Galactosamine-induced Hepatotoxicity Research Articles

Hepatoprotective effects of bioactive compounds from traditional herb Tulsi (Ocimum sanctum Linn) against galactosamine-induced hepatotoxicity in rats.

Ocimum sanctum L. (Tulsi; Family: libiaceae), also known as "The Queen of herbs" or "Holy Basil," is an omnipresent, multipurpose plant that has been used in folk medicine of many countries as a remedy against several pathological conditions, including anticancer, antidiabetic, cardio-protective, antispasmodic, diaphoretic, and adaptogenic actions. This study aims to assess O. sanctum L.'s hepatoprotective potential against galactosamine-induced toxicity, as well as investigate bioactive compounds in each extract and identify serum metabolites. The extraction of O. sanctum L as per Ayurveda was simultaneously standardized and quantified for biochemical markers: rutin, ellagic acid, kaempferol, caffeic acid, quercetin, and epicatechin by HPTLC. Hepatotoxicity was induced albino adult rats by intra-peritoneal injection of galactosamine (400mg/kg). The quantified hydroalcoholic and alcoholic extract of O. sanctum L (100 and 200mg/kg body weight/day) were compared for evaluation of hepatoprotective potential, which were assessed in terms of reduction in histological damage, change in serum enzymes such as AST, ALT, ALP and increase TBARS. Twenty chemical constituents of serum metabolites of O. sanctum were identified and characterized based on matching recorded mass spectra by GC-MS with those obtained from the library-Wiley/NIST. We evaluated the hepatoprotective activity of various fractions of hydroalcoholic extracts based on the polarity and investigated the activity at each phase (hexane, chloroform, and ethyl acetate) in vitro to determine how they affected the toxicity of CCL4 (40mM) toward Chang liver cells. The ethyl acetate fraction of the selected plants had a higher hepatoprotective activity than the other fractions, so it was used in vacuum liquid chromatography (VLC). The ethyl acetate fraction contains high amounts of rutin (0.34% w/w), ellagic acid (2.32% w/w), kaempferol (0.017% w/w), caffeic acid (0.005% w/w), quercetin (0.038% w/w), and epicatechin (0.057% w/w) which are responsible for hepatoprotection. In comparison to standard silymarin, isolated bioactive molecules displayed the most significant hepatoprotective activity in Chang liver cells treated to CCl4 toxicity. The significant high hepatoprotection provided by standard silymarin ranged from 77.6% at 100μg/ml to 83.95% at 200μg/ml, purified ellagic acid ranged from 70% at 100μg/ml to 81.33% at 200μg/ml, purified rutin ranged from 63.4% at 100μg/ml to 76.34% at 200μg/ml purified quercetin ranged from 54.33% at 100μg/ml to 60.64% at 200μg/ml, purified epicatechin ranged from 53.22% at 100μg/ml to 65.6% at 200μg/ml, and purified kaempferol ranged from 52.17% at 100μg/ml to 60.34% at 200μg/ml. These findings suggest that the bioactive compounds in O. sanctum L. have significant protective effects against galactosamine-induced hepatotoxicity.

Hepatoprotective and Antioxidant Capacity of Mallotus repandus Ethyl Acetate Stem Extract against d-Galactosamine-Induced Hepatotoxicity in Rats.

Mallotus repandus (M. repandus) is traditionally used to treat muscle pain, itching, fever, rheumatic arthritis, and a variety of liver disorders. The aim of the present work was to evaluate the hepatoprotective activity and the antioxidant potential of the ethyl acetate stem extract of M. repandus (ESMR) against d-galactosamine (d-GalN)-induced hepatopathy, along with a possible mechanism of action in rats. In vivo hepatoprotective activity of ESMR was examined using d-galactosamine (d-GalN)-induced hepatotoxicity in Sprague–Dawley rats. For this purpose, levels of serum diagnostic markers, activity of hepatic antioxidant enzymes, and liver histo-architecture were employed to assess the protective efficacy of ESMR. Furthermore, the total phenolic, flavonoid, and tannin contents were quantitated, and the antioxidant capacity of the extract was evaluated using different methods such as 2,2′-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), hydrogen peroxide (H2O2), and hydroxyl radical (OH•) scavenging assays. Intraperitoneal d-GalN injection triggered hepatotoxicity, as shown by the noticeable increase in the serum hepatic marker enzymes, bilirubin content, γ-glutamyl transferase (GGT), total cholesterol (TC), triglycerides (TGs), and malondialdehyde (MDA), whereas glutathione, superoxide dismutase, and catalase levels were significantly lower compared with that of the control. Pretreatment with ESMR reduced the hepatic enzyme levels along with bilirubin, GGT, and MDA compared to the d-GalN-intoxicated group. These results were supported by histopathological studies, where d-galactosamine caused coagulative necrosis, hemorrhage, and inflammation. However, pretreatment with ESMR ameliorated the histo-architectural changes and brought them back to normal. Results also revealed that the total polyphenolic, flavonoid, and tannin content, and total antioxidant capacity of ESMR were 136.30 ± 0.78 mg GAE/g mg, 38.72 ± 0.85 mg QE/g, 75.88 ± 0.54 mg TAE/g, and 123.16 ± 0.24 mg AAE/g, respectively. In addition, ESMR inhibited free radicals with IC50 values of 94.47 ± 0.51, 127.33 ± 0.36, 164.12 ± 0.45, and 254.14 ± 0.35 μg/mL in DPPH, NO, H2O2, and OH• free radical scavenging assays, respectively. These findings highlight the protective role of ESMR against hepatic injury induced by d-GalN, which may be attributed to its higher antioxidant properties, thereby scientifically justifying its traditional use.

Dependence of developmental toxicity for polyaromatic hydrocarbons on aryl hydrocarbon receptor: Range-finding with benzo(a)pyrene

Two methods based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography–mass spectrometry (GC–MS) were developed to study in vitro the volatile exometabolome, which were then further tested in a pilot study to evaluate galactosamine-induced hepatotoxicity. The analysis of volatile organic compounds (VOCs) was carried out directly in the headspace of the cell culture medium, while some other volatile organic compounds such as volatile carbonyl compounds (VCCs) (aldehydes and ketones) were determined in the headspace of the cell culture medium after a previous derivatization step with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). Fiber selection was performed using a univariate mode, whereas a central composite design (CCD) was used in the optimization of several other parameters that affect the extraction conditions. VOCs showed optimal extraction results using a DVB/CAR/PDMS fiber, by adding 0.43 g of NaCl to a sample volume of 2 mL and allowing the sample to equilibrate for 10 min at 45 °C with a subsequent extraction for 39 min at the same temperature. For VCCs, the best extraction response was achieved after in-solution (2 mL) derivatization with 0.94 g L−1 of PFBHA (final concentration), followed by an incubation period of 6 min and an extraction time of 37 min at 53 °C, using a PDMS/DVB fiber. The applicability of both optimized methods was then tested, through a untargeted study, on cell culture medium samples obtained from primary mouse hepatocytes (PMH) exposed to three low concentrations (LC01, LC10 and LC30) of the well-known hepatotoxic agent galactosamine (GalN). The results obtained by both methods showed that volatile compounds from GalN exposed cells are separated from controls in a concentration-dependent manner. Several volatile compounds, namely aldehydes, ketones and alcohols, suffered significant alterations, suggesting that GalN induces marked metabolic alterations in cells even at low, non-toxic concentrations. Although preliminary, this metabolomics approach proved its potential to be used in future studies to evaluate toxicity of different xenobiotics.

Analysis of extracellular metabolome by HS-SPME/GC–MS: Optimization and application in a pilot study to evaluate galactosamine-induced hepatotoxicity

Two methods based on headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography–mass spectrometry (GC–MS) were developed to study in vitro the volatile exometabolome, which were then further tested in a pilot study to evaluate galactosamine-induced hepatotoxicity. The analysis of volatile organic compounds (VOCs) was carried out directly in the headspace of the cell culture medium, while some other volatile organic compounds such as volatile carbonyl compounds (VCCs) (aldehydes and ketones) were determined in the headspace of the cell culture medium after a previous derivatization step with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA). Fiber selection was performed using a univariate mode, whereas a central composite design (CCD) was used in the optimization of several other parameters that affect the extraction conditions. VOCs showed optimal extraction results using a DVB/CAR/PDMS fiber, by adding 0.43 g of NaCl to a sample volume of 2 mL and allowing the sample to equilibrate for 10 min at 45 °C with a subsequent extraction for 39 min at the same temperature. For VCCs, the best extraction response was achieved after in-solution (2 mL) derivatization with 0.94 g L−1 of PFBHA (final concentration), followed by an incubation period of 6 min and an extraction time of 37 min at 53 °C, using a PDMS/DVB fiber. The applicability of both optimized methods was then tested, through a untargeted study, on cell culture medium samples obtained from primary mouse hepatocytes (PMH) exposed to three low concentrations (LC01, LC10 and LC30) of the well-known hepatotoxic agent galactosamine (GalN). The results obtained by both methods showed that volatile compounds from GalN exposed cells are separated from controls in a concentration-dependent manner. Several volatile compounds, namely aldehydes, ketones and alcohols, suffered significant alterations, suggesting that GalN induces marked metabolic alterations in cells even at low, non-toxic concentrations. Although preliminary, this metabolomics approach proved its potential to be used in future studies to evaluate toxicity of different xenobiotics.

Nitric oxide as a mediator of fructose 1,6-bisphosphate protection in galactosamine-induced hepatotoxicity in rats

Fructose 1,6-bisphosphate (F1,6BP) has been widely used as a therapeutic agent for different harmful conditions in a variety of tissues. The hypothesis of the present work was that the increase in nitric oxide production and the prevention of oxidative stress induced by exogenous F1,6BP mediate its protective effect against the hepatotoxic action of GalN.Experimental groups used were sham, F1,6BP (2g/kg bw i.p.), GalN (0.4g/kg bw i.p), l-NAME (10mg/kg bw i.v.), F1,6BP+GalN, l-NAME+GalN and l-NAME+F1,6BP+GalN. Animals were killed after 24h of bolus administration.F1,6BP induced an increase in NO and the redox ratio (GSH/GSSG) in liver. Western blot assays pointed to overexpression of liver eNOS in F1,6BP-treated rats. The hepatic injury induced by GalN increased transaminases in plasma and decreased the reduced/oxidized glutathione ratio in liver. The concomitant administration of F1,6BP reversed this damage, while the addition of l-NAME worsened the liver injury. We provided evidence that this F1,6BP-induced protection may be related to the increase in NO production through the positive modulation of eNOS, and the increase in intracellular reduced glutathione, thus providing a higher reducing capacity.

Evaluation of Full-Resolution J-Resolved 1H NMR Projections of Biofluids for Metabonomics Information Retrieval and Biomarker Identification

Spectroscopic profiling of biological samples is an integral part of metabolically driven top-down systems biology and can be used for identifying biomarkers of toxicity and disease. However, optimal biomarker information recovery and resonance assignment still pose significant challenges in NMR-based complex mixture analysis. The reduced signal overlap as achieved when projecting two-dimensional (2D) J-resolved (JRES) NMR spectra can be exploited to mitigate this problem and, here, full-resolution (1)H JRES projections have been evaluated as a tool for metabolic screening and biomarker identification. We show that the recoverable information content in JRES projections is intrinsically different from that in the conventional one-dimensional (1D) and Carr-Purcell-Meiboom-Gill (CPMG) spectra, because of the combined result of reduction of the over-representation of highly split multiplet peaks and relaxation editing. Principal component and correlation analyses of full-resolution JRES spectral data demonstrated that peak alignment is necessary. The application of statistical total correlation spectroscopy (STOCSY) to JRES projections improved the identification of previously overlapped small molecule resonances in JRES (1)H NMR spectra, compared to conventional 1D and CPMG spectra. These approaches are demonstrated using a galactosamine-induced hepatotoxicity study in rats and show that JRES projections have a useful and complementary role to standard one-dimensional experiments in complex mixture analysis for improved biomarker identification.

Protective effect of Cichorium glandulosum root extract on carbon tetrachloride-induced and galactosamine-induced hepatotoxicity in mice

Cichorium glandulosum Boiss. et Huet is a native plant used in Traditional Uighur Medicine, especially for treating a variety of liver disorders. In the present study, in vivo hepatoprotective effect of C. glandulosum root extract (CGRE) was evaluated using two experimental models, carbon tetrachloride (CCl4)- and galactosamine (GalN)-induced acute hepatotoxicity in mice. Pretreatment with CGRE (800 mg/kg/day, p.o.) for seven days significantly reduced the impact of CCl4 toxicity (10 mL/kg, i.p.) on the serum markers of liver damage, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). Protective effect was reconfirmed against GalN-induced injury (800 mg/kg b.w., i.p.) and elevated serum enzymatic levels were significantly ( p < 0.05)and dose dependently restored towards normalization by the extracts. Furthermore, considering the well-known implication of free radicals in tissue injury, in vitro antioxidant properties of the extract were determined with a view to suggest the possible mechanism of activity. The extract showed noticeable antioxidant activity, comparable with standard antioxidants, through its ability to scavenge several free radicals (DPPH, O 2 - , NO ) and efficiency against lipid peroxidation. Therefore, presented results suggest that CGRE is potent hepatoprotective agent that could protect liver against the acute injury and this ability might be attributed to its antioxidant potential.

Protective Effect of Pinitol againstD-Galactosamine-Induced Hepatotoxicity in Rats Fed on a High-Fat Diet

The protective effect of pinitol against D-galactosamine (GalN)-induced liver damage was examined. Forty male Sprague-Dawley rats were divided into normal control, GalN control, and pinitol groups (0.5%, 1%, and 2%). After 8 weeks of feeding, a single dose of GalN (650 mg/kg) was administered 24 h before their sacrifice. The serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and tumor necrosis factor-alpha (TNF-alpha) levels were significantly increased after an injection with GalN (P<0.05), but pinitol supplementation at the level of 0.5% reversed these changes to normal levels. Significant decreases in serum triglyceride and cholesterol and increases in hepatic cholesterol were observed in GalN-intoxicated rats. However, supplementation with pinitol significantly attenuated these trends. In addition, pinitol elevated the Mn-superoxide dismutase, glutathione reductase, and catalase activities, prevented hepatic lipid peroxidation, and restored the hepatic GSH levels and cytochrome P450 2E1 function. Thus, 0.5% pinitol supplementation protected the rats from the hepatotoxicity induced by GalN, at least part of its effect being attributable to attenuation of the oxidative stress and inflammatory process promoted by GalN.

Heteronuclear 1H−31P Statistical Total Correlation NMR Spectroscopy of Intact Liver for Metabolic Biomarker Assignment: Application to Galactosamine-Induced Hepatotoxicity

As part of our ongoing development of methods for enhanced biomarker information recovery from spectroscopic data we present the first example of a new hetero-nuclear statistical total correlation spectroscopy (HET-STOCSY) approach applied to intact tissue samples collected as part of a toxicological study. One-dimensional 1H and 31P-{1H} magic angle spinning (MAS) NMR spectra of intact liver samples after galactosamine (galN) treatment to rats and after cotreatment of galN plus uridine were collected at 275 K. Individual samples were also followed by 1H and 31P-{1H} MAS NMR through time generating time dependent modulations in metabolite signatures relating to toxicity. High-resolution 1H NMR spectra of urine and plasma and clinical chemical data were also collected to establish a biological framework in which to place these novel statistical heterospectroscopic data. In HET-STOCSY, calculation of the covariance between the 31P-{1H} and 1H NMR signals of phosphorus containing metabolites allows their molecular connectivities to be established and the construction of virtual two-dimensional heteronuclear correlation spectra that connect all protons on the molecule to the heteroatom. We show how HET-STOCSY applied to MAS NMR spectra of liver samples can be used to augment biomarker detection. This approach is generic and can be applied to correlate the covarying signals for any spin-active nuclei where there is parallel or serial collection of data.

S-Adenosylmethionine but not glutathione protects against galactosamine-induced cytotoxicity in rat hepatocyte cultures

A gradual but extensive depletion of hepatic GSH has long been known to accompany development of galactosamine-induced hepatotoxicity in rats, and some protection from liver injury has been observed after administration of sulfhydryl-donating compounds. Although these observations support a key role for GSH in the underlying mechanism, the impact of GSH depletion and repletion on the hepatotoxic response to galactosamine is unclear. To investigate the role of GSH in galactosamine-induced liver injury, we examined the effect of modulating GSH content on galactosamine toxicity in rat primary hepatocyte cultures. Galactosamine (4 mM) cytotoxicity was assessed by release of lactate dehydrogenase into the culture medium, and hepatocellular GSH content was measured by HPLC with electrochemical detection. The data indicated that prior depletion of GSH with either diethyl maleate or buthionine sulfoximine significantly enhanced galactosamine toxicity; however, addition of GSH-ester or alternate sulfur nucleophiles at various times during the incubation did not abrogate toxicity. In contrast, co-addition of S-adenosylmethionine (SAMe) with galactosamine exerted a marked protective effect without significantly altering hepatocyte GSH content. These data suggest that GSH depletion is not directly involved in the sequelae for galactosamine-induced hepatotoxicity, and raise the possibility that SAMe may have hepatoprotective effects that are not dependent on its ability to enhance GSH synthesis.

Lack of Protective Effect of D-003, a Mixture of High-Molecular-Weight Primary Acids from Sugar Cane Wax, on Liver Damage Induced by Galactosamine in Rats

D-003 is a mixture of very-high-molecular-weight aliphatic primary acids purified from sugar cane wax, wherein octacosanoic acid is the most abundant. Experimental and clinical studies have shown that D-003 lowers cholesterol and prevents plasma lipoprotein peroxidation (LP). D-003 has protected against the histological changes characteristic of CCl4- and paracetamol-induced hepatic injury in rats, in which LP plays a pivotal role for explaining the resulting hepatotoxicity. Galactosamine induces hepatotoxicity associated with depressed RNA and protein synthesis, not with LP. The aim of this study was to evaluate whether D-003 could prevent hepatoxicity induced by mechanisms others than increased LP. We investigated the effects on galactosamine hepatotoxicity in rats distributed into five groups: a negative control group, a positive control group, and three groups treated with galactosamine and D-003 (5, 25, and 100 mg/kg). To induce liver damage, galactosamine (800 mg/kg) was injected intraperitoneally 30 minutes after dosing with vehicle or D-003. Twenty-four hours later, rats were sacrificed, and livers were immediately removed for histopathological studies. Livers from positive controls showed the characteristic pattern of galactosamine-induced damage. Galactosamine significantly reduced the percentage of normal hepatocytes, increasing both necrotic or lipid-rich hepatocytes compared with negative controls. D-003, however, did not increase the percentage of normal hepatocytes compared with positive controls, indicating that treatment was not effective for preventing the hepatic injury induced with galactosamine. Likewise, D-003 failed to change the content of necrotic and lipid-rich hepatocytes relative to positive controls. It is concluded that D-003 did not protect against the histological changes of galactosamine-induced hepatotoxicity.

375 Gene expression analysis of galactosamine-induced hepatotoxicity in-vivo and in-vitro

Plasma hyaluronan (HA) concentration and the rate of HA uptake by the isolated, perfused liver were measured in rats treated with saline, D-galactosamine (GaINH2, 50 mg/100 g body wt), gadolinium chloride (GdCl3) (0.5 mg/100 g body wt), and GdCl3 + GaINH2. GdCl3 was given 24 hr before GaINH2 or saline. Plasma L-alanine:2-oxoglutarate aminotransferase (EC 2.6.1.2), a marker for hepatocyte damage, was increased by 8 hr and remained elevated for 24 hr after GaINH2 injection. GdCl3 did not affect plasma enzyme levels when given alone or in association with, but prior to, GaINH2. Plasma HA levels were increased (200%) within 2 hr GaI administration. A plateau was reached at 8 hr, which was maintained for at least 24 hr. Although GdCl3 alone did not affect plasma HA levels, it slightly delayed the increase in HA concentration in GaINH2-treated rats. Liver, isolated 24 hr after GaINH2 treatment, exhibited a severe depression (approximately 67%) of HA uptake. GdCL3 did not prevent this suppression. The data presented indicate that: (1) one of the sinusoidal endothelial cell-dependent functions of the liver, i.e. removal of HA from the blood stream, is profoundly impaired during galactosamine-induced hepatitis, and (2) the adverse effect of GaINH2 on this sinusoidal endothelial cell function may not be dependent on GdCl3-suppressible Kupffer cell functions.

4-Nitrobenzylidene malononitrile reduces apoptosis-mediated liver injury in mice

Background : Apoptosis plays a role in experimental and clinically related liver damage. Inhibitors of tyrosine kinases were shown to modulate apoptosis induced by different agents in various cell types. Aims : Investigation of the effect of 4-nitrobenzylidene malononitrile (belonging to the tyrphostins family which are selective inhibitors of protein tyrosine kinases) on apoptosis-mediated acute liver injury. Methods : Two murine experimental models exhibiting apoptosis-mediated liver injury were used: (1) mice treated with tumor necrosis factor- α and d -galactosamine; and (2) mice treated with anti-Fas antibody. Liver injury was assessed by serum levels of transaminases and by microscopic analysis. Apoptosis was assessed by labeling of apoptotic cells in the liver by the TUNEL assay and by determination of caspase-3 activity. Results : Pretreatment of mice with 4-nitrobenzylidene malononitrile reduced tumor necrosis factor- α/ d -galactosamine-induced hepatotoxicity. TUNEL positive cells in sections from livers treated with vehicle (control), 4-nitrobenzylidene malononitrile, tumor necrosis factor- α/ d -galactosamine and tumor necrosis factor- α/ d -galactosamine and 4-nitrobenzylidene malononitrile, were >0.2, >0.2, 49±2.3 and 4±0.2 per mm 2, respectively. 4-Nitrobenzylidene malononitrile also reduced hepatotoxicity induced by anti-Fas antibody. Caspase-3 activation induced by either tumor necrosis factor- α/ d -glactosamine or by anti-Fas treatment, was reduced by pretreatment with N -nitrobenzylidene malononitrile Conclusions: The findings may provide a base for development of a new therapeutic modality to reduce apoptosis-mediated liver damage.

Effects of acetylbergenin against [formula omitted] -galactosamine-induced hepatotoxicity in rats

The hepatoprotective effects of acetylbergenin were examined against D -galactosamine (GalN)-induced liver damage in rats, compared with that of bergenin reported previously. Acetylbergenin was synthesized from acetylation of bergenin, isolated from Mallotus japonicus, to increase lipophilic and physiological activities. Acetylbergenin was administered orally once daily for 7 days and then GalN (400 mg kg−1, i.p.) was injected at 24 h and 96 h after the final administration of acetylbergenin. Acetylbergenin reduced the elevated serum enzyme activities of alanine/aspartate aminotransferase, sorbitol dehydrogenase and γ -glutamyltransferase and the formation of hepatic malondialdehyde induced by GalN. Acetylbergenin also significantly restored towards normalization the decreased levels of glutathione and the decreased activities of glutathione S-transferase and glutathione reductase induced by GalN. Therefore, these results suggest that acetylbergenin has hepatoprotective effects against GalN-induced hepatotoxicity by inhibiting lipid peroxidation and maintaining an adequate level of GSH for the detoxification of xenobiotics as underlying hepatoprotective mechanisms. In addition, lipophilic acetylbergenin showed more activity in the hepatoprotection than that of the much less lipophilic bergenin reported previously.

Animal models of fulminant hepatic failure: a critical evaluation.

Few conditions in medicine are more dramatic or more devastating than acute liver failure. Our understanding and treatment of this condition have been limited by the lack of satisfactory animal models. The most widely used models consist of surgical anhepatic and devascularization procedures and hepatotoxins, such as galactosamine and acetaminophen. Potential disadvantages with surgical models are their inability to recreate the inflammatory milieu that exists in acute liver failure and their reliance on surgical expertise. Models using hepatotoxins are free of such constraints. Galactosamine-induced hepatotoxicity is more predictable than acetaminophen, but its cost and lack of a human equivalent clinical syndrome has restricted its use. Acetaminophen-based models offer the greatest potential but have proven the most difficult to develop because of difficulties with reproducibility and refractory anemia. Although progress has been made, research must continue in this area to establish an animal model with minimal disadvantages that would accurately reflect the clinical syndrome seen in humans.

Exogenous fructose 1,6-bisphosphate reduces K+ permeability in isolated rat hepatocytes.

The relationship between the protective effect of fructose 1,6-bisphosphate (F-1,6-P2) against cell injury and the modifications produced in the metabolic fluxes and in the membrane permeability to K+ was studied in isolated rat hepatocytes. Incubation of these cells in the presence of F-1,6-P2 reduced metabolic activity without affecting the ATP content, which suggests a downregulation of the ATP turnover. Using 86Rb+ as a tracer, we analyzed the relationship between these metabolic changes and alterations in K+ fluxes. In the presence of F-1,6-P2 the passive and the active K+ fluxes in hepatocytes decreased. However, the Na(+)-K+ pump from semipurified membranes was not directly affected by F-1,6-P2, which suggests a secondarily induced reduction of Na(+)-K+ pump activity. Moreover, galactosamine-treated cells showed a marked increase in permeability to K+ that was abolished by the presence of F-1,6-P2. This protective effect may be related to the prevention of K+ efflux. The results reported here strongly suggest the induction of channel arrest, and the associated metabolic downregulation, as the primary protective effect of F-1,6-P2, as has been shown in the prevention of galactosamine-induced hepatotoxicity.

Prevention of Galactosamine-Induced Hepatotoxicity in Rats with Fructose-16-Diphosphate

Galactosamine (GalN) administration produces hepatitis-like liver injury in animals. The hepatotoxicity of GalN is attenuated by several interventions, including activation of the reticuloendothelial system (RES). Fructose-1,6-diphosphate (FDP) administration significantly increases the phagocytic activity of the RES in animals. Thus, investigations were designed to determine whether FDP affords protection against GalN toxicity. Rats were injected with GalN (375 mg/kg) and treated with 0.9% NaCl (n = 8) or FDP (n = 9). Eight rats were sham-operated. Serum glutamic oxaloacetic transaminase was 40 times higher in the saline group as compared to the FDP-treated rats (p less than 0.0001). Glutamic pyruvic transaminase, gamma-glutamyltranspeptidase and bilirubin were similarly elevated (saline vs. FDP, p less than 0.005, p less than 0.01 and p less than 0.05, respectively). These values were not different between FDP-treated and sham-operated rats. Extensive hepatic necrosis was observed in all saline-treated rats, whereas in the FDP group only isolated foci of hepatocellular necrosis were noted. The hepatoprotective effect of FDP in this model is attributed to its ability to enhance the phagocytic activity of RES and to suppress release of oxyradicals by the leukocytes during the inflammatory phase.

Cystamine modulation of galactosamine-induced hepatotoxicity

The ability of cystamine treatment to protect against galactosamine-induced hepatic necrosis was investigated. Reduced hepatotoxicity was observed following galactosamine hydrochloride (400 mg/kg, ip) in male Sprague-Dawley rats that received cystamine dihydrochloride (300 mg/kg, po) 30 min prior to or 2, 4, 6, 8, or 12 hr after galactosamine, In contrast, uridine treatment only protected against galactosamine-induced liver damage if administered within 2 hr of galactosamine. Protection by cystamine was found to extend over 3 days during which time the lesion was resolving. The degree of protection was dose related when administered 12 hr after galactosamine. Cystamine did not prevent or alter the increase in hepatic Ca 2+ seen following galactosamine administration. The results indicate that the protective effects of cystamine on galactosamine-induced hepatotoxicity are unrelated to prevention of the early biochemical events that initiate the injury. Furthermore, prevention of Ca 2+ accumulation in damaged hepatocytes is not the mechanism of protection and hence is not necessarily an irreversible cytotoxic event.

In Vitro and In Vivo Evaluation of Hepatoprotective Activity of Gymnema Sylvestre

Leaves of Gymnema sylvestre were extracted by hot and cold maceration. Qualitative phytochemical analysis of the plant extract showed the presence of majority of compounds like alkaloids, carbohydrates, flavonoids, terpienoids, glycosides, proteins, amino acids, phenolic compounds and tannins.. Among the two extracts, the hydro- alcoholic extract prepared by the hot maceration has shown high phenol content 6.51 ± 0.231 mg/g, high total favonolid content 89.51 ± 0.100 mg/g. By DPPH method, total antioxidant capacity, reducing power ability of the hydro-alcoholic extract prepared by hot maceration process was evaluated. The freshly prepared rat hepatocytes were treated with different concentration of hydro-alcoholic extract prepared by the hot maceration process. The antihepatotoxicity produced by the extract at the concentration of 200, 400,600 µg/ml was found effective against the D – galactosamine-induced hepatotoxicity, where as at the concentration of 800 µg/ml was found to be cytotoxic. A significant increase in the levels of ASAT, ALAT,ALP, total bilirubin, direct bilirubin ( P&lt; 0.001) were observed. The cells were treated with the hydro-alcoholic extract different extracts of Gymnema sylvestre showed a significant restoration of the altered biochemical parameters towards the normal (P&lt;0.001) when compared to D- galactosamine treated groups and were found to be dose dependent. A similar result was obtained when D- galactosamine intoxicated hepatocytes were treated with silymarin.