Effect of tetrahydrocurcumin on erythromycin estolate-induced lipid peroxidation in rats.

Erythromycin estolate (EME), a potent macrolide antibiotic, generates free radicals, but their role in the development of liver toxicity is not yet well understood. The present study was carried out to investigate the effect of the antioxidant drug tetrahydrocurcumin (a metabolite of curcumin, the main component of turmeric) against EME-induced lipid peroxidation in rats. The oral administration of combined THC (80 mg/kg body weight) and EME (800 mg/kg body weight) for 15 days significantly decreased lipid peroxidation and enhanced cellular antioxidant defenses when compared with the group treated with EME alone. Supplemental histopathological examination of liver sections revealed that THC had a better antioxidant effect than Silymarin (200 mg/kg body weight), a reference drug. The results of this study indicate that THC affords significant protection against EME-induced lipid peroxidation.

Cytotoxic effects of erythromycin estolate and chlorpromazine on hepatocytes isolated from rats of varying ages: a brief note.

Hepatocytes isolated from young (1 month) rats were as sensitive to the cytotoxic effects of erythromycin estolate and chlorpromazine as were liver cells obtained from older (3, 10 and 24 months) rats. The hepatocytes from the 24-month-old rats released aspartate transaminase more slowly than did parenchymal cells isolated from the younger rats.

Protective effect of flavonoids on drug-induced hepatotoxicity in vitro.

Primary cell cultures of neonatal hepatocytes were used to examine the protective effect of flavonoids in the presence of hepatotoxins. Catechin (CAT) and silybin (SIL) protected the hepatocytes against cell injury produced by erythromycin estolate (EE), amitriptyline (AT), nortriptyline (NT), and tert-butylhydroperoxide (TBOOH). Leakage of lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), as well as morphological parameters, were used as indices of hepatotoxicity. Hepatocytes were exposed to EE (1 X 10(-4) M and 2 X 10(-4) M), AT, NT, and TBOOH (1 X 10(-4) M and 1 X 10(-3) M) for a 2-h period. These hepatotoxins caused significant LDH, AST, and ALT leakage (P less than 0.05) when compared to untreated control groups. NT was less toxic than its parent compound, AT. Changes in morphology were evident after 1 h of treatment with the toxicants, including: vacuole formation, size deformation and cell necrosis. As the concentration of hepatotoxins was increased, the changes were more pronounced. Pretreatment of the cultures with either CAT or SIL resulted in less enzyme leakage and morphological alterations by the hepatotoxins. The results of this study suggest that CAT and SIL may act by stabilizing the plasma membrane against toxic insult.

Protective effect of diosmetin on in vitro cell membrane damage and oxidative stress in cultured rat hepatocytes.

Primary cultures of rat hepatocytes were used to study the effects of the flavonoids diosmin and its main metabolite diosmetin on the cell membrane damage caused by erythromycin estolate (EE) and oxidative stress caused by tert-butylhydroperoxide (TBHP). The damage was evaluated by the leakage of intracellular enzymes lactate dehydrogenase, aspartate-aminotransferase and the residual cell content of a lysosomal marker acid phosphatase (AP). After treating the cells for 40 h with diosmetin EE induced less enzyme leakage. The content of AP was kept higher by diosmetin pretreatment after 6 h exposure to EE. Diosmin at the same concentrations had barely any effect. Diosmetin, but not diosmin, also protected against TBHP toxicity and this was related to lower lipid peroxidation and higher glutathione content caused by pretreatment with the flavonoid. When the cells were treated simultaneously with TBHP and diosmetin after 21 h of culture, the protection by the flavonoid was even higher. In fact the antioxidant activity of diosmetin was considerably greater than that of diosmin. After 40 h exposure to both flavonoids diosmin but not diosmetin was detectable in the cell membrane fraction, suggesting that the latter's protective effect is associated with its metabolites.

Prevention of the toxicity of erythromycin estolate in the perfused rat liver by endotoxin.

The possibility that endotoxin pretreatment could prevent the hepatotoxic effects of erythromycin estolate (EE) was investigated using the isolated perfused rat liver. The addition of E. coli endotoxin (25 micrograms/ml) to the perfusate, 30 min prior to EE administration at 150 or 200 microM, significantly ameliorated the decreases in bile and perfusate flow caused by either concentrations of the drug in control liver preparations. This phenomenon was also studied using liver isolated from rats pretreated in vivo with endotoxin for three days. In these preparations, EE at both concentrations did not alter bile flow and caused reductions of perfusate flow which were far less than those observed in untreated control livers. Furthermore, in livers from endotoxin-treated rats EE induced less reduction of bile acid excretion and, at 150 microM, it did not increase the bile to perfusate ratio of sucrose seen in control preparations after the drug, which may be an expression of altered hepatocytic membrane permeability. Since it is known that both endotoxin and EE interact with membranes, it is suggested that the "protective" effects of endotoxin may occur at the membrane level.

Erythromycin estolate-induced toxicity in cultured rat hepatocytes.

Primary cultures of rat hepatocytes were exposed to several concentrations of erythromycin estolate (EE). Hepatotoxicity was evaluated using lactate dehydrogenase (LDH) leakage and morphometric analysis of representative populations of cells examined optically. Results of the two techniques provided parallel information: cells exposed to the higher concentrations of EE had significantly greater LDH release and higher percentages of morphologically damaged cells. Planimetric analysis of a second set of hepatocytes showed increasing swelling of cells with increasing concentration of EE. Severe cellular swelling preceded disintegration, as hepatocytes became progressively more damaged by EE.

Protective effect of Livex, a herbal formulation against erythromycin estolate induced hepatotoxicity in rats.

Livex, a compound herbal formulation, was investigated for its possible hepatoprotective effect in Wistar rats against erythromycin estolate induced toxicity. Oral administration of Livex significantly prevented the occurrence of erythromycin estolate induced hepatic damage. The increased level of serum enzymes (aspartate transaminase, alanine transaminase, alkaline phosphatase), bilirubin, serum and tissue cholesterol, triglycerides, phospholipids and free fatty acids observed in rats treated with erythromycin estolate were very much reduced in rats treated with Livex and erythromycin estolate. These biochemical observations were supplemented by histopathological examination of liver sections. Results of this study revealed that Livex could afford a significant protection against erythromycin estolate induced hepatocellular damage.

Protective effect of Sesbania grandiflora against erythromycin estolate-induced hepatotoxicity.

Sesbania grandiflora, commonly known as 'sesbania', is widely used in Indian folk medicine for the treatment of liver disorders. Oral administration of an ethanolic extract of S. grandiflora leaves (200 mg/kg/day) for 15 days produced significant hepatoprotection against erythromycin estolate (800 mg/kg/day)-induced hepatotoxicity in rats. The increased level of serum enzymes (aspartate transaminase, alanine transaminase, alkaline phosphatase), bilirubin, cholesterol, triglycerides, phospholipids, free fatty acids, plasma thiobarbituric acid reactive substances and hydroperoxides observed in rats treated with erythromycin estolate were significantly decreased in rats treated concomitantly with sesbania extract and erythromycin estolate. The sesbania extract also restored the depressed levels of antioxidants to near normal. The results of the study reveal that sesbania could afford a significant protective effect against erythromycin estolate-induced hepatotoxicity. The effect of sesbania was compared with that of silymarin, a reference hepatoprotective drug.

Integrated systems toxicology approaches identified the possible involvement of ABC transporters pathway in erythromycin estolate-induced liver injury in rat.

Erythromycin estolate (EE), a macrolide antibiotic, has caused hepatotoxicity both in human and experimental animals. The objective of this study was to integrate general toxicology, transcriptomics, and metabonomics approaches to determine the mechanisms of EE-induced liver injury. Histopathological examinations unveiled dose-dependent hydropicdegenerationof hepatocytes after EE administration. Further biochemical analysis of treated rats confirmed that cholestasis and oxidative stress were induced by EE treatments. Microarray analysis of the livers from EE-treated rats showed that differentially expressed genes were enriched in the ABC transporters, cell cycle, and p53 signaling pathways. Metabonomics analysis revealed that EE exposure could lead to disturbances in energy metabolism, amino acid metabolism, lipid metabolism, and nucleotide metabolism, which may be attributable to EE toxicological effects on the liver through oxidative stress. 5-Oxoproline may be used as a biomarker of EE-induced liver injury. More importantly, the integrated analysis of transcriptomics and metabonomics datasets demonstrated that the induction of ABC transporters pathway severed as an anti-cholestatic adaptive mechanism in EE-induced cholestasis. In addition, EE-induced liver injury was also related to alteration in glycogen and sucrose metabolism, arachidonic acid metabolism, and linoleic acid metabolism pathways.

Erythromycin estolate vs. erythromycin base, surface excess properties and surface scanning changes in isolated liver cell systems.

Chang liver cells and isolated rat hepatocytes were exposed to medium containing different concentrations of erythromycin estolate or erythromycin base for 1-5 h. Hepatotoxicity was quantitated by measuring leakage of enzymes from cells into surrounding medium and the damage to the plasma cell membrane seen under surface scanning electron microscopy. Only the cells exposed to erythromycin estolate showed significantly greater enzyme leakage than controls and appeared severely affected by cytopathic changes when observed under scanning electron microscopy.

Erythromycin estolate impairs the mitochondrial and microsomal calcium homeostasis: correlation with hepatotoxicity.

The effects of erythromycin estolate, a well known hepatotoxic macrolide antibiotic, on isolated rat hepatocyte viability and on subcellular Ca2+ transport have been investigated. Erythromycin estolate (0.5 mM), but not erythromycin base and erythromycin ethylsuccinate, induced 100% cell death after 60 min incubation, and caused maximal inhibition of mitochondrial and microsomal Ca2+ sequestration activities at 0.1 mM concentration. Sodium lauryl sulphate, which is the surfactant moiety of the erythromycin estolate molecule, caused effects similar to those exhibited by erythromycin estolate. Disorders of the intracellular calcium homeostasis seem to play a role in the lauryl sulphate-mediated hepatotoxic action of erythromycin estolate.

Erythromycin toxicity in primary cultures of rat hepatocytes.

Cultured rat hepatocytes were used to study the toxicity of erythromycin base (EB), erythromycin estolate (EE) and a new fluorinated derivative, (8S)-8-fluoroerythromycin A (EF). EF was not cytotoxic after 18 h incubation at concentrations up to 8 X 10(-4) M and EE was much more toxic than EB at all concentrations studied. EE toxicity was greater in a serum-free medium and was not increased by induction of cytochrome P-450 with phenobarbitone. In hepatocytes co-cultured with rat-liver epithelial cells EE, but not EF, raised the cytochrome P-450 content and formed stable cytochrome P-450 complexes with about 40% of the haemoprotein. The lack of correlation between cytochrome P-450 content and cytotoxicity suggests that some of the parent erythromycin drugs and not their metabolites are the toxic entities.

Comparison of dantrolene sodium with erythromycin estolate using primary cultures of rat hepatocytes.

Using primary cultures of parenchymal hepatocytes as a model system, the cytotoxic potential of dantrolene sodium (DS) was compared with that of erythromycin estolate (EE)--a known hepatotoxin. Parallel morphological and functional comparisons were made, following 4-, 8-, or 24-h exposures of hepatocyte cultures, using phase contrast microscopy and lactate dehydrogenase (LDH) leakage, respectively. Four-hour exposures of cultures to rather low concentrations of EE (i.e. 50 microM) resulted in cellular necrosis and significantly elevated LDH release. As the concentration of this hepatotoxin was increased, the changes were more pronounced. However, even 4- or 8-h exposures of cultures to a maximum of 100 microM DS did not affect LDH leakage or morphological integrity, although marginally detectable morphological changes did not occur at the highest concentration after 24-h. The value of using primary parenchymal hepatocyte cultures as a model system for the assessment of xenobiotic-induced hepatotoxicity was confirmed.