Inhibition of doxorubicin-induced membrane damage by thiol compounds: toxicologic implications of a glutathione-dependent microsomal factor

Protective effect of N-acetylcysteine, caffeic acid and vitamin E on doxorubicin hepatotoxicity

The aim of this study was to compare the possible protective effects of N-acetylcysteine (NAC), caffeic acid (CAPE) and vitamin E (Vit-E) on doxorubicin-induced hepatotoxicity. Thirty-two male Wistar albino rats, weighing between 250 and 350 g were supplied and randomly divided into five groups. Animals in study groups were pretreated with a single dose of doxorubicin (Dox), which was administered intraperitoneally (i.p.). Control group (Group I) was treated with intraperitoneal saline injection. Group II did not received any antioxidant agent after the injection. Group III and Group IV were given CAPE and intraperitoneal vitamin E injection for eight days, respectively. Group V received NAC for eight days. The study was finished after 10 days. Tissue samples were collected from all animals and histopathological examination was performed. There was statistically significant difference between the experiment groups and controls by means of mononuclear cell infiltration and diameters of hepatic sinusoid, terminal hepatic venule (central vein) and portal area (portal canal). Changes related with hepatocellular damage were more prominent, whereas there was no significant difference between Dox and NAC given groups histopathologically. It was observed that structural changes were regressed after CAPE administration. However, this recovery was more prominent in vitamin E given group. These findings suggest that Dox induced liver damage could be efficiently reversed by vitamin E administration. It has been found that CAPE, but not NAC has protective effects on Dox-induced hepatocellular damage. Human & Experimental Toxicology (2007) 26, 519—525

Comparative normal/failing rat myocardium cell membrane chromatographic analysis system for screening specific components that counteract doxorubicin-induced heart failure from Acontium carmichaeli

Cell membrane chromatography (CMC) derived from pathological tissues is ideal for screening specific components acting on specific diseases from complex medicines owing to the maximum simulation of in vivo drug-receptor interactions. However, there are no pathological tissue-derived CMC models that have ever been developed, as well as no visualized affinity comparison of potential active components between normal and pathological CMC columns. In this study, a novel comparative normal/failing rat myocardium CMC analysis system based on online column selection and comprehensive two-dimensional (2D) chromatography/monolithic column/time-of-flight mass spectrometry was developed for parallel comparison of the chromatographic behaviors on both normal and pathological CMC columns, as well as rapid screening of the specific therapeutic agents that counteract doxorubicin (DOX)-induced heart failure from Acontium carmichaeli (Fuzi). In total, 16 potential active alkaloid components with similar structures in Fuzi were retained on both normal and failing myocardium CMC models. Most of them had obvious decreases of affinities on failing myocardium CMC compared with normal CMC model except for four components, talatizamine (TALA), 14-acetyl-TALA, hetisine, and 14-benzoylneoline. One compound TALA with the highest affinity was isolated for further in vitro pharmacodynamic validation and target identification to validate the screen results. Voltage-dependent K⁺ channel was confirmed as a binding target of TALA and 14-acetyl-TALA with high affinities. The online high throughput comparative CMC analysis method is suitable for screening specific active components from herbal medicines by increasing the specificity of screened results and can also be applied to other biological chromatography models.

N-acetylcysteine modulates doxorubicin-induced oxidative stress and antioxidant vitamin concentrations in liver of rats

Doxorubicin (DOX) is a chemotherapeutic agent, and is widely used in cancer treatment. The most common side effect of DOX was indicated on cardiovascular system by experimental studies. There are some studies suggesting oxidative stress-induced toxic changes on liver related to DOX administration. The aim of the present study was to evaluate whether antioxidant N-acetylcysteine (NAC) relieves oxidative stress in DOX- induced liver injury in rat. Twenty-four male rats were equally divided into three groups. First group was used as a control. Second group received single dose of DOX. NAC for 10 days was given to constituting the third group after giving one dose of DOX. After 10 days of the experiment, liver tissues were taken from all animals. Lipid peroxidation (LP) levels were higher in the DOX group than in control whereas LP levels were lower in the DOX+NAC group than in control. Vitamin C and vitamin E levels were lower in the DOX group than in control whereas vitamin C and vitamin E levels were higher in the DOX+NAC group than in the DOX group. Reduced glutathione levels were higher in the DOX+NAC group than in control and DOX group. Glutathione peroxidase, vitamin A and β-carotene values were not changed in the three groups by DOX and NAC administrations. In histopathological evaluation of DOX group, there were mononuclear cell infiltrations, vacuolar degeneration, hepatocytes with basophilic nucleus and sinusoidal dilatations. The findings were totally recovered by NAC administration. In conclusion, N-acetylcysteine induced modulator effects on the doxorubicin-induced hepatoxicity by inhibiting free radical production and supporting the antioxidant vitamin levels.

How to protect doxorubicin-induced cardiomyopathy in male albino rats?

The present study was designed to compare the cardioprotective effects of the combination of lisinopril with growth hormone over lisinopril alone in doxorubicin (Dox)-induced cardiomyopathy in rats. Forty male Wister albino rats were divided into 4 groups: group 1, control group; group 2, received Dox; group 3, received lisinopril + Dox; and group 4, received lisinopril + Dox + growth hormone. Dox (cumulative dose) was administered to rats in 6 equal intraperitoneal injections over a period of 2 weeks. Histopathological changes and plasma aspartate aminotransferase, lactate dehydrogenase, and creatine kinase and plasma levels of matrix metalloproteinase (MMP)-2, tissue inhibitor matrix metalloproteinase (TIMP)-1, and cardiac inducible nitric oxide synthase (iNOS) messenger RNA (mRNA) expression were determined 9 weeks after the first dose of Dox. Dox produced cardiac structural injury and significant elevation in plasma levels of cardiac enzymes, MMP-2, and cardiac iNOS mRNA expression together with significant reduction in plasma TIMP-1 level. Lisinopril significantly decreases plasma MMP-2 level and cardiac iNOS mRNA expression by 13% and 15%, respectively, in group 3 compared with 36% and 47%, respectively, in group 4 as compared with group 2. In addition, compared with Dox group, lisinopril significantly increases plasma TIMP-1 level by 23% compared with 49% in group 4. We can conclude that the combination of lisinopril and growth hormone produced better cardioprotective effect against Dox-induced cardiomyopathy. This effect may be attributed on their antiremodeling actions by regulating plasma MMP-2/TIMP-1 levels and to the reduction of cardiac iNOS mRNA expression.

A novel thiol oxidation-based mechanism for adriamycin-induced cell injury in human macrophages

Adriamycin is a widely used antitumor antibiotic, but its use has been limited by its cytotoxicity in both cardiomyocytes and non-cardiac tissues. While adriamycin's ability to redox cycle via one-electron transfer reactions and generate ROS is thought to promote cardiotoxicity, the mechanisms involved in non-cardiac tissue injury are not clear. Here we show that prolonged exposure (48 h) of human monocyte-derived macrophages to adriamycin at concentrations as low as 1 microM promotes caspase-independent cell death. Treatment of cells with scavengers of superoxide and peroxyl radicals blocked adriamycin-induced oxidation of dichlorodihydrofluorescein (DCFH) but did not prevent macrophage injury. Macrophages treated with either adriamycin or the thiol oxidant diamide showed elevated levels of glutathione disulfide and increased protein-S-glutathionylation prior to cell injury, indicating that thiol oxidation is involved in adriamycin-induced macrophage death. Furthermore, inhibition of glutathione reductase (GR) with 1,3-bis[2-chloroethyl]-1-nitrosourea or transfection of macrophages with small inhibitory RNA (siRNA) directed against GR or glutaredoxin (Grx) potentiated adriamycin-induced macrophage injury. Thus, both GR and Grx appear to play a crucial role in protecting macrophages from adriamycin-induced cell injury. These findings suggest a new mechanism for adriamycin-induced tissue injury whereby thiol oxidation, rather than one-electron redox cycling and ROS generation, mediates adriamycin-induced cell damage.

Alpha-lipoic acid ameliorates myocardial toxicity induced by doxorubicin

The effect of alpha-lipoic acid (LA) on the cardiotoxicity induced by doxorubicin (DOX) was investigated. A single dose of DOX (15 mg kg(-1), i.p) induced cardiotoxicity manifested biochemically by a significant elevation of serum creatine phosphokinase (CK; EC: 2.7.3.2) and lactate dehydrogenase (LDH; EC: 1.1.1.27) 48 h later. Moreover, cardiotoxicity was further confirmed by the significant increase in lipid peroxides measured as malondialdehyde (MDA), and significant decrease in protein thiols (Protein-SH) content in heart tissues. Administration of LA (100 mg kg(-1)) orally for 5 days before and 2 days after DOX injection produced a significant protection against cardiotoxicity induced by DOX. The amelioration of cardiotoxicity was evident by significant reductions in serum CK and LDH. Moreover, LA prevented the rise of MDA as well as the significant reduction of Protein-SH. These results may suggest that LA has a protective effect against cardiotoxicity induced by DOX and it may, therefore, improve the therapeutic index of DOX.

Dietary fish oil and vitamin E enhance doxorubicin effects in P388 tumor-bearing mice

In this study, four kinds of rodent diets, CO, FO, CVe, and FVe, were used by addition of canola oil, oil mixture (fish oil + canola oil), canola oil plus vitamin E, and oil mixture plus vitamin E, respectively, to a basic diet, AIN-93G, to investigate the influence of dietary fish oil and vitamin E on doxorubicin (DOX) treatment in P388 ascitic mice. Animal life span (LS) and heart damage were recorded in mice fed the four different diets and treated with different doses of DOX. The optimal doses of DOX for antitumor effect as manifested by increased LS were 6.0 and 9.0 mg/kg. Both fish oil and vitamin E significantly enhanced this effect. On the other hand, DOX at 12.0 mg/kg induced severe heart damage, which was also significantly aggravated by both fish oil and vitamin E, as shown by both decreased LS and increased serum creatine phosphokinase activity. Fish oil and vitamin E appeared to enhance the antitumor effect of optimal doses of DOX but to aggravate cardiotoxicity owing to DOX overdose.

Involvement of phenoxyl radical intermediates in lipid antioxidant action of myricetin in iron-treated rat hepatocyte culture

Supplementation of rat hepatocyte cultures with the flavonoid myricetin (300 microM) led to the formation of phenoxyl radical intermediates, as detected in intact cells by electron paramagnetic resonance (EPR) spectroscopy. These radicals corresponded to one-electron oxidation products of myricetin. The level of phenoxyl radicals was significantly reduced when myricetin-treated hepatocyte cultures were also supplemented with iron (Fe-NTA 100 microM). This suggested that iron could accelerate the oxidation flux of myricetin. Moreover, myricetin was found to be able to inhibit lipid peroxidation induced by iron in hepatocyte culture. Free malondialdehyde (MDA) levels and the amount of radicals derived from oxidized lipids were greatly reduced when myricetin was added to iron-treated cultures. This showed that myricetin was a good inhibitor of lipid peroxidation in this model and that the intermediate generation of phenoxyl radicals might contribute to the antioxidant mechanism of myricetin.