Effects of levocarnitine on mitochondrial antioxidant systems and oxidative stress in aged rats

A prospective study to evaluate the efficacy and safety of vitamin E and levocarnitine prophylaxis against doxorubicin-induced cardiotoxicity in adult breast cancer patients

BACKGROUND

Doxorubicin induces acute and chronic cardiotoxicity. This study is aimed to evaluate the efficacy and safety of vitamin E and levocarnitine (EL) as cardioprotective agents against acute doxorubicin cardiotoxicity in female adult breast cancer patients.

METHODS

A prospective, randomized controlled study was conducted in patients treated with doxorubicin and cyclophosphamide (AC). Patients were randomly assigned to EL plus AC or AC alone for the duration of 4 cycles. Cardiac enzymes (B-type natriuretic peptide, creatine kinase, troponin I (Trop)) and cardiac events were monitored during treatment to evaluate the cardioprotective efficacy of EL.

RESULTS

Seventy-four patients were recruited and received four cycles of chemotherapy. The intervention group (n = 35) showed a significant reduction in both the B-type natriuretic peptide and creatine kinase cardiac enzymes compared to the control group (n = 39). The median (IQR) change for BNP was 0.80 (0.00-4.00) for IG versus 1.80 (0.40-3.60) for CG groups (p < 0.001); creatine kinase was -0.08 (-0.25-0.05) for IG versus 0.20 (0.05-0.50) for CG (p < 0.001). The addition of EL decreased the cardiac events by 24.2% (p = 0.02). All adverse events were tolerable and manageable.

CONCLUSION

This study supports the addition of EL as prophylaxis against acute doxorubicin cardiotoxicity and it was also very well tolerated by a majority of the patients. The co-administration of EL at higher doxorubicin (240 mg/m2) dose should be further investigated.

Vitamin E and levocarnitine as prophylaxis against doxorubicin-induced cardio toxicity in the adult cancer patient: A review

OBJECTIVE

Doxorubicin, a component of the anthracycline group, is a highly effective in the treatment of hematologic and solid malignancies. Because of the cardiotoxic adverse effects, use is limited. Antioxidants may negate this anthracycline-induced cardiotoxicity, although the literature is not conclusive with regards to the cardioprotective benefits of antioxidants. This review assessed and mapped evidence of the efficacy of vitamin E and levocarnitine against doxorubicin-induced cardiotoxicity in adult cancer patients.

DATA SOURCES

This review was based on the Arksey and O'Malley methodology. Potentially relevant literature in English published between January 1960 and April 2021 was identified through a database search. Oxford Quality Scoring System and AMSTR2 were used to assess the quality of trials and systematic reviews respectively, as well as the risks of potential bias.

DATA SUMMARY

Nineteen of the 10 268 (0.2%) articles from the initial search were included in the final analysis (12 clinical trials and 7 systematic reviews). Vitamin E was included in seven prospective clinical trials. Levocarnitine was included in five clinical trials as an individual agent and a single trial as a combination treatment. No trials could be found investigating the combination of vitamin E and levocarnitine in humans.

CONCLUSIONS

This review found that levocarnitine trials showed some cardioprotective effects but the results from vitamin E trials were controversial and inconclusive. Most of the trials reviewed had some shortcomings. Further investigations are therefore needed to determine the efficacy of vitamin E and levocarnitine in preventing doxorubicin-induced cardiotoxicity in adult cancer patients.

Anxiolytic and anti-stress effects of acute administration of acetyl-L-carnitine in zebrafish

Studies have suggested that oxidative stress may contribute to the pathogenesis of mental disorders. In this context, molecules with antioxidant activity may be promising agents in the treatment of these deleterious conditions. Acetyl-L-carnitine (ALC) is a multi-target molecule that modulates the uptake of acetyl-CoA into the mitochondria during fatty acid oxidation, acetylcholine production, protein, and membrane phospholipid synthesis, capable of promoting neurogenesis in case of neuronal death. Moreover, neurochemical effects of ALC include modulation of brain energy and synaptic transmission of multiple neurotransmitters, including expression of type 2 metabotropic glutamate (mGlu2) receptors. The aim of this study was to investigate the effects of ALC in zebrafish by examining behavioral and biochemical parameters relevant to anxiety and mood disorders in zebrafish. ALC presented anxiolytic effects in both novel tank and light/dark tests and prevented the anxiety-like behavior induced by an acute stressor (net chasing). Furthermore, ALC was able to prevent the lipid peroxidation induced by acute stress in the zebrafish brain. The data presented here warrant further investigation of ALC as a potential agent in the treatment of neuropsychiatric disorders. Its good tolerability also subsidizes the additional studies necessary to assess its therapeutic potential in clinical settings.

Oral carnitine supplementation influences mental health parameters and biomarkers of oxidative stress in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial

INTRODUCTION

Limited data are available assessing the effects of oral carnitine supplementation on mental health parameters and biomarkers of oxidative stress of women with polycystic ovary syndrome (PCOS).This study was designed to determine the effects of oral carnitine supplementation on mental health parameters and biomarkers of oxidative stress in women with PCOS.

METHODS

In the current randomized, double-blind, placebo-controlled trial, 60 patients diagnosed with PCOS were randomized to take either 250 mg carnitine supplements (n = 30) or placebo (n = 30) for 12 weeks.

RESULTS

After 12 weeks' intervention, compared with the placebo, carnitine supplementation resulted in a significant improvement in Beck Depression Inventory total score (-2.7 ± 2.3 versus -0.2 ± 0.7, p < 0.001), General Health Questionnaire scores (-6.9 ± 4.9 versus -0.9 ± 1.5, p < 0.001) and Depression Anxiety and Stress Scale scores (-8.7 ± 5.9 versus -1.2 ± 2.9, p = 0.001). In addition, changes in plasma total antioxidant capacity (TAC) (+84.1 ± 151.8 versus +4.6 ± 64.5 mmol/L, p = 0.01), malondialdehyde (MDA) (-0.4 ± 1.0 versus  +0.5 ± 1.5 μmol/L, p = 0.01) and MDA/TAC ratio (-0.0005 ± 0.0010 versus +0.0006 ± 0.0019, p = 0.003) in the supplemented group were significantly different from the changes in these indicators in the placebo group.

CONCLUSIONS

Overall, our study demonstrated that carnitine supplementation for 12 weeks among patients with PCOS had favorable effects on parameters of mental health and biomarkers of oxidative stress.

L-carnitine prevents memory impairment induced by chronic REM-sleep deprivation

Sleep deprivation (SD) negatively impacts memory, which was related to oxidative stress induced damage. L-carnitine is a naturally occurring compound, synthesized endogenously in mammalian species and known to possess antioxidant properties. In this study, the effect of L-carnitine on learning and memory impairment induced by rapid eye movement sleep (REM-sleep) deprivation was investigated. REM-sleep deprivation was induced using modified multiple platform model (8h/day, for 6 weeks). Simultaneously, L-carnitine was administered (300mg/kg/day) intraperitoneally for 6 weeks. Thereafter, the radial arm water maze (RAWM) was used to assess spatial learning and memory. Additionally, the hippocampus levels of antioxidant biomarkers/enzymes: reduced glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG ratio, glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD) and thiobarbituric acid reactive substance (TBARS) were assessed. The results showed that chronic REM-sleep deprivation impaired both short- and long-term memory (P<0.05), whereas L-carnitine treatment protected against this effect. Furthermore, L-carnitine normalized chronic REM-sleep deprivation induced reduction in the hippocampus ratio of GSH/GSSG, activity of catalase, GPx, and SOD. No change was observed in TBARS among tested groups (P>0.05). In conclusion, chronic REM-sleep deprivation induced memory impairment, and treatment with L-carnitine prevented this impairment through normalizing antioxidant mechanisms in the hippocampus.

The effect of L-carnitine on oxidative stress responses of experimental contrast-induced nephropathy in rats

This study was conducted to investigate the prophylactic effects of carnitine against contrast-induced nephropathy (CIN) and its relation to oxidant/antioxidant status in kidney, liver, heart, spleen and lung tissues in a CIN rat model. Twenty-eight adult male Wistar rats were divided into 4 groups, the control, contrast media (CM), carnitine and contrast media+carnitine (CM+carnitine) groups. Animals were placed in individual metabolism cages, and on the 2nd day, rats were deprived of water for 24 hr. On the 3rd day, contrast media were administered to groups CM and CM+carnitine. L-carnitine was administered on days 2, 3 and 4. Histopathological changes were evaluated in the right kidney after euthanization. Superoxide dismutase (SOD) and catalase (CAT) activities and glutathione (GSH) and malondialdehyde (MDA) levels were measured in renal, liver, heart, spleen and lung tissues. The SOD activities in the renal (P<0.05), liver (P<0.001) and spleen (P<0.05) tissues were increased in the carnitine group. The CAT activities in the spleen tissue were decreased (P<0.01) only in the CM group. Renal (P<0.05), liver (P<0.001), spleen (P<0.001) and lung tissue (P<0.01) GSH levels were found to be higher in the carnitine group. In renal, liver and lung tissues, the MDA levels increased in the CM group (P<0.001). The histopathological findings showed that L-carnitine may have a preventative effect in alleviating the negative effects of CIN. Similar to this, L-carnitine may play a major role in the stability of the antioxidant status in the kidney, liver, spleen and lung of the CIN rat model.

The protective role of l-carnitine against cylindrospermopsin-induced oxidative stress in tilapia (Oreochromis niloticus)

Cylindrospermopsin (CYN) is one of the most important cyanotoxins in terms of both human health and environmental quality and is produced by several different species of cyanobacteria, including Aphanizomenon ovalisporum. The principal mechanisms of action of CYN involve inhibition of protein and glutathione synthesis. In addition, CYN-mediated genotoxicity results from DNA fragmentation. The results of both in vivo and in vitro studies suggest that oxidative stress also plays a significant role in CYN pathogenesis in fish. We investigated the protective effects of l-carnitine (LC) pre-treatment on A. ovalisporum-induced oxidative stress in cells containing CYN and deoxy-CYN, or pure standard CYN, in tilapia (Oreochromis niloticus) that had been acutely exposed via oral administration. Various oxidative stress markers, including lipid peroxidation (LPO), protein oxidation, DNA oxidation, and the ratio of reduced glutathione to oxidised glutathione (GSH/GSSG), and the activities of NADPH oxidase, superoxide dismutase (SOD), catalase (CAT), and gamma-glutamyl-cysteine synthetase (γ-GCS), were evaluated in the livers and kidneys of fish in the absence and presence of 400 or 880mgLC/kgfish/day during a 21 day period prior to CYN-intoxication. The results of our study demonstrated for the first time the beneficial antioxidant effects of LC dietary supplementation on oxidative stress status in fish. No pro-oxidant effects were detected at any of the LC doses assayed, suggesting that LC is a chemoprotectant that reduces hepatic and renal oxidative stress and may be effective when used for the prophylaxis and treatment of CYN-related intoxication in fish.

Preliminary study comparing the effects of locally and systemically applied L-carnitine on the healing of full-thickness skin defects

BACKGROUND AND AIMS

L-carnitine as an endogenous cofactor has a role in the regulation of energy flow between different oxidative sources. The purpose of this study is to investigate that the clinical and histopathologic effects of L-carnitine locally and systemically on secondary healing in wounds of full thickness defects. We also measured the effects of L-carnitine on wound tensile strength as mechanical.

MATERIAL AND METHODS

sixty adult male Sprague-Dawley rats were divided into three groups randomly; group 1 (control group, n = 20), group 2 (local experimental group, n = 20), group 3 (systemic experimental group, n = 20). Group 1 was not given any pharmacologic agents. L-carnitine was administered locally in the group 2, and systemically in group 3 for a total of 14 days. The healing days of all groups were recorded. On the 7th, 10th,14th and 21st postoperative days, biopsy specimens, including tissue samples both from healing wound sites and sur-rounding healthy skin were evaluated for neovascularization, inflammation, the amount of collagen deposit, fibroblast migration and re-epithelization. Tensile strength was measured in the samples which completed healing on the 30th day. The results were evaluated by nonparametric Kruskall-Wallis test followed by Mann Whitney-U test.

RESULTS

the mean clinical healing days were 18.25 days, 16.5 days, 15 days for the control group, local experimental and systemic group, respectively. The differences between groups were statistically significant (p < 0.005). Mean tensile strength values were 762.10 centinewton (cN), 801.69 cN and 786.13 cN for the control group, local experimental group and systemic experimental group, respectively. There were no statistically significant differences between groups (p > 0.05). There was no statistically significant difference in the histopathologic ex-amination on the 7th, 10th, 14th and 21st days in the neovascularization, inflammation and fibroblast migration. Collagen deposit was most prevalent in the systemic experimental group and was least in the control group. Complete wound closure rate was observed on the 7th day in the systemic administration group, on the 10th day in local administration group and on the 14th day in the control group. Re-epithelization thickness in the systemic carnitine group was more than the other groups.

CONCLUSIONS

L-carnitine administered locally or systemically has positive effects on wound healing rate and tensile strength in rats.

L-carnitine supplementation to diet: a new tool in treatment of nonalcoholic steatohepatitis--a randomized and controlled clinical trial

OBJECTIVES

Nonalcoholic steatohepatitis (NASH) is a known metabolic disorder of the liver. No treatment has been conclusively shown to improve NASH or prevent disease progression. The function of L-carnitine to modulate lipid profile, glucose metabolism, oxidative stress, and inflammatory responses has been shown. The aim of this study was to evaluate the effects of L-carnitine's supplementation on regression of NASH.

METHODS

In patients with NASH and control subjects, we randomly dispensed one 1-g L-carnitine tablet after breakfast plus diet and one 1 g tablet after dinner plus diet for 24 weeks or diet alone at the same dosage and regimen. We evaluated liver enzymes, lipid profile, fasting plasma glucose, C-reactive protein (CRP), tumor necrosis factor (TNF)-alpha, homeostasis model assessment (HOMA)-IR, body mass index, and histological scores.

RESULTS

At the end of the study, L-carnitine-treated patients showed significant improvements in the following parameters: aspartate aminotransferase (P=0.000), alanine aminotransferase (ALT) (P=0.000), gamma-glutamyl-transpeptidase (gamma-GT) (P=0.000), total cholesterol (P=0.000), low-density lipoprotein (LDL) (P=0.000), high-density lipoprotein (HDL) (P=0.000), triglycerides (P=0.000), glucose (P=0.000), HOMA-IR (P=0.000), CRP (P=0.000), TNF-alpha (P=0.000), and histological scores (P=0.000).

CONCLUSIONS

L-carnitine supplementation to diet is useful for reducing TNF-alpha and CRP, and for improving liver function, glucose plasma level, lipid profile, HOMA-IR, and histological manifestations of NASH.

A systematic review of experimental treatments for mitochondrial dysfunction in sepsis and multiple organ dysfunction syndrome

Sepsis and multiple organ dysfunction syndrome (MODS) are major causes of morbidity and mortality in the intensive care unit. Recently mitochondrial dysfunction has been proposed as a key early cellular event in critical illness. A growing body of experimental evidence suggests that mitochondrial therapies are effective in sepsis and MODS. The aim of this article is to undertake a systematic review of the current experimental evidence for the use of therapies for mitochondrial dysfunction during sepsis and MODS and to classify these mitochondrial therapies. A search of the MEDLINE and PubMed databases (1950 to July 2009) and a manual review of reference lists were conducted to find experimental studies containing data on the efficacy of mitochondrial therapies in sepsis and sepsis-related MODS. Fifty-one studies were included in this review. Five categories of mitochondrial therapies were defined-substrate provision, cofactor provision, mitochondrial antioxidants, mitochondrial reactive oxygen species scavengers, and membrane stabilizers. Administration of mitochondrial therapies during sepsis was associated with improvements in mitochondrial electron transport system function, oxidative phosphorylation, and ATP production and a reduction in cellular markers of oxidative stress. Amelioration of proinflammatory cytokines, caspase activation, and prevention of the membrane permeability transition were reported. Restoration of mitochondrial bioenergetics was associated with improvements in hemodynamic parameters, organ function, and overall survival. A substantial body of evidence from experimental studies at both the cellular and the organ level suggests a beneficial role for the administration of mitochondrial therapies in sepsis and MODS. We expect that mitochondrial therapies will have an increasingly important role in the management of sepsis and MODS. Clinical trials are now required.

L-Carnitine in the lipid and protein protection against ethanol-induced oxidative stress

Chronic ethanol intoxication induces oxidative stress participating in the development of many diseases. Nutrition and the interaction of food nutrients with ethanol metabolism may modulate alcohol toxicity. One such compound is l-carnitine (l-3-hydroxy-4-N,N,N-trimethylaminobutyrate), which also reveals antioxidant abilities. The present study has been designed to investigate the effect of l-carnitine as an antioxidant on the serum and liver of rats chronically intoxicated with ethanol. Rats received l-carnitine solution (1.5g/1L) for 5 weeks and/or were treated intragastrically with ethanol for 4 weeks. In the serum and liver, the level of nonenzymatic antioxidants and lipid and protein oxidation markers were determined. It was shown that alcohol caused the increase in the level of lipid peroxidation products-conjugated dienes (by about 70% and 60% in the liver and blood serum, respectively), malondialdehyde (MDA) (by about 60% and 30% in the liver and blood serum, respectively), 4-hydroxynonenal (4-HNE) (by about 35% and 25% in the liver and blood serum, respectively), and changes in the level of protein oxidative markers-increase in dityrosine and decrease in tryptophan (by about 40%) in the serum and liver of rats. Moreover, the decrease in vitamin E level (by about 30%) and the level of glutathione (GSH) (by about 20% in the liver and blood serum) was also observed. Administration of l-carnitine to rats intoxicated with ethanol significantly protects lipids and proteins against oxidative modifications in the serum and liver. The level of conjugated dienes, MDA, and 4-HNE was decreased by about 30%, 30%, and 20% in the liver, respectively, and by about 20%, 10%, and 10% in the blood serum in comparison to the ethanol group. Moreover, the level of tryptophan was increased and dityrosine decreased by about 10% and 20% in the liver, respectively, and by about 30% and 10% in the blood serum in comparison to the ethanol group. l-carnitine partially protects nonenzymatic antioxidants against oxidative stress. The level of vitamin E was increased by about 20% and the level of GSH was increased by about 25% in the liver and blood serum in comparison to the ethanol group. It is possible that beneficial effect of l-carnitine is connected with its abilities to scavenge free radicals and to chelate metal ions.

L-Carnitine supplementation reduces oxidized LDL cholesterol in patients with diabetes

BACKGROUND

Patients with type 2 diabetes are under high oxidative stress, and levels of hyperglycemia correlate strongly with levels of LDL oxidation. Carnitine favorably modulates oxidative stress.

OBJECTIVE

This objective of this study was to evaluate the efficacy of L-carnitine on the reduction of oxidized LDL cholesterol in patients with type 2 diabetes.

DESIGN

Eighty-one patients with diabetes were randomly assigned to 1 of 2 treatment groups for 3 mo. The 2 groups received either 2 g L-carnitine once daily (n = 41) or placebo (n = 40). The following variables were assessed at baseline, after washout, and at 1, 2, and 3 mo of treatment: body mass index, fasting plasma glucose, glycosylated hemoglobin, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, apolipoprotein A1, apolipoprotein B-100, oxidized LDL cholesterol, thiobarbituric acid-reactive substances, and conjugated dienes.

RESULTS

At the end of the study period, the L-carnitine-treated patients showed significant improvements compared with the placebo group in the following markers: oxidized LDL levels decreased by 15.1 compared with 3.0 U/L (P < 0.001); LDL cholesterol decreased by 0.45 compared with 0.16 mmol/L (P < 0.05); triglycerides decreased by 1.02 compared with 0.09 mmol/L (P < 0.001); apolipoprotein A1 concentrations decreased by 0.12 compared with 0.03 mg/dL (P < 0.05); apolipoprotein B-100 concentrations decreased by 0.13 compared with 0.04 mg/dL (P < 0.05); thiobarbituric acid-reactive substance concentrations decreased by 1.92 compared with 0.05 (P < 0.001), and conjugated diene concentrations decreased by 0.72 compared with 0.11 in the placebo group (P < 0.001).

CONCLUSION

Our study indicates that oral administration of L-carnitine reduces oxidized LDL cholesterol levels in patients with type 2 diabetes.

Rat testicular mitochondrial antioxidant defence system and its modulation by aging

Accumulation of oxidative damage caused by reactive oxygen species (ROS) underlies fundamental changes found during aging. In the present study, age related effect on testicular mitochondrial oxidant generation and antioxidant defence profile was investigated in Wistar rats at 3 months (young adults), 12 months (old adults) and 24 months (senescent animals) of age. Mitochondrial oxidative stress parameters viz., lipid peroxidation (LPx), protein carbonylation, hydrogen peroxide (H2O2) generation and activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), levels of total, oxidized (GSSG) and reduced glutathione (GSH) were studied to find out their roles in maintenance of mitochondrial glutathione redox pool as a function of age. Increased levels of LPx, H2O2 and decreased GSH content accompanied by a decline in activities of SOD, GPx and GR with advancing age suggest that antioxidant defense profile of testicular mitochondria exhibit age related alterations which might play a critical role in regulating physiological functions of the testis such as steroidogenesis and spermatogenesis.

The Influence of L-Carnitine on Oxidative Modification of LDL In Vitro

Owing to their structure and function, low-density lipoproteins (LDLs) are particularly susceptible to the oxidative modifications. To prevent against oxidative modification of LDL, L-carnitine, with endogenous small water-soluble quaternary amine possessing antioxidative properties, was used. The aim of this paper was to prove the in vitro influence of L-carnitine on the degree of oxidative modification of the lipid part (estimated by conjugated dienes, lipid hydroperoxides, and malondialdehyde levels) and the protein part (estimated by dityrosine and tryptophan levels) of LDL native and oxidized by cooper ions. The level of lipophylic LDL antioxidant-alpha-tocopherol was also measured.Oxidation of LDL by Cu(2+) enhanced lipid peroxidation. That was manifested by a statistically significant increase in the content of malondialdehyde (threefold), conjugated dienes (up to about 30%), and lipid hydroperoxides (up to about 50%). Cu(2+) ions were also the cause of oxidative modifications of the protein part of LDLs. It was manifested by a significant increase in dityrosine (by about 50%), whereas the level of tryptophan was significantly decreased threefold in relation to native LDL. Incubation of LDL with Cu(2+) ions also caused a significant sixfold decrease of alpha-tocopherol content in oxidized LDL. However, L-carnitine caused a decrease in the level of conjugated dienes, lipid hydroperoxide, malondialdehyde, and dityrosine by about 20% to 30%, and a significant increase (by about 50%) in the content of tryptophan in comparison with oxidative LDL and in a smaller degree significant changes with native LDL. Additionally, L-carnitine caused a significant twofold increase in alpha-tocopherol content in oxidized LDL.The above results indicate that L-carnitine protects the lipid as well as protein part of LDL particles against oxidative modifications, and this natural antioxidant might be used to prevent against diseases of oxidative origin.

Aberrant insulin receptor signaling and amino acid homeostasis as a major cause of oxidative stress in aging

The mechanisms leading to the increase in free radical-derived oxidative stress in "normal aging" remains obscure. Here we present our perspective on studies from different fields that reveal a previously unnoticed vicious cycle of oxidative stress. The plasma cysteine concentrations during starvation in the night and early morning hours (the postabsorptive state) decreases with age. This decrease is associated with a decrease in tissue concentrations of the cysteine derivative and quantitatively important antioxidant glutathione. The decrease in cysteine reflects changes in the autophagic protein catabolism that normally ensures free amino acid homeostasis during starvation. Autophagy is negatively regulated by the insulin receptor signaling cascade that is enhanced by oxidative stress in the absence of insulin. This synopsis of seemingly unrelated processes reveals a novel mechanism of progressive oxidative stress in which decreasing antioxidant concentrations and increasing basal (postabsorptive) insulin receptor signaling activity compromise not only the autophagic protein catabolism but also the activity of FOXO transcription factors (i.e., two functions that were found to have an impact on lifespan in several animal models of aging). In addition, the aging-related decrease in glutathione levels is likely to facilitate certain "secondary" disease-related mechanisms of oxidative stress. Studies on cysteine supplementation show therapeutic promise.

L-Carnitine ameliorates methotrexate-induced oxidative organ injury and inhibits leukocyte death

Methotrexate (MTX), a folic acid antagonist widely used for the treatment of a variety of tumors and inflammatory diseases, affects normal tissues that have a high rate of proliferation, including the hematopoietic cells of the bone marrow and the gastrointestinal mucosal cells. To elucidate the role of free radicals and leukocytes in MTX-induced oxidative organ damage and the putative protective effect of L-carnitine (L-Car), Wistar albino rats were administered a single dose of MTX (20 mg/kg) followed by either saline or L-Car (500 mg/kg) for 5 days. After decapitation of the rats, trunk blood was obtained, and the ileum, liver, and kidney were removed for histological examination and for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity, and collagen content. Our results showed that MTX administration increased the MDA and MPO activities and collagen content and decreased GSH levels in all tissues, while these alterations were reversed in L-Car-treated group. The elevated serum TNF-alpha level observed following MTX treatment was depressed with L-Car. The oxidative burst of neutrophils stimulated by Annexin V was reduced in the saline-treated MTX group, while L-Car abolished this inhibition. Similarly, flow cytometric measurements revealed that leukocyte apoptosis was increased in MTX-treated animals, while L-Car reversed these effects. Severe degeneration of the intestinal mucosa, liver parenchyma, and glomerular and tubular epithelium observed in the saline-treated MTX group was improved by L-Car treatment. These results suggest that L-Car, possibly via its free radical scavenging and antioxidant properties, ameliorates MTX-induced oxidative organ injury and inhibits leukocyte apoptosis. Thus, supplementation with L-Carnitine as an adjuvant therapy may be promising in alleviating the systemic side-effects of chemotherapeutics.

Oxidative Stress and DNA Single Strand Breaks in Skeletal Muscle of Aged Rats: Role of Carnitine and Lipoicacid

The exposure of biological system to various conditions of oxidative stress is the major contributor for aging process. Oxidative stress in turn increases the cellular levels of oxidatively modified proteins, lipids and nucleic acids resulting in a loss of physical activity and metabolic integrity. In this study, we evaluated the role of L-carnitine and DL-alpha-lipoic acid in minimizing oxidant generation and macromolecular damage in skeletal muscle of aged rats. We found that the oxidant generation was increased in aged rat skeletal muscle when compared to young rats. There was a simultaneous increase in the levels of lipid peroxidation, protein carbonyl content and DNA strand breaks in aged rat skeletal muscle. Administration of L-carnitine (300 mg/kg body wt/day) and DL-alpha-lipoic acid (100 mg/kg body wt/day) to aged rats for 30 days, decreased the oxidant generation, lipid peroxidation, protein carbonylation and DNA strand breaks. We concluded that co-administration of carnitine and lipoic acid to aged rats has the potential to prevent oxidative stress mediated macromolecular damage in skeletal muscle of aged rats by their putative role as efficient antioxidants.

Effects of L-carnitine on oxidant/antioxidant status in acetic acid-induced colitis

Recently, the role of oxidative stress in the pathogenesis of ulcerative colitis has been investigated. This study was designed to evaluate the possible beneficial effects of L-carnitine on tissue injury and oxidative stress in acetic acid-induced colitis in rats. Acetic acid administration induced severe damage macroscopically and histopathologically in colon and significantly increased the levels of malondialdehyde and myeloperoxidase in colonic tissue. Supplementation of L-carnitine to acetic acid-treated rats did not prove to induce any improvements in macroscopic scores, while L-carnitine administration improved histopathologic scores and significantly decreased malondialdehyde and myeloperoxidase levels in treatment groups. Acetic acid administration significantly decreased reduced glutathione, superoxide dismutase, and catalase levels in colonic homogenate. Supplementation of L-carnitine prevented the depletion of reduced glutathione levels but significantly increased superoxide dismutase levels. On the other hand, no significant change in catalase activity was observed. In conclusion, these results may reflect that L-carnitine could be beneficial as a complementary agent in treatment of ulcerative colitis.

Mitochondrial dysfunction in NASH: causes, consequences and possible means to prevent it

Calorie-enriched diet and lack of exercise are causing a worldwide surge of obesity, insulin resistance and lipid accretion in liver (i.e. hepatic steatosis), which can lead to steatohepatitis. Steatosis and nonalcoholic steatohepatitis (NASH) can also be induced by drugs such as amiodarone, tamoxifen and some antiretroviral drugs, including stavudine and zidovudine. There is accumulating evidence that mitochondrial dysfunction (more particularly respiratory chain deficiency) plays a key role in the physiopathology of NASH whatever its initial cause. In contrast, the mitochondrial beta-oxidation of fatty acids can be either increased (as in insulin resistance-associated NASH) or decreased (as in drug-induced NASH). However, in both circumstances, generation of reactive oxygen species (ROS) by the damaged respiratory chain can be augmented. ROS generation in an environment enriched in lipids in turn induces lipid peroxidation which releases highly reactive aldehydic derivatives (e.g. malondialdehyde) that have diverse detrimental effects on hepatocytes and other hepatic cells. In hepatocytes, ROS, reactive nitrogen species and lipid peroxidation products further impair the respiratory chain, either directly or indirectly through oxidative damage to the mitochondrial genome. This consequently leads to the generation of more ROS and a vicious cycle occurs. Mitochondrial dysfunction can also lead to apoptosis or necrosis depending on the energy status of the cell. ROS and lipid peroxidation products also increase the generation of several cytokines (TNF-alpha, TGF-beta, Fas ligand) playing a key role in cell death, inflammation and fibrosis. Recent investigations have shown that some genetic polymorphisms can significantly increase the risk of steatohepatitis and that several drugs can prevent or even reverse NASH. Interestingly, most of these drugs could exert their beneficial effects by improving directly or indirectly mitochondrial function in liver. Finding a drug, which could fully prevent oxidative stress and mitochondrial dysfunction in NASH is a major challenge for the next decade.

Oxidative stress and ageing: is ageing a cysteine deficiency syndrome?

Reactive oxygen species (ROS) are constantly produced in biological tissues and play a role in various signalling pathways. Abnormally high ROS concentrations cause oxidative stress associated with tissue damage and dysregulation of physiological signals. There is growing evidence that oxidative stress increases with age. It has also been shown that the life span of worms, flies and mice can be significantly increased by mutations which impede the insulin receptor signalling cascade. Molecular studies revealed that the insulin-independent basal activity of the insulin receptor is increased by ROS and downregulated by certain antioxidants. Complementary clinical studies confirmed that supplementation of the glutathione precursor cysteine decreases insulin responsiveness in the fasted state. In several clinical trials, cysteine supplementation improved skeletal muscle functions, decreased the body fat/lean body mass ratio, decreased plasma levels of the inflammatory cytokine tumour necrosis factor alpha (TNF-alpha), improved immune functions, and increased plasma albumin levels. As all these parameters degenerate with age, these findings suggest: (i) that loss of youth, health and quality of life may be partly explained by a deficit in cysteine and (ii) that the dietary consumption of cysteine is generally suboptimal and everybody is likely to have a cysteine deficiency sooner or later.

Decreasing Oxidative Stress with Choline and Carnitine in Women

OBJECTIVE

Fatty acid oxidation is predominantly a mitochondrial event, which is enhanced by dietary choline and carnitine supplementation resulting in extra reactive oxygen species (ROS) load. The objective was to assess oxidative stress level by thiobarbituric acid reactive substances [TBARS] in choline and carnitine supplemented healthy women before and after mild exercise.

METHODS

Nineteen free-living women completed the placebo control study in which choline and/or L-carnitine was orally taken for 21 days. Anthropometric measurements, dietary recall, exercise routine and blood samples were analyzed to determine body composition, nutrients intake, distance walked and biochemical markers related to oxidative stress.

RESULTS

TBARS were significantly lower in the groups supplemented with choline, carnitine or both and the mild exercise (walking) was not a deterrent in this effect of the supplements. Serum vitamin A and E concentrations were higher in the supplemented groups even though the consumption of these nutrients was not different among the groups.

CONCLUSION

Choline and carnitine supplementation lowers lipid peroxidation, and promotes conservation of retinol and alpha-tocopherol in free-living women.

Supplementation of L-carnitine improves mitochondrial enzymes in heart and skeletal muscle of aged rats

Aging is characterized by a general decline in physiological functions that affects many tissues and increases the risk of death. Deterioration of mitochondria, the major source and target of reactive oxygen species (ROS), is implicated in aging and a variety of age-related diseases. In the present study, the activities of citric acid cycle enzymes, such as isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase, were found to be decreased in aged rats as well as that of electron-transferring enzymes such as NADH dehydrogenase and cytochrome c oxidase. After supplementation of carnitine to aged rats, the activities of these enzymes reverted nearer to that of young control rats. These findings suggest that L-carnitine improves the activities of mitochondrial enzymes, increases the electron flow through the electron transport chain, and improves reducing equivalence, thereby improves energy status in aged rats.

Oxidative stress on mitochondrial antioxidant defense system in the aging process: Role of dl-α-lipoic acid and l-carnitine

BACKGROUND

Oxidative damage is hypothesized to accumulate throughout the lifetime of an organism, eventually giving rise to aging. The mitochondria may be the primary cellular source and target of endogenous ROS as they are produced as a normal byproduct of the electron transport system.

METHODS

Male albino Wistar rats were used in this study. The animals were divided into 6 groups, each group consisting of 6 animals. Groups I, III, and V were young, middle-aged and aged control rats and Groups II, IV, and VI were treated with carnitine (300 mg/kg bw) and dl-alpha-lipoic acid (150 mg/kg bw), respectively. After the treatment period, the animals were sacrificed and the heart and skeletal muscle were removed for analysis.

RESULT

There was a significant reduction in the levels of antioxidants in both middle-aged and aged rats whereas the thiobarbituric acid reactive substances were found to be increased. Co-supplementation of carnitine and lipoic acid improved the antioxidant status and brought down the levels of TBARS.

CONCLUSION

Co-supplementation of lipoic acid with carnitine has a beneficial effect in reversing the age-related abnormalities seen in aging. This effect was associated with the decrease in free radical production and rise in antioxidant levels by carnitine and lipoic acid, thereby lowering oxidative stress.