Antioxidants effectively prevent oxidation-induced protein damage in OLN 93 cells

Use of modified CUPRAC and dinitrophenylhydrazine colorimetric methods for simultaneous measurement of oxidative protein damage and antioxidant defense against oxidation

A modified CUPRAC (cupric reducing antioxidant capacity) method was developed for the simultaneous estimation of protein oxidation and counteracting antioxidant defense, and the results were compared with those of a modified 2,4-dinitrophenylhydrazine (DNPH) carbonyl assay. The alkaline carbonyl method was cleared off interferences by solvent extraction using a cationic surfactant. Both solution and Nafion membrane sensor CUPRAC methods were used to measure the oxidative hazard in protein solutions. Bovine serum albumin, fetal bovine serum and egg white were used as protein probes, exposed to oxidation by Fe(II)-induced Fenton reaction in the absence and presence of selected antioxidants (ascorbic acid, cysteine, gallic acid, glutathione, and N-acetyl cysteine). Protein probes were initially unreactive toward the CUPRAC and DNPH reagents, but produced colored products upon Fenton oxidation which were bleached by antioxidants, enabling an indirect measurement of antioxidant activity (AOA) by difference. Spearman's rank test for antioxidants demonstrated that there was a strong correlation (+0.7 to +0.9) between the modified CUPRAC and carbonyl assays. There was also a strong correlation between the results of the solution phase and optical sensing CUPRAC methods (R² > 0.95). As opposed to conventional antioxidant assays not using biologically relevant probes, this work utilizes protein probes for AOA assessment.

Simvastatin interferes with process outgrowth and branching of oligodendrocytes

Statins have attracted interest as a treatment option for multiple sclerosis (MS) because of their pleiotropic antiinflammatory and immunomodulatory effects. However, contradictory results have been described when they are applied to oligodendrocytes (OLGs), the cell type predominantly affected in MS. In this study we focus on the in vitro effect of statins on process outgrowth in OLN-93 cells, a well-characterized OLG-derived cell line, and primary cultures of neonatal rat OLGs. Application of the lipophilic simvastatin, as low as 0.1-1 μM, disturbs process formation of both cell types, leading to less ramified cells. We show that both protein isoprenylation and cholesterol synthesis are required for the normal differentiation of OLGs. It is further demonstrated that the expression of 2',3'-cyclic-nucleotide-3' phosphodiesterase (CNP) and tubulin is lowered, concomitant with a reduction of membrane-bound CNP as well as tubulin. Therefore, we propose that lack of isoprenylation of CNP could help to explain the altered morphological and biochemical differentiation state of treated OLGs. Moreover, expression of specific myelin markers, such as myelin basic protein, myelin-associated glycoprotein, and myelin oligodendrocyte glycoprotein, was compromised after treatment. We conclude that simvastatin treatment has detrimental effects on OLG process outgrowth, the prior step in (re)myelination, thereby mortgaging long-term healing of MS lesions.

Physicochemical characteristics, cytotoxicity, and antioxidant activity of three lipid nanoparticulate formulations of alpha-lipoic acid

Exogenously supplied alpha-lipoic acid (LA) has proven to be effective as an antioxidant. In an effort to develop a water-soluble formulation for topical administration, LA was formulated in the form of solid lipid nanoparticles (SLN), nanostructure lipid carriers (NLC), and nanoemulsion (NE) and characterized in terms of physical and biological properties. Mean particle size of 113, 110, and 121 nm were obtained for NE, NLC, and SLN, respectively, with narrow size distribution. Zeta potential was approximately in the range of -25 to -40 mV. Disc and spherical structures of nanoparticles were observed by cryo-scanning electron microscopy. Entrapment efficiency of LA in three formulations was found to be more than 70%. After 120 days of storage at 25 degrees C, physical stability of all formulations remained unchanged whereas the entrapment efficiency of SLN and NLC could be maintained, suggesting relative long-term stability. Prolonged release of LA formulation following the Higuchi model was found where a faster release was observed from NE compared with that of SLN and NLC. More than 80% of cell survivals were found up to 1 microM of LA concentrations. Antioxidant activity analysis demonstrated that all LA-loaded formulations expressed antioxidant activity at a similar magnitude as pure LA. These results suggest that chosen compositions of lipid nanoparticles play an important role on drug loading, stability, and biological activity of nanoparticles. Both SLN and NLC demonstrated their potential as alternative carriers for aqueous topical administration of LA.

Coenzyme Q10 in cardiovascular disease

In this review we summarise the current state of knowledge of the therapeutic efficacy and mechanisms of action of CoQ(10) in cardiovascular disease. Our conclusions are: 1. There is promising evidence of a beneficial effect of CoQ(10) when given alone or in addition to standard therapies in hypertension and in heart failure, but less extensive evidence in ischemic heart disease. 2. Large scale multi-centre prospective randomised trials are indicated in all these areas but there are difficulties in funding such trials. 3. Presently, due to the notable absence of clinically significant side effects and likely therapeutic benefit, CoQ(10) can be considered a safe adjunct to standard therapies in cardiovascular disease.

Paraquat-induced Oxidative Stress in Drosophila melanogaster: Effects of Melatonin, Glutathione, Serotonin, Minocycline, Lipoic Acid and Ascorbic Acid

The efficacy of melatonin, glutathione, serotonin, minocycline, lipoic acid and ascorbic acid in counteracting the toxicity of paraquat in Drosophila melanogaster was examined. Male Oregon wild strain flies were fed for 5 days with control food or food containing the test substance. They were transferred in groups of five to vials containing only filter paper soaked with 20 mM paraquat in 5% sucrose solution. Survival was determined 24 and 48 h later. All the substances assayed increased the survival of D. melanogaster. At equimolar concentrations (0.43 mM) melatonin was more effective than serotonin, lipoic acid and ascorbic acid. However, lower concentrations of glutathione (0.22 mM) and minocycline (0.05 mM) were as efficient as melatonin. The highest survival rate (38.6%) after 48 h of paraquat treatment was found with 2.15 mM of lipoic acid. No synergistic effect of melatonin with glutathione, serotonin, minocycline, lipoic acid and ascorbic acid was detected.

Effects of different types of oxidative stress in RPE cells

Oxidative damage to retinal pigmented epithelial (RPE) cells and photoreceptors has been implicated in the pathogenesis of age-related macular degeneration (AMD). In order to develop new treatments, it is necessary to characterize the antioxidant defense system in RPE cells to better define their vulnerabilities and how they can be remedied. In this study, we sought to investigate the effects of three different types of oxidative stress on cultured RPE cells. Carbonyl content in RPE cells increased with increasing concentrations of oxidants or increasing duration of exposure with high reproducibility, validating ELISA for carbonyl content as a valuable quantitative measure of oxidative damage. Compared to other cell types, RPE cells were able to survive exposure to H2O2 quite well and exposure to paraquat extremely well. Comparison of the total amount of oxidative damage at the IC50 for each type of stress showed a rank order of hyperoxia > paraquat > H2O2, and since these stressors primarily target different cellular compartments, it suggests that the endogenous defense system against oxidative damage in RPE cells protects well against damage to mitochondria and endoplasmic reticulum, and is less able to handle oxidative damage at the cell surface. Supplementation of media with ascorbic acid provided significant protection from H2O2-induced oxidative damage, but not that induced by paraquat or hyperoxia. Supplementation with docosahexaenoic acid or alpha-tocopherol significantly reduced oxidative damage from H2O2 or hyperoxia, but not that induced by paraquat. We conclude that exposure to different types of oxidative stress results in different patterns of accrual of oxidative damage to proteins in RPE cells, different patterns of loss of viability, and is differentially countered by antioxidants. This study suggests that multiple types of oxidant stress should be used to probe the vulnerabilities of the retina and RPE in vivo, and that ELISA for carbonyl content provides a valuable tool for quantitative assessment of oxidative damage for such studies.

Complement activation in diabetic ketoacidosis brains

The metabolic crisis of diabetic ketoacidosis (DKA) and its treatment can result in the life-threatening complication of clinical brain edema. However, there is limited information available regarding either the pathophysiology or histology of this acute complication. It has been reported that DKA and its treatment are associated with a systemic inflammatory response involving the activation of the complement cascade with increases of SC5b-9 serum level. We studied the brains of two patients, both of whom died as the result of DKA-related brain edema, for the presence of C5b-9, C1q and the expression of the CD59. Apoptosis was also evaluated by the TUNEL method. All regions of the brain demonstrated varying degrees of C5b-9 deposits on neurons, oligodendrocytes and blood vessels. C5b-9 was co-localized with C1q, suggesting the activation of classical pathway. No expression of CD59 was found on neurons, oligodendrocytes or blood vessels in DKA brain, but this complement inhibitor was present on these cells in the normal brain. Rarely, C5b-9 was co-localized with apoptotic neurons and OLG. Our data demonstrate that the metabolic crisis of DKA results in a loss of CD59 expression and assembly of C5b-9 on neurons and oligodendrocytes, suggesting that complement activation and C5b-9 may play a role in the pathophysiology of the brain edema of DKA.

Antioxidants and polyunsaturated fatty acids in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Oligodendrocyte damage and subsequent axonal demyelination is a hallmark of this disease. Different pathomechanisms, for example, immune-mediated inflammation, oxidative stress and excitotoxicity, are involved in the immunopathology of MS. The risk of developing MS is associated with increased dietary intake of saturated fatty acids. Polyunsaturated fatty acid (PUFA) and antioxidant deficiencies along with decreased cellular antioxidant defence mechanisms have been observed in MS patients. Furthermore, antioxidant and PUFA treatment in experimental allergic encephalomyelitis, an animal model of MS, decreased the clinical signs of disease. Low-molecular-weight antioxidants may support cellular antioxidant defences in various ways, including radical scavenging, interfering with gene transcription, protein expression, enzyme activity and by metal chelation. PUFAs may not only exert immunosuppressive actions through their incorporation in immune cells but also may affect cell function within the CNS. Both dietary antioxidants and PUFAs have the potential to diminish disease symptoms by targeting specific pathomechanisms and supporting recovery in MS.