Serum and cerebrospinal fluid antioxidant activity and lipid peroxidation in Guillain-Barre syndrome and multiple sclerosis patients

Oxidative Stress Markers in Multiple Sclerosis

The pathogenesis of multiple sclerosis (MS) is not completely understood, but genetic factors, autoimmunity, inflammation, demyelination, and neurodegeneration seem to play a significant role. Data from analyses of central nervous system autopsy material from patients diagnosed with multiple sclerosis, as well as from studies in the main experimental model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), suggest the possibility of a role of oxidative stress as well. In this narrative review, we summarize the main data from studies reported on oxidative stress markers in patients diagnosed with MS and in experimental models of MS (mainly EAE), and case-control association studies on the possible association of candidate genes related to oxidative stress with risk for MS. Most studies have shown an increase in markers of oxidative stress, a decrease in antioxidant substances, or both, with cerebrospinal fluid and serum/plasma malonyl-dialdehyde being the most reliable markers. This topic requires further prospective, multicenter studies with a long-term follow-up period involving a large number of patients with MS and controls.

Construction and evaluation of a prognostic prediction model based on the mEGOS score for patients with Guillain-Barré syndrome

Background

Guillain-Barré syndrome (GBS) is an immune-mediated acute peripheral neuropathy in which up to 20% patients remain unable to walk independently after 6 months of onset. This study aimed to develop a clinical prognostic model based on the modified Erasmus GBS Outcome Score (mEGOS) for predicting the prognosis of GBS patients at 6 months of onset.

Methods

The clinical data of 201 GBS patients were retrospectively analyzed. According to the GBS disability score (GBS-DS) at 6 months of onset, patients were divided into a good prognosis group (GBS-DS <3 points) and a poor prognosis group (GBS-DS≥3 points). Univariate and multivariate analysis was used to screen out independent risk factors for poor prognosis, and a prediction model was accordingly constructed for GBS prognosis.

Results

The mEGOS score, serum albumin (ALB) and fasting plasma glucose (FPG) were independent risk factors for poor prognosis in patients with GBS, and the above risk factors were used to construct a prognostic model of mEGOS-I and a nomogram. The receiver operating characteristic (ROC) curve showed that the area under curve (AUC) of mEGOS-I at admission and at 7 days of admission to predict poor prognosis at 6 months of GBS onset was 0.891 and 0.916, respectively, with sensitivities of 82.7% and 82.6% and specificities of 86.5% and 86.6%, respectively. Decision curve analysis showed that the nomogram had a very high clinical benefit.

Conclusion

To our knowledge, this is the first report of the construction of a prognostic prediction model based on the mEGOS score, ALB, and FPG that can accurately and stably predict the prognosis of GBS patients at 6 months of onset.

COVID-19 as a trigger of Guillain-Barré syndrome: A review of the molecular mechanism

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic with serious complications. After coronavirus disease 2019 (COVID-19), several post-acute COVID-19 syndromes (PACSs) and long-COVID sequels were reported. PACSs involve many organs, including the nervous, gustatory, and immune systems. One of the PACSs after SARS-CoV-2 infection and vaccination is Guillain-Barré syndrome (GBS). The incidence rate of GBS after SARS-CoV-2 infection or vaccination is low. However, the high prevalence of COVID-19 and severe complications of GBS, for example, autonomic dysfunction and respiratory failure, highlight the importance of post-COVID-19 GBS. It is while patients with simultaneous COVID-19 and GBS seem to have higher admission rates to the intensive care unit, and demyelination is more aggressive in post-COVID-19 GBS patients. SARS-CoV-2 can trigger GBS via several pathways like direct neurotropism and neurovirulence, microvascular dysfunction and oxidative stress, immune system disruption, molecular mimicry, and autoantibody production. Although there are few molecular studies on the molecular and cellular mechanisms of GBS occurrence after SARS-CoV-2 infection and vaccination, we aimed to discuss the possible pathomechanism of post-COVID-19 GBS by gathering the most recent molecular evidence.

The early clinical and laboratory predictors of GBS outcome: hospital-based study, Assiut University, Upper Egypt

Background

This study was designed to identify factors that influence outcomes in a large group of well-defined Guillain–Barré syndrome (GBS) patients with a 3-month follow-up period. Sixty-two cases of GBS with a mean age of 37.15 ± 17.60 years (33 males and 29 females) were recruited in the first 2 weeks after onset. Clinical history, examination, and a variety of rating scales including Medial Research Council sum score (MRC), Erasmus Guillain-Barré respiratory insufficiency score (EGRIS), at admission and 10 days later were performed. Follow-up investigations at 3 months included the Hughes Disability Scale (HDS), and Overall Neuropathy Limitation Scale (ONLS).

Results

64.5% of participants had cranial nerve deficits, 45% had neck muscle weakness, 30.6% had dysautonomia, and 8.1% were mechanically ventilated. C-reactive protein was elevated in 38.7%, and hyponatremia was recorded in 30.6% of patients. Older age, antecedent events particularly diarrhea, neck muscles weakness, low MRC sum score, impaired cough reflex, dysautonomia, and hyponatremia, were all significantly associated with poor outcomes at 3 months using HDS and ONLS. Regression analysis with dependent variables of HDS outcome showed that the presence of an antecedent event particularly diarrhea, neck muscle weakness, hyponatremia and the presence cytoalbuminous dissociation of CSF at onset, and low MRC sum score at 10th day after treatment, were predictors of poor outcome.

Conclusion

Clinical and laboratory predictors of poor outcome were older age, the presence of an antecedent event particularly diarrhea, low MRC sum score at the 10th day, elevated CRP, hyponatremia and the presence cytoalbuminous dissociation.

Impact of CYBA genotypes on severity and progression of multiple sclerosis

BACKGROUND AND PURPOSE

The NOX2 enzyme of myeloid cells generates reactive oxygen species (ROS) that have been implicated in the pathology of multiple sclerosis (MS). We aimed to determine the impact of genetic variation within CYBA, which encodes the functional CYBA/p22phox subunit of NOX2, on MS severity and progression.

METHODS

One hundred three MS patients with up to 49 (median = 17) years follow-up time from first MS diagnosis were genotyped at the single nucleotide polymorphisms rs1049254 and rs4673 within CYBA. Results were matched with disease severity and time to diagnosis of secondary progressive MS (SPMS). NOX2-mediated formation of ROS was measured by chemiluminescence in blood myeloid cells from healthy donors (n = 55) with defined genotypes at rs1049254 and rs4673.

RESULTS

The rs1049254/G and rs4673/A CYBA alleles were associated with reduced formation of ROS and were thus defined as low-ROS alleles. Patients carrying low-ROS alleles showed reduced multiple sclerosis severity score (p = 0.02, N = 103, linear regression) and delayed onset of SPMS (p = 0.02, hazard ratio [HR] = 0.46, n = 100, log-rank test). In a cohort examined after 2005, patients carrying low-ROS CYBA alleles showed >20 years longer time to secondary progression (p = 0.003, HR = 0.29, n = 59, log-rank test).

CONCLUSIONS

These results implicate NOX2 in MS, in particular for the development of secondary progressive disease, and point toward NOX2-reductive therapy aiming to delay secondary progression.

Association of Oxidative Stress with Neurological Disorders

BACKGORUND

Oxidative stress is one of the main contributing factors involved in cerebral biochemical impairment. The higher susceptibility of the central nervous system to reactive oxygen species mediated damage could be attributed to several factors. For example, neurons use a greater quantity of oxygen, many parts of the brain have higher concentraton of iron, and neuronal mitochondria produce huge content of hydrogen peroxide. In addition, neuronal membranes have polyunsaturated fatty acids, which are predominantly vulnerable to oxidative stress (OS). OS is the imbalance between reactive oxygen species generation and cellular antioxidant potential. This may lead to various pathological conditions and diseases, especially neurodegenerative diseases such as, Parkinson's, Alzheimer's, and Huntington's diseases.

OBJECTIVES

In this study, we explored the involvement of OS in neurodegenerative diseases.

METHODS

We used different search terms like "oxidative stress and neurological disorders" "free radicals and neurodegenerative disorders" "oxidative stress, free radicals, and neurological disorders" and "association of oxidative stress with the name of disorders taken from the list of neurological disorders. We tried to summarize the source, biological effects, and physiologic functions of ROS.

RESULTS

Finally, it was noted that more than 190 neurological disorders are associated with oxidative stress.

CONCLUSION

More elaborated studies in the future will certainly help in understanding the exact mechanism involved in neurological diseases and provide insight into revelation of therapeutic targets.

Neuroprotective Role of Nutritional Supplementation in Athletes

BACKGROUND

Neurodegenerative disorders belong to different classes of progressive/chronic conditions that affect the peripheral/central nervous system. It has been shown through studies that athletes who play sports involving repeated head trauma and sub-concussive impacts are more likely to experience neurological impairments and neurodegenerative disorders in the long run.

AIMS

The aim of the current narrative review article is to provide a summary of various nutraceuticals that offer promise in the prevention or management of sports-related injuries, especially concussions and mild traumatic brain injuries.

METHODS

This article reviews the various potential nutraceutical agents and their possible mechanisms in providing a beneficial effect in the injury recovery process. A thorough survey of the literature was carried out in the relevant databases to identify studies published in recent years. In the present article, we have also highlighted the major neurological disorders along with the associated nutraceutical(s) therapy in the management of disorders.

RESULTS

The exact pathological mechanism behind neurodegenerative conditions is complex as well as idiopathic. However, mitochondrial dysfunction, oxidative stress as well as intracellular calcium overload are some common reasons responsible for the progression of these neurodegenerative disorders. Owing to the multifaceted effects of nutraceuticals (complementary medicine), these supplements have gained importance as neuroprotective. These diet-based approaches inhibit different pathways in a physiological manner without eliciting adverse effects. Food habits and lifestyle of an individual also affect neurodegeneration.

CONCLUSION

Studies have shown nutraceuticals (such as resveratrol, omega-3-fatty acids) to be efficacious in terms of their neuroprotection against several neurodegenerative disorders and to be used as supplements in the management of traumatic brain injuries. Protection prior to injuries is needed since concussions or sub-concussive impacts may trigger several pathophysiological responses or cascades that can lead to long-term complications associated with CNS. Thus, the use of nutraceuticals as prophylactic treatment for neurological interventions has been proposed.

Serum malondialdehyde as a lipid peroxidation marker in multiple sclerosis patients and its relation to disease characteristics

Introduction Oxidative stress has been suggested to play a key role in pathogenesis of multiple sclerosis (MS), but clinical data on oxidative stress markers in MS patients and their influence on clinical and radiologic characteristics of the disease are inconsistent. The aim of this study is to assess the serum levels of malondialdehyde (MDA) as a measure of lipid peroxidation in MS patients and its relation to disease characteristics. Methods This case control study included 120 patients with clinically definite relapsing remitting multiple sclerosis (RRMS) compared to 120 age and sex -matched healthy controls. MDA levels were measured using thiobarbituric acid reactive substances (TBARS) assay. Results MDA levels are significantly higher in patients with MS than those in control (P<0.001) especially during relapse, MDA levels are higher in patients taking no disease modifying therapy (DMT) than those taking interferon (IFN-β). MDA levels significantly correlate with expanded disability status scale (EDSS) (P<0.001). Conclusions The results of this study can provide evidence about the incrimination of oxidative stress in MS pathogenesis and disease disability and support the use of antioxidants as a new target of treatment that focuses on neutralizing free radicals and increases antioxidant capacity.

The Neuroimmunology of Guillain-Barré Syndrome and the Potential Role of an Aging Immune System

Guillain-Barré syndrome (GBS) is a paralyzing autoimmune condition affecting the peripheral nervous system (PNS). Within GBS there are several variants affecting different aspects of the peripheral nerve. In general, there appears to be a role for T cells, macrophages, B cells, and complement in initiating and perpetuating attacks on gangliosides of Schwann cells and axons. Of note, GBS has an increased prevalence and severity with increasing age. In addition, there are alterations in immune cell functioning that may play a role in differences in GBS with age alongside general age-related declines in reparative processes (e.g., delayed de-differentiation of Schwann cells and decline in phagocytic ability of macrophages). The present review will explore the immune response in GBS as well as in animal models of several variants of the disorder. In addition, the potential involvement of an aging immune system in contributing to the increased prevalence and severity of GBS with age will be theorized.

Increased Cerebrospinal Fluid Uric Acid Levels in Guillain-Barré Syndrome

Uric acid (UA) is a natural scavenger for peroxynitrite and can reflect antioxidant activity and oxidative stress in several neurological disorders. Changes in serum and cerebrospinal fluid (CSF) levels of UA have been reported in patients with multiple sclerosis and neuromyelitis optica spectrum disorders. The levels of UA in CSF are relatively poorly understood in patients with Guillain–Barré syndrome (GBS). It remains unclear whether UA can play an antioxidant role and reflect oxidative stress in GBS. The purpose of this study is to investigate CSF and serum UA levels in patients with GBS and their relationship with clinical characteristics. The CSF and serum UA levels were detected in 43 patients with GBS, including 14 acute inflammatory demyelinating polyneuropathy (AIDP), 6 acute motor axonal neuropathy (AMAN), 13 with acute motor and sensory axonal neuropathy (AMSAN), 7 Miller Fisher syndrome (MFS), and 3 unclassified, and 25 patients with non-inflammatory neurological disorders (NIND) as controls. Moreover, serum UA levels were also detected in 30 healthy controls. The levels of UA were measured using uricase-based methods with an automatic biochemical analyzer. CSF UA levels were significantly increased in patients with GBS (p = 0.011), particularly in patients with AIDP (p = 0.004) when compared with NIND. Among patients with GBS, CSF UA levels were higher in those with demyelination (p = 0.022), although the difference was not significant after multiple testing correction. CSF UA levels in GBS were positively correlated with serum UA levels (r = 0.455, p = 0.022) and CSF lactate (r = 0.499, p = 0.011). However, no significant correlations were found between CSF UA levels and GBS disability scores. There were no significant differences in serum UA levels among GBS, NIND, and healthy controls. These results suggest that CSF UA may be related to the pathogenesis of demyelination in patients with GBS and may be partially determined by serum UA and the impaired blood–nerve barrier.

Monitoring the Redox Status in Multiple Sclerosis

Worldwide, over 2.2 million people suffer from multiple sclerosis (MS), a multifactorial demyelinating disease of the central nervous system. MS is characterized by a wide range of motor, autonomic, and psychobehavioral symptoms, including depression, anxiety, and dementia. The blood, cerebrospinal fluid, and postmortem brain samples of MS patients provide evidence on the disturbance of reduction-oxidation (redox) homeostasis, such as the alterations of oxidative and antioxidative enzyme activities and the presence of degradation products. This review article discusses the components of redox homeostasis, including reactive chemical species, oxidative enzymes, antioxidative enzymes, and degradation products. The reactive chemical species cover frequently discussed reactive oxygen/nitrogen species, infrequently featured reactive chemicals such as sulfur, carbonyl, halogen, selenium, and nucleophilic species that potentially act as reductive, as well as pro-oxidative stressors. The antioxidative enzyme systems cover the nuclear factor erythroid-2-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1 (KEAP1) signaling pathway. The NRF2 and other transcriptional factors potentially become a biomarker sensitive to the initial phase of oxidative stress. Altered components of the redox homeostasis in MS were discussed in search of a diagnostic, prognostic, predictive, and/or therapeutic biomarker. Finally, monitoring the battery of reactive chemical species, oxidative enzymes, antioxidative enzymes, and degradation products helps to evaluate the redox status of MS patients to expedite the building of personalized treatment plans for the sake of a better quality of life.

Nanocarriers for effective nutraceutical delivery to the brain

Neurodegenerative disorders are common among aging populations around the globe. Most are characterized by loss of neurons, protein aggregates, oxidative stress, mitochondrial damage, neuroinflammation among others. Although symptomatic treatment using conventional pharmacotherapy has been widely employed, their therapeutic success is limited due to varied reasons. In the need to identify an alternative approach, researchers successfully demonstrated the therapeutic utility of plant-derived nutraceuticals in cell and animal models of neurodegenerative conditions. However, most nutraceuticals failed during clinical trials in humans owing to their poor bioavailability in vivo and limited permeability across the blood brain barrier (BBB). The current emphasis is therefore on the improved delivery of nutraceuticals to the brain. In this regard, development of nanoparticle conjugated nutraceuticals to enhance bioavailability and therapeutic efficacy in the brain has gained attention. Here, we review the research advances in nanoparticles conjugated nutraceuticals applied in neurodegenerative disorders and discuss their advantages and limitations, clinical trials and toxicity concerns.

Oxidative Stress Marker Aberrations in Multiple Sclerosis: A Meta-Analysis Study

Oxidative stress has been suggested to play a key role in multiple sclerosis (MS), but clinical data on oxidative stress markers in MS patients were inconsistent. This study sought to quantitatively summarize the data of oxidative stress markers in the blood and cerebrospinal fluid (CSF) of patients with MS in the literature. We conducted a systematic search of PubMed and Web of Science and included studies if they provided data on the concentrations of oxidative stress markers in the peripheral blood and CSF of MS patients and healthy control (HC) subjects. The systematic search resulted in the inclusion of 31 studies with 2,001 MS patients and 2,212 HC subjects for meta-analysis. Random-effects meta-analysis demonstrated that patients with MS had significantly increased concentrations of blood oxidative stress markers compared with HC subjects for malondialdehyde (MDA; Hedges' g, 2.252; 95% CI, 1.080 to 3.424; p < 0.001) and lipid hydroperoxide by tert-butyl hydroperoxide-initiated chemiluminescence (CL-LOOH; Hedges' g, 0.383; 95% CI, 0.065 to 0.702; p = 0.018). In contrast, concentrations of albumin (Hedges' g, −1.036; CI, −1.679 to −0.394; p = 0.002) were significantly decreased in MS patients when compared with those in HC subjects. However, the other analyzed blood oxidative stress markers did not show significant differences between cases and controls. Furthermore, this meta-analysis showed significant association between CSF MDA and MS (Hedges' g, 3.275; 95% CI, 0.859 to 5.691; p = 0.008). Taken together, our results revealed increased blood and CSF MDA and decreased blood albumin levels in patients with MS, strengthening the clinical evidence of increased oxidative stress in MS.

Nutraceuticals in Neurological Disorders

Neurological diseases are one of the major healthcare issues worldwide. Posed lifestyle changes are associated with drastically increased risk of chronic illness and diseases, posing a substantial healthcare and financial burden to society globally. Researchers aim to provide fine treatment for ailing disorders with minimal exposed side effects. In recent decades, several studies on functional foods have been initiated to obtain foods that have fewer side effects and increased therapeutic activity. Hence, an attempt has been made to unravel several extraction techniques to acquire essential bioactive compounds or phytochemicals from therapeutically active food products. This has led to the conception of the term functional foods being meddled with other similar terms like "pharmafoods," "medifoods", "vitafoods", or "medicinal foods". With a dire need to adhere towards healthy options, the demand of nutraceuticals is widely increasing to combat neurological interventions. An association between food habits and the individual lifestyle with neurodegeneration has been manifested, thereby proposing the role of nutraceuticals as prophylactic treatment for neurological interventions. The current review covers some of the major neurological disorders and nutraceutical therapy in the prevention of disease.

Immunomodulatory and anti-oxidative effect of the direct TRPV1 receptor agonist capsaicin on Schwann cells

Background

Only few studies describe the impact of nutritive factors on chronic inflammatory demyelinating polyneuropathy (CIDP), an inflammatory disease of the peripheral nervous system. The active component of chili pepper, capsaicin, is the direct agonist of the transient receptor potential channel vanilloid subfamily member 1. Its anti-inflammatory effect in the animal model experimental autoimmune neuritis (EAN) has been previously demonstrated.

Methods

In the present study, we describe the anti-inflammatory and anti-oxidative influence of capsaicin on Schwann cells (SCs) in an in vitro setting. Hereby, we analyze the effect of capsaicin on Schwann cells’ gene expression pattern, major histocompatibility complex class II (MHC-II) presentation, and H₂O₂-induced oxidative stress. Furthermore, the effect of capsaicin on myelination was examined in a SC-dorsal root ganglia (DRG) coculture by myelin basic protein staining. Finally, in order to investigate the isolated effect of capsaicin on SCs in EAN pathology, we transplant naïve and capsaicin pre-treated SCs intrathecally in EAN immunized rats and analyzed clinical presentation, electrophysiological parameters, and cytokine expression in the sciatic nerve.

Results

In SC monoculture, incubation with capsaicin significantly reduces interferon gamma-induced MHC-II production as well as toll-like receptor 4 and intercellular adhesion molecule 1 mRNA expression. Calcitonin gene-related peptide mRNA production is significantly upregulated after capsaicin treatment. Capsaicin reduces H₂O₂-induced oxidative stress in SC in a preventive, but not therapeutic setting. In a SC-DRG coculture, capsaicin does not affect myelination rate. After intrathecal transplantation of naïve and capsaicin pre-treated SCs in EAN-immunized rats, naïve, but not capsaicin pre-treated intrathecal SCs, ameliorated EAN pathology in rats.

Conclusions

In conclusion, we were able to demonstrate a direct immunomodulatory and anti-oxidative effect of capsaicin in a SC culture by reduced antigen presentation and expression of an anti-inflammatory profile. Furthermore, capsaicin increases the resistance of SCs against oxidative stress. A primary effect of capsaicin on myelination was not proven. These results are in concordance with previous data showing an anti-inflammatory effect of capsaicin, which might be highly relevant for CIDP patients.

Early predictors of functional disability in Guillain-Barré Syndrome

This study investigated the predictors of prognosis at admission and after the first month in Guillain-Barré syndrome (GBS) patients. This retrospective study used the electronic records of 81 GBS patients. Age, gender, previous GBS history, antecedent febrile illness and presence of cranial nerve dysfunction were recorded. Detailed neurological examinations, routine biochemical and haematological investigations, cerebrospinal fluid (CSF) analysis and electrophysiological studies, GBS subtypes and treatments were assessed. Hughes disability scores (HDSs) were evaluated at the end of the first day and first month. The GBS patient group included 44 male (54.3%) and 37 female (45.7%) patients. The mean age was 52.2 ± 18.5. The mean HDS score was 2.96 at admission and 1.94 at the end of the first month. Plasma sodium, albumin, and CSF protein levels were significantly correlated with low admission HDS scores (p = 0.03, p  = 0.011, p  = 0.036, and p  < 0.001, respectively). Age, plasma sodium, albumin, neutrophil, neutrophil/lymphocyte ratio (NLR) levels, C-reactive protein (CRP) and CSF protein levels were significantly correlated with poor prognosis at the end of the first month (p < 0.05). Concomitant cranial nerve palsies were significantly correlated with low HDS scores (p = 0.011, p = 0.02) but antecedent events were not correlated with functional disability (p = 0.686, p = 0.413). Decreased albumin and sodium levels and increased CSF protein levels indicated poor GBS prognosis. Higher age, elevated NLR, and higher CRP levels indicated worse prognosis at the end of the first month. However, further studies are needed.

Oxidative Stress Related to Iron Metabolism in Relapsing Remitting Multiple Sclerosis Patients With Low Disability

Oxidative status may play a role in chronic inflammation and neurodegeneration which are considered critical etiopathogenetic factors in Multiple Sclerosis (MS), both in the early phase of the disease and in the progressive one. The aim of this study is to explore oxidative status related to iron metabolism in peripheral blood of stable Relapsing-Remitting MS with low disability. We studied 60 Relapsing-Remitting MS patients (age 37.2 ± 9.06, EDSS median 1.0), and 40 healthy controls (age 40.3 ± 10.86). We measured total hydroperoxides (dROMs test) and Total Antioxidant Status (TAS), along with the iron metabolism biomarkers: Iron (Fe), ferritin (Ferr), transferrin (Tf), transferrin saturation (Tfsat), and ceruloplasmin (Cp) panel biomarkers [concentration (iCp) and enzymatic activity (eCp), copper (Cu), ceruloplasmin specific activity (eCp:iCp), copper to ceruloplasmin ratio (Cu:Cp), non-ceruloplasmin copper (nCp-Cu)]. We computed also the Cp:Tf ratio as an index of oxidative stress related to iron metabolism. We found lower TAS levels in MS patients than in healthy controls (CTRL) and normal reference level and higher dROMs and Cp:Tf ratio in MS than in healthy controls. Cp and Cu were higher in MS while biomarkers of iron metabolism were not different between patients and controls. Both in controls and MS, dROMs correlated with iCp (CTRL r = 0.821, p < 0.001; MS r = 0.775 p < 0.001) and eCp (CTRL r = 0.734, p < 0.001; MS r = 0.820 p < 0.001). Moreover, only in MS group iCp correlated negatively with Tfsat (r = -0.257, p = 0.047). Dividing MS patients in “untreated” group and “treated” group, we found a significant difference in Fe values [F(2, 97) = 10.136, p < 0.001]; in particular “MS untreated” showed higher mean values (mean = 114.5, SD = 39.37 μg/dL) than CTRL (mean 78.6, SD = 27.55 μg/dL p = 0.001) and “MS treated” (mean = 72.4, SD = 38.08 μg/dL; p < 0.001). Moreover, “MS untreated” showed significantly higher values of Cp:Tf (mean = 10.19, SD = 1.77^∗10^-2; p = 0.015), than CTRL (mean = 9.03, SD = 1.46 ^∗10^-2). These results suggest that chronic oxidative stress is relevant also in the remitting phase of the disease in patients with low disability and short disease duration. Therefore, treatment with antioxidants may be beneficial also in the early stage of the disease to preserve neuronal reserve.

Dynamic thiol-disulphide homeostasis in patients with Guillain-Barre Syndrome

OBJECTIVE

The aim of this study was to evaluate dynamic thiol-disulphide homeostasis as a novel oxidative stress parameter in patients with Guillain-Barre syndrome (GBS).

METHODS

A total of 130 participants were included in this study, 70 of whom were diagnosed with GBS. Total thiol (-SH+-S-S-) and native thiol (-SH) levels in serum were measured in all patients and healthy individuals. Amount of dynamic disulphide bond were calculated from these values. In the GBS patients, disability status was determined by the Hughes and Medical Research Center (MRC) sum scores at the time of admission and 3 months thereafter.

RESULTS

Total and native thiol levels were significantly lower in patients with GBS compared with healthy individuals. There was no statistically significant difference in the number of dynamic disulphide bonds between groups. There was a negative correlation between total thiol levels in patients with GBS and Hughes scores at month 3.

DISCUSSION

Oxidative stress is among the molecular changes underlying the pathogenesis of GBS. In this study, we have investigated the dynamic thiol-disulfide homeostasis in patients with epilepsy using a new method in the literature. Also, functional recovery in Guillain-Barré syndrome patients could be promoted by increasing antioxidant activity.

Salivary biomarkers for the diagnosis and monitoring of neurological diseases

Current research efforts on neurological diseases are focused on identifying novel disease biomarkers to aid in diagnosis, provide accurate prognostic information and monitor disease progression. With advances in detection and quantification methods in genomics, proteomics and metabolomics, saliva has emerged as a good source of samples for detection of disease biomarkers. Obtaining a sample of saliva offers multiple advantages over the currently tested biological fluids as it is a non-invasive, painless and simple procedure that does not require expert training or harbour undesirable side effects for the patients. Here, we review the existing literature on salivary biomarkers and examine their validity in diagnosing and monitoring neurodegenerative and neuropsychiatric disorders such as autism and Alzheimer's, Parkinson's and Huntington's disease. Based on the available research, amyloid beta peptide, tau protein, lactoferrin, alpha-synuclein, DJ-1 protein, chromogranin A, huntingtin protein, DNA methylation disruptions, and micro-RNA profiles provide display a reliable degree of consistency and validity as disease biomarkers.

Alterations of plasma concentrations of lipophilic antioxidants are associated with Guillain-Barre syndrome

BACKGROUND

Guillain-Barré syndrome (GBS) is an acute inflammatory polyneuropathy resulting in demyelination in peripheral nervous system. Myelin enriched in lipids is easily oxidized by reactive oxygen species during inflammation. Oxidative stress and lipophilic anti-oxidative capacities in GBS patients have not been fully explored. To evaluate the redox status of GBS patients, we measured malondialdehyde (MDA), myeloperoxidase (MPO), lipophilic antioxidants, and tocopherols concentrations in plasma from GBS patients and age-matched healthy controls.

RESULTS

Concentrations of γ-tocopherol and δ-tocopherol decreased significantly, and α-carotene significantly increased in GBS patients compared to healthy controls. However, no significant changes in MDA and MPO concentrations were detected. In GBS patients, the γ-tocopherol concentration correlated positively with concentrations of δ-tocopherol, α-tocopherol, lutein, Q10, and γ-CEHC, respectively. Similarly, the δ-tocopherol concentration correlated positively with γ-tocopherol, α-tocopherol, lutein, Q10, δ-CEHC, and γ-CEHC concentrations, respectively. The receiver operating characteristics curve analysis showed that γ-tocopherol may serve as a good predictor for GBS.

CONCLUSIONS

Diminished lipophilic antioxidant defense, mainly γ-tocopherol and δ-tocopherol, in GBS patients accounting for their lowered resistance to reactive oxygen species is probably associated with pathogenesis of GBS, and potentially useful for the development of therapeutic strategies.

Low serum levels of uric acid and albumin in patients with Guillain-Barre syndrome

Free radical toxicity due to poorly maintained cellular redox levels is crucial events that have been associated with the pathogenesis of Guillain-Barre syndrome (GBS) patients. Uric acid (UA) and albumin correlate with oxidative stress in some degree. We aimed to evaluate the relationship between GBS and serum levels of UA and albumin in the present study.The serum levels of UA and albumin were determined in 203 individuals including 88 patients with GBS and 153 healthy controls (HC).We found that serum levels of UA and albumin in patients with GBS were significantly lower than those in HC group. Besides, similar phenomenon was observed when the male and female subgroups were estimated, respectively. Additionally, we found that there is no statistic difference among subgroups of GBS regarding UA and albumin. The univariate analysis revealed that both the high UA and high albumin were protective factors for patients with GBS (odds ratio [OR] 0.140; 95% confidence interval [CI]: 0.074-0.264; P < .001 and OR 0.016; 95% CI: 0.006-0.038; P < .001, respectively). It was further confirmed by the multivariable logistic regression analysis after adjusting for other potential confounding factors (OR 0.168; 95% CI: 0.055-0.514; P = .002 and OR 0.027; 95% CI: 0.011-0.071; P < .001, respectively).In conclusion, we found that patients with GBS had significantly low serum UA and albumin levels. Moreover, we demonstrated that both the high UA and high albumin were protective factors for patients with GBS.

Anticonvulsant and Neuroprotective Activities of Phragmanthera austroarabica Extract in Pentylenetetrazole-Kindled Mice

Anticonvulsant and neuroprotective activity of Phragmanthera austroarabica extract were tested in pentylenetetrazole-kindled mice. All the chemical constituents of the plant extract were identified. Additionally, the extract was standardized and proved to contain total phenolic contents equal to 379.92 ± 1.32 mg gallic acid equivalents/g dry plant extract. Induction of kindling was achieved by repeated intraperitoneal administration of pentylenetetrazole (35 mg/kg) twice weekly. Male albino mice were given P. austroarabica extract (200, 400, or 800 mg/kg). The two higher doses (400 or 800 mg/kg) of the extract significantly caused notable reduction in seizure activity and hippocampal malondialdehyde level compared to pentylenetetrazole control group. The highest dose enhanced cortical GSH level and showed intact DNA in the laddering assay. Upon studying the neuroprotective effect, mice treated with the higher dose of the extract demonstrated an improvement in the percent of surviving neurons in the cortex and hippocampus. We concluded that P. austroarabica extract ameliorated seizure activity and protected cortical and hippocampal neurons against pentylenetetrazole-induced kindling in mice.

Thyroid hormone level is associated with the frequency and severity of acute transverse myelitis

Acute transverse myelitis (ATM) is a progressive and autoimmune disease with inflammatory cell infiltrates into the spinal cord, and thyroid hormone (TH) level is associated with the oxidative and antioxidant status. Variations in oxidative stress and antioxidant levels are related to the pathogenesis of autoimmune and inflammatory diseases. Our study aimed to investigate the possible correlation between ATM and TH levels of thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), and FT4/FT3. We measured serum concentrations of TSH, FT4, and FT3 in 205 individuals, including 42 ATM patients, 49 multiple sclerosis patients, and 114 healthy controls. Our findings show that ATM patients had lower levels of TSH and FT3 and higher levels of FT4 and FT4/FT3 compared with healthy controls, whether male or female. Moreover, levels of TSH and FT3 in patients with ATM were inversely correlated with disease severity measured by the Expanded Disability Status Scale. Variations in TH level may represent the oxidative status and are surrogate biomarkers of the incidence and severity of ATM.

Excitotoxins, Mitochondrial and Redox Disturbances in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). There is increasing evidence that MS is not only characterized by immune mediated inflammatory reactions, but also by neurodegenerative processes. There is cumulating evidence that neurodegenerative processes, for example mitochondrial dysfunction, oxidative stress, and glutamate (Glu) excitotoxicity, seem to play an important role in the pathogenesis of MS. The alteration of mitochondrial homeostasis leads to the formation of excitotoxins and redox disturbances. Mitochondrial dysfunction (energy disposal failure, apoptosis, etc.), redox disturbances (oxidative stress and enhanced reactive oxygen and nitrogen species production), and excitotoxicity (Glu mediated toxicity) may play an important role in the progression of the disease, causing axonal and neuronal damage. This review focuses on the mechanisms of mitochondrial dysfunction (including mitochondrial DNA (mtDNA) defects and mitochondrial structural/functional changes), oxidative stress (including reactive oxygen and nitric species), and excitotoxicity that are involved in MS and also discusses the potential targets and tools for therapeutic approaches in the future.

Thyroid hormone level is associated with the frequency and severity of Guillain-Barré syndrome

OBJECTIVE

Guillain-Barré syndrome (GBS) is a neurodegenerative and inflammatory demyelination disorder, and oxidative stress is concerned with the pathogenesis of the disease. Also, we found that thyroid hormone level is correlated to the oxidative and antioxidant status in previous studies. Our study was aimed to find the possible relationship between the frequency and severity of GBS and thyroid hormone levels.

MATERIALS AND METHODS

We measured serum levels of thyroid-stimulating hormone (TSH), free thyroxine (FT₄) and free triiodothyronine (FT₃) in 238 individuals, including 90 GBS, 44 multiple sclerosis and 104 healthy controls.

RESULTS

Our findings demonstrate that the patients with GBS had lower TSH and higher FT_4, FT₄/FT₃ than healthy controls in the normal range. Furthermore, it was also shown in our study that TSH levels in patients with GBS were correlated with disease severity measured by the Hughes Functional Grading Scale.

CONCLUSION

Lower TSH, higher FT₄ and FT₄/FT₃ stand for the oxidative status and are associated with the incidence and severity of GBS.

Assessment of Serum Nitrogen Species and Inflammatory Parameters in Relapsing-Remitting Multiple Sclerosis Patients Treated with Different Therapeutic Approaches

The role of nitric oxide and its reactive derivatives (NO _x ) is well known in the pathogenesis of multiple sclerosis, which is an inflammatory disease while NO _x seems to be important in coordinating inflammatory response. The purpose of the present study was to assess serum NO _x as one of the nitrogen species and inflammatory parameters in relapsing-remitting multiple sclerosis patients and to compare the effectiveness of various types of disease-modifying therapies that reduce nitric oxide and inflammatory biomarkers. Elevated NO _x level was observed in patients who received the first-line disease-modifying therapy (interferons beta-1a and beta-1b) in comparison with the subjects treated with the second-line disease-modifying therapy (natalizumab; fingolimod) and healthy controls without significant differences in C-reactive protein and interleukin-1 beta. A negative correlation was observed between serum NO _x level and the duration of multiple sclerosis confirmed in the whole study population and in subjects treated with the first-line agents. Only serum NO _x , concentration could reveal a potential efficacy of disease-modifying therapy with a better reduction in NO _x level due to the second-line agents of disease-modifying therapy.

Oxidative stress-related biomarkers in multiple sclerosis: a review

AIM

To provide an up-to-date review of oxidative stress biomarkers in multiple sclerosis and thus identify candidate molecules with greatest promise as biomarkers of diagnosis, disease activity or prognosis.

METHOD

A semi-systematic literature search using PubMed and other databases.

RESULTS

Nitric oxide metabolites, superoxide dismutase, catalase, glutathione reductase, inducible nitric oxide synthase, protein carbonyl, 3-nitrotyrosine, isoprostanes, malondialdehyde and products of DNA oxidation have been identified across multiple studies as having promise as diagnostic, therapeutic or prognostic markers in MS.

CONCLUSION

Heterogeneity of study design, particularly patient selection, limits comparability across studies. Further cohort studies are needed, and we would recommend promising markers be incorporated into future clinical trials to prospectively validate their potential.

Effect of natalizumab on oxidative damage biomarkers in relapsing-remitting multiple sclerosis

BACKGROUND

Natalizumab is a monoclonal antibody used to treat multiple sclerosis. This study sought to determine whether the protective action of natalizumab involved a reduction in oxidative damage.

METHODS

Twenty-two multiple sclerosis patients fulfilling the revised McDonald criteria were assigned to treatment with 300 mg natalizumab intravenously once monthly (infusion every 4 weeks) in accordance with Spanish guidelines. Carbonylated proteins, 8-hydroxy-2'-deoxyguanosine, total glutathione, reduced glutathione, superoxide dismutase, glutathione peroxidase, and myeloperoxidase levels were measured at baseline and after 14 months' treatment, and the antioxidant gap was calculated.

RESULTS

Natalizumab prompted a drop in oxidative-damage biomarker levels, together with a reduction both in myeloperoxidase levels and in the myeloperoxidase/neutrophil granulocyte ratio. Interestingly, natalizumab induced nuclear translocation of Nrf2 and a fall in serum vascular cell adhesion molecule-1 levels.

CONCLUSION

These findings suggest that natalizumab has a beneficial effect on oxidative damage found in MS patients.

NQO1 gene rs1800566 variant is not associated with risk for multiple sclerosis

BACKGROUND

A possible role of oxidative stress in the pathogenesis of multiple sclerosis (MS) and in experimental autoimmune encephalomyelitis has been suggested. The detoxification enzyme NAD(P)H dehydrogenase, quinone 1 (NQO1) has been found up-regulated in MS lesions. A previous report described an association between the SNP rs1800566 in the NQO1 gene and the risk for MS in the Greek population. The aim of this study was to replicate a possible influence of the. SNP rs1800566 in the NQO1 gene in the risk for MS in the Spanish Caucasian population.

METHODS

We analyzed allelic and genotypic frequency of NQO1 rs1800566 in 290 patients with MS and 310 healthy controls, using TaqMan Assays.

RESULTS

NQO1 rs1800566 allelic and genotypic frequencies did not differ significantly between MS patients and controls, and were unrelated with age of onset of MS, gender, and clinical type of MS.

CONCLUSIONS

Our results indicate that NQO1 rs1800566 does not have an effect on MS disease risk.

Oxidative stress is differentially present in multiple sclerosis courses, early evident, and unrelated to treatment

BACKGROUND

Oxidative stress is well documented in multiple sclerosis (MS) lesions, but its correspondence at peripheral level is still controversial. Objective. To evaluate peripheral oxidative stress markers in MS patients.

METHODS

We studied total blood levels of Coenzyme Q10 (CoQ10), oxidized and reduced forms of glutathione, malondialdehyde, reactive oxygen species (ROS), anti-oxidized-low-density lipoproteins (anti-oxLDL) antibodies, and antioxidant power (PAO) in 87 patients with different MS clinical phenotypes and in 77 controls.

RESULTS

CoQ10 was lower whereas anti-oxLDL antibodies titer was higher in MS patients than in controls. The benign variant of MS displayed both higher CoQ10 and higher anti-oxLDL than other MS clinical variants. Female patients had lower CoQ10 and PAO and higher ROS than male patients. Differences were greater in younger patients with shorter disease duration. Surprisingly, there was no difference for these markers between treated and untreated patients.

CONCLUSION

We found lower antioxidant agents and higher anti-oxLDL antibodies in MS, and the highest antibody titers occurred in the benign form. We suggest that natural anti-oxLDL antibodies can be protective against MS, saving blood brain barrier integrity. Our findings also suggest that milder MS is associated with a distinct oxidative stress pattern, which may provide a useful biomarker of disease prognosis.

Improved neuroprotective effects by combining Bacopa monnieri and Rosmarinus officinalis supercritical CO2 extracts

Ethnobotanical evidence suggests that herbs such as brahmi (Bacopa monnieri) and rosemary (Rosmarinus officinalis) may possess antioxidant and neuroprotective properties. We compared the antioxidant and neuroprotective effects of supercritical extract of Bacopa monnieri and rosemary antioxidant extract obtained from Rosmarinus officinalis as well as their combination to examine the effects on human glial (U-87 MG) and embryonic mouse hypothalamus cells. Bacopa monnieri extract, rosemary antioxidant extract, and their combination (1:1) are not cytotoxic in both glial and embryonic mouse hypothalamus cell lines up to 200 μg/mL concentration. The combination of extracts of Bacopa monnieri + rosemary antioxidant has better antioxidant potential and antilipid peroxidation activity than either agent alone. Although the extract of Bacopa monnieri + rosemary antioxidant showed almost similar inhibition of phospho tau expression as Bacopa monnieri or rosemary antioxidant extract alone, the combination has better inhibitory effect on amyloid precursor protein synthesis and higher brain-derived neurotrophic factor production in hypothalamus cells than single agents. These results suggest that the extract of Bacopa monnieri + rosemary antioxidant is more neuroprotective than Bacopa monnieri or rosemary antioxidant extract.

Multiple sclerosis: molecular mechanisms and therapeutic opportunities

The pathophysiology of multiple sclerosis (MS) involves several components: redox, inflammatory/autoimmune, vascular, and neurodegenerative. All of them are supported by the intertwined lines of evidence, and none of them should be written off. However, the exact mechanisms of MS initiation, its development, and progression are still elusive, despite the impressive pace by which the data on MS are accumulating. In this review, we will try to integrate the current facts and concepts, focusing on the role of redox changes and various reactive species in MS. Knowing the schedule of initial changes in pathogenic factors and the key turning points, as well as understanding the redox processes involved in MS pathogenesis is the way to enable MS prevention, early treatment, and the development of therapies that target specific pathophysiological components of the heterogeneous mechanisms of MS, which could alleviate the symptoms and hopefully stop MS. Pertinent to this, we will outline (i) redox processes involved in MS initiation; (ii) the role of reactive species in inflammation; (iii) prooxidative changes responsible for neurodegeneration; and (iv) the potential of antioxidative therapy.

Modulation of oxidative stress, apoptosis, and calcium entry in leukocytes of patients with multiple sclerosis by Hypericum perforatum

OBJECTIVES

Hypericum perfortarum (HP, St John's wort) is a modulator of Ca(2+) entry in neutrophils and it may modulate intracellular free Ca(2+) ([Ca(2+)]i) entry in leukocytes of patients with multiple sclerosis (MS). We investigated effects of HP on oxidative stress, apoptosis, and [Ca(2+)]i concentrations in serum and leukocytes of patients with MS.

METHODS

Neutrophils of nine newly diagnosed MS patients and nine healthy subjects within four subgroups were used in the study. The first group was a control; the second group was patients with MS. The neutrophils from patient group were incubated non-specific TRPM2 channel blocker (2-APB), voltage-gated calcium channel blockers, verapamil and diltiazem (V + D) with HP before N-formyl-L-methionyl-L-leucyl-L-phenylalanine stimulation, respectively.

RESULTS

Neutrophil and serum lipid peroxidation, neutrophil apoptosis and [Ca(2+)]i levels in patients with MS were higher than in control although their levels were decreased by HP, 2-APB, and V + D incubations. The modulator role of V + D in MS and MS + HP groups was higher than in the 2-APB group. Neutrophilic glutathione peroxidase (GSH-Px) and serum vitamin A and E concentrations were lower in the MS group than in control. However, the neutrophil GSH-Px activity was increased by HP incubation. The neutrophil reduced glutathione, serum vitamin C and β-carotene concentrations did not change in control and patients.

DISCUSSION

We observed that HP-induced protective effects on oxidative stress and [Ca(2+)]i concentrations by modulating transient receptor potential and voltage gated calcium channel in the patients with MS. Thus, it may provide useful treatment of neutrophil activity in the patients.

Redox processes in neurodegenerative disease involving reactive oxygen species

Much attention has been devoted to neurodegenerative diseases involving redox processes. This review comprises an update involving redox processes reported in the considerable literature in recent years. The mechanism involves reactive oxygen species and oxidative stress, usually in the brain. There are many examples including Parkinson’s, Huntington’s, Alzheimer’s, prions, Down’s syndrome, ataxia, multiple sclerosis, Creutzfeldt-Jacob disease, amyotrophic lateral sclerosis, schizophrenia, and Tardive Dyskinesia. Evidence indicates a protective role for antioxidants, which may have clinical implications. A multifaceted approach to mode of action appears reasonable.

Evaluation of serum oxidant/antioxidant balance in multiple sclerosis

The total oxidative status (TOS)/total anti-oxidative status (TAS) ratio can provide information on an individual's absolute oxidative stress index (OSI). We investigated the alterations in the oxidant-antioxidant balance by measuring the oxidant parameters OSI, TOS, and malondialdehyde (MDA) together with the antioxidant parameters such as TAS, and superoxide dismutase (SOD) in patients with relapsing remitting multiple sclerosis (MS). To our knowledge, this is the first study to evaluate OSI in patients with relapsing remitting MS. 35 ambulatory patients with relapsing-remitting MS (35.8 ± 8.7 years) and 32 age- and activity-matched healthy control subjects (35.1 ± 3.7 years) that participated in the study. Serum TAS and TOS levels were determined using new automated methods. MS patients had higher concentrations of MDA (151.5 ± 51.1 vs. 111.3 ± 27.4 nmol/g protein, respectively; p < 0.001), TOS (148.1 ± 162.5 vs. 48.3 ± 46.4 mmol H(2)O(2) Equiv./g protein, respectively; p = 0.002), OSI (21124 ± 32543 vs. 5294 ± 5562, respectively; p = 0.008), and SOD (4.5 ± 0.7 vs. 3.4 ± 0.6 U/L, respectively; p < 0.001) compared with healthy controls. On the other hand, MS patients had lower concentrations of NO (12.3 ± 6.9 vs. 17.4 ± 2.5 μmol/g protein, respectively; p < 0.001) and TAS (0.82 ± 0.27 vs. 0.26 ± 0.15, respectively; p = 0.011) compared with healthy controls. In conclusion, these findings indicate that the oxidative stress plays an important role in the pathogenesis of MS.

Peripheral oxidative stress in relapsing-remitting multiple sclerosis

OBJECTIVES

To evaluate levels of oxidative stress in blood samples in patients with relapsing-remitting MS (RR-MS).

DESIGN AND METHODS

Peripheral blood samples were collected from 24 RR-MS patients and 15 healthy controls. Levels of the following were measured: carbonylated proteins, 8-hydroxy-2'deoxyguanosine (8OHdG), total glutathione, reduced glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG ratio, superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GRd), glutathione-S-transferase (GST), myeloperoxidase (MPO), antioxidant gap, total antioxidant capacity (PAO), global oxidative stress (GOS), serum vascular cell adhesion molecule-1 (sVCAM-1) and serum inter-cellular adhesion molecule 1 (sICAM-1).

RESULTS

Values for carbonylated proteins, 8OHdG, total glutathione, GSH, GSH/GSSG ratio, SOD, GRd and GOS were significantly higher in RR-MS patients than in healthy controls. By contrast, PAO, GSSG, GPx and GST were lower in RR-MS patients.

CONCLUSION

Oxidative stress plays a major role in MS, and is observed prior to relapse.

Effects of alcohol consumption on biomarkers of oxidative damage to DNA and lipids in ethanol-fed pigs

Chronic alcohol consumption is known to result in tissue injury, particularly in the liver, and is considered a major risk factor for cancers of the upper respiratory tract. Here we assessed the oxidative effects of subchronic ethanol consumption on DNA and lipids by measuring biomarkers 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and malondialdehyde (MDA), respectively. Physiological responses of pigs (n = 4) administered ethanol in drinking water for 39 days were compared with those of water-fed pigs (n = 4). Alcoholisation resulted in serum ethanol concentration of 1.90 g L(-1) and in a moderate but significant increase in alanine aminotransferase activity, an index of liver injury. However, between the alcoholised and control groups there were no significant differences in the levels of 8-oxodG (8-oxodG per 10(6) 2'deoxyguanosine) from leucocytes (2.52 ± 0.42 Vs 2.39 ± 0.34) or from target organs, liver, cardia and oesophagus. Serum MDA levels were also similar in ethanol-fed pigs (0.33 ± 0.04 μM) and controls (0.28 ± 0.03 μM). Interestingly, levels of 8-oxodG in cardia were positively correlated with those in oesophagus (Spearman correlation coefficient R = 1, P < 0.0001). Our results suggest that alcohol consumption may not cause oxidative damage to DNA and lipids as measured by 8-oxodG and MDA, respectively. The duration of alcoholisation and the potential alcohol-induced nutritional deficiency may be critical determinants of ethanol toxicity. Relevant biomarkers, such as factors involved in sensitization to ethanol-induced oxidative stress are required to better elucidate the relationship between alcohol consumption, oxidative stress and carcinogenesis.

Nutraceutical antioxidants as novel neuroprotective agents

A variety of antioxidant compounds derived from natural products (nutraceuticals) have demonstrated neuroprotective activity in either in vitro or in vivo models of neuronal cell death or neurodegeneration, respectively. These natural antioxidants fall into several distinct groups based on their chemical structures: (1) flavonoid polyphenols like epigallocatechin 3-gallate (EGCG) from green tea and quercetin from apples; (2) non-flavonoid polyphenols such as curcumin from tumeric and resveratrol from grapes; (3) phenolic acids or phenolic diterpenes such as rosmarinic acid or carnosic acid, respectively, both from rosemary; and (4) organosulfur compounds including the isothiocyanate, L-sulforaphane, from broccoli and the thiosulfonate allicin, from garlic. All of these compounds are generally considered to be antioxidants. They may be classified this way either because they directly scavenge free radicals or they indirectly increase endogenous cellular antioxidant defenses, for example, via activation of the nuclear factor erythroid-derived 2-related factor 2 (Nrf2) transcription factor pathway. Alternative mechanisms of action have also been suggested for the neuroprotective effects of these compounds such as modulation of signal transduction cascades or effects on gene expression. Here, we review the literature pertaining to these various classes of nutraceutical antioxidants and discuss their potential therapeutic value in neurodegenerative diseases.