampicin, isoniazid and pyrazinamide on spleen, blood and bone marrow. MATERIALS AND METHODS: Different parameters were evaluated like lipid peroxidation, glutathione (GSH) and protein content in spleen by spectrophotometric evaluation, hematological evaluation by determining total hemoglobin, total leukocyte count, differential leukocyte count and scanning electron microscopy studies in blood, genotoxicity studied by bone marrow chromosomal analysis and DNA fragmentation. The female rats n = 12 (150-200 g) were grouped as control group orally given saline and toxicant group given INH (30.85 mg/kg b.wt.) + RIF (61.7 mg/kg b.wt.) + PZA (132.65 mg/kg b.wt.) dosage extrapolated from dose that is used in human for 28 d once daily. RESULTS: After 28 d-oral co-administration of anti-TB drugs (INH (30.85 mg/kg b.wt.) + RIF (61.7 mg/kg b.wt.) + PZA (132.65 mg/kg b.wt.)), it was revealed that there were an increase thiobarbituric acid reactive substances, decrease in GSH and protein contents in spleen. Marked changes in hematological parameters, DNA fragmentation and chromosomes were also observed. CONCLUSION: This can be concluded from this work that co-administration of first-line ATDs is toxic to spleen and blood also these drugs can cause damage at genetic level.

Adverse effects of anti-tuberculosis drugs on HepG2 cell bioenergetics.

Tuberculosis (TB) is an intractable chronic infection. Disease treatment with anti-TB drugs remains challenging due to drug-induced hepatotoxicity. The toxicity of the anti-TB drugs rifampicin (RIF), isoniazid (INH) and pyrazinamide (PZA) either alone or in combination was investigated in HepG2 cells. Assays of intracellular adenosine triphosphate (ATP) levels at 4-, 24- and 48-h post-exposure to gradient concentrations of RIF, INH and PZA were conducted. Drug-induced effects on mitochondrial membrane potential (MMP), mitochondrial complex I and complex III activity, nicotinamide adenine dinucleotide (NAD+) levels and cellular lactate production were assessed. Decreased ATP levels were dose-dependent and correlated with drug exposure duration. Approximate 24-h IC50s were 0.5 mM, 70 mM and 84 mM for RIF, INH and PZA, respectively. Twenty-four hours post-drug treatment, reductions of MMP ( p = 0.0005), mitochondrial complex I and III activities ( p = 0.0001 and p = 0.0003, respectively), NAD+ levels ( p = 0.0057) and increased lactate production ( p < 0.0001) were observed. Drug combinations used to mimic cumulative drug treatments induced a synergistic inhibition of mitochondrial complex I activity. An assessment of cellular ultrastructure using transmission electron microscopy indicated drug-induced mitophagy. Collectively, our study suggests that hepatotoxicity of commonly employed anti-TB drugs is mediated by their curtailment of mitochondrial function.

Antimycobacterial activity of pyrazinoate prodrugs in replicating and non-replicating Mycobacterium tuberculosis.

Tuberculosis (TB) is an important infectious disease caused by Mycobacterium tuberculosis (Mtb) and responsible for thousands of deaths every year. Although there are antimycobacterial drugs available in therapeutics, just few new chemical entities have reached clinical trials, and in fact, since introduction of rifampin only two important drugs had reached the market. Pyrazinoic acid (POA), the active agent of pyrazinamide, has been explored through prodrug approach to achieve novel molecules with anti-Mtb activity, however, there is no activity evaluation of these molecules against non-replicating Mtb until the present. Additionally, pharmacokinetic must be preliminary evaluated to avoid future problems during clinical trials. In this paper, we have presented six POA esters as prodrugs in order to evaluate their anti-Mtb activity in replicating and non-replicating Mtb, and these showed activity highly influenced by medium composition (especially by albumin). Lipophilicity seems to play the main role in the activity, possibly due to controlling membrane passage. Novel duplicated prodrugs of POA were also described, presenting interesting activity. Cytotoxicity of these prodrugs set was also evaluated, and these showed no important cytotoxic profile.

Pyrazinamide Induced Rat Cholestatic Liver Injury through Inhibition of FXR Regulatory Effect on Bile Acid Synthesis and Transport.

Pyrazinamide (PZA) is an indispensable first-line drug used for the treatment of tuberculosis which may cause serious hepatotoxicity; however, the mechanisms underlying these toxicities are poorly understood. Cholestasis plays an important role in drug-induced liver injury. Since there were no previous published works reported cholestasis and PZA hepatotoxicity relationship, this study aimed to identify whether PZA can induce liver injury with characterized evidences of cholestasis and to clarify expression changes of proteins related to both bile acid synthesis and transport in PZA-induced liver injury. PZA (2 g/kg) was administered for 7 consecutive days by oral gavage. Results showed there were 2-fold elevation in both ALT and AST serum levels in PZA-treated rats. In addition, a 10-fold increment in serum total bile acid was observed after PZA administration. The mRNA and protein expressions of bile acid synthesis and transport parameters were markedly altered, in which FXR, Bsep, Mrp2, Mdr2, Ostα/ß, Oatp1a1, Oatp1b2, and Cyp8b1 were decreased (P < .05), while Mrp3, Ntcp, Oatp1a4, and Cyp7a1 were increased (P < .05). Moreover, treatment with the FXR agonist obeticholic acid (OCA) generated obvious reductions in serum ALT, AST, and TBA levels in PZA-treated rats. Those effects were due to transcriptional regulation of pre-mentioned target genes by OCA. Taken together, these results suggested that PZA-induced cholestatic liver injury was related to FXR inhibition, leading to the dysfunction in bile acid synthesis and transport.

Ameliorative Effects of Kolaviron, a Biflavonoid Fraction from Garcinia Kola Seed, on Hepato-renal Toxicity of Anti-tuberculosis Drugs in Wistar Rats.

BACKGROUND: Tuberculosis (TB) is an infectious disease of international health priority. The combination of anti-TB drugs (4-Tabs)- isoniazid (INH), rifampicin (RIF), pyrazinamide (PZA) and ethambutol (ETB) are effective in the management of the disease, however, their toxic effect is a major concern. PURPOSE: The study was designed to evaluate the toxicity of anti-TB drugs in male Wistar rats and possible ameliorative effects of kolaviron (KV), a biflavonoid from Garcinia kola seeds. METHODS: Twenty-eight rats were assigned into four groups; Group 1 (Control) received corn oil, Group 2 (4-Tabs) received therapeutic doses of INH (5 mg/kg), RIF (10 mg/kg), PZA (15 mg/kg) and ETB (15 mg/kg) in combination, Group 3 (4-Tabs + KV) received INH, RIF, PZA, ETB and KV (200 mg/kg) and Group 4 (KV) received KV (200 mg/kg) by oral gavage three times per week for 8 consecutive weeks. RESULTS: Administration of 4-Tabs caused oxidative stress resulting in significant (p = 0.031, 0.027) increase in malondialdehyde levels in the liver and kidney of rats by 101% and 34%, respectively. Also, 4-Tabs caused significant (p = 0.023-0.035) elevation of serum alanine and aspartate aminotransferases by 41% and 48%, creatinine by 252% and total bilirubin by 89%, respectively. In contrast, hepatic and renal antioxidant indices- reduced glutathione, glutathione peroxidase, glutathione-s-transferase and superoxide dismutase were significantly (p = 0.028-0.039) decreased in 4-Tabs-treated rats. Co-administration of KV with 4-Tabs significantly restored the antioxidant parameters and biochemical indices to near normal. CONCLUSION: These findings suggest that anti-TB drugs elicit oxidative damage in liver and kidney of rats while KV protects against the adverse effects via antioxidative mechanism.

Pyrazinamide induced hepatic injury in rats through inhibiting the PPARα pathway.

Pyrazinamide (PZA) causes serious hepatotoxicity, but little is known about the exact mechanism by which PZA induced liver injury. The peroxisome proliferator-activated receptors alpha (PPARα) is highly expressed in the liver and modulates the intracellular lipidmetabolism. So far, the role of PPARα in the hepatotoxicity of PZA is unknown. In the present study, we described the hepatotoxic effects of PZA and the role of PPARα and its target genes in the downstream pathway including L-Fabp, Lpl, Cpt-1b, Acaa1, Apo-A1 and Me1 in this process. We found PZA induced the liver lipid metabolism disorder and PPARα expressionwas down-regulated which had a significant inverse correlation with liver injury degree. These changeswere ameliorated by fenofibrate, the co-treatment that acts as a PPARα agonist. In contrast, short-termstarvation significantly aggravated the severity of PZA-induced liver injury. In conclusion, this study demonstrated the critical role played by PPARα in PZA-induced hepatotoxicity and provided a better understanding of the molecular mechanisms underlying PZA-induced liver injury. Copyright © 2016 John Wiley & Sons, Ltd.

Characteristic molecular and proteomic signatures of drug-induced liver injury in a rat model.

Drug-induced liver injury (DILI) is a major safety concern during drug development and remains one of the main reasons for withdrawal of drugs from the market. Although it is crucial to develop methods that will detect potential hepatotoxicity of drug candidates as early and as quickly as possible, there is still a lack of sensitive and specific biomarkers for DILI that consequently leads to a scarcity of reliable hepatotoxic data. Hence, in this study, we assessed characteristic molecular signatures in rat liver treated with drugs (pyrazinamide, ranitidine, enalapril, carbamazepine and chlorpromazine) that are known to cause DILI in humans. Unsupervised hierarchical clustering analysis of transcriptome changes induced by DILI-causing drugs resulted in three different subclusters on dendrogram, i.e., hepatocellular, cholestatic and mixed type of DILI at early time points (2 days), and multiclassification analysis suggested 31 genes as discernible markers for each DILI pattern. Further analysis for characteristic molecular signature of each DILI pattern provided a molecular basis for different modes of DILI action. A proteomics study of the same rat livers was used to confirm the results, and the two sets of data showed 60 matching classifiers. In conclusion, the data of different DILI-causing drug treatments from genomic analysis in a rat model suggest that DILI-specific molecular signatures can discriminate different patterns of DILI at an early exposure time point, and that they provide useful information for mechanistic studies that may lead to a better understanding of the molecular basis of DILI.

Hepatoprotective potential of Cassia auriculata roots on ethanol and antitubercular drug-induced hepatotoxicity in experimental models.

CONTEXT: Tarvada [Cassia auriculata Linn. (Caesalpiniaceae)] is used against liver ailments in Indian folk medicine, but there is a lack of scientific evidence for this traditional claim. OBJECTIVE: The present study investigated the protective effect of methanol extract of tarvada (MECA) roots on ethanol and antitubercular drug induced hepatotoxicity in rats. MATERIALS AND METHODS: In the therapeutic model, ethanol (40%, 4 g/kg b.w., p.o.) was administered to rats for 21 days and the intoxicated rats were treated with MECA (300 and 600 mg/kg, b.w.) and silymarin (100 mg/kg, b.w.) for next 7 days. In the prophylactic model, MECA and silymarin were administered simultaneously along with a combination of isoniazid (27 mg/kg, b.w.), rifampicin (54 mg/kg, b.w.) and pyrazinamide (135 mg/kg, b.w.) for 30 days. After the study duration, serum levels of AST, ALT, ALP, total bilirubin, total cholesterol, total protein, albumin were estimated along with hepatic catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA) and liver histopathology in each group. RESULTS: Administration of tarvada root extract significantly (p < 0.01 and p < 0.05) lowered the elevated levels of serum AST, ALT, ALP, total bilirubin, total cholesterol, total protein and restored the abnormal levels of enzymatic antioxidants and MDA in liver due to toxicant administration in a dose-dependent manner. These results were confirmed by histopathological analysis. DISCUSSION AND CONCLUSION: Results suggest that tarvada root extract possess potent hepatoprotective activity against ethanol and antitubercular drug-induced hepatotoxicity in rats, which could be due to an inhibition of hepatic metabolizing enzymes and antioxidant activity.