Recycling and redox cycling of phenolic antioxidants

Cryopreservation of organoids: Strategies, innovation, and future prospects

Organoid technology has demonstrated unique advantages in multidisciplinary fields such as disease research, tumor drug sensitivity, clinical immunity, drug toxicology, and regenerative medicine. It will become the most promising research tool in translational research. However, the long preparation time of organoids and the lack of high-quality cryopreservation methods limit the further application of organoids. Although the high-quality cryopreservation of small-volume biological samples such as cells and embryos has been successfully achieved, the existing cryopreservation methods for organoids still face many bottlenecks. In recent years, with the development of materials science, cryobiology, and interdisciplinary research, many new materials and methods have been applied to cryopreservation. Several new cryopreservation methods have emerged, such as cryoprotectants (CPAs) of natural origin, ice-controlled biomaterials, and rapid rewarming methods. The introduction of these technologies has expanded the research scope of cryopreservation of organoids, provided new approaches and methods for cryopreservation of organoids, and is expected to break through the current technical bottleneck of cryopreservation of organoids. This paper reviews the progress of cryopreservation of organoids in recent years from three aspects: damage factors of cryopreservation of organoids, new protective agents and loading methods, and new technologies of cryopreservation and rewarming.

Vitamin E/Coenzyme Q-Dependent "Free Radical Reductases": Redox Regulators in Ferroptosis

Significance: Lipid peroxidation and its products, oxygenated polyunsaturated lipids, act as essential signals coordinating metabolism and physiology and can be deleterious to membranes when they accumulate in excessive amounts. Recent Advances: There is an emerging understanding that regulation of polyunsaturated fatty acid (PUFA) phospholipid peroxidation, particularly of PUFA-phosphatidylethanolamine, is important in a newly discovered type of regulated cell death, ferroptosis. Among the most recently described regulatory mechanisms is the ferroptosis suppressor protein, which controls the peroxidation process due to its ability to reduce coenzyme Q (CoQ). Critical Issues: In this study, we reviewed the most recent data in the context of the concept of free radical reductases formulated in the 1980-1990s and focused on enzymatic mechanisms of CoQ reduction in different membranes (e.g., mitochondrial, endoplasmic reticulum, and plasma membrane electron transporters) as well as TCA cycle components and cytosolic reductases capable of recycling the high antioxidant efficiency of the CoQ/vitamin E system. Future Directions: We highlight the importance of individual components of the free radical reductase network in regulating the ferroptotic program and defining the sensitivity/tolerance of cells to ferroptotic death. Complete deciphering of the interactive complexity of this system may be important for designing effective antiferroptotic modalities. Antioxid. Redox Signal. 40, 317-328.

Associations of dietary oxidative balance score with femur osteoporosis in postmenopausal women: data from the National Health and Nutrition Examination Survey

We used data from the NHANES to explore associations of DOBS with femur BMD and osteoporosis in postmenopausal women. We found that DOBS was positively associated with femur BMD and negatively associated with the risk of osteoporosis in postmenopausal women.

PURPOSE

The study aimed to investigate the relationship between dietary oxidative balance score (DOBS) and the risk of osteoporosis in American postmenopausal women.

METHODS

A total of 3043 participants were included in this study. The linear relationship between DOBS and femur BMD was evaluated using a weighted multivariate linear regression model. The association between DOBS and the risk of osteoporosis was assessed using a weighted logistic regression model, with odds ratios (ORs) and 95% confidence intervals (CIs) calculated. Moreover, the relationship was further characterized through smooth curve fitting (SCF) and weighted generalized additive model (GAM) analysis.

RESULTS

After adjusting for all covariates, the weighted multivariable linear regression models showed a positive correlation between DOBS and femur BMD. Moreover, the weighted logistic regression model demonstrated that compared to the first tertile of DOBS, the highest tertile of DOBS was significantly associated with a lower risk of osteoporosis, with ORs of 0.418 (95% CI, 0.334, 0.522) for individuals under the age of 70 and 0.632 (95% CI, 0.506, 0.790) for individuals aged 70 or above. Similar trends were also observed in SCF and GAM models.

CONCLUSION

The present study indicated that postmenopausal women with a higher DOBS have a lower risk of femur osteoporosis. This finding may highlight the potential protective role of an antioxidant-rich diet for the bones of the postmenopausal population. Moreover, DOBS may also be a valuable tool in identifying individuals with osteoporosis. Screening and early intervention for osteoporosis may be essential for postmenopausal women with low DOBS.

Higher oxidative balance scores are associated with lower nonalcoholic fatty liver disease and not with fibrosis in US adults

BACKGROUND AND AIMS

Little research have focused on the relationship between systemic oxidative stress status and NAFLD and fibrosis. The Oxidative Balance Score (OBS) is employed to evaluate whole-body lifestyle and diet exposures related to oxidative stress, with higher OBS scores implying exposure to more antioxidants. This study aimed to explore whether OBS is correlated with NAFLD and NAFLD-related fibrosis.

METHODS AND RESULTS

12,223 participants from NHANES 2003-2018 were enrolled in this study. NAFLD was defined as USFLI ≥30 and liver fibrosis was determined as FIB-4 ≥ 2.67. OBS was scored by 20 lifestyle and dietary factors. Weighted logistic regression and restricted cubic splines were used to assess the association between OBS and NAFLD and fibrosis. The prevalence of NAFLD was 29.67%. There was a significant negative correlation between OBS, dietary OBS, lifestyle OBS and NAFLD and no correlation with NAFLD-related fibrosis. Compared to the lowest quartile, the adjusted ORs for the highest quartile of OBS, lifestyle OBS, dietary OBS and NAFLD were 0.55(95%CI:0.35,0.85), 0.12(95%CI:0.08,0.16), 0.70(95%CI:0.52,0.94) respectively. In stratified analyses, lifestyle OBS was negatively associated with NAFLD across gender, dietary OBS was only negatively correlated with NAFLD in men, and any OBS was not observed to be relevant to NAFLD-related fibrosis.

CONCLUSIONS

OBS was negatively associated with NAFLD, but not with NAFLD-related fibrosis. The findings underline the significance of adhering to an antioxidant lifestyle and diet, which can help prevent NAFLD but seems to be ineffective in preventing fibrosis in individuals with NAFLD.

Preservation of Fresh-Cut 'Maradol' Papaya with Polymeric Nanocapsules of Lemon Essential Oil or Curcumin

Papaya is one of the most consumed fruits in the world; however, tissue damage caused by cuts quickly leads to its decay. Therefore, this study aimed to prepare and characterize lemon oil and curcumin nanocapsules to evaluate their capacity for preserving fresh-cut papaya. Lemon essential oil and curcumin nanocapsules were prepared using ethyl cellulose (EC) and poly-(ε-caprolactone) (PCL) by the emulsification-diffusion method coupled with ultrasound. The particles had sizes smaller than 120 nm, with polydispersity indices below 0.25 and zeta potentials exceeding -12 mV, as confirmed by scanning electron microscopy. The nanoparticles remained stable for 27 days, with sedimentation being the instability mechanism observed. These nanoparticles were employed to coat fresh-cut papaya, which was stored for 17 days. The results demonstrated their remarkable efficacy in reducing the respiration rate. Furthermore, nanocapsules maintained the pH and acidity levels of the papayas for an extended period. The lemon oil/EC nanocapsule treatment retained the color better. Additionally, all systems exhibited the ability to minimize texture loss associated with reduced pectin methylesterase activity. Finally, the nanocapsules showed a notable reduction in polyphenol oxidase activity correlating with preserving total phenolic compounds in the fruit. Therefore, the lemon oil and curcumin nanoparticles formed using EC and PCL demonstrated their effectiveness in preserving fresh-cut 'Maradol' papaya.

Micronutrient optimization for tissue engineered articular cartilage production of type II collagen

Tissue Engineering of cartilage has been hampered by the inability of engineered tissue to express native levels of type II collagen in vitro. Inadequate levels of type II collagen are, in part, due to a failure to recapitulate the physiological environment in culture. In this study, we engineered primary rabbit chondrocytes to express a secreted reporter, Gaussia Luciferase, driven by the type II collagen promoter, and applied a Design of Experiments approach to assess chondrogenic differentiation in micronutrient-supplemented medium. Using a Response Surface Model, 240 combinations of micronutrients absent in standard chondrogenic differentiation medium, were screened and assessed for type II collagen promoter-driven Gaussia luciferase expression. While the target of this study was to establish a combination of all micronutrients, alpha-linolenic acid, copper, cobalt, chromium, manganese, molybdenum, vitamins A, E, D and B7 were all found to have a significant effect on type II collagen promoter activity. Five conditions containing all micronutrients predicted to produce the greatest luciferase expression were selected for further study. Validation of these conditions in 3D aggregates identified an optimal condition for type II collagen promoter activity. Engineered cartilage grown in this condition, showed a 170% increase in type II collagen expression (Day 22 Luminescence) and in Young's tensile modulus compared to engineered cartilage in basal media alone.Collagen cross-linking analysis confirmed formation of type II-type II collagen and type II-type IX collagen cross-linked heteropolymeric fibrils, characteristic of mature native cartilage. Combining a Design of Experiments approach and secreted reporter cells in 3D aggregate culture enabled a high-throughput platform that can be used to identify more optimal physiological culture parameters for chondrogenesis.

Hormone-linked redox status and its modulation by antioxidants

Hormones have been considered as key factors involved in the maintenance of the redox status of the body. We are making considerable progress in understanding interactions between the endocrine system, redox status, and oxidative stress with the dynamics of life, which encompasses fertilization, development, growth, aging, and various pathophysiological states. One of the reasons for changes in redox states of vertebrates leading to oxidative stress scenario is the disruption of the endocrine system. Comprehending the dynamics of hormonal status to redox state and oxidative stress in living systems is challenging. It is more difficult to come to a unifying conclusion when some hormones exhibit oxidant properties while others have antioxidant features. There is a very limited approach to correlate alteration in titers of hormones with redox status and oxidative stress with growth, development, aging, and pathophysiological stress. The situation is further complicated when considering various tissues and sexes in vertebrates. This chapter discusses the beneficial impacts of hormones with antioxidative properties, such as melatonin, glucagon, insulin, estrogens, and progesterone, which protect cells from oxidative damage and reduce pathophysiological effects. Additionally, we discuss the protective effects of antioxidants like vitamins A, E, and C, curcumin, tempol, N-acetyl cysteine, α-lipoic acid, date palm pollen extract, resveratrol, and flavonoids on oxidative stress triggered by hormones such as aldosterone, glucocorticoids, thyroid hormones, and catecholamines. Inflammation, pathophysiology, and the aging process can all be controlled by understanding how antioxidants and hormones operate together to maintain cellular redox status. Identifying the hormonal changes and the action of antioxidants may help in developing new therapeutic strategies for hormonal imbalance-related disorders.

Natural Antioxidant Evaluation: A Review of Detection Methods

Antioxidants have drawn the attention of the scientific community due to being related to the prevention of various degenerative diseases. The antioxidant capacity has been extensively studied in vitro, and different methods have been used to assess its activity. However, the main issues related to studying natural antioxidants are evaluating whether these antioxidants demonstrate a key role in the biological system and assessing their bioavailability in the organism. The majority of outcomes in the literature are controversial due to a lack of method standardization and their proper application. Therefore, this study aims to compile the main issues concerning the natural antioxidant field of study, comparing the most common in vitro methods to evaluate the antioxidant activity of natural compounds, demonstrating the antioxidant activity in biological systems and the role of the main antioxidant enzymes of redox cellular signaling and explaining how the bioavailability of bioactive compounds is evaluated in animal models and human clinical trials.

Association between the Oxidative Balance Score and Telomere Length from the National Health and Nutrition Examination Survey 1999-2002

Purpose. Leukocyte telomere length (LTL) is an important biomarker of aging. The oxidative balance score (OBS) is used to assess the oxidative stress-related exposures of diet and lifestyle. This study is aimed at exploring if the OBS was associated with LTL. Methods. 3220 adults were included in this study from the National Health and Nutrition Examination Survey (NHANES) 1999-2002. LTL was assayed from leukocyte DNA. Twenty dietary and lifestyle factors were selected to score the OBS. Survey-based multivariable linear regression was conducted to assess the association between the OBS and log-transformed LTL. Results. The association between the OBS and log-transformed LTL was positive in females but not males. For females, compared with the lowest OBS category as a reference, the multivariable-adjusted beta estimate (95% confidence interval, CI) for the highest OBS category was 0.0701 (0.0205–0.1197) ( $p$ for $\text{trend}<0.01$ ), and the multivariable-adjusted beta estimate (95% CI) of the continuous OBS was 0.0039 (0.0014–0.0065). There was also the gender difference in the correlations of the dietary OBS and the lifestyle OBS with log-transformed LTL. Conclusion. There was a positive association between the OBS and LTL in females. This result suggested that diet and lifestyle might affect LTL by regulating oxidative balance.

Oxidative Stress in the Brain: Basic Concepts and Treatment Strategies in Stroke

The production of free radicals is inevitably associated with metabolism and other enzymatic processes. Under physiological conditions, however, free radicals are effectively eliminated by numerous antioxidant mechanisms. Oxidative stress occurs due to an imbalance between the production and elimination of free radicals under pathological conditions. Oxidative stress is also associated with ageing. The brain is prone to oxidative damage because of its high metabolic activity and high vulnerability to ischemic damage. Oxidative stress, thus, plays a major role in the pathophysiology of both acute and chronic pathologies in the brain, such as stroke, traumatic brain injury or neurodegenerative diseases. The goal of this article is to summarize the basic concepts of oxidative stress and its significance in brain pathologies, as well as to discuss treatment strategies for dealing with oxidative stress in stroke.

Changes in Glutathione, Ascorbate, and Antioxidant Enzymes during Olive Fruit Ripening

The content of glutathione, ascorbate (ASC), and the enzymatic antioxidants, superoxide dismutase and catalase, and components of the ascorbate-glutathione cycle were investigated in the olive fruit (cv. Picual) selected at the green, turning, and mature ripening stages. The changes observed in total and reduced glutathione (GSH), oxidized glutathione (GSSG), the ratio GSH/GSSG, ASC, and antioxidant enzymes (mainly superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) indicate a shift to a moderate cellular oxidative status during ripening and suggest a role for antioxidants in the process. The antioxidant composition of olive oils obtained from the olive fruits of the study was investigated. A model is proposed for the recycling of antioxidant polyphenols mediated by endogenous molecular antioxidants in the olive fruit.

Redox phospholipidomics of enzymatically generated oxygenated phospholipids as specific signals of programmed cell death

High fidelity and effective adaptive changes of the cell and tissue metabolism to changing environments require strict coordination of numerous biological processes. Multicellular organisms developed sophisticated signaling systems of monitoring and responding to these different contexts. Among these systems, oxygenated lipids play a significant role realized via a variety of re-programming mechanisms. Some of them are enacted as a part of pro-survival pathways that eliminate harmful or unnecessary molecules or organelles by a variety of degradation/hydrolytic reactions or specialized autophageal processes. When these "partial" intracellular measures are insufficient, the programs of cells death are triggered with the aim to remove irreparably damaged members of the multicellular community. These regulated cell death mechanisms are believed to heavily rely on signaling by a highly diversified group of molecules, oxygenated phospholipids (PLox). Out of thousands of detectable individual PLox species, redox phospholipidomics deciphered several specific molecules that seem to be diagnostic of specialized death programs. Oxygenated cardiolipins (CLs) and phosphatidylethanolamines (PEs) have been identified as predictive biomarkers of apoptosis and ferroptosis, respectively. This has led to decoding of the enzymatic mechanisms of their formation involving mitochondrial oxidation of CLs by cytochrome c and endoplasmic reticulum-associated oxidation of PE by lipoxygenases. Understanding of the specific biochemical radical-mediated mechanisms of these oxidative reactions opens new avenues for the design and search of highly specific regulators of cell death programs. This review emphasizes the usefulness of such selective lipid peroxidation mechanisms in contrast to the concept of random poorly controlled free radical reactions as instruments of non-specific damage of cells and their membranes. Detailed analysis of two specific examples of phospholipid oxidative signaling in apoptosis and ferroptosis along with their molecular mechanisms and roles in reprogramming has been presented.

Redox Epiphospholipidome in Programmed Cell Death Signaling: Catalytic Mechanisms and Regulation

A huge diversification of phospholipids, forming the aqueous interfaces of all biomembranes, cannot be accommodated within a simple concept of their role as membrane building blocks. Indeed, a number of signaling functions of (phospho)lipid molecules has been discovered. Among these signaling lipids, a particular group of oxygenated polyunsaturated fatty acids (PUFA), so called lipid mediators, has been thoroughly investigated over several decades. This group includes oxygenated octadecanoids, eicosanoids, and docosanoids and includes several hundreds of individual species. Oxygenation of PUFA can occur when they are esterified into major classes of phospholipids. Initially, these events have been associated with non-specific oxidative injury of biomembranes. An alternative concept is that these post-synthetically oxidatively modified phospholipids and their adducts with proteins are a part of a redox epiphospholipidome that represents a rich and versatile language for intra- and inter-cellular communications. The redox epiphospholipidome may include hundreds of thousands of individual molecular species acting as meaningful biological signals. This review describes the signaling role of oxygenated phospholipids in programs of regulated cell death. Although phospholipid peroxidation has been associated with almost all known cell death programs, we chose to discuss enzymatic pathways activated during apoptosis and ferroptosis and leading to peroxidation of two phospholipid classes, cardiolipins (CLs) and phosphatidylethanolamines (PEs). This is based on the available LC-MS identification and quantitative information on the respective peroxidation products of CLs and PEs. We focused on molecular mechanisms through which two proteins, a mitochondrial hemoprotein cytochrome c (cyt c), and non-heme Fe lipoxygenase (LOX), change their catalytic properties to fulfill new functions of generating oxygenated CL and PE species. Given the high selectivity and specificity of CL and PE peroxidation we argue that enzymatic reactions catalyzed by cyt c/CL complexes and 15-lipoxygenase/phosphatidylethanolamine binding protein 1 (15LOX/PEBP1) complexes dominate, at least during the initiation stage of peroxidation, in apoptosis and ferroptosis. We contrast cell-autonomous nature of CLox signaling in apoptosis correlating with its anti-inflammatory functions vs. non-cell-autonomous ferroptotic signaling facilitating pro-inflammatory (necro-inflammatory) responses. Finally, we propose that small molecule mechanism-based regulators of enzymatic phospholipid peroxidation may lead to highly specific anti-apoptotic and anti-ferroptotic therapeutic modalities.

Hormones and oxidative stress: an overview

In aerobes, oxygen is essential for maintenance of life. However, incomplete reduction of oxygen leads to generation of reactive oxygen species. These oxidants oxidise biological macromolecules present in their vicinity and thereby impair cellular functions causing oxidative stress (OS). Aerobes have evolved both enzymatic and nonenzymatic antioxidant defences to protect themselves from OS. Although hormones as means of biological coordination involve in regulation of physiological activities of tissues by regulating metabolism, any change in their normal titre leads to pathophysiological states. While, hormones such as melatonin, insulin, oestrogen, progesterone display antioxidant features, thyroid hormone, corticosteroids and catecholamines elicit free radical generation and OS, and the role of testosterone in inducing OS is debateable. This review is an attempt to understand the impact of free radical generation and cross talk between the hormones modulating antioxidant defence system under various pathophysiological conditions.

Blood Pressure-Lowering by the Antioxidant Resveratrol Is Counterintuitively Mediated by Oxidation of cGMP-Dependent Protein Kinase

Supplemental Digital Content is available in the text.

Background:

The health-promoting and disease-limiting abilities of resveratrol, a natural polyphenol, has led to considerable interest in understanding the mechanisms of its therapeutic actions. The polyphenolic rings of resveratrol enable it to react with and detoxify otherwise injurious oxidants. Whilst the protective actions of resveratrol are commonly ascribed to its antioxidant activity, here we show that this is a misconception.

Methods:

The ability of resveratrol to oxidize cGMP-dependent PKG1α (protein kinase 1α) was assessed in isolated rat aortic smooth muscle cells, and the mechanism of action of this polyphenol was characterized using in vitro experiments, mass spectrometry and electron paramagnetic resonance. The blood pressure of wild-type and C42S knock-in mice was assessed using implanted telemetry probes. Mice were made hypertensive by administration of angiotensin II via osmotic mini-pumps and blood pressure monitored during 15 days of feeding with chow diet containing vehicle or resveratrol.

Results:

Oxidation of the phenolic rings of resveratrol paradoxically leads to oxidative modification of proteins, explained by formation of a reactive quinone that oxidizes the thiolate side chain of cysteine residues; events that were enhanced in cells under oxidative stress. Consistent with these observations and its ability to induce vasodilation, resveratrol induced oxidative activation of PKG1α and lowered blood pressure in hypertensive wild-type mice, but not C42S PKG1α knock-in mice that are resistant to disulfide activation.

Conclusions:

Resveratrol mediates lowering of blood pressure by paradoxically inducing protein oxidation, especially during times of oxidative stress, a mechanism that may be a common feature of antioxidant molecules.

Mitochondrial ROS Drive Sudden Cardiac Death and Chronic Proteome Remodeling in Heart Failure

RATIONALE

Despite increasing prevalence and incidence of heart failure (HF), therapeutic options remain limited. In early stages of HF, sudden cardiac death (SCD) from ventricular arrhythmias claims many lives. Reactive oxygen species (ROS) have been implicated in both arrhythmias and contractile dysfunction. However, little is known about how ROS in specific subcellular compartments contribute to HF or SCD pathophysiology. The role of ROS in chronic proteome remodeling has not been explored.

OBJECTIVE

We will test the hypothesis that elevated mitochondrial ROS (mROS) is a principal source of oxidative stress in HF and in vivo reduction of mROS mitigates SCD.

METHODS AND RESULTS

Using a unique guinea pig model of nonischemic HF that recapitulates important features of human HF, including prolonged QT interval and high incidence of spontaneous arrhythmic SCD, compartment-specific ROS sensors revealed increased mROS in resting and contracting left ventricular myocytes in failing hearts. Importantly, the mitochondrially targeted antioxidant (MitoTEMPO) normalized global cellular ROS. Further, in vivo MitoTEMPO treatment of HF animals prevented and reversed HF, eliminated SCD by decreasing dispersion of repolarization and ventricular arrhythmias, suppressed chronic HF-induced remodeling of the expression proteome, and prevented specific phosphoproteome alterations. Pathway analysis of mROS-sensitive networks indicated that increased mROS in HF disrupts the normal coupling between cytosolic signals and nuclear gene programs driving mitochondrial function, antioxidant enzymes, Ca²⁺ handling, and action potential repolarization, suggesting new targets for therapeutic intervention.

CONCLUSIONS

mROS drive both acute emergent events, such as electrical instability responsible for SCD, and those that mediate chronic HF remodeling, characterized by suppression or altered phosphorylation of metabolic, antioxidant, and ion transport protein networks. In vivo reduction of mROS prevents and reverses electrical instability, SCD, and HF. Our findings support the feasibility of targeting the mitochondria as a potential new therapy for HF and SCD while identifying new mROS-sensitive protein modifications.

Ameliorated Effects of (-)-Epigallocatechin Gallate Against Toxicity Induced by Vanadium in the Kidneys of Wistar Rats

The aim of the study was to assess the protective effect of (-)-epigallocatechin gallate (EGCG), a flavonoid abundant in green tea, against ammonium metavanadate (AMV)-induced oxidative stress in male Wistar rats. Four groups of animals have been used, a control group and three test groups. In the first test group, AMV was intra-peritoneally (i.p) injected daily (5 mg/kg body weight for five consecutive days). The second test group of animals was also injected daily with EGCG (5 mg/kg body weight) during the same period. However, the third test group was i.p. injected with both AMV and EGCG (5 mg/kg body weight for five consecutive days). When given alone, AMV induced an oxidative stress evidenced by an increase of lipid peroxidation levels (expressed as TBARS concentration) in kidney. In these animals, activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) were significantly decreased, suggesting significant reduction of the antioxidant defense system at the cell level. Kidney histological sections, showed glomerular hypertrophy and tubular dilatation. In AMV-treated animals receiving EGCG, the oxidative stress was much less pronounced and activities of antioxidant enzymes were kept close to control values. Histopathological changes were less prominent. Our results confirm that green tea and other sources of flavonoids might confer a strong protection against ammonium metavanadate-induced oxidative stress.

A synthetic cell permeable antioxidant protects neurons against acute oxidative stress

Excessive reactive oxygen species (ROS) can damage proteins, lipids, and DNA, which result in cell damage and death. The outcomes can be acute, as seen in stroke, or more chronic as observed in age-related diseases such as Parkinson’s disease. Here we investigate the antioxidant ability of a novel synthetic flavonoid, Proxison (7-decyl-3-hydroxy-2-(3,4,5-trihydroxyphenyl)-4-chromenone), using a range of in vitro and in vivo approaches. We show that, while it has radical scavenging ability on par with other flavonoids in a cell-free system, Proxison is orders of magnitude more potent than natural flavonoids at protecting neural cells against oxidative stress and is capable of rescuing damaged cells. The unique combination of a lipophilic hydrocarbon tail with a modified polyphenolic head group promotes efficient cellular uptake and moderate mitochondrial enrichment of Proxison. Importantly, in vivo administration of Proxison demonstrated effective and well tolerated neuroprotection against cell loss in a zebrafish model of dopaminergic neurodegeneration.

Extra-Cellular But Extra-Ordinarily Important for Cells: Apoplastic Reactive Oxygen Species Metabolism

Reactive oxygen species (ROS), by their very nature, are highly reactive, and it is no surprise that they can cause damage to organic molecules. In cells, ROS are produced as byproducts of many metabolic reactions, but plants are prepared for this ROS output. Even though extracellular ROS generation constitutes only a minor part of a cell's total ROS level, this fraction is of extraordinary importance. In an active apoplastic ROS burst, it is mainly the respiratory burst oxidases and peroxidases that are engaged, and defects of these enzymes can affect plant development and stress responses. It must be highlighted that there are also other less well-known enzymatic or non-enzymatic ROS sources. There is a need for ROS detoxification in the apoplast, and almost all cellular antioxidants are present in this space, but the activity of antioxidant enzymes and the concentration of low-mass antioxidants is very low. The low antioxidant efficiency in the apoplast allows ROS to accumulate easily, which is a condition for ROS signaling. Therefore, the apoplastic ROS/antioxidant homeostasis is actively engaged in the reception and reaction to many biotic and abiotic stresses.

Stabilization of anthocyanins in blackberry juice by glutathione fortification

Blackberry anthocyanins provide attractive color and antioxidant activity.

Induced oxidative stress management in wounds through phenolic acids engineered fibrous protein: An in vitro assessment using polymorphonuclear (PMN) cells

The present study explores the preparation, characterization and the role of phenolic acid tethered fibrous protein in the management of induced oxidative stress studied under in vitro conditions. In brief, the biomaterial is prepared by engineering the fibrous protein with dihydroxy and trihydroxy phenolic acid moieties and subjected to characterization to ensure the tethering. The resultant biomaterial studied for its efficacy as a free radical scavenger using polymorphonuclear (PMN) cells with induced oxidative stress and also as an agent for cell migration using fibroblasts cells. Results revealed that induced oxidative stress in PMN cells after exposure to UVB radiation managed well with the prepared biomaterial by reducing the levels of superoxide anion, oxygen and hydroxyl radicals. Further, the protein and the phenolic acid interaction supports the cell migration as evidenced from the scratch assay. In conclusion, though phenolic acids are well known for their antimicrobial and antioxidant potential, indenting these acids directly to the wounds is not sensible, but tethering to protein explored the scavenging activity as expected. The present study infers that phenolic acid engineered protein has a significant role in managing the imbalance in the redox state prevailing in wounds and supports the healing at appreciable level.

An iron-deficient diet during development induces oxidative stress in relation to age and gender in Wistar rats

Iron is a trace element and a structural part of antioxidant enzymes, and its requirements vary according to age and gender. We hypothesized that iron deficiency (ID) leads to an increase in free radicals which mainly affect the brain, and the severity of damage would therefore be dependent on age and gender. Two groups of Wistar rats were evaluated evolutionarily: 100 rats (50 males; 50 females) with ID diet and 100 rats (50 males; 50 females) with standard diet. Both groups were offspring from mothers who were previously under the same dietary intervention. The ages studied roughly correspond to stages of human development: birth (0 postnatal day "PND" in rats), childhood (21 PND), early adolescence (42 PND), late adolescence (56 PND), and adulthood (70 PND). The following biomarkers in the brain, blood, and liver were analyzed: lipid peroxidation products (LPO), protein carbonyl content and activity of the antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase. It was demonstrated that ID subjects are born with high levels of LPO in the brain and low antioxidant activity, the damage being more severe in males. After birth, antioxidant defense focuses on the central level (brain) in ID females and on the peripheral level (blood and liver) in ID males. In two critical stages of development, birth and late adolescence, antioxidant protection is insufficient to counteract oxidative damage in ID subjects. Moreover, we observed that the variability of results in the literature on oxidative stress and ID comes from gender and age of the subjects under study. With this, we can establish patterns and exact moments to carry out studies or treatments.

Effect of Thermal Treatment on the Antioxidant Activity and Content of Carotenoids and Phenolic Compounds of Cactus Pear Cladodes (Opuntia ficus-indica)

Cactus pears (Opuntia ficus-indica) are draught resistant plants originated in Mexico. Their flattened stem segments, called cladodes, have moisture, protein and fibre contents of 92, 1-2 and 4-6% respectively, and a pectin content in the range of 0.8-3.3% depending on the species. They also contain certain concentration of carotenoids which are of special interest because of their antioxidant activity. This work is aimed to identify and quantify the main carotenoids present in the stems and to evaluate the effect of thermal treatments on the antioxidant activity and concentration of carotenoids and phenolic compounds. The carotenoids -cryptoxanthin, -carotene and lutein were identified in the cladodes, the latter having the highest concentration. Thermal treatments increased the extractability of these pigments and the antioxidant activity was related to the carotenoids concentration. Total phenolic content decreased after the thermal treatments; however this result had little effect on the antioxidant activity. Mucilage present in the stems decreased the extractability of the carotenoids.

Differential physiological responses of two Salvinia species to hexavalent chromium at a glance

In plants of Salvinia rotundifolia and Salvinia minima the effect of two Cr(VI) concentrations (5 and 20mgL(-1)) applied for 7days was assessed by measuring changes in biomass, photosynthetic pigments, Cr accumulation, malondialdehyde (MDA), membrane stability index (MSI), thiols (TT, NPT and PBT), and phenolics (SP and IP). Biomass in S. minima was decreased at highest Cr(VI) concentration, but there were no changes in S. rotundifolia. Metal accumulation was different in both species. S. minima accumulates more metal in fronds, but S. rotundifolia accumulates more metal in lacinias. Results also showed that S. minima translocates more Cr to fronds than S. rotundifolia, but at the whole plant level higher accumulation occurred in this last. Tolerance index (Ti) was higher in S. rotundifolia. Chl b and carotenoids were decreased only upon exposure to high Cr(VI) concentration in both species. Cr(VI) treatment did not enhance MDA accumulation. Cr exposure had no impact on MSI values when comparing with Cr-untreated values. Thiols in fronds and lacinias showed different distribution patterns between species. IP and NPT were higher in S. rotundifolia lacinias that accumulate more Cr than S. minima lacinias. Whilst SP and NPT were higher in S. minima fronds compared with S. rotundifolia ones. This may indicate that these species can cope with Cr(VI) toxicity, either through metal complexation and/or metal reduction or by the scavenging of ROS derived from Cr-induced oxidative stress. Based on Cr accumulation and biomass production, S. rotundifolia seems more suitable to remove Cr(VI) from polluted waters.

Accumulation of Flavonols over Hydroxycinnamic Acids Favors Oxidative Damage Protection under Abiotic Stress

Efficient detoxification of reactive oxygen species (ROS) is thought to play a key role in enhancing the tolerance of plants to abiotic stresses. Although multiple pathways, enzymes, and antioxidants are present in plants, their exact roles during different stress responses remain unclear. Here, we report on the characterization of the different antioxidant mechanisms of tomato plants subjected to heat stress, salinity stress, or a combination of both stresses. All the treatments applied induced an increase of oxidative stress, with the salinity treatment being the most aggressive, resulting in plants with the lowest biomass, and the highest levels of H2O2 accumulation, lipid peroxidation, and protein oxidation. However, the results obtained from the transcript expression study and enzymatic activities related to the ascorbate-glutathione pathway did not fully explain the differences in the oxidative damage observed between salinity and the combination of salinity and heat. An exhaustive metabolomics study revealed the differential accumulation of phenolic compounds depending on the type of abiotic stress applied. An analysis at gene and enzyme levels of the phenylpropanoid metabolism concluded that under conditions where flavonols accumulated to a greater degree as compared to hydroxycinnamic acids, the oxidative damage was lower, highlighting the importance of flavonols as powerful antioxidants, and their role in abiotic stress tolerance.

Characterization of dehydroascorbate-mediated modification of glutaredoxin by mass spectrometry

Ascorbate is as a potent antioxidant in vivo protecting the organism against oxidative stress. In this process, ascorbate is oxidized in two steps to dehydroascorbate (DHA), which if not efficiently reduced back to ascorbate decomposes irreversibly to a complex mixture of products. We demonstrate that a component of this mixture specifically reacts with the thiol group of cysteine residues at physiological pH to give a protein adduct involving the addition of a 5-carbon fragment of DHA (+112 Da). Incubations of glutaredoxin-1 expressed in Escherichia coli and dehydroascorbate revealed abundant adducts of +112, +224 and +336 Da due to the addition of one, two and three conjugation products of DHA, respectively. ESI-MS of carbamidomethylated glutaredoxin-1 before incubation with DHA, deuterium exchange together with tandem mass spectrometry analysis and LC-ESIMS/MS of modified peptides confirmed structure and sites of modification in the protein. Modification of protein thiols by a DHA-derived product can be involved in oxidative stress-mediated cellular toxicity.

Membrane protein oxidation determines neuronal degeneration

Oxidative stress is an early hallmark in neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. However, the critical biochemical effector mechanisms of oxidative neurotoxicity have remained surprisingly elusive. In screening various peroxides and potential substrates of oxidation for their effect on neuronal survival, we observed that intramembrane compounds were significantly more active than aqueous or amphiphilic compounds. To better understand this result, we synthesized a series of competitive and site-specific membrane protein oxidation inhibitors termed aminoacyllipids, whose structures were designed on the basis of amino acids frequently found at the protein-lipid interface of synaptic membrane proteins. Investigating the aminoacyllipids in primary neuronal culture, we found that the targeted protection of transmembrane tyrosine and tryptophan residues was sufficient to prevent neurotoxicity evoked by hydroperoxides, kainic acid, glutathione-depleting drugs, and certain amyloidogenic peptides, but ineffective against non-oxidative inducers of apoptosis such as sphingosine or Akt kinase inhibitors. Thus, the oxidative component of different neurotoxins appears to converge on neuronal membrane proteins, irrespective of the primary mechanism of cellular oxidant generation. Our results indicate the existence of a one-electron redox cycle based on membrane protein aromatic surface amino acids, whose disturbance or overload leads to excessive membrane protein oxidation and neuronal death. Membrane proteins have rarely been investigated as potential victims of oxidative stress in the context of neurodegeneration. This study provides evidence that excessive one-electron oxidation of membrane proteins from within the lipid bilayer, depicted in the graphic, is a functionally decisive step toward neuronal cell death in response to different toxins.

High membrane protein oxidation in the human cerebral cortex

Oxidative stress is thought to be one of the main mediators of neuronal damage in human neurodegenerative disease. Still, the dissection of causal relationships has turned out to be remarkably difficult. Here, we have analyzed global protein oxidation in terms of carbonylation of membrane proteins and cytoplasmic proteins in three different mammalian species: aged human cortex and cerebellum from patients with or without Alzheimer's disease, mouse cortex and cerebellum from young and old animals, and adult rat hippocampus and cortex subjected or not subjected to cerebral ischemia. Most tissues showed relatively similar levels of protein oxidation. However, human cortex was affected by severe membrane protein oxidation, while exhibiting lower than average cytoplasmic protein oxidation. In contrast, ex vivo autooxidation of murine cortical tissue primarily induced aqueous protein oxidation, while in vivo biological aging or cerebral ischemia had no major effect on brain protein oxidation. The unusually high levels of membrane protein oxidation in the human cortex were also not predicted by lipid peroxidation, as the levels of isoprostane immunoreactivity in human samples were considerably lower than in rodent tissues. Our results indicate that the aged human cortex is under steady pressure from specific and potentially detrimental membrane protein oxidation. The pronounced difference between humans, mice and rats regarding the primary site of cortical oxidation might have contributed to the unresolved difficulties in translating into therapies the wealth of data describing successful antioxidant neuroprotection in rodents.

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Membrane proteins from the human cerebral cortex show specific and severe oxidation.

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This contrasts to human cerebellum and to mouse cortex and cerebellum of any age.

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It also contrasts to adult rat cortex and hippocampus with or without ischemia.

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Lipid peroxidation is not a predictor of membrane protein oxidation.

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Membrane protein oxidation might be related to impending neurodegeneration.

Mitochondria-derived reactive oxygen species mediate caspase-dependent and -independent neuronal deaths

Mitochondrial dysfunction and oxidative stress are implicated in many neurodegenerative diseases. Mitochondria-targeted drugs that effectively decrease oxidative stress, protect mitochondrial energetics, and prevent neuronal loss may therefore lend therapeutic benefit to these currently incurable diseases. To investigate the efficacy of such drugs, we examined the effects of mitochondria-targeted antioxidants MitoQ10 and MitoE2 on neuronal death induced by neurotrophin deficiency. Our results indicate that MitoQ10 blocked apoptosis by preventing increased mitochondria-derived reactive oxygen species (ROS) and subsequent cytochrome c release, caspase activation, and mitochondrial damage in nerve growth factor (NGF)-deprived sympathetic neurons, while MitoE2 was largely ineffective. In this paradigm, the most proximal point of divergence was the ability of MitoQ10 to scavenge mitochondrial superoxide (O2(-)). MitoQ10 also prevented caspase-independent neuronal death in these cells demonstrating that the mitochondrial redox state significantly influences both apoptotic and nonapoptotic pathways leading to neuronal death. We suggest that mitochondria-targeted antioxidants may provide tools for delineating the role and significance of mitochondrial ROS in neuronal death and provide a new therapeutic approach for neurodegenerative conditions involving trophic factor deficits and multiple modes of cell death.

Coenzyme Q10 benefits symptoms in Gulf War veterans: results of a randomized double-blind study

We sought to assess whether coenzyme Q10 (CoQ10) benefits the chronic multisymptom problems that affect one-quarter to one-third of 1990-1 Gulf War veterans, using a randomized, double-blind, placebo-controlled study. Participants were 46 veterans meeting Kansas and Centers for Disease Control criteria for Gulf War illness. Intervention was PharmaNord (Denmark) CoQ10 100 mg per day (Q100), 300 mg per day (Q300), or an identical-appearing placebo for 3.5 ± 0.5 months. General self-rated health (GSRH), the primary outcome, differed across randomization arms at baseline, and sex significantly predicted GSRH change, compelling adjustment for baseline GSRH and prompting sex-stratified analysis. GSRH showed no significant benefit in the combined-sex sample. Among males (85% of participants), Q100 significantly benefited GSRH versus placebo and versus Q300, providing emphasis on Q100. Physical function (summary performance score, SPS) improved on Q100 versus placebo. A rise in CoQ10 approached significance as a predictor of improvement in GSRH and significantly predicted SPS improvement. Among 20 symptoms each present in half or more of the enrolled veterans, direction-of-difference on Q100 versus placebo was favorable for all except sleep problems; sign test 19:1, p=0.00004) with several symptoms individually significant. Significance for these symptoms despite the small sample underscores large effect sizes, and an apparent relation of key outcomes to CoQ10 change increases prospects for causality. In conclusion, Q100 conferred benefit to physical function and symptoms in veterans with Gulf War illness. Examination in a larger sample is warranted, and findings from this study can inform the conduct of a larger trial.

Peroxidase activity in scutella of maize in association with anatomical changes during germination and grain storage

The embryo of the maize grain (Zea mays L.) is separated from the starchy endosperm by a fibrous structure, which is called the fibrous layer (FL). Using histochemical staining, it was determined that the FL is composed of collapsed cellular layers that contain phenols, neutral lipids, and 1,3-β-glucan. Due to its composition, the FL prevents free diffusion and separates the embryo from the endosperm during germination. Twenty-four hours after imbibition, the scutellum epidermis initiated a series of asynchronous spatial modifications, including cell growth, the perforation of cell walls, increased peroxidase activity in the apoplastic space, and elevated levels of superoxide, phenols, and other components that interact with the fibrous layer, enabling its transformation in addition to the free flow between compartments. During storage at high relative humidity levels, which leads to fast or slow deterioration depending on the temperature, the activity of phenol peroxidase in the scutellum was associated with a loss of vigor and reduced germination capacity when compared with low temperature and low relative humidity conditions. Such deterioration is associated with alterations in autofluorescent emissions from endogenous compounds in the scutellum, indicating changes in the microenvironment or in the differential proportions of epidermal and FL components.

NMDA and AMPA receptor mediated excitotoxicity in cerebral cortex of streptozotocin induced diabetic rat: ameliorating effects of curcumin

Functional activity of neurotransmitter receptor and their sensitivity to regulation are altered in DM. We evaluated the neuroprotective effect of curcumin in glutamate mediated excitotoxicity in cerebral cortex of streptozotocin induced diabetic rats. Gene expression studies in diabetic rats showed a down regulation of glutamate decarboxylase mRNA leading to accumulation of glutamate. Radioreceptor binding assays showed a significant increase in α-amino-3-hydroxy-5-methyl-4-isoxazole propionate and N-methyl-D-aspartate receptors density which was confirmed by immunohistochemical studies. Decreased glutathione peroxidases gene expression indicates enhanced oxidative stress in diabetic rats. This leads to decreased expression of glutamate aspartate transporter, which in turn reduces glutamate transport. All these events lead to excitotoxic neuronal death in the cerebral cortex, which was confirmed by the increased expression of caspase 3, caspase 8 and BCL2-associated X protein. Curcumin and insulin treatment reversed these altered parameters to near control. We establish, a novel therapeutic role of curcumin by reducing the glutamate mediated excitotoxicity in cerebral cortex of diabetes through modulating the altered neurochemical parameters.

Succinobucol-eluting stents increase neointimal thickening and peri-strut inflammation in a porcine coronary model

Objective

The aim of this study was to assess the efficacy of stent-based delivery of succinobucol alone and in combination with rapamycin in a porcine coronary model. Background: Current drugs and polymers used to coat coronary stents remain suboptimal in terms of long term efficacy and safety. Succinobucol is a novel derivative of probucol with improved antioxidant and anti-inflammatory properties.

Methods

Polymer-free Yukon stents were coated with 1% succinobucol (SucES), 2% rapamycin (RES), or 1% succinobucol plus 2% rapamycin solutions (SucRES) and compared with a bare metal stent (BMS).

Results

The in vivo release profile of SucES indicated drug release up to 28 days (60% drug released at 7 days); 41 stents (BMS, n = 11; SucES, n =10; RES, n = 10; SucRES, n = 10) were implanted in the coronary arteries of 17 pigs. After 28 days, mean neointimal thickness was 0.31 ± 0.14 mm for BMS, 0.51 ± 0.14 mm for SucES, 0.19 ± 0.11 mm for RES, and 0.36 ± 0.17 mm for SucRES (P < 0.05 for SucES vs. BMS). SucES increased inflammation and fibrin deposition compared with BMS (P < 0.05), whereas RES reduced inflammation compared with BMS (P < 0.05).

Conclusion

In this model, stent-based delivery of 1% succinobucol using a polymer-free stent platform increased neointimal formation and inflammation following coronary stenting. © 2012 Wiley Periodicals, Inc.

A hypothesis on chemical mechanism of the effect of hydrogen

Many studies have shown that hydrogen can play important roles on the antioxidant, anti-inflammatory and other protective effects. Ohsawa et al have proved that hydrogen can electively and directly scavenge hydroxyl radical. But this mechanism cannot explain more new experimental results. In this article, the hypothesis, which is inspired by H2 could bind to the metal as a ligand, come up to explain its extensive biology effect: Hydrogen could regulate particular metalloproteins by bonding (M-H2 interaction) it. And then it could affect the metabolization of ROS and signal transduction. Metalloproteins may be ones of the target molecules of H2 action. Metal ions may be appropriate role sites for H2 molecules. The hypothesis pointed out a new direction to clarify its mechanisms.

Transcriptome modification of white blood cells after dietary administration of curcumin and non-steroidal anti-inflammatory drug in osteoarthritic affected dogs

The dietary effect of non-steroidal anti-inflammatory drug (NSAID) or curcumin on the gene expression of peripheral white blood cells in osteoarthritis (OA) affected dogs was investigated using a 44K oligo microarray. Two groups of OA dogs and one group of healthy dogs (6 dogs each) were clinically evaluated and blood was sampled before (T0) and after 20days (T20) of dietary administration of NSAID (NSAID group) or curcumin (CURCUMIN group). Differentially expressed genes (P<0.05) in comparison to the control group were identified with MeV software and were functional annotated and monitored for signaling pathways and candidate biomarkers using the Ingenuity Pathways Analysis (IPA). After 20days of treatment, the differentially expressed transcripts significantly (P<0.05) decreased from 475 to 173 in NSAID group and from 498 to 141 in CURCUMIN group. Genes involved in "inflammatory response" and in "connective tissue development and function" dramatically decreased at T20. Other genes, included in "cellular movement", "cellular compromise" and "immune cell trafficking", were differentially expressed at T0 but not at T20 in both groups. Specific molecular targets of CURCUMIN, not observed for NSAID, were the IkB up regulation in the "TNRF1 signaling pathway" and IL18 down regulation in the "role of cytokines in mediating communication between immune cells". The activity of CURCUMIN was also evidenced from the inhibition of macrophages proliferation (HBEGF), related to a strong down regulation of TNFα and to activation of fibrinolysis (SERPINE1). The results would suggest that curcumin offers a complementary antinflammatory support for OA treatment in dogs.

Antioxidant, antitubercular and cytotoxic activities of Piper imperiale

Phenolic compounds are widely distributed in Nature and act as pharmacologically active constituents in many herbal medicines. They have multiple biological properties, most notably antioxidant, antibacterial and cytotoxic activities. In the present study an attempt to correlate the phenolic composition of leaf, flower and wood extracts of Piper imperiale, with antioxidant, antitubercular and cytotoxic activities was undertaken. The total phenol content ranged from 1.98 to 6.94 mg GAE/gDW among ethanolic extracts, and gallic acid, catechin, epicatechin, ferulic acid, resveratrol and quercetin were identified and quantified by HPLC. DPPH and ABTS assays showed high antioxidant activity of the leaf extract (EC_50ABTS = 15.6 µg/mL, EC_50DPPH = 27.3 µg/mL) with EC₅₀ in the same order of magnitude as the hydroxyquinone (EC_50ABTS = 10.2 µg/mL, EC_50DPPH = 15.7 µg/mL). The flower extract showed strong antimicrobial activity against Mycobacterium tuberculosis H₃₇Rv. All the extracts exhibited dose-dependent cytotoxic effects against MCF-7 cancer cells. This is the first time that a Piper extract has been found to be highly active against M. tuberculosis. This study shows the biological potential of Piper imperiale extracts and gives way to bio-guided studies with well-defined biological activities.

The effects of resveratrol and selected metabolites on the radiation and antioxidant response

Excess reactive oxygen species (ROS) generated from ionizing radiation (IR) or endogenous sources like cellular respiration and inflammation produce cytotoxic effects that can lead to carcinogenesis. Resveratrol (RSV), a polyphenol with antioxidant and anticarcinogenic capabilities, has shown promise as a potential radiation modifier. The present study focuses on examining the effects of RSV or RSV metabolites as a radiation modifier in normal tissue. RSV or a RSV metabolite, piceatannol (PIC) did not protect human lung fibroblasts (1522) from the radiation-induced cell killing. Likewise, neither RSV nor PIC afforded protection against lethal total body IR in C3H mice. Additional research has shown protection in cells against hydrogen peroxide when treated with RSV. Therefore, clonogenic survival was measured in 1522 cells with RSV and RSV metabolites. Only the RSV derivative, piceatannol (PIC), showed protection against hydrogen peroxide mediated cytotoxicity; whereas, RSV enhanced hydrogen peroxide sensitivity at a 50 µM concentration; the remaining metabolites evaluated had little to no effect on survival. PIC also showed enhancement to peroxide exposure at a higher concentration (150 µM). A potential mechanism for RSV-induced sensitivity to peroxides could be its ability to block 1522 cells in the S-phase, which is most sensitive to hydrogen peroxide treatment. In addition, both RSV and PIC can be oxidized to phenoxyl radicals and quinones, which may exert cytotoxic effects. These cytotoxic effects were abolished when HBED, a metal chelator, was added. Taken together RSV and many of its metabolic derivatives are not effective as chemical radioprotectors and should not be considered for clinical use.

Key roles of vitamins A, C, and E in aflatoxin B1-induced oxidative stress

Aflatoxins (Aspergillus flavus toxins) are one of the natural toxic molecules which are produced by a group of fungi called Aspergillus. Foods and drinks contaminated with aflatoxins cause global health and environmental problems. Today in many developing countries, these toxins are leading cause of some liver cancers and serious gastrointestinal problems. Aflatoxins, which are well known to be mutagenic, carcinogenic, hepatotoxic, and immunosuppressive, exert inhibitory effects on biological processes including DNA synthesis, DNA-dependent RNA synthesis, DNA repair, and protein synthesis. Aflatoxins B(1) (AFB(1)) is the most widespread oxidative agent of the aflatoxins. Numerous diverse compounds and extracts have been reported to reduce the aflatoxins induced oxidative stress in the body. Most of these inhibitors including phenylpropanoids, terpenoids, alkaloids, and vitamins are originally derived from plants. Among these, being essential biomolecules, vitamins are used as coenzymes in very significant biological reactions. They also function as nonenzymatic antioxidative agents protecting the cells from oxidative stress-induced toxicity and transformation. This chapter reviews the mechanism of AFB(1)-induced oxidative stress and focuses on the protective effects of vitamins A, C, and E on reducing this stress.

Lipid antioxidants: free radical scavenging versus regulation of enzymatic lipid peroxidation

The essentiality of polyunsaturated lipids makes membranes susceptible to peroxidative modifications. One of the most contemporary examples includes selective peroxidation of cardiolipin in mitochondria of cells undergoing apoptosis. Cardiolipin peroxidation products are required for the mitochondrial membrane permeabilization, release of pro-apoptotic factors and completion of the cell death program. Therefore, search for effective inhibitors of cardiolipin peroxidation is critical to discovery and development of anti-apoptotic antioxidants. Mitochondria contain significant amounts of α-tocopherol, a well known scavenger of reactive free radicals. In the present study, we used an oxidative lipidomics approach to evaluate the effect of α-tocopherol and its homologues with different lengths of the side-chain such as 2,5,7,8,-tetramethyl-2(4-methylpentyl)-6-chromanol and 2,2,5,7,8-pentamethyl-6-chromanol, on oxidation of tetralinoleoyl cardiolipin induced by cytochrome c in the presence of hydrogen peroxide. Our data indicate that vitamin E homologues inhibit not only accumulation of tetralinoleoyl cardiolipin hydroperoxides but also hydroxy-derivatives of tetralinoleoyl cardiolipin formed in the enzymatic peroxidase half-reaction catalyzed by cytochrome c. This suggests that protective effects of vitamin E homologues against tetralinoleoyl cardiolipin peroxidation catalyzed by cytochrome c/hydrogen peroxide are realized largely due to their effects on the peroxidase activity of cytochrome c towards tetralinoleoyl cardiolipin rather than via their scavenging activity.

The hydroxyl functional group of N-(4-hydroxyphenyl)retinamide mediates cellular uptake and cytotoxicity in premalignant and malignant human epithelial cells

In a previous study, we demonstrated that the anticancer synthetic retinoid N-(4-hydroxyphenyl)retinamide (4HPR) redox cycles at the mitochondrial enzyme dihydroorotate dehydrogenase to trigger anomalous reactive oxygen species (ROS) production and attendant apoptosis in transformed human epithelial cells. Furthermore, we speculated that the hydroxyl functional group of 4HPR was required for this pro-oxidant property. In this study, we investigated the role of the hydroxyl functional group in the in vitro cytotoxicity of 4HPR. Using 4HPR, its primary in vivo metabolite N-(4-methoxyphenyl)retinamide (4MPR), and the synthetic derivative N-(4-trifluoromethylphenyl)retinamide (4TPR), we examined the pro-oxidant and apoptotic effects, as well as the cellular uptake, of these three N-(4-substituted-phenyl)retinamides in premalignant and malignant human skin, prostate, and breast epithelial cells. Compared to 4HPR, both 4MPR and 4TPR were ineffective in promoting conspicuous cellular ROS production, mitochondrial disruption, or DNA fragmentation in these transformed cells. Interestingly, both 4MPR and 4TPR were not particularly cell permeative relative to 4HPR in skin or breast epithelial cells, which implied an additional role for the hydroxyl functional group in the cellular uptake of 4HPR. Moreover, the short-term uptake of 4HPR was directly proportional to cell size, but this characteristic, in obvious contrast to cellular bioenergetic status and/or dihydroorotate dehydrogenase expression, was not fundamentally influential in the overall sensitivity to the promotion of cellular ROS production and apoptosis induction by this agent. Together, these results strongly implicate the hydroxyl functional group in the cytotoxic effects of 4HPR.

Protein reactivity of 3,4-dihydroxyphenylacetaldehyde, a toxic dopamine metabolite, is dependent on both the aldehyde and the catechol

Dopamine (DA) has been implicated as an endogenous neurotoxin to explain selective neurodegeneration, as observed for Parkinson's disease (PD). However, previous work demonstrated that 3,4-dihydroxyphenylacetaldehyde (DOPAL) was more toxic than DA. DOPAL is generated as a part of DA catabolism via the activity of monoamine oxidase, and the mechanism of DOPAL toxicity is proposed to involve protein modification. Previous studies have demonstrated protein reactivity via the aldehyde moiety; however, DOPAL contains two reactive functional groups (catechol and aldehyde), both with the potential for protein adduction. The goal of this work was to determine whether protein modification by DOPAL occurs via a thiol-reactive quinone generated from oxidation of the catechol, which is known to occur for DA, or if the aldehyde forms adducts with amine nucleophiles. To accomplish this objective, the reactivity of DOPAL toward N-acetyl-lysine (NAL), N-acetyl-cysteine (NAC), and two model proteins was determined. In addition, several DOPAL analogues were obtained and used for comparison of reactivity. Results demonstrate that at pH 7.4 and 37 degrees C, the order of DOPAL reactivity is NAL >> NAC and the product of NAL and DOPAL is stable in the absence of reducing agent. Moreover, DOPAL will react with model proteins, but in the presence of amine-selective modifiers citraconic anhydride and 2-iminothiolane hydrochloride, the reactivity of DOPAL toward the proteins is diminished. In addition, DOPAL-mediated protein cross-linking is observed when a model protein or a protein mixture (i.e., mitochondria lysate) is treated with DOPAL at concentrations of 5-100 microM. Protein cross-linking was diminished in the presence of ascorbate, suggesting the involvement of a quinone in DOPAL-mediated protein modification. These data indicate that DOPAL is highly reactive toward protein nucleophiles with the potential for protein cross-linking.

Neuroprotective role of curcumin in the cerebellum of streptozotocin-induced diabetic rats

AIMS

Chronic hyperglycaemia in diabetes involves a direct neuronal damage caused by intracellular glucose which leads to altered neurotransmitter functions and reduced motor activity. The present study investigated the effect of curcumin in the functional regulation of muscarinic and alpha7 nicotinic acetylcholine receptors, insulin receptors, acetylcholine esterase and Glut3 in the cerebellum of streptozotocin (STZ)-induced diabetic rats.

MAIN METHODS

All studies were done in the cerebellum of male Wistar rats. Radioreceptor binding assays were done for total muscarinic, M(1) and M(3) receptors using specific ligands, and the gene expression was also studied using specific probes.

KEY FINDINGS

Our results showed an increased gene expression of acetylcholine esterase, Glut3, muscarinic M1, M3, alpha7 nicotinic acetylcholine and insulin receptors in the cerebellum of diabetic rats in comparison to control. Scatchard analysis of total muscarinic, M1 and M3 receptors showed an increased binding parameter, B(max) in diabetic rats compared to control. Curcumin and insulin inhibited diabetes-induced elevation in the gene expression of acetylcholine esterase, Glut3, insulin and cholinergic receptors in the cerebellum of diabetic rats.

SIGNIFICANCE

Our studies suggest that curcumin plays a vital role in regulating the activity of cholinergic and insulin receptors and mechanism of glucose transportation through Glut3, which results in normalizing the diabetes-mediated cerebellar disorders. Thus, curcumin has a significant role in a therapeutic application for the prevention or progression of diabetic complications in the cerebellum.

Mechanisms and implications of reactive oxygen species generation during the unfolded protein response: roles of endoplasmic reticulum oxidoreductases, mitochondrial electron transport, and NADPH oxidase

Cellular mechanisms governing redox homeostasis likely involve their integration with other stresses. Endoplasmic reticulum (ER) stress triggers complex adaptive or proapoptotic signaling defined as the unfolded protein response (UPR), involved in several pathophysiological processes. Since protein folding is highly redox-dependent, convergence between ER stress and oxidative stress has attracted interest. Evidence suggests that ROS production and oxidative stress are not only coincidental to ER stress, but are integral UPR components, being triggered by distinct types of ER stressors and contributing to support proapoptotic, as well as proadaptive UPR signaling. Thus, ROS generation can be upstream or downstream UPR targets and may display a UPR-specific plus a nonspecific component. Enzymatic mechanisms of ROS generation during UPR include: (a) Multiple thiol-disulfide exchanges involving ER oxidoreductases including flavooxidase Ero1 and protein disulfide isomerase (PDI); (b) Mitochondrial electron transport; (c) Nox4 NADPH oxidase complex, particularly Nox4. Understanding the roles of such mechanisms and how they interconnect with the UPR requires more investigation. Integration among such ROS sources may depend on Ca(2+) levels, ROS themselves, and PDI, which associates with NADPH oxidase and regulates its function. Oxidative stress may frequently integrate with a background of ER stress/UPR in several diseases; here we discuss a focus in the vascular system.

Antioxidant therapy in the management of acute, chronic and post-ERCP pancreatitis: A systematic review

We systematically reviewed the clinical trials which recruited antioxidants in the therapy of pancreatitis and evaluated whether antioxidants improve the outcome of patients with pancreatitis. Electronic bibliographic databases were searched for any studies which investigated the use of antioxidants in the management of acute pancreatitis (AP) or chronic pancreatitis (CP) and in the prevention of post-endoscopic retrograde cholangio-pancreatography (post-ERCP) pancreatitis (PEP) up to February 2009. Twenty-two randomized, placebo-controlled, clinical trials met our criteria and were included in the review. Except for a cocktail of antioxidants which showed improvement in outcomes in three different clinical trials, the results of the administration of other antioxidants in both AP and CP clinical trials were incongruent and heterogeneous. Furthermore, antioxidant therapy including allopurinol and N-acetylcysteine failed to prevent the onset of PEP in almost all trials. In conclusion, the present data do not support a benefit of antioxidant therapy alone or in combination with conventional therapy in the management of AP, CP or PEP. Further double blind, randomized, placebo-controlled clinical trials with large sample size need to be conducted.

Islet transplantation and antioxidant management: A comprehensive review

Islet transplantation as a promising treatment for type 1 diabetes has received widespread attention. Oxidative stress plays an essential role in cell injury during islet isolation and transplantation procedures. Antioxidants have been used in various studies to improve islet transplantation procedures. The present study reviews the role of oxidative stress and the benefits of antioxidants in islet transplantation procedures. The bibliographical databases Pubmed and Scopus were searched up to November 2008. All relevant human and animal in-vivo and in-vitro studies, which investigated antioxidants on islets, were included. Almost all the tested antioxidants used in the in-vitro studies enhanced islet viability and insulin secretion. Better control of blood glucose after transplantation was the major outcome of antioxidant therapy in all in-vivo studies. The data also indicated that antioxidants improved islet transplantation procedures. Although there is still insufficient evidence to draw definitive conclusions about the efficacy of individual supplements, the benefits of antioxidants in islet isolation procedures cannot be ignored.