The chemistry of cell signaling by reactive oxygen and nitrogen species and 4-hydroxynonenal

YAP-mediated DDX3X confers resistance to ferroptosis in breast cancer cells by reducing lipid peroxidation

Metabolic shifts in cancer cells were found to participate in tumorigenesis, especially driving chemotherapeutic resistance. Ferroptosis is a newly discovered form of cell death induced by excessive accumulations of iron and lipid peroxidation. Susceptibility to ferroptosis can be intrinsically regulated by various cellular metabolic pathways. Therefore, inducing ferroptosis might be a promising anticancer therapeutic strategy. DEAD-box helicase 3 X-linked (DDX3X), a critical modulator of RNA metabolism, was identified as an oncogene in breast cancer and also participates in cancer metabolism and chemotherapeutic resistance. However, the molecular regulation of the association between DDX3X and ferroptosis is largely unknown. Herein, we investigated the correlation between resistance to ferroptosis and DDX3X expression in breast cancer cells. We found that elevation of DDX3X was associated with increased resistance to a ferroptosis inducer in breast cancer cells, and manipulating DDX3X expression regulated the sensitivity to the ferroptosis inducer. Importantly, DDX3X upregulated expression of the anti-ferroptotic enzyme glutathione peroxidase 4 (GPX4) gene to confer ferroptosis resistance in breast cancer cells. Moreover, DDX3X was transcriptionally upregulated by the yes-associated protein (YAP). Knockdown of YAP downregulated DDX3X mRNA expression and facilitated lipid peroxidation, but that were restored in the presence of DDX3X. Clinically, coexpression of DDX3X and YAP was found in a variety of malignancy, and their elevation conferred poor survival prognosis in patients with breast cancer. Together, our findings reveal the crucial role of DDX3X in sensitivity to ferroptosis and underscore its potential as a diagnostic marker and therapeutic target. DDX3X renders resistance to ferroptosis and plays a role in mitigating lipid peroxidation, paving the way for therapeutic vulnerability via targeting cancer metabolism.

Fructose-mediated AGE-RAGE axis: approaches for mild modulation

Fructose is a valuable and healthy nutrient when consumed at normal levels (≤50 g/day). However, long-term consumption of excessive fructose and elevated endogenous production can have detrimental health impacts. Fructose-initiated nonenzymatic glycation (fructation) is considered as one of the most likely mechanisms leading to the generation of reactive species and the propagation of nonenzymatic processes. In the later stages of glycation, poorly degraded advanced glycation products (AGEs) are irreversibly produced and accumulated in the organism in an age- and disease-dependent manner. Fructose, along with various glycation products-especially AGEs-are present in relatively high concentrations in our daily diet. Both endogenous and exogenous AGEs exhibit a wide range of biological effects, mechanisms of which can be associated with following: (1) AGEs are efficient sources of reactive species in vivo, and therefore can propagate nonenzymatic vicious cycles and amplify glycation; and (2) AGEs contribute to upregulation of the specific receptor for AGEs (RAGE), amplifying RAGE-mediated signaling related to inflammation, metabolic disorders, chronic diseases, and aging. Therefore, downregulation of the AGE-RAGE axis appears to be a promising approach for attenuating disease conditions associated with RAGE-mediated inflammation. Importantly, RAGE is not specific only to AGEs; it can bind multiple ligands, initiating a complex RAGE signaling network that is not fully understood. Maintaining an appropriate balance between various RAGE isoforms with different functions is also crucial. In this context, mild approaches related to lifestyle-such as diet optimization, consuming functional foods, intake of probiotics, and regular moderate physical activity-are valuable due to their beneficial effects and their ability to mildly modulate the fructose-mediated AGE-RAGE axis.

An overview on glycation: molecular mechanisms, impact on proteins, pathogenesis, and inhibition

The formation of a heterogeneous set of advanced glycation end products (AGEs) is the final outcome of a non-enzymatic process that occurs in vivo on long-life biomolecules. This process, known as glycation, starts with the reaction between reducing sugars, or their autoxidation products, with the amino groups of proteins, DNA, or lipids, thus gaining relevance under hyperglycemic conditions. Once AGEs are formed, they might affect the biological function of the biomacromolecule and, therefore, induce the development of pathophysiological events. In fact, the accumulation of AGEs has been pointed as a triggering factor of obesity, diabetes-related diseases, coronary artery disease, neurological disorders, or chronic renal failure, among others. Given the deleterious consequences of glycation, evolution has designed endogenous mechanisms to undo glycation or to prevent it. In addition, many exogenous molecules have also emerged as powerful glycation inhibitors. This review aims to provide an overview on what glycation is. It starts by explaining the similarities and differences between glycation and glycosylation. Then, it describes in detail the molecular mechanism underlying glycation reactions, and the bio-molecular targets with higher propensity to be glycated. Next, it discusses the precise effects of glycation on protein structure, function, and aggregation, and how computational chemistry has provided insights on these aspects. Finally, it reports the most prevalent diseases induced by glycation, and the endogenous mechanisms and the current therapeutic interventions against it.

Insights into the Management of Chronic Hepatitis in Children-From Oxidative Stress to Antioxidant Therapy

Recent research has generated awareness of the existence of various pathophysiological pathways that contribute to the development of chronic diseases; thus, pro-oxidative factors have been accepted as significant contributors to the emergence of a wide range of diseases, from inflammatory to malignant. Redox homeostasis is especially crucial in liver pathology, as disturbances at this level have been linked to a variety of chronic diseases. Hepatitis is an umbrella term used to describe liver inflammation, which is the foundation of this disease regardless of its cause. Chronic hepatitis produces both oxidative stress generated by hepatocyte inflammation and viral inoculation. The majority of hepatitis in children is caused by a virus, and current studies reveal that 60-80% of cases become chronic, with many young patients still at risk of advancing liver damage. This review intends to emphasize the relevance of understanding these pathological redox pathways, as well as the need to update therapeutic strategies in chronic liver pathology, considering the beneficial effects of antioxidants.

Oral administration of resveratrol reduces oxidative stress generated in the hippocampus of Wistar rats in response to consumption of ethanol

Introduction

Chronic ethanol intake has been found to favor hippocampal deterioration and alter neuronal morphological maturation; resveratrol has been suggested as an antioxidant that may counteract these effects. The objective of this study was to analyze the effect of resveratrol on oxidative stress markers, endogenous antioxidant system in the hippocampus, and the behavior of male Wistar rats administered different concentrations of ethanol.

Methods

The animals, at 3 months old, were randomly distributed into 11 study groups (n = 6/group), orally administered (5 days on, 2 days off) with water (control), ethanol (10, 20, 30, 40 or 50%), or ethanol (10, 20, 30, 40 or 50%) plus resveratrol (10 mg/Kg/day) for 2 months. Subsequently, the production of nitrites, malondialdehyde, and 4-hydroxy-alkenal (HNE) and the enzymatic activity of catalase and superoxide dismutase (SOD) were quantified.

Results

The levels of nitric oxide and lipid peroxidation products were significantly increased in each ethanol concentration and were statistically different compared to the control group; however, resveratrol significantly reduced oxidative stress caused by high ethanol concentration. The SOD and CAT did not present significant changes with respect to the controls in any of the study groups. In the different concentrations of ethanol used, GR increases significantly in the groups administered with resveratrol but not GPx. Resveratrol was shown to maintain the results similar to the control at most ethanol concentrations.

Discussion

Our results suggest that resveratrol prevents oxidative stress induced by ethanol in the hippocampus by decreasing cellular lipid peroxidation, but does not prevent the activation of catalase or SOD enzymes; however, allows glutathione to be kept active and in adequate concentrations in its reduced form and avoids alterations in the locomotor system.

Aldehyde Dehydrogenase and Aldo-Keto Reductase Enzymes: Basic Concepts and Emerging Roles in Diabetic Retinopathy

Diabetic retinopathy (DR) is a complication of diabetes mellitus that can lead to vision loss and blindness. It is driven by various biochemical processes and molecular mechanisms, including lipid peroxidation and disrupted aldehyde metabolism, which contributes to retinal tissue damage and the progression of the disease. The elimination and processing of aldehydes in the retina rely on the crucial role played by aldehyde dehydrogenase (ALDH) and aldo-keto reductase (AKR) enzymes. This review article investigates the impact of oxidative stress, lipid-derived aldehydes, and advanced lipoxidation end products (ALEs) on the advancement of DR. It also provides an overview of the ALDH and AKR enzymes expressed in the retina, emphasizing their growing importance in DR. Understanding the relationship between aldehyde metabolism and DR could guide innovative therapeutic strategies to protect the retina and preserve vision in diabetic patients. This review, therefore, also explores various approaches, such as gene therapy and pharmacological compounds that have the potential to augment the expression and activity of ALDH and AKR enzymes, underscoring their potential as effective treatment options for DR.

Reversibility and Low Commitment to Forward Catalysis in the Conjugation of Lipid Alkenals by Glutathione Transferase A4-4

High concentrations of electrophilic lipid alkenals formed during oxidative stress are implicated in cytotoxicity and disease. However, low concentrations of alkenals are required to induce antioxidative stress responses. An established clearance pathway for lipid alkenals includes conjugation to glutathione (GSH) via Michael addition, which is catalyzed mainly by glutathione transferase isoform A4 (GSTA4-4). Based on the ability of GSTs to catalyze hydrolysis or retro-Michael addition of GSH conjugates, and the antioxidant function of low concentrations of lipid alkenals, we hypothesize that GSTA4-4 contributes a homeostatic role in lipid metabolism. Enzymatic kinetic parameters for retro-Michael addition with trans-2-Nonenal (NE) reveal the chemical competence of GSTA4-4 in this putative role. The forward GSTA4-4-catalyzed Michael addition occurs with the rapid exchange of the C2 proton of NE in D₂O as observed by NMR. The isotope exchange was completely dependent on the presence of GSH. The overall commitment to catalysis, or the ratio of first order k_cat,f for 'forward' Michael addition to the first order k_cat,ex for H/D exchange is remarkably low, approximately 3:1. This behavior is consistent with the possibility that GSTA4-4 is a regulatory enzyme that contributes to steady-state levels of lipid alkenals, rather than a strict 'one way' detoxication enzyme.

Glutathione-Related Enzymes and Proteins: A Review

The tripeptide glutathione is found in all eukaryotic cells, and due to the compartmentalization of biochemical processes, its synthesis takes place exclusively in the cytosol. At the same time, its functions depend on its transport to/from organelles and interorgan transport, in which the liver plays a central role. Glutathione is determined as a marker of the redox state in many diseases, aging processes, and cell death resulting from its properties and reactivity. It also uses other enzymes and proteins, which enables it to engage and regulate various cell functions. This paper approximates the role of these systems in redox and detoxification reactions such as conjugation reactions of glutathione-S-transferases, glyoxylases, reduction of peroxides through thiol peroxidases (glutathione peroxidases, peroxiredoxins) and thiol-disulfide exchange reactions catalyzed by glutaredoxins.

Can amniotic fluid protect developing fetal lungs against the harmful effects of oxidative stress?

BACKGROUND

Preterm births cause fetuses to be born without completing the development of their organs. Due to this undesirable situation, it is the pulmonary tissue which has to be most exposed to harmful effects of extrauterine environment. Early disappearance of the prophylactic and constructive effects of amniotic fluid (AF) on developing tissues, such as pulmonary tissue, facilitates the formation of pulmonary morbidities resulting from oxygen. Setting out from this knowledge, we wanted, in addition to assessing the beneficent effects of AF on pulmonary tissue, to study the importance of AF in morbidities of this tissue thought to originate from oxygen.

METHODS

In this experimental study, while the study group was made up of the fetuses of pregnant rats exposed to hyperbaric oxygen, (hyperoxic pregnant rat fetuses-HPRF), the control group was formed of the fetuses of the rats pregnant in the usual room setting (normoxic pregnant rat fetuses-NPRF). The pulmonary and hepatic tissues taken from the fetuses of these pregnant rats on the 21st day of their pregnancy were compared biochemically and histologically. For biochemical assessment, total glutathione (tGSH), catalase (CAT), malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α) values and for histopathological assessment, apoptosis, alveolar wall count (AWC), vena centralis count (VCC) were included.

RESULTS

Statistical significance was found in the pulmonary tissue values of tGSH on behalf of NPRF, and MDA on behalf of HPRF (p < 0.05). In liver tissue, statistical significance was detected in tGSH and CAT values in favor of NPRF and in MDA, and TNF-α values in favor of HPRF (p < 0.05).

DISCUSSION

: Our study has demonstrated that AF protects the pulmonary tissue from the harmful effects of oxygen in the intrauterine period. In addition, our data have suggested that the pulmonary tissue's being deprived of the useful effects of AF owing to premature birth may be an important trigger in the occurrence of the pulmonary morbidities thought to result from oxygen.

Redox Properties, Bioactivity and Health Effects of Indicaxanthin, a Bioavailable Phytochemical from Opuntia ficus indica, L.: A Critical Review of Accumulated Evidence and Perspectives

Phytochemicals from plant foods are considered essential to human health. Known for their role in the adaptation of plants to their environment, these compounds can induce adaptive responses in cells, many of which are directed at maintaining the redox tone. Indicaxanthin is a long-known betalain pigment found in the genus Opuntia of cactus pear and highly concentrated in the edible fruits of O. ficus indica, L. whose bioactivity has been overlooked until recently. This review summarizes studies conducted so far in vitro and in vivo, most of which have been performed in our laboratory. The chemical and physicochemical characteristics of Indicaxanthin are reflected in the molecule's reducing properties and antioxidant effects and help explain its ability to interact with membranes, modulate redox-regulated cellular pathways, and possibly bind to protein molecules. Measurement of bioavailability in volunteers has been key to exploring its bioactivity; amounts consistent with dietary intake, or plasma concentration after dietary consumption of cactus pear fruit, have been used in experimental setups mimicking physiological or pathophysiological conditions, in cells and in animals, finally suggesting pharmacological potential and relevance of Indicaxanthin as a nutraceutical. In reporting experimental results, this review also aimed to raise questions and seek insights for further basic research and health promotion applications.

Oxidative stress, lipid peroxidation and premature placental senescence in preeclampsia

Accelerated placental senescence is associated with preeclampsia (PE) and other pregnancy complications. It is characterized by an accelerated decline in placental function due to the accumulation of senescence patterns such as telomere shortening, mitochondrial dysfunction, oxidative damages, increased expression of phosphorylated (serine-139) histone γ-H2AX, a sensitive marker of double-stranded DNA breaks, accumulation of cross-linked ubiquitinated proteins and sirtuin inhibition. Among the lipid oxidation products generated by the peroxidation of polyunsaturated fatty acids, aldehydes such as acrolein, 4-hydroxy-2-nonenal, 4-oxo-2-nonenal, are present in the blood and placenta from PE-affected women and could contribute to PE pathogenesis and accelerated placental aging. In this review we summarize the current knowledge on premature placental senescence and the role of oxidative stress and lipid oxidation-derived aldehydes in this process, as well as their links with PE pathogenesis. The interest of developing (or not) new therapeutic strategies targeting lipid peroxidation is discussed, the objective being a better understanding of accelerated placental aging in PE pathophysiology, and the prevention of PE bad outcomes.

Accumulation of acetaldehyde in aldh2.1 zebrafish causes increased retinal angiogenesis and impaired glucose metabolism

Reactive carbonyl species (RCS) are spontaneously formed in the metabolism and modify and impair the function of DNA, proteins and lipids leading to several organ complications. In zebrafish, knockout of the RCS detoxifying enzymes glyoxalase 1 (Glo 1), aldehyde dehydrogenase 3a1 (Aldh3a1) and aldo-ketoreductase 1a1a (Akr1a1a) showed a signature of elevated RCS which specifically regulated glucose metabolism, hyperglycemia and diabetic organ damage. aldh2.1 was compensatory upregulated in glo1^−/− animals and therefore this study aimed to investigate the detoxification ability for RCS by Aldh2.1 in zebrafish independent of ethanol exposure. aldh2.1 knockout zebrafish were generated using CRISPR/Cas9 and subsequently analyzed on a histological, metabolomic and transcriptomic level. aldh2.1^−/− zebrafish displayed increased endogenous acetaldehyde (AA) inducing an increased angiogenesis in retinal vasculature. Expression and pharmacological interventional studies identified an imbalance of c-Jun N-terminal kinase (JNK) and p38 MAPK induced by AA, which mediate an activation of angiogenesis. Moreover, increased AA in aldh2.1^−/− zebrafish did not induce hyperglycemia, instead AA inhibited the expression of glucokinase (gck) and glucose-6-phosphatase (g6pc), which led to an impaired glucose metabolism. In conclusion, the data have identified AA as the preferred substrate for Aldh2.1's detoxification ability, which subsequently causes microvascular organ damage and impaired glucose metabolism.

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ALDH2.1 was compensatory upregulated in glyoxalase 1 zebrafish mutants.

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Loss of ALDH2.1 increases acetaldehyde leading to vascular retinal alterations.

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Acetaldehyde controls glucose metabolism via glucose-6-phosphate and glucokinase.

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Altered JNK and p38 cause microvascular complications.

Mechanism of quercetin therapeutic targets for Alzheimer disease and type 2 diabetes mellitus

Quercetin has demonstrated antioxidant, anti-inflammatory, hypoglycemic, and hypolipidemic activities, suggesting therapeutic potential against type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD). In this study, potential molecular targets of quercetin were first identified using the Swiss Target Prediction platform and pathogenic targets of T2DM and AD were identified using online Mendelian inheritance in man (OMIM), DisGeNET, TTD, DrugBank, and GeneCards databases. The 95 targets shared among quercetin, T2DM, and AD were used to establish a protein-protein interaction (PPI) network, top 25 core genes, and protein functional modules using MCODE. Metascape was then used for gene ontology and kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis. A protein functional module with best score was obtained from the PPI network using CytoHubba, and 6 high-probability quercetin targets (AKT1, JUN, MAPK, TNF, VEGFA, and EGFR) were confirmed by docking simulations. Molecular dynamics simulation was carried out according to the molecular docking results. KEGG pathway enrichment analysis suggested that the major shared mechanisms for T2DM and AD include "AGE-RAGE signaling pathway in diabetic complications," "pathways in cancer," and "MAPK signaling pathway" (the key pathway). We speculate that quercetin may have therapeutic applications in T2DM and AD by targeting MAPK signaling, providing a theoretical foundation for future clinical research.

Reduced Acrolein Detoxification in akr1a1a Zebrafish Mutants Causes Impaired Insulin Receptor Signaling and Microvascular Alterations

Increased acrolein (ACR), a toxic metabolite derived from energy consumption, is associated with diabetes and its complications. However, the molecular mechanisms are mostly unknown, and a suitable animal model with internal increased ACR does not exist for in vivo studying so far. Several enzyme systems are responsible for acrolein detoxification, such as Aldehyde Dehydrogenase (ALDH), Aldo-Keto Reductase (AKR), and Glutathione S-Transferase (GST). To evaluate the function of ACR in glucose homeostasis and diabetes, akr1a1a-/- zebrafish mutants are generated using CRISPR/Cas9 technology. Accumulated endogenous acrolein is confirmed in akr1a1a-/- larvae and livers of adults. Moreover, a series of experiments are performed regarding organic alterations, the glucose homeostasis, transcriptome, and metabolomics in Tg(fli1:EGFP) zebrafish. Akr1a1a-/- larvae display impaired glucose homeostasis and angiogenic retina hyaloid vasculature, which are caused by reduced acrolein detoxification ability and increased internal ACR concentration. The effects of acrolein on hyaloid vasculature can be reversed by acrolein-scavenger l-carnosine treatment. In adult akr1a1a-/- mutants, impaired glucose tolerance accompanied by angiogenic retina vessels and glomerular basement membrane thickening, consistent with an early pathological appearance in diabetic retinopathy and nephropathy, are observed. Thus, the data strongly suggest impaired ACR detoxification and elevated ACR concentration as biomarkers and inducers for diabetes and diabetic complications.

The role of nitric oxide in ocular surface physiology and pathophysiology

Nitric oxide (NO) has a wide array of biological functions including the regulation of vascular tone, neurotransmission, immunomodulation, stimulation of proinflammatory cytokine expression and antimicrobial action. These functions may depend on the type of isoform that is responsible for the synthesis of NO. NO is found in various ocular tissues playing a pivotal role in physiological mechanisms, namely regulating vascular tone in the uvea, retinal blood circulation, aqueous humor dynamics, neurotransmission and phototransduction in retinal layers. Unregulated production of NO in ocular tissues may result in production of toxic superoxide free radicals that participate in ocular diseases such as endotoxin-induced uveitis, ischemic proliferative retinopathy and neurotoxicity of optic nerve head in glaucoma. However, the role of NO on the ocular surface in mediating physiology and pathophysiological processes is not fully understood. Moreover, methods used to measure levels of NO in the biological samples of the ocular surface are not well established due to its rapid oxidation. The purpose of this review is to highlight the role of NO in the physiology and pathophysiology of ocular surface and propose suitable techniques to measure NO levels in ocular surface tissues and tears. This will improve the understanding of NO's role in ocular surface biology and the development of new NO-based therapies to treat various ocular surface diseases. Further, this review summarizes the biochemistry underpinning NO's antimicrobial action.

Is carbonyl/AGE/RAGE stress a hallmark of the brain aging?

Recent studies have linked carbonyl stress to many physiological processes. Increase in the levels of carbonyl compounds, derived from both endogenous and exogenous sources, is believed to accompany normal age-related decline as well as different pathologies. Reactive carbonyl species (RCS) are capable of damaging biomolecules via their involvement in a net of nonspecific reactions. In the advanced stages of RCS metabolism, variety of poorly degraded adducts and crosslinks, collectively named advanced glycoxidation end products (AGEs), arises. They are accumulated in an age-dependent manner in different tissues and organs and can contribute to inflammatory processes. In particular, detrimental effects of the end products are realized via activation of the specific receptor for AGEs (RAGE) and RAGE-dependent inflammatory signaling cascade. Although it is unclear, whether carbonyl stress is causal for age-associated impairments or it results from age- and disease-related cell damages, increased levels of RCS and AGEs are tightly related to inflammaging, and therefore, attenuation of the RAGE signaling is suggested as an effective approach for the treatment of inflammation and age-related disorders. The question raised in this review is whether specific metabolism in the aging brain related to carbonyl/RCS/AGE/RAGE stress.

Oxidative Stress and Vascular Damage in the Context of Obesity: The Hidden Guest

The vascular system plays a central role in the transport of cells, oxygen and nutrients between different regions of the body, depending on the needs, as well as of metabolic waste products for their elimination. While the structure of different components of the vascular system varies, these structures, especially those of main arteries and arterioles, can be affected by the presence of different cardiovascular risk factors, including obesity. This vascular remodeling is mainly characterized by a thickening of the media layer as a consequence of changes in smooth muscle cells or excessive fibrosis accumulation. These vascular changes associated with obesity can trigger functional alterations, with endothelial dysfunction and vascular stiffness being especially common features of obese vessels. These changes can also lead to impaired tissue perfusion that may affect multiple tissues and organs. In this review, we focus on the role played by perivascular adipose tissue, the activation of the renin-angiotensin-aldosterone system and endoplasmic reticulum stress in the vascular dysfunction associated with obesity. In addition, the participation of oxidative stress in this vascular damage, which can be produced in the perivascular adipose tissue as well as in other components of the vascular wall, is updated.

Role of oxidative stress in the dysfunction of the placental endothelial nitric oxide synthase in preeclampsia

Preeclampsia (PE) is a multifactorial pregnancy disease, characterized by new-onset gestational hypertension with (or without) proteinuria or end-organ failure, exclusively observed in humans. It is a leading cause of maternal morbidity affecting 3–7% of pregnant women worldwide. PE pathophysiology could result from abnormal placentation due to a defective trophoblastic invasion and an impaired remodeling of uterine spiral arteries, leading to a poor adaptation of utero-placental circulation. This would be associated with hypoxia/reoxygenation phenomena, oxygen gradient fluctuations, altered antioxidant capacity, oxidative stress, and reduced nitric oxide (NO) bioavailability. This results in part from the reaction of NO with the radical anion superoxide (O₂^•−), which produces peroxynitrite ONOO^-, a powerful pro-oxidant and inflammatory agent. Another mechanism is the progressive inhibition of the placental endothelial nitric oxide synthase (eNOS) by oxidative stress, which results in eNOS uncoupling via several events such as a depletion of the eNOS substrate L-arginine due to increased arginase activity, an oxidation of the eNOS cofactor tetrahydrobiopterin (BH4), or eNOS post-translational modifications (for instance by S-glutathionylation). The uncoupling of eNOS triggers a switch of its activity from a NO-producing enzyme to a NADPH oxidase-like system generating O₂^•−, thereby potentiating ROS production and oxidative stress. Moreover, in PE placentas, eNOS could be post-translationally modified by lipid peroxidation-derived aldehydes such as 4-oxononenal (ONE) a highly bioreactive agent, able to inhibit eNOS activity and NO production. This review summarizes the dysfunction of placental eNOS evoked by oxidative stress and lipid peroxidation products, and the potential consequences on PE pathogenesis.

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Physiological ROS production is enhanced during pregnancy.

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eNOS is one of the main target of oxidative stress in PE placenta.

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eNOS is S-glutathionylated in PE placentas.

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eNOS is modified by lipid oxidation products in PE placentas.

Age-related alteration in HNE elimination enzymes

4-hydroxynonenal (HNE, 4-hydroxy-2-nonenal) is a primary α,β-unsaturated aldehyde product of lipid peroxidation. The accumulation of HNE increases with aging and the mechanisms are mainly attributable to increased oxidative stress and decreased capacity of HNE elimination. In this review article, we summarize the studies on age-related change of HNE concentration and alteration of HNE metabolizing enzymes (GCL, GST, ALDHs, aldose reductase, and 20S-proteasome), and discuss potential mechanism of age-related decrease in HNE-elimination capacity by focusing on Nrf2 redox signaling.

A Comprehensive Review on Source, Types, Effects, Nanotechnology, Detection, and Therapeutic Management of Reactive Carbonyl Species Associated with Various Chronic Diseases

Continuous oxidation of carbohydrates, lipids, and amino acids generate extremely reactive carbonyl species (RCS). Human body comprises some important RCS namely hexanal, acrolein, 4-hydroxy-2-nonenal, methylglyoxal, malondialdehyde, isolevuglandins, and 4-oxo-2- nonenal etc. These RCS damage important cellular components including proteins, nucleic acids, and lipids, which manifests cytotoxicity, mutagenicity, multitude of adducts and crosslinks that are connected to ageing and various chronic diseases like inflammatory disease, atherosclerosis, cerebral ischemia, diabetes, cancer, neurodegenerative diseases and cardiovascular disease. The constant prevalence of RCS in living cells suggests their importance in signal transduction and gene expression. Extensive knowledge of RCS properties, metabolism and relation with metabolic diseases would assist in development of effective approach to prevent numerous chronic diseases. Treatment approaches for RCS associated diseases involve endogenous RCS metabolizers, carbonyl metabolizing enzyme inducers, and RCS scavengers. Limited bioavailability and bio efficacy of RCS sequesters suggest importance of nanoparticles and nanocarriers. Identification of RCS and screening of compounds ability to sequester RCS employ several bioassays and analytical techniques. Present review describes in-depth study of RCS sources, types, properties, identification techniques, therapeutic approaches, nanocarriers, and their role in various diseases. This study will give an idea for therapeutic development to combat the RCS associated chronic diseases.

Mitochondria and cellular redox state on the route from ageing to Alzheimer's disease

Several theories have been postulated, trying to explain why and how living organisms age. Despite some controversies and still huge open questions, a growing body of evidence suggest alterations of mitochondrial functionality and redox-homeostasis occur during the ageing process. Oxidative damage and mitochondrial dysfunction do not represent the cause of ageing per se but they have to be analyzed within the complexity of those series of processes occurring during lifespan. The establishment of a crosstalk among them is a shared common feature of many chronic age-related diseases, including neurodegenerative disorders, for which ageing is a major risk factor. The challenge is to understand when and how the interplay between these two systems move towards from normal ageing process to a pathological phenotype. Here in this review, we discuss the crosstalk between mitochondria and cytosolic-ROS. Furthermore, through a visual data mining approach, we attempt to describe the dynamic interplay between mitochondria and cellular redox state on the route from ageing to an AD phenotype.

Biomolecules and Electrochemical Tools in Chronic Non-Communicable Disease Surveillance: A Systematic Review

Over recent three decades, the electrochemical techniques have become widely used in biological identification and detection, because it presents optimum features for efficient and sensitive molecular detection of organic compounds, being able to trace quantities with a minimum of reagents and sample manipulation. Given these special features, electrochemical techniques are regularly exploited in disease diagnosis and monitoring. Specifically, amperometric electrochemical analysis has proven to be quite suitable for the detection of physiological biomarkers in monitoring health conditions, as well as toward the control of reactive oxygen species released in the course of oxidative burst during inflammatory events. Besides, electrochemical detection techniques involve a simple and swift assessment that provides a low detection-limit for most of the molecules enclosed biological fluids and related to non-transmittable morbidities.

The relevance of pathophysiological alterations in redox signaling of 4-hydroxynonenal for pharmacological therapies of major stress-associated diseases

Modern analytical methods combined with the modern concepts of redox signaling revealed 4-hydroxy-2-nonenal (4-HNE) as particular growth regulating factor involved in redox signaling under physiological and pathophysiological circumstances. In this review current knowledge of the relevance of 4-HNE as "the second messenger of reactive oxygen species" (ROS) in redox signaling of representative major stress-associated diseases is briefly summarized. The findings presented allow for 4-HNE to be considered not only as second messenger of ROS, but also as one of fundamental factors of the stress- and age-associated diseases. While standard, even modern concepts of molecular medicine and respective therapies in majority of these diseases target mostly the disease-specific symptoms. 4-HNE, especially its protein adducts, might appear to be the bioactive markers that would allow better monitoring of specific pathophysiological processes reflecting their complexity. Eventually that could help development of advanced integrative medicine approach for patients and the diseases they suffer from on the personalized basis implementing biomedical remedies that would optimize beneficial effects of ROS and 4-HNE to prevent the onset and progression of the illness, perhaps even providing the real cure.

Measurement of Enzymatic and Nonenzymatic Polyunsaturated Fatty Acid Oxidation Products in Plasma and Urine of Macular Degeneration Using LC-QTOF-MS/MS

Oxidized polyunsaturated fatty acids (PUFA) are associated to pathogenesis of diseases including cardiovascular and neurodegeneration. The novel products are not only biomarkers but also lipid mediators in gene regulation and signaling pathways. Herein, simultaneous quantitation of 28 products derived from nonenzymatic and enzymatic oxidation of PUFA i.e. 5-, 15-F_2t -isoprostanes, 7-, 17-F_2t -dihomo-isoprostanes, 7-, 17-F_2t -dihomo-isofurans, 5-, 8-, 18-F_3t -isoprostanes, 4-, 10-, 13-, 14-, 20-F_4t -neuroprostanes, 5-, 8-, 9-, 11-,12-, 15-, 20-HETE, 4-, 7-, 11-, 14-, 17-HDHA, RvE1, and NPD1 using LC-(ESI)-QTOF-MS/MS was developed. These products were measurable in a single sample and the analytical time was relative short (~15 min). Furthermore, we showed that the use of internal standards is a requisite to normalize matrix effects and preparation loss for the quantitation. Validation assays indicated the method to be robust for plasma and mid-stream urine sample analysis in particular from those of age-related macular degeneration subjects, where the accuracy of quantitation displayed good repeatability.

Molecular mechanisms by which iNOS uncoupling can induce cardiovascular dysfunction during sepsis: Role of posttranslational modifications (PTMs)

Human sepsis is the result of a multifaceted pathological process causing marked dysregulation of cardiovascular responses. A more sophisticated understanding of the pathogenesis of sepsis is certainly prerequisite. Evidence from studies provide further insight into the role of inducible nitric oxide synthase (iNOS) isoform. Results on inhibition of iNOS in sepsis models remain inconclusive. Concern has been devoted to improving our knowledge and understanding of the role of iNOS. The aim of this review is to define the role of iNOS in redox homeostasis disturbance, the detailed mechanisms linking iNOS and posttranslational modifications (PTMs) to cardiovascular dysfunctions, and their future implications in sepsis settings. Many questions related to the iNOS and PTMs still remain open, and much more work is needed on this.

Reactive Carbonyls Induce TOR- and Carbohydrate-Dependent Hormetic Response in Yeast

The induction of the beneficial and detrimental effects by reactive carbonyl species in yeast has been investigated. In this study, we have presented evidence that glyoxal and methylglyoxal at low concentrations were able to induce a hormetic adaptive response in glucose-grown but not fructose-grown yeast. The hormetic effect was also TOR-dependent. The mutation in genes encoding either TOR1 or TOR2 protein makes yeast highly sensitive to both α-dicarbonyls studied. Simultaneous disruption of TOR1 and TOR2 resulted in higher yeast sensitivity to the α-dicarbonyls as compared to parental cells, but double mutant survived better under carbonyl stress than its single mutant counterparts. The data obtained are consistent with the previous works which reported high toxicity of the α-dicarbonyls and extend them with the report on the beneficial TOR-dependent hormetic effect of glyoxal and methylglyoxal.

Optimization of Ethanol Production using Nitrosative Stress Exposed S.cerevisiae

S.cerevisiae is an industrially important organism known for its ability to produce ethanol as the demand for ethanol is increasing day by day all over the world, the need to find better and alternative ways to increase ethanol production is also rising. In this work we have proposed such alternative but effective method for producing ethanol by S.cerevisiae. Here, we are reporting for the first time the effect of nitrosative stress on ethanol production. Under in vivo condition, nitrosative stress is marked by the modification of macromolecules in the presence of reactive nitrogen species (RNS). Our result showed that treated cells were more capable for ethanol production compared with untreated cells. Our result also showed enhanced alcohol dehydrogenase activity under stressed condition. Further ethanol production was also optimized by using Response Surface Methodology (RSM) with stressed cells. Further, production of ethanol with immobilized beads of stress affected Saccharomyces cerevisiae was also determined. Overall, the obtained data showed that under nitrosative stress, the maximum ethanol production is 34.4 g/l after 24 h and such higher production was observed even after several cycles of fermentation. This is the first report of this kind showing the relation between nitrosative stress and ethanol production in Saccharomyces cerevisiae which may have important industrial application.

Modification of endothelial nitric oxide synthase by 4-oxo-2(E)-nonenal(ONE) in preeclamptic placentas

Preeclampsia (PE) is a leading cause of pregnancy complications, affecting 3-7% of pregnant women worldwide. The pathophysiology of preeclampsia involves a redox imbalance, oxidative stress and a reduced nitric oxide (NO) bioavailability. The molecular and cellular mechanisms leading to the dysfunction of the placental endothelial NO synthase (eNOS) are not clarified. This study was designed to investigate whether aldehydes generated by lipid peroxidation products (LPP), may contribute to placental eNOS dysfunction in PE. The analysis of placentas from PE-affected patients and normal pregnancies, showed a significant increase in protein carbonyl content, indicative of oxidative stress-induced protein modification, as shown by the accumulation of acrolein, 4-hydroxynonenal (HNE), and 4-oxo-2(E)-nonenal (ONE) adducts in PE placentas. In contrast, the levels of these LPP-adducts were low in placentas from normal pregnancies. Immunofluorescence and confocal experiments pointed out a colocalization of eNOS with ONE-Lys adducts, whereas eNOS was not modified in normal placentas. LC-MS/MS analysis of recombinant eNOS preincubated with ONE, allowed to identify several ONE-modified Lys-containing peptides, confirming that eNOS may undergo post-translational modification by LPP. The preincubation of HTR-8/SVneo human trophoblasts (HTR8) with ONE, resulted in ONE-Lys modification of eNOS and a reduced generation of NO. ONE inhibited the migration of HTR8 trophoblasts in the wound closure model, and this was partly restored by the NO donor, NOC-18, which confirmed the important role of NO in the invasive potential of trophoblasts. In conclusion, placental eNOS is modified by ONE in PE placentas, which emphasizes the sensitivity of this protein to oxidative stress in the disturbed redox environment of preeclamptic pregnancies.

Mitochondria as a Source and a Target for Uremic Toxins

Elucidation of molecular and cellular mechanisms of the uremic syndrome is a very challenging task. More than 130 substances are now considered to be "uremic toxins" and represent a very diverse group of molecules. The toxicity of these molecules affects many cellular processes, and expectably, some of them are able to disrupt mitochondrial functioning. However, mitochondria can be the source of uremic toxins as well, as the mitochondrion can be the site of complete synthesis of the toxin, whereas in some scenarios only some enzymes of the pathway of toxin synthesis are localized here. In this review, we discuss the role of mitochondria as both the target and source of pathological processes and toxic compounds during uremia. Our analysis revealed about 30 toxins closely related to mitochondria. Moreover, since mitochondria are key regulators of cellular redox homeostasis, their functioning might directly affect the production of uremic toxins, especially those that are products of oxidation or peroxidation of cellular components, such as aldehydes, advanced glycation end-products, advanced lipoxidation end-products, and reactive carbonyl species. Additionally, as a number of metabolic products can be degraded in the mitochondria, mitochondrial dysfunction would therefore be expected to cause accumulation of such toxins in the organism. Alternatively, many uremic toxins (both made with the participation of mitochondria, and originated from other sources including exogenous) are damaging to mitochondrial components, especially respiratory complexes. As a result, a positive feedback loop emerges, leading to the amplification of the accumulation of uremic solutes. Therefore, uremia leads to the appearance of mitochondria-damaging compounds, and consecutive mitochondrial damage causes a further rise of uremic toxins, whose synthesis is associated with mitochondria. All this makes mitochondrion an important player in the pathogenesis of uremia and draws attention to the possibility of reducing the pathological consequences of uremia by protecting mitochondria and reducing their role in the production of uremic toxins.

Differential effects of N-acetylcysteine on retinal degeneration in two mouse models of normal tension glaucoma

N-acetylcysteine (NAC) is widely used as a mucolytic agent and as an antidote to paracetamol overdose. NAC serves as a precursor of cysteine and stimulates the synthesis of glutathione in neural cells. Suppressing oxidative stress in the retina may be an effective therapeutic strategy for glaucoma, a chronic neurodegenerative disease of the retinal ganglion cells (RGCs) and optic nerves. Here we examined the therapeutic potential of NAC in two mouse models of normal tension glaucoma, in which excitatory amino-acid carrier 1 (EAAC1) or glutamate/aspartate transporter (GLAST) gene was deleted. EAAC1 is expressed in retinal neurons including RGCs, whereas GLAST is mainly expressed in Müller glial cells. Intraperitoneal administration of NAC prevented RGC degeneration and visual impairment in EAAC1-deficient (knockout; KO) mice, but not in GLAST KO mice. In EAAC1 KO mice, oxidative stress and autophagy were suppressed with increased glutathione levels by NAC treatment. Our findings suggest a possibility that systemic administration of NAC may be available for some types of glaucoma patients.

Maintaining a Healthy Proteome during Oxidative Stress

Some of the most challenging stress conditions that organisms encounter during their lifetime involve the transient accumulation of reactive oxygen and chlorine species. Extremely reactive to amino acid side chains, these oxidants cause widespread protein unfolding and aggregation. It is therefore not surprising that cells draw on a variety of different strategies to counteract the damage and maintain a healthy proteome. Orchestrated largely by direct changes in the thiol oxidation status of key proteins, the response strategies involve all layers of protein protection. Reprogramming of basic biological functions helps decrease nascent protein synthesis and restore redox homeostasis. Mobilization of oxidative stress-activated chaperones and production of stress-resistant non-proteinaceous chaperones prevent irreversible protein aggregation. Finally, redox-controlled increase in proteasome activity removes any irreversibly damaged proteins. Together, these systems pave the way to restore protein homeostasis and enable organisms to survive stress conditions that are inevitable when living an aerobic lifestyle.

Clair WH, St. Clair DK. Redox Paradox: A Novel Approach to Therapeutics-Resistant Cancer

SIGNIFICANCE

Cancer cells that are resistant to radiation and chemotherapy are a major problem limiting the success of cancer therapy. Aggressive cancer cells depend on elevated intracellular levels of reactive oxygen species (ROS) to proliferate, self-renew, and metastasize. As a result, these aggressive cancers maintain high basal levels of ROS compared with normal cells. The prominence of the redox state in cancer cells led us to consider whether increasing the redox state to the condition of oxidative stress could be used as a successful adjuvant therapy for aggressive cancers. Recent Advances: Past attempts using antioxidant compounds to inhibit ROS levels in cancers as redox-based therapy have met with very limited success. However, recent clinical trials using pro-oxidant compounds reveal noteworthy results, which could have a significant impact on the development of strategies for redox-based therapies.

CRITICAL ISSUES

The major objective of this review is to discuss the role of the redox state in aggressive cancers and how to utilize the shift in redox state to improve cancer therapy. We also discuss the paradox of redox state parameters; that is, hydrogen peroxide (H2O2) as the driver molecule for cancer progression as well as a target for cancer treatment.

FUTURE DIRECTIONS

Based on the biological significance of the redox state, we postulate that this system could potentially be used to create a new avenue for targeted therapy, including the potential to incorporate personalized redox therapy for cancer treatment.

Chemical kinetics in an atmospheric pressure helium plasma containing humidity

Atmospheric pressure plasmas are sources of biologically active oxygen and nitrogen species, which makes them potentially suitable for the use as biomedical devices. Here, experiments and simulations are combined to investigate the formation of the key reactive oxygen species, atomic oxygen (O) and hydroxyl radicals (OH), in a radio-frequency driven atmospheric pressure plasma jet operated in humidified helium. Vacuum ultra-violet high-resolution Fourier-transform absorption spectroscopy and ultra-violet broad-band absorption spectroscopy are used to measure absolute densities of O and OH. These densities increase with increasing H2O content in the feed gas, and approach saturation values at higher admixtures on the order of 3 × 1014 cm-3 for OH and 3 × 1013 cm-3 for O. Experimental results are used to benchmark densities obtained from zero-dimensional plasma chemical kinetics simulations, which reveal the dominant formation pathways. At low humidity content, O is formed from OH+ by proton transfer to H2O, which also initiates the formation of large cluster ions. At higher humidity content, O is created by reactions between OH radicals, and lost by recombination with OH. OH is produced mainly from H2O+ by proton transfer to H2O and by electron impact dissociation of H2O. It is lost by reactions with other OH molecules to form either H2O + O or H2O2. Formation pathways change as a function of humidity content and position in the plasma channel. The understanding of the chemical kinetics of O and OH gained in this work will help in the development of plasma tailoring strategies to optimise their densities in applications.

Lipid peroxidation biomarkers for evaluating oxidative stress in equine neuroaxonal dystrophy

BACKGROUND

Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disorder affecting genetically predisposed foals maintained on an α-tocopherol (α-TOH) deficient diet. Currently no antemortem diagnostic test for eNAD/EDM is available.

HYPOTHESIS

Because α-TOH deficiency is associated with increased lipid peroxidation, it was hypothesized that F2 -isoprostanes (F2 IsoP), F4 -neuroprostanes (F4 NP) and oxysterols derived from free radical oxidation would be increased in the cerebrospinal fluid (CSF) and neural tissue of eNAD/EDM affected horses and could serve as potential biomarkers for disease.

ANIMALS

Isoprostane Study A: 14 Quarter horse foals (10 healthy foals and 4 eNAD/EDM affected foals) at 1 and 6 months of age. Isoprostane Study B: 17 eNAD/EDM affected and 10 unaffected horses ≥ 1-4 years of age. Oxysterol study: eNAD/EDM affected (n = 14, serum; n = 11, CSF; n = 10, spinal cord [SC]) and unaffected horses 1-4 years of age (n = 12, serum; n = 10, CSF; n = 7, SC).

PROCEDURES

Cerebrospinal fluid [F2 IsoP] and [F4 NP] were assessed using gas chromatography-negative ion chemical ionization mass spectrometry. Serum, CSF, and cervical SC [oxysterols] were quantified using high performance liquid chromatography mass spectrometry. Results were compared with respective α-TOH concentrations.

RESULTS

Spinal cord [7-ketocholesterol], [7-hydroxycholesterol], and [7-keto-27-hydrocholesterol] were higher in eNAD/EDM horses whereas [24-ketocholesterol] was lower. No significant difference was found in CSF [F2 IsoP] and [F4 NP], serum [oxysterols] and CSF [oxysterols] between eNAD/EDM affected and unaffected horses. No correlation was found between [F2 IsoP], [F4 NP], or [oxysterols] and respective [α-TOH].

CONCLUSIONS AND CLINICAL IMPORTANCE

In the SC, targeted markers of cholesterol oxidation were significantly increased in horses with eNAD/EDM.

Modulation of the Oxidative Stress and Lipid Peroxidation by Endocannabinoids and Their Lipid Analogues

Growing evidence supports the pivotal role played by oxidative stress in tissue injury development, thus resulting in several pathologies including cardiovascular, renal, neuropsychiatric, and neurodegenerative disorders, all characterized by an altered oxidative status. Reactive oxygen and nitrogen species and lipid peroxidation-derived reactive aldehydes including acrolein, malondialdehyde, and 4-hydroxy-2-nonenal, among others, are the main responsible for cellular and tissue damages occurring in redox-dependent processes. In this scenario, a link between the endocannabinoid system (ECS) and redox homeostasis impairment appears to be crucial. Anandamide and 2-arachidonoylglycerol, the best characterized endocannabinoids, are able to modulate the activity of several antioxidant enzymes through targeting the cannabinoid receptors type 1 and 2 as well as additional receptors such as the transient receptor potential vanilloid 1, the peroxisome proliferator-activated receptor alpha, and the orphan G protein-coupled receptors 18 and 55. Moreover, the endocannabinoids lipid analogues N-acylethanolamines showed to protect cell damage and death from reactive aldehydes-induced oxidative stress by restoring the intracellular oxidants-antioxidants balance. In this review, we will provide a better understanding of the main mechanisms triggered by the cross-talk between the oxidative stress and the ECS, focusing also on the enzymatic and non-enzymatic antioxidants as scavengers of reactive aldehydes and their toxic bioactive adducts.

Competing trends of ROS and RNS-mediated protein modifications during hypoxia as an alternate mechanism of NO benefits

Hypoxia, especially altitude associated hypoxia is known to cause severe physiological alterations and life-threatening conditions. Impaired redox balance along with oxidative stress, protein carbonylation and instigation of apoptotic events are common sub-cellular events that follow the hypoxic insult. The role of nitric oxide (NO) is very dynamic and versatile in preventing the ill effects of hypoxia vis-a-vis reacting with oxidative species and causing protein nitrosylation. Although several mechanisms of NO-mediated cytoprotection are known during hypoxic insult, limited pieces of evidence are available to support the relationship between two downstream events of oxidative stress, protein carbonylation (caused by carbonyl; CO radical) and protein nitrosylation/nitration (caused by NO/peroxynitrite; ONOO radical). In this study, we investigated an entirely new aspect of NO protection in hypoxia involving crosstalk between carbonylation and nitrosylation. Using standard NO inhibitor l-NAME and simulated hypoxic conditions in hypoxia-sensitive cell line H9c2, we evaluated the levels of radicals, cell death, mitochondrial membrane potential, levels of protein nitrosylation, protein nitration and carbonylation and glutathione content. The results were then carefully analyzed in light of NO bioavailability. Our study shows that reducing NO during hypoxia caused cell death via the increased degree of carbonylation in proteins. This provides a new aspect of NO benefits which furthers opens new possibilities to explore potential mechanisms and effects of cross-talk between nitrosylation, protein nitration and carbonylation, especially through some common antioxidant mediators such as glutathione and thioredoxin.

A mitochondria-targeted fluorescent probe for imaging endogenous malondialdehyde in HeLa cells and onion tissues

The mitochondria-targeted turn-on fluorescent probe (Mito-FMP) based on a benzoxadiazole platform was developed for detection of malondialdehyde (MDA). Mito-FMP performed with large enhancement of the optical signal (774-fold) in response to MDA in an aqueous system and has the capability of monitoring endogenous MDA in HeLa cells and onion tissues.

Antioxidants in dermatology

The skin cells continuously produce, through cellular respiration, metabolic processes or under external aggressions, highly reactive molecules oxidation products, generally called free radicals. These molecules are immediately neutralized by enzymatic and non-enzymatic systems in a physiological and dynamic balance. In situations where this balance is broken, various cellular structures, such as the cell membrane, nuclear or mitochondrial DNA may suffer structural modifications, triggering or worsening skin diseases. several substances with alleged antioxidant effects has been offered for topical or oral use, but little is known about their safety, possible associations and especially their mechanism of action. The management of topical and oral antioxidants can help dermatologist to intervene in the oxidative processes safely and effectively, since they know the mechanisms, limitations and potential risks of using these molecules as well as the potential benefits of available associations.

4-Hydroxynonenal metabolites and adducts in pre-carcinogenic conditions and cancer

4-hydroxy-2-nonenal (HNE) is an amazing reactive compound, originating from lipid peroxidation within cells but also in food and considered as a "second messenger" of oxidative stress. Due to its chemical features, HNE is able to make covalent links with DNA, proteins and lipids. The aim of this review is to give a comprehensive summary of the chemical properties of HNE and of the consequences of its reactivity in relation to cancer development. The formation of exocyclic etheno-and propano-adducts and genotoxic effects are addressed. The adduction to cellular proteins and the repercussions on the regulation of cell signaling pathways involved in cancer development are reviewed, notably on the Nrf2/Keap1/ARE pathway. The metabolic pathways leading to the inactivation/elimination or, on the contrary, to the bioactivation of HNE are considered. A special focus is given on the link between HNE and colorectal cancer development, due to its occurrence in foodstuffs and in the digestive lumen, during digestion.

4-hydroxynonenal-mediated signaling and aging

4-Hydroxy-2-nonenal (HNE), one of the major α, β-unsaturated aldehydes produced during lipid peroxidation, is a potent messenger in mediating signaling pathways. Lipid peroxidation and HNE production appear to increase with aging. Although the cause and effect relation remains arguable, aging is associated with significant changes in diverse signaling events, characterized by enhanced or diminished responses of specific signaling pathways. In this review we will discuss how HNE may contribute to aging-related alterations of signaling pathways.

Cancer growth regulation by 4-hydroxynonenal

While reactive oxygen species (ROS) gain their carcinogenic effects by DNA mutations, if generated in the vicinity of genome, lipid peroxidation products, notably 4-hydroxynonenal (HNE), have much more complex modes of activities. Namely, while ROS are short living and have short efficiency distance range (in nm or µm) HNE has strong binding affinity for proteins, thus forming relatively stable adducts. Hence, HNE can diffuse from the site or origin changing structure and function of respective proteins. Consequently HNE can influence proliferation, differentiation and apoptosis of cancer cells on one hand, while on the other it can affect genome functionality, too. Although HNE is considered to be important factor of carcinogenesis due to its ability to covalently bind to DNA, it might also be cytotoxic for cancer cells, as well as it can modulate their growth. In addition to direct cytotoxicity, HNE is also involved in activity mechanisms by which several cytostatic drugs and radiotherapy exhibit their anticancer effects. Complementary to that, the metabolic pathway for HNE detoxification through RLIP76, which is enhanced in cancer, may be a target for anti-cancer treatments. In addition, some cancer cells can undergo apoptosis or necrosis, if exposed to supraphysiological HNE levels in the cancer microenvironment, especially if challenged additionally by pro-oxidative cytostatics and/or inflammation. These findings could explain previously observed disappearance of HNE from invading cancer cells, which is associated with the increase of HNE in non-malignant cells close to invading cancer utilizing cardiolipin as the source of cancer-inhibiting HNE.

The para isomer of dinitrobenzene disrupts redox homeostasis in liver and kidney of male wistar rats

Background

Para-Dinitrobenzene (p-DNB) is one of the isomers of dinitrobenzene which have been detected as environmental toxicants. Skin irritation and organ toxicities are likely for industrial workers exposed to p-DNB. This study evaluated the effect of sub-chronic exposure of rats to p-DNB on cellular redox balance, hepatic and renal integrity.

Methods

Forty eight male Wistar rats weighing 160–180 g were administered 50, 75, 1000 and 2000 mg/kg b.wt (body weight) of p-DNB or an equivalent volume of vehicle (control) orally and topically for 14 days. After the period of treatment, the activities of kidney and liver catalase (CAT), alkaline phosphatase (ALP) and superoxide dismutase (SOD) as well as extent of renal and hepatic lipid peroxidation (LPO) were determined. Serum ALP activity and plasma urea concentration were also evaluated.

Results

Compared with control animals, p-DNB -administered rats showed decrease in the body and relative kidney and liver weights as well as increased renal and hepatic hydrogen peroxide and lipid peroxidation levels accompanied by decreased superoxide dismutase and catalase activities. However, p-DNB caused a significant increase in plasma urea concentration and serum, liver and kidney ALP activities relative to control. In addition, p-DNB caused periportal infiltration, severe macro vesicular steatosis and hepatic necrosis in the liver.

Conclusions

Our findings show that sub-chronic oral and sub-dermal administration of p-DNB may produce hepato-nephrotoxicity through oxidative stress.

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Activities of kidney and liver catalase and superoxide dismutase were decreased by p-DNB.

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p-DNB increased serum, liver and kidney activity of alkaline phosphatase.

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Plasma urea concentration was increased by p-DNB.

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Lipid peroxidation and H₂O₂ level were increased by p-DNB.

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p-DNB caused histopathological changes in liver and kidney tissues.

In vivo ROS production and use of oxidative stress-derived biomarkers to detect the onset of diseases such as Alzheimer's disease, Parkinson's disease, and diabetes

Breakthroughs in biochemistry have furthered our understanding of the onset and progression of various diseases, and have advanced the development of new therapeutics. Oxidative stress and reactive oxygen species (ROS) are ubiquitous in biological systems. ROS can be formed non-enzymatically by chemical, photochemical and electron transfer reactions, or as the byproducts of endogenous enzymatic reactions, phagocytosis, and inflammation. Imbalances in ROS homeostasis, caused by impairments in antioxidant enzymes or non-enzymatic antioxidant networks, increase oxidative stress, leading to the deleterious oxidation and chemical modification of biomacromolecules such as lipids, DNA, and proteins. While many ROS are intracellular signaling messengers and most products of oxidative metabolisms are beneficial for normal cellular function, the elevation of ROS levels by light, hyperglycemia, peroxisomes, and certain enzymes causes oxidative stress-sensitive signaling, toxicity, oncogenesis, neurodegenerative diseases, and diabetes. Although the underlying mechanisms of these diseases are manifold, oxidative stress caused by ROS is a major contributing factor in their onset. This review summarizes the relationship between ROS and oxidative stress, with special reference to recent advancements in the detection of biomarkers related to oxidative stress. Further, we will introduce biomarkers for the early detection of neurodegenerative diseases and diabetes, with a focus on our recent work.

DNA damage by lipid peroxidation products: implications in cancer, inflammation and autoimmunity

Oxidative stress and lipid peroxidation (LPO) induced by inflammation, excess metal storage and excess caloric intake cause generalized DNA damage, producing genotoxic and mutagenic effects. The consequent deregulation of cell homeostasis is implicated in the pathogenesis of a number of malignancies and degenerative diseases. Reactive aldehydes produced by LPO, such as malondialdehyde, acrolein, crotonaldehyde and 4-hydroxy-2-nonenal, react with DNA bases, generating promutagenic exocyclic DNA adducts, which likely contribute to the mutagenic and carcinogenic effects associated with oxidative stress-induced LPO. However, reactive aldehydes, when added to tumor cells, can exert an anticancerous effect. They act, analogously to other chemotherapeutic drugs, by forming DNA adducts and, in this way, they drive the tumor cells toward apoptosis. The aldehyde-DNA adducts, which can be observed during inflammation, play an important role by inducing epigenetic changes which, in turn, can modulate the inflammatory process. The pathogenic role of the adducts formed by the products of LPO with biological macromolecules in the breaking of immunological tolerance to self antigens and in the development of autoimmunity has been supported by a wealth of evidence. The instrumental role of the adducts of reactive LPO products with self protein antigens in the sensitization of autoreactive cells to the respective unmodified proteins and in the intermolecular spreading of the autoimmune responses to aldehyde-modified and native DNA is well documented. In contrast, further investigation is required in order to establish whether the formation of adducts of LPO products with DNA might incite substantial immune responsivity and might be instrumental for the spreading of the immunological responses from aldehyde-modified DNA to native DNA and similarly modified, unmodified and/or structurally analogous self protein antigens, thus leading to autoimmunity.

Subcellular Redox Targeting: Bridging in Vitro and in Vivo Chemical Biology

Networks of redox sensor proteins within discrete microdomains regulate the flow of redox signaling. Yet, the inherent reactivity of redox signals complicates the study of specific redox events and pathways by traditional methods. Herein, we review designer chemistries capable of measuring flux and/or mimicking subcellular redox signaling at the cellular and organismal level. Such efforts have begun to decipher the logic underlying organelle-, site-, and target-specific redox signaling in vitro and in vivo. These data highlight chemical biology as a perfect gateway to interrogate how nature choreographs subcellular redox chemistry to drive precision redox biology.