Effects of vitamin E on cytotoxicity of amiodarone and N-desethylamiodarone in isolated hamster lung cells

Effects of N-acetyl cysteine, vitamin E and vitamin C on liver glutathione levels following amiodarone treatment in rats

Introduction

Amiodarone, a pharmaceutical extensively used to suppress atrial and ventricular tachyarrhythmias, is also known to cause many side effects on many tissues. N-acetyl-cysteine (NAC), vitamin E and vitamin C are known as antioxidants for their ability to minimize oxidative stress. In the peer-reviewed literature, there is no study reporting on the protective effects of these antioxidant agents against its hepatotoxicity.

Aim

We investigated the oxidative effects of NAC, vitamins E and C on liver tissue after amiodarone treatment.

Material and methods

Rats were randomly assigned to: control; amiodarone group; amiodarone + NAC treated group; amiodarone + Vit. E group and amiodarone + Vit. C group. Liver tissues were isolated from animals and total glutathione levels were measured.

Results

In all time intervals, the level of glutathione increased. When all time intervals were compared, the amiodarone group revealed the lowest levels. The antioxidant co-administered group was studied; the glutathione levels were statistically significantly higher than the sole amiodarone group. When vitamins E, C or N-acetyl cysteine were examined, there was no statistically significant difference among them.

Conclusions

In this study we found that hepatotoxicity capacity of amiodarone may be reduced by taking up antioxidants. In addition, the effect documented here may be reproducible and may be applied to clinical settings.

Association between N-desethylamiodarone/amiodarone ratio and amiodarone-induced thyroid dysfunction

PURPOSE

We used a retrospective data mining approach to explore the association between serum amiodarone (AMD) and N-desethylamiodarone (DEA) concentrations and thyroid-related hormone levels.

METHODS

Laboratory data sets from January 2012 to April 2016 were extracted from the computerized hospital information system database at the National Cerebral and Cardiovascular Center (NCVC). Data sets that contained serum AMD and DEA concentrations and thyroid function tests, including thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3), were analyzed.

RESULTS

A total of 1831 clinical laboratory data sets from 330 patients were analyzed. Data sets were classified into five groups (euthyroidism, hyperthyroidism, subclinical hyperthyroidism, hypothyroidism, and subclinical hypothyroidism) based on the definition of thyroid function in our hospital. Most abnormal levels of thyroid hormones were observed within the therapeutic range of serum AMD and DEA concentrations. The mean DEA/AMD ratio in the hyperthyroidism group was significantly higher than that in the euthyroidism group (0.95 ± 0.42 vs. 0.87 ± 0.28, p = 0.0209), and the mean DEA/AMD ratio in the hypothyroidism group was significantly lower than that in the euthyroidism group (0.77 ± 0.26 vs. 0.87 ± 0.28, p = 0.0038). The suppressed TSH group (0.98 ± 0.41 vs. 0.87 ± 0.28, p < 0.001) and the elevated FT4 level group (0.90 ± 0.33 vs. 0.84 ± 0.27, p = 0.0037) showed significantly higher DEA/AMD ratios compared with normal level groups. The elevated TSH group showed a significantly lower DEA/AMD ratio compared with the normal group (0.81 ± 0.25 vs. 0.87 ± 0.28, p < 0.0001).

CONCLUSIONS

High and low DEA/AMD ratios were associated with AMD-induced hyperthyroidism and hypothyroidism, respectively. The DEA/AMD ratio may be a predictive marker for AMD-induced thyroid dysfunction.

Passion fruit peel extract attenuates bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis is a progressive fatal lung disease characterized by excessive collagen deposition, with no effective treatments. We investigated the efficacy of natural products with high anti-inflammatory activity, such as passion fruit peel extract (PFPE), in a mouse model of bleomycin-induced pulmonary fibrosis (PF). C57BL/6J mice were subjected to a single intratracheal instillation of bleomycin to induce PF. Daily PFPE treatment significantly reduced loss of body mass and mortality rate in mice compared with those treated with bleomycin. While bleomycin-induced PF resulted in elevated total numbers of inflammatory cells, macrophages, lymphocytes, and neutrophils in bronchoalveolar lavage fluid on both days 7 and 21, PFPE administration significantly attenuated these phenomena compared with bleomycin group. On day 7, the decreased superoxide dismutase and myeloperoxidase activities observed in the bleomycin group were significantly restored with PFPE treatment. On day 21, enhanced hydroxyproline deposition in the bleomycin group was also suppressed by PFPE administration. PFPE treatment significantly attenuated extensive inflammatory cell infiltration and accumulation of collagen in lung tissue sections of bleomycin-induced mice on days 7 and 21, respectively. Our results indicate that administration of PFPE decreased bleomycin-induced PF because of anti-inflammatory and antioxidant activities.

Ameliorative effect of grapefruit juice on amiodarone-induced cytogenetic and testicular damage in albino rats

OBJECTIVE

To evaluate the ameliorative role of grapefruit juice on the cytogenetic and testicular damage induced by the antiarrythmic drug amiodarone in albino rats.

METHODS

Animals were divided into four groups. Group I was considered as control. Group II was given grapefruit juice at a dose level of 27 mL/kg body weight. Group III was orally administered amiodarone (18 mg/kg body weight) daily for 5 weeks. Animals were sacrificed after 5 weeks of treatment. Bone marrow was collected from the femurs for analysis of chromosomal aberrations and mitotic indices. Testes were removed and stained with H&E for histological examination. Sperms were collected from epidedymis for detection of sperm head abnormalities. Comet assay was used to detect DNA damage.

RESULTS

Amiodarone treatment caused a significant increase in the percentage of chromosomal aberrations, decreased the mitotic index and increased DNA damage. The testis showed many histopathological alterations, inhibition of spermatogenesis and morphometric changes. The number of sperm head abnormalities was increased. Treating animals with amiodarone and grapefruit juice caused a reduction in chromosomal aberrations, mitotic index, DNA damage and testicular alterations caused by amiodarone.

CONCLUSIONS

The results of this study indicated that grapefruit juice ameliorates the cytotoxicty and testicular alterations induced by amiodarone in albino rats and this is may be due to the potent antioxidant effects of its components.

May toxicity of amiodarone be prevented by antioxidants? A cell-culture study

BACKGROUND

Atrial Fibrillation is the most common arrhythmia encountered following cardiac surgery. The most commonly administered drug used in treatment and prophylaxis is amiodarone which has several toxic effects on major organ functions. There are few clinical data concerning prevention of toxic effects and there is no routinely suggested agent. The aim of this study is to document the cytotoxic effects of amiodarone on cell culture media and compare the cytoprotective effects of commonly used antioxidant agents.

METHODS

L929 mouse fibroblast cell line was cultured and 100,000 cells/well-plate were obtained. First group of cells were treated with increasing concentrations of amiodarone (20 to 180 μM) alone. Second and third group of cells were incubated with one-fold equimolar dose of vitamin C and N-acetyl cysteine prior to amiodarone exposure. The viability of cells were measured by MTT assay and the cytoprotective effect of each agent was compared.

RESULTS

The cytotoxicity of amiodarone was significant with concentrations of 100 μM and more. The viabilities of both vitamin C and N-acetyl cysteine treated cells were higher compared to untreated cells.

CONCLUSIONS

Vitamin C and N-acetyl cysteine are commonly used in the clinical setting for different purposes in context of their known antioxidant actions. Their role in prevention of amiodarone induced cytotoxicity is not fully documented. The study fully demonstrates the cytoprotective role of both agents in amiodarone induced cytotoxicity on cell culture media; more pronounced with vitamin C in some concentrations. The findings may be projectile for further clinical studies.

The effect of vitamin C on amiodarone-induced toxicity in rat thymocytes

Although, the antiarrhythmic effect of amiodarone (AMD) is well characterized, the mechanism of its toxicity on extracardiac tissues is still poorly understood. Several antioxidants have been shown to prevent AMD-induced toxicity by antioxidant and/or non-antioxidant mechanisms. In the current study, we evaluated the possible protective effect, in vitro, of vitamin C on AMD-induced toxicity in rat thymocytes. Rat thymocytes were cultured with increasing AMD concentrations (1–20 μM) with or without vitamin C (1000 μg/ml), for 24 hours. Cells treatment with AMD resulted in a concentration-dependent increase of hypodiploid cells and a significant decrease in cellular glutathione content. Vitamin C combined with AMD significantly decreased the proportion of hypodiploid cells and markedly increased the cellular glutathione content, compared with AMD treatment alone. These results suggest that treatment with vitamin C may prevent AMD-induced toxicity in rat thymocytes by restoring cellular glutathione content.

Cytotoxicity effects of amiodarone on cultured cells

Amiodarone is a potent anti-arrhythmic drug used for the treatment of cardiac arrhythmias. Although, the effects of amiodarone are well characterized on post-ischemic heart and cardiomyocytes, its toxicity on extra-cardiac tissues is still poorly understood. To this aim, we have monitored the cytotoxicity effects of this drug on three cultured cell lines including hepatocytes (HepG2), epithelial cells (EAhy 926) and renal cells (Vero). We have investigated the effects of amiodarone on (i) cell viabilities, (ii) heat shock protein expressions (Hsp 70) as a parameter of protective and adaptive response and (iii) oxidative damage.Our results clearly showed that amiodarone inhibits cell proliferation, induces an over-expression of Hsp 70 and generates significant amount of reactive oxygen species as measured by lipid peroxidation occurrence. However, toxicity of amiodarone was significantly higher in renal and epithelial cells than in hepatocytes. Vitamin E supplement restores the major part of cell mortalities induced by amiodarone showing that oxidative damage is the predominant toxic effect of the drug.Except its toxicity for the cardiac system, our findings demonstrated that amiodarone can target other tissues. Therefore, kidneys present a high sensibility to this drug which may limit its use with subjects suffering from renal disorders.

Neferine, a bisbenzylisoquinline alkaloid attenuates bleomycin-induced pulmonary fibrosis

In this study, we evaluated the potential anti-fibrotic property of neferine, a bisbenzylisoquinline alkaloid extracted from the seed embryo of Nelumbo mucifera Gaertn. Intratracheal bleomycin administration resulted in pulmonary fibrosis 14 and 21 days posttreatment, as evidenced by increased hydroxyproline content in bleomycin group (255.77+/-97.17 microg/lung and 269.74+/-40.92 microg/lung) compared to sham group (170.78+/-76.46 microg/lung and 191.24+/-60.45 microg/lung), and the hydroxyproline was significantly suppressed (193.07+/-39.55 microg/lung and 201.08+/-71.74 microg/lung) by neferine administration (20mg/kg, b.i.d). The attenuated-fibrosis condition was also validated by histological observations. Biochemical measurements revealed that bleomycin caused a significant decrease in lung superoxidae dismutase (SOD) activity, which was accompanied with a significant increase in malondialdehyde (MDA) levels and myeloperoxidase (MPO) activity on the 7th and 14th days. However, neferine reversed the decrease in SOD activity as well as the increase in MDA and MPO activity. Enzyme-linked immunosorbent assay and radio-immunity assay showed that treatment with neferine alleviated bleomycin-induced increase of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and endothelin-1 in plasma or in tissue. Additionally, neferine blocked bleomycin-induced increases of NF-kappaB in nuclear extracts and TGF-beta(1) in total protein extracts of murine RAW264.7 macrophages. In summary, neferine attenuates bleomycin-induced pulmonary fibrosis in vitro and in vivo. The beneficial effect of neferine might be associated with its activities of anti-inflammation, antioxidation, cytokine and NF-kappaB inhibition.

Cytotoxic components of Pereskia bleo (Kunth) DC. (Cactaceae) leaves

Dihydroactinidiolide (1) and a mixture of sterols [campesterol (2), stigmasterol (3) and β-sitosterol (4)], together with the previously isolated individual compounds β-sitosterol (4), 2,4-di-tert-butylphenol (5), α-tocopherol (6), phytol (7) were isolated from the active ethyl acetate fraction of Pereskia bleo (Kunth) DC. (Cactaceae) leaves. Cytotoxic activities of the above mentioned compounds against five human carcinoma cell lines, namely the human nasopharyngeal epidermoid carcinoma cell line (KB), human cervical carcinoma cell line (CasKi), human colon carcinoma cell line (HCT 116), human hormone-dependent breast carcinoma cell line (MCF7) and human lung carcinoma cell line (A549); and non-cancer human fibroblast cell line (MRC-5) were investigated. Compound 5 possessed very remarkable cytotoxic activity against KB cells, with an IC₅₀ value of 0.81µg/mL. This is the first report on the cytotoxic activities of the compounds isolated from Pereskia bleo.

Role of vitamin-E on rat liver-amiodarone: an ultrastructural study

BACKGROUND/AIM

Amiodarone, a class III antiarrhythmic drug, has been found to be effective in the management of patients with life-threatening ventricular arrhythmias. The aim of this study was to test whether the co administration of vitamin-E with amiodarone can reduce amiodarone-induced liver damage.

MATERIALS AND METHODS

Twelve male albino rats were divided into three groups (ml vegetable oil/day by oral gavages daily for 2 weeks and were used as control group. The rats of the second group received 5.4 mg amiodarone/100 gm rat dissolved in vegetable oil daily by oral gavages for 2 weeks. In the third group, the rats received 5.4 mg amiodarone and 5 mg vitamin-E/100 gram rat dissolved in 2 ml vegetable oil by oral gavages daily for 2 weeks. Two weeks after treatment, the rats were sacrificed and liver specimens were immediately taken and processed for transmission electron microscopic examinations.

RESULTS

Sections from the rat liver receiving amiodarone examined by electron microscopy showed disrupted hepatocytes with increased vacuolations. Degenerated organelles and disrupted nuclei were observed. The microvilli of bile canaliculi were disrupted and the hepatocytes showed increased lipid contents. Both endothelial cells and Kupffer cells were damaged. Phospholipids inside the mitochondria showed a loss of cristae. Sections from the liver of rats received amiodarone and vitamin-E showed lesser effects, especially in depositions of phospholipids in the mitochondria and the whole organelles and the nucleus showed minor damage in comparison to the previous group.

CONCLUSION

Milder hepatotoxic effects are seen in rats administered amiodarone and vitamin E simultaneously suggesting that vitamin-E may play a role in amelioration of the effects of amiodarone.

Interaction with the hERG channel and cytotoxicity of amiodarone and amiodarone analogues

BACKGROUND AND PURPOSE

Amiodarone (2-n-butyl-3-[3,5 diiodo-4-diethylaminoethoxybenzoyl]-benzofuran, B2-O-CH(2)CH(2)-N-diethyl) is an effective class III antiarrhythmic drug demonstrating potentially life-threatening organ toxicity. The principal aim of the study was to find amiodarone analogues that retained human ether-a-go-go-related protein (hERG) channel inhibition but with reduced cytotoxicity.

EXPERIMENTAL APPROACH

We synthesized amiodarone analogues with or without a positively ionizable nitrogen in the phenolic side chain. The cytotoxic properties of the compounds were evaluated using HepG2 (a hepatocyte cell line) and A549 cells (a pneumocyte line). Interactions of all compounds with the hERG channel were measured using pharmacological and in silico methods.

KEY RESULTS

Compared with amiodarone, which displayed only a weak cytotoxicity, the mono- and bis-desethylated metabolites, the further degraded alcohol (B2-O-CH(2)-CH(2)-OH), the corresponding acid (B2-O-CH(2)-COOH) and, finally, the newly synthesized B2-O-CH(2)-CH(2)-N-pyrrolidine were equally or more toxic. Conversely, structural analogues such as the B2-O-CH(2)-CH(2)-N-diisopropyl and the B2-O-CH(2)-CH(2)-N-piperidine were significantly less toxic than amiodarone. Cytotoxicity was associated with a drop in the mitochondrial membrane potential, suggesting mitochondrial involvement. Pharmacological and in silico investigations concerning the interactions of these compounds with the hERG channel revealed that compounds carrying a basic nitrogen in the side chain display a much higher affinity than those lacking such a group. Specifically, B2-O-CH(2)-CH(2)-N-piperidine and B2-O-CH(2)-CH(2)-N-pyrrolidine revealed a higher affinity towards hERG channels than amiodarone.

CONCLUSIONS AND IMPLICATIONS

Amiodarone analogues with better hERG channel inhibition and cytotoxicity profiles than the parent compound have been identified, demonstrating that cytotoxicity and hERG channel interaction are mechanistically distinct and separable properties of the compounds.

Direct mitochondrial dysfunction precedes reactive oxygen species production in amiodarone-induced toxicity in human peripheral lung epithelial HPL1A cells

Amiodarone (AM), a drug used in the treatment of cardiac dysrrhythmias, can produce severe pulmonary adverse effects, including fibrosis. Although the pathogenesis of AM-induced pulmonary toxicity (AIPT) is not clearly understood, several hypotheses have been advanced, including increased inflammatory mediator release, mitochondrial dysfunction, and free-radical formation. The hypothesis that AM induces formation of reactive oxygen species (ROS) was tested in an in vitro model relevant for AIPT. Human peripheral lung epithelial HPL1A cells, as surrogates for target cells in AIPT, were susceptible to the toxicity of AM and N-desethylamiodarone (DEA), a major AM metabolite. Longer incubations (> or =6 h) of HPL1A cells with 100 microM AM significantly increased ROS formation. In contrast, shorter incubations (2 h) of HPL1A cells with AM resulted in mitochondrial dysfunction and cytoplasmic cytochrome c translocation. Preexposure of HPL1A cells to ubiquinone and alpha-tocopherol was more effective than that with Trolox C or 5,5-dimethylpyrolidine N-oxide (DMPO) at preventing AM cytotoxicity. These data suggest that mitochondrial dysfunction, rather than ROS overproduction, represents an early event in AM-induced toxicity in peripheral lung epithelial cells that may be relevant for triggering AIPT, and antioxidants that target mitochondria may potentially have beneficial effects in AIPT.

Effects of Vitamin E on airway responses and biochemical parameters in guinea pigs sensitized to ovalbumin

The effect of dietary supplementation with Vitamin E was studied in sensitized guinea pigs. After measurement of baseline airway reactivity and sensitization with ovalbumin, the animals were randomized into two groups: Group A, on a commercial feed and Group B, on dietary supplementation with oral Vitamin E (0.7 IU/kg). These were challenged with inhaled ovalbumin after 4 weeks. The following outcomes were studied: airway responses to ovalbumin inhalation, airway reactivity, sodium and calcium ion influx in isolated tracheal cells, Na+ K+ ATPase and Ca2+ ATPase activity in tracheal homogenate and plasma malonaldehyde. Sensitization increased airway reactivity in Group A but not in Group B. The tracheal cells of animals in Group B showed significantly lower rates of 45Ca and 22Na influx and lower activities of tracheal Na+ K+ ATPase and Ca2+ ATPase as compared to Group A. Plasma malonaldehyde was similar between two groups. We concluded that Vitamin E suppresses the increase in airway reactivity following sensitization and has membrane stabilizing actions.

Silymarin and vitamin E reduce amiodarone-induced lysosomal phospholipidosis in rats

Several antioxidants have been shown to reduce lysosomal phospholipidosis, which is a potential mechanism of amiodarone toxicity, and prevent amiodarone toxicity by antioxidant and/or non-antioxidant mechanisms. The aim of this study was to test whether the co-administration of two structurally different antioxidants vitamin E and silymarin with amiodarone can reduce amiodarone-induced lysosomal phospholipidosis, and if yes, by reducing the tissue concentration of amiodarone and desethylamiodarone or by their antioxidant action. To this end, male Fischer 344 rats were treated by gavage once a day for 3 weeks and randomly assigned to the following four experimental groups: 1, control; 2, amiodarone (150 mg/(kg per day)); 3, amiodarone (150 mg/(kg per day)) plus vitamin E (100 mg/(kg per day)); 4, amiodarone (150 mg/(kg per day)) plus silymarin (60 mg/(kg per day)) treated groups. Total plasma phospholipid (PL), liver-conjugated diene, thiobarbituric acid reactive substances (TBARSs), amiodarone and desethylamiodarone concentrations were determined and the extent of lysosomal phospholipidosis in the liver was estimated by a semi-quantitative electron microscopic method. Amiodarone treatment increased significantly the liver-conjugated diene (P<0.001), TBARS (P=0.012), plasma total PL (P<0.001) concentrations compared with control. Antioxidants combined with amiodarone significantly decreased the liver-conjugated diene (P<0.001 for both), TBARS (P=0.016 for vitamin E, P=0.053 borderline for silymarin) and plasma total PL (P=0.058 borderline for vitamin E, P<0.01 for silymarin) concentrations compared with amiodarone treatment alone. Silymarin significantly (P=0.021) reduced liver amiodarone, but only tended to decrease desethylamiodarone concentration; however, vitamin E failed to do so. Amiodarone treatment increased lysosomal phospholipidosis (P<0.001) estimated by semi-quantitative electron microscopic method and both antioxidants combined with amiodarone reduced significantly (P<0.001 for both) the amiodarone-induced lysosomal phospholipidosis. In conclusion, silymarin presumably reduced lysosomal phospholipidosis by both antioxidant action and its liver amiodarone concentration decreasing effect, while vitamin E exerted similar effect by antioxidant action alone. Thus, both antioxidant action and inhibition of tissue uptake of amiodarone might have an important role in the preventative effect of antioxidants against amiodarone toxicity.

Attenuation of amiodarone-induced pulmonary fibrosis by vitamin E is associated with suppression of transforming growth factor-beta1 gene expression but not prevention of mitochondrial dysfunction

Amiodarone (AM) is an efficacious antidysrhythmic agent that can cause numerous adverse effects, including potentially life-threatening pulmonary fibrosis. The current study was undertaken to investigate potential protective mechanisms of vitamin E against AM-induced pulmonary toxicity (AIPT) in the hamster. Three weeks after intratracheal administration of AM (1.83 micromol), increased pulmonary hydroxyproline content and histological damage were observed, indicative of fibrosis. These effects were preceded by increased pulmonary levels of transforming growth factor (TGF)-beta1 mRNA at 1 week post-AM, which remained elevated 3 weeks post-AM. Dietary supplementation with vitamin E resulted in rapid pulmonary accumulation of the vitamin, and prevention of AM-induced increases in TGF-beta1, hydroxyproline, and histological damage. Although dietary supplementation also markedly elevated lung mitochondrial vitamin E content, it did not attenuate AM-induced inhibition of mitochondrial respiration or disruption of mitochondrial membrane potential in vitro, or lung mitochondrial respiratory inhibition resulting from in vivo AM administration. These results suggest that vitamin E reduces the extent of pulmonary damage after AM administration via down-regulating TGF-beta1 overexpression but that it does not modify AM-induced mitochondrial dysfunction, a potential initiating event in AIPT.

Effects of vitamin E on cytotoxicity of amiodarone and N-desethylamiodarone in isolated hamster lung cells

Amiodarone (AM) is a potent and efficacious antidysrhythmic agent that can cause potentially life-threatening pulmonary fibrosis. Vitamin E has been demonstrated to decrease AM-induced pulmonary fibrosis in vivo in hamsters. In the present in vitro study, we investigated the effects of vitamin E on cell death induced by AM and its primary metabolite, N-desethylamiodarone (DEA), in freshly isolated hamster lung cells. Following incubation for 24 or 36 h, 300 microM vitamin E decreased (P<0.05) 100 microM AM-induced cytotoxicity (0.5% trypan blue uptake) in alveolar macrophages by 11.7+/-3% or 21.4+/-12%, respectively, but did not decrease cytotoxicity in fractions enriched with alveolar type II cells or non-ciliated bronchiolar epithelial (Clara cells) or in isolated unseparated cells (cell digest). Vitamin E had no effect on 50 microM DEA-induced cytotoxicity. Vitamin E did not alter cellular levels of AM or DEA in any cell fraction. Lipid peroxidation (assessed by isoprostane formation) was increased (P<0.05) in cell digest, alveolar type II cell and Clara cell enriched fractions incubated with 500 microM carbon tetrachloride (CCl(4)) for 4 h but not in enriched fractions of cells exposed to 100 microM AM or 50 microM DEA. No AM-induced loss of viability was observed at this time point, but DEA decreased (P<0.05) Clara cell viability by approximately 25%. These results demonstrate cell type selective protection against AM-induced cytotoxicity by vitamin E, and suggest that lipid peroxidation does not initiate AM- or DEA-induced cytotoxicity in isolated hamster lung cells.