Free radical biology - terminology and critical thinking

Diphlorethohydroxycarmalol inhibits Müller cell gliosis by disrupting CXCR4/CXCL12 interaction in violet-blue light-induced retinal phototoxicity

Müller gliosis is a complex process that impairs the ability of retinal Müller glial cells to respond to various forms of retinal injury or disease, leading to retinal damage. Blue light (BL) exposure is a known cause of retinal damage. In this study, we aimed to investigate the potential of DPHC in inhibiting Müller gliosis in models of BL-exposure. We conducted in silico binding analysis to evaluate the binding of DPHC to CXCR4. Then, we developed in vitro and in vivo experimental models to assess the effects of DPHC and BL exposure on Müller gliosis using MIO-M1 cells and zebrafish. Our findings show that DPHC can suppress the Müller gliosis process in BL-exposed MIO-M1 cells in vitro and in BL-exposed zebrafish in vivo. In silico molecular docking, we identified CXCR4 as the target of active site 1 of DPHC. In BL-exposed MIO-M1 cells, DPHC inhibited CXCR4 activity and altered the expression of Müller gliosis markers and NF-κB-related ERK and AKT signaling. In BL-exposed zebrafish, DPHC prevented retinal thickness reduction and inhibited CXCR4 expression and retinal cell apoptosis. This study suggests that DPHC could be a potential therapeutic agent for retinal diseases involving Müller gliosis. By inhibiting CXCR4 activity, DPHC downregulates the ERK/AKT/NF-κB pathway, reducing retinal cell apoptosis and altered expression of Müller gliosis markers. These findings highlight the potential of natural bioactive compounds for treating various diseases, and further research should investigate the therapeutic potential of DPHC and its derivatives.

Effects of oxygen levels and temperature on growth and physiology of pikeperch juveniles cultured in a recirculating aquaculture system

This study aimed to understand how environmental factors, specifically water temperature and oxygen saturation, affect the growth performance and physiology of pikeperch (Sander lucioperca) juveniles in recirculating aquaculture systems (RASs). Given the importance of optimising growth conditions in aquaculture to maximise efficiency, it aims to assess whether different combinations of oxygen levels and temperatures can enhance growth while maintaining the physiological health and welfare of the fish. The experimental design included the culturing pikeperch juveniles (22.7 ± 7.1 g) were exposed to hypoxia (78 ± 14%), normoxia (105 ± 12%), and hyperoxia (140 ± 18%) conditions for 72 days. This was conducted at two temperatures, 20 °C and 23 °C, each in a separate but identical RAS. The level of oxygen supply was controlled with micro bubble diffusers on the bottom of each tank. The hyperoxia at 23 °C positively affected total length, BW, specific growth rate, feed intake and feed conservation rate (FCR). The slowest growth and feed intake, along with the highest FCR, were observed in hypoxia at 20 °C. Fish reared under 23 °C exhibited significantly higher visceral-somatic index (3.54 ± 0.83 at 23 °C and 2.76 ± 0.73 at 20 °C) regardless of oxygen levels. It was primarily responsible for the observed growth difference (Final BW: 58.3 ± 18.8 g at 23 °C and 53.0 ± 18.3 g at 20 °C). The water temperature also affected haematocrit, haemoglobin, leucocyte count, mean corpuscular haemoglobin, mean corpuscular volume (MCV) of the blood cells; the concentration of lymphocytes, neutrophile granulocyte bands and segments. Among biochemical markers, temperature affected cytoplasmic and mitochondrial enzymes, ammonia and triglyceride levels in blood plasma. Elevated antioxidant activity was observed in muscle, intestine and liver tissues. Oxygen levels demonstrated significant effects on growth, feed intake and conversion, the MCV of the blood cells, the concentration of the glucose, lactate and ammonia in blood plasma, and antioxidant biomarkers in the liver tissue. The analysis indicated a significant effect of oxygen on energy metabolism. The results showed hyperoxia under 23 °C create conditions for the highest growth and feed intake, high feed utilisation. There are, however, concerns about the physiological conditions and welfare of intensively cultured pikeperch juveniles, as higher feed intake led to increased visceral fat content in the body, elevated antioxidant activity in the liver, muscle and intestine tissues, morphology of blood cell, and energy metabolism.

Exploring the anticancer potential of new 3-cyanopyridine derivatives bearing N-acylhydrazone motif: Synthesis, DFT calculations, cytotoxic evaluation, molecular modeling, and antioxidant properties

3-Cyanopyridine derivatives are known for exhibiting excellent anticancer activity due to their strong capability to inhibit various biological targets, including Pim-1 kinase, survivin, and tubulin polymerization. On the other hand, N-acylhydrazones (NAH) are known to be a very versatile motif in medicinal chemistry and drug design. Based on these data, we report in this paper, the synthesis of novel 3-cyanopyridines incorporating N-acyl hydrazine scaffold, the evaluation of their cytotoxicity on the breast (MCF-7) and ovarian (A-2780) cancer cell lines and their antioxidant properties. Excluding 4a and 4d, all tested molecules exhibited high cytotoxicity against A-2780, with IC50 values ranging from 1.14 to 1.76 µM. Conversely, only four molecules 3d, 4b, 4c, and 4d demonstrated cytotoxicity against MCF-7, with IC50 values ranging from 1.14 to 3.38 µM. On the other hand, all the tested molecules exhibited a moderate antioxidant capacity in both the DPPH and metal chelation assays. Docking and molecular dynamics studies revealed that 2d, 3d, and 4d are potential inhibitors of tubulin and the œstrogen receptor, which may explain their high cytotoxicity. These results are promising to study these newly synthesized 3-cyanopyridine-N-acylhydrazones in depth for use as potential anticancer candidates.

Perceiving the functions of vitamin E through neutron and X-ray scattering

Take your vitamins, or don't? Vitamin E is one of the few lipophilic vitamins in the human diet and is considered an essential nutrient. Over the years it has proven to be a powerful antioxidant and is commercially used as such, but this association is far from linear in physiology. It is increasingly more likely that vitamin E has multiple legitimate biological roles. Here, we review past and current work using neutron and X-ray scattering to elucidate the influence of vitamin E on key features of model membranes that can translate to the biological function(s) of vitamin E. Although progress is being made, the hundred year-old mystery remains unsolved.

Deferoxamine protects cochlear hair cells and hair cell-like HEI-OC1 cells against tert-butyl hydroperoxide-induced ototoxicity

Oxidative stress is the common mechanism of sensorineural hearing loss (SNHL) caused by many factors, such as noise, drugs and ageing. Here, we used tert-butyl hydroperoxide (t-BHP) to cause oxidative stress damage in HEI-OC1 cells and in an in vitro cochlear explant model. We observed lipid peroxidation, iron accumulation, mitochondrial shrinkage and vanishing of mitochondrial cristae, which caused hair cell ferroptosis, after t-BHP exposure. Moreover, the number of TUNEL-positive cells in cochlear explants and HEI-OC1 cells increased significantly, suggesting that t-BHP caused the apoptosis of hair cells. Administration of deferoxamine (DFOM) significantly attenuated t-BHP-induced hair cell loss and disordered hair cell arrangement in cochlear explants as well as HEI-OC1 cell death, including via apoptosis and ferroptosis. Mechanistically, we found that DFOM treatment reduced t-BHP-induced lipid peroxidation, iron accumulation and mitochondrial pathological changes in hair cells, consequently mitigating apoptosis and ferroptosis. Moreover, DFOM treatment alleviated GSH depletion caused by t-BHP and activated the Nrf2 signalling pathway to exert a protective effect. Furthermore, we confirmed that the protective effect of DFOM mainly depended on its ability to chelate iron by constructing Fth1 knockout (KO), TfR1 KO and Nrf2 KO HEI-OC1 cell lines using CRISPR/Cas9 technology and a Flag-Fth1 (overexpression) HEI-OC1 cell line using the FlpIn™ System. Our findings suggest that DFOM is a potential drug for SNHL treatment due to its ability to inhibit apoptosis and ferroptosis by chelating iron and scavenging reactive oxygen species (ROS).

Mitophagy-promoting agents and their ability to promote healthy-aging

The removal of damaged mitochondrial components through a process called mitochondrial autophagy (mitophagy) is essential for the proper function of the mitochondrial network. Hence, mitophagy is vital for the health of all aerobic animals, including humans. Unfortunately, mitophagy declines with age. Many age-associated diseases, including Alzheimer's and Parkinson's, are characterized by the accumulation of damaged mitochondria and oxidative damage. Therefore, activating the mitophagy process with small molecules is an emerging strategy for treating multiple aging diseases. Recent studies have identified natural and synthetic compounds that promote mitophagy and lifespan. This article aims to summarize the existing knowledge about these substances. For readers' convenience, the knowledge is presented in a table that indicates the chemical data of each substance and its effect on lifespan. The impact on healthspan and the molecular mechanism is reported if known. The article explores the potential of utilizing a combination of mitophagy-inducing drugs within a therapeutic framework and addresses the associated challenges of this strategy. Finally, we discuss the process that balances mitophagy, i.e. mitochondrial biogenesis. In this process, new mitochondrial components are generated to replace the ones cleared by mitophagy. Furthermore, some mitophagy-inducing substances activate biogenesis (e.g. resveratrol and metformin). Finally, we discuss the possibility of combining mitophagy and biogenesis enhancers for future treatment. In conclusion, this article provides an up-to-date source of information about natural and synthetic substances that activate mitophagy and, hopefully, stimulates new hypotheses and studies that promote healthy human aging worldwide.

Sulodexide Prevents Hyperglycemia-Induced Endothelial Dysfunction and Oxidative Stress in Porcine Retinal Arterioles

Diabetes mellitus may cause severe damage to retinal blood vessels. The central aim of this study was to test the hypothesis that sulodexide, a mixture of glycosaminoglycans, has a protective effect against hyperglycemia-induced endothelial dysfunction in the retina. Functional studies were performed in isolated porcine retinal arterioles. Vessels were cannulated and incubated with highly concentrated glucose solution (HG, 25 mM D-glucose) +/- sulodexide (50/5/0.5 μg/mL) or normally concentrated glucose solution (NG, 5.5 mM D-glucose) +/- sulodexide for two hours. Endothelium-dependent and endothelium-independent vasodilatation were measured by videomicroscopy. Reactive oxygen species (ROS) were quantified by dihydroethidium (DHE) fluorescence. Using high-pressure liquid chromatography (HPLC), the intrinsic antioxidant properties of sulodexide were investigated. Quantitative PCR was used to determine mRNA expression of regulatory, inflammatory, and redox genes in retinal arterioles, some of which were subsequently quantified at the protein level by immunofluorescence microscopy. Incubation of retinal arterioles with HG caused significant impairment of endothelium-dependent vasodilation, whereas endothelium-independent responses were not affected. In the HG group, ROS formation was markedly increased in the vascular wall. Strikingly, sulodexide had a protective effect against hyperglycemia-induced ROS formation in the vascular wall and had a concentration-dependent protective effect against endothelial dysfunction. Although sulodexide itself had only negligible antioxidant properties, it prevented hyperglycemia-induced overexpression of the pro-oxidant redox enzymes, NOX4 and NOX5. The data of the present study provide evidence that sulodexide has a protective effect against hyperglycemia-induced oxidative stress and endothelial dysfunction in porcine retinal arterioles, possibly by modulation of redox enzyme expression.

Enzymatic Recording of Local Hydrogen Peroxide Generation Using Genetically Encodable Enzyme

Reactive oxygen species (ROS) are endogenously generated in live cells and essential for cell signaling. However, excess ROS generation can cause oxidative damage to biomolecules, which are implicated in various human diseases, including aging. Here, we developed an in vivo hydrogen peroxide monitoring method using a genetically encodable peroxidase (APEX2)-based system. We confirmed that APEX2 is activated by endogenous H₂O₂ and generates phenoxyl radicals to produce biotinylated signals (i.e., biotin-phenol) and fluorescent signals (i.e., AmplexRed), which can be detected using a fluorescence microscope. We observed that all subcellular targeted APEX2s were activated by local H₂O₂ generation by menadione treatment. Among them, the endoplasmic reticulum lumen and lysosome-targeted APEX2 showed the highest response upon addition of menadione which implies that local H₂O₂ levels in those spaces are highly increased by menadione treatment. Using APEX2, we also found that a minimum amount of menadione (>10 μM) is required to generate detectable levels of H₂O₂ in all subcellular compartments. We also checked the local H₂O₂-quenching effect of N-acetylcysteine using our system. As APEX2 can be genetically expressed in diverse live organisms (e.g., cancer cell lines, mice, fly, worm, and yeast), our method can be effectively used to detect local generation of endogenously produced H₂O₂ in diverse live models.

Study of the Antioxidative Effects of Bombyx mori Silk Sericin in Cultures of Murine Retinal Photoreceptor Cells

The availability of natural substances able to fulfill the role of antioxidants in a physiologic environment is important for the development of therapies against diseases associated with excessive production of reactive oxygen species and ensuing oxidative stress. Antioxidant properties have been reported episodically for sericin, a proteinaceous constituent of the silk thread in the cocoons generated by the larvae of the Lepidoptera order. We investigated the sericin fractions isolated from the cocoons spun by the domesticated (Bombyx mori) silkworm. Three fractions were isolated and evaluated, including two peptidoid fractions, the crude sericin and the purified (dialyzed) sericin, and the non-peptidoid methanolic extract of the crude fraction. When subjected to Trolox equivalent antioxidant capacity (TEAC) assay, the extract showed much higher antioxidant capacity as compared to the crude or purified sericin fractions. The three fractions were also evaluated in cultures of murine retinal photoreceptor cells (661 W), a cell line that is highly susceptible to oxidants and is crucially involved in the retinopathies primarily caused by oxidative stress. The extract displayed a significant dose-dependent protective effect on the cultured cells exposed to hydrogen peroxide. In identical conditions, the crude sericin showed a certain level of antioxidative activity at a higher concentration, while the purified sericin did not show any activity. We concluded that the non-peptidoid components accompanying sericin were chiefly responsible for the previously reported antioxidant capacity associated with sericin fractions, a conclusion supported by the qualitative detection of flavonoids in the extract but not in the purified sericin fraction.

Insights Into the Role of Mitochondria in Vascular Calcification

Vascular calcification (VC) is a growing burden in aging societies worldwide, and with a significant increase in all-cause mortality and atherosclerotic plaque rupture, it is frequently found in patients with aging, diabetes, atherosclerosis, or chronic kidney disease. However, the mechanism of VC is still not yet fully understood, and there are still no effective therapies for VC. Regarding energy metabolism factories, mitochondria play a crucial role in maintaining vascular physiology. Discoveries in past decades signifying the role of mitochondrial homeostasis in normal physiology and pathological conditions led to tremendous advances in the field of VC. Therapies targeting basic mitochondrial processes, such as energy metabolism, damage in mitochondrial DNA, or free-radical generation, hold great promise. The remarkably unexplored field of the mitochondrial process has the potential to shed light on several VC-related diseases. This review focuses on current knowledge of mitochondrial dysfunction, dynamics anomalies, oxidative stress, and how it may relate to VC onset and progression and discusses the main challenges and prerequisites for their therapeutic applications.

The redox signal: A physiological perspective

A signal in biology is any kind of coded message sent from one place in an organism to another place. Biology is rich in claims that reactive oxygen and nitrogen species transmit signals. Therefore, we define a "redox signal as an increase/decrease in the level of reactive species". First, as in most biology disciplines, to analyze a redox signal you need first to deconstruct it. The essential components that constitute a redox signal and should be characterized are: (i) the reactivity of the specific reactive species, (ii) the magnitude of change, (iii) the temporal pattern of change, and (iv) the antioxidant condition. Second, to be able to translate the physiological fate of a redox signal you need to apply novel and bioplausible methodological strategies. Important considerations that should be taken into account when designing an experiment is to (i) assure that redox and physiological measurements are at the same or similar level of biological organization and (ii) focus on molecules that are at the highest level of the redox hierarchy. Third, to reconstruct the redox signal and make sense of the chaotic nature of redox processes, it is essential to apply mathematical and computational modeling. The aim of the present study was to collectively present, for the first time, those elements that essentially affect the redox signal as well as to emphasize that the deconstructing, decoding and reconstructing of a redox signal should be acknowledged as central to design better studies and to advance our understanding on its physiological effects.

Sea Buckthorn in Plant Based Diets. An Analytical Approach of Sea Buckthorn Fruits Composition: Nutritional Value, Applications, and Health Benefits

Current nutritional trends include plant-based diets as nutritional behavior of consumers who are increasingly concerned about a healthy lifestyle. Sea buckthorn (Hippophaë rhamnoides L.) is a plant with great virtues, containing more than 100 types of compounds. It is a plant with versatile properties, multiple economic advantages and a rich history, which still continues in natural medicine, and it is hence included in the daily diet by more and more people for the prevention and treatment of diet-related diseases. Its uniqueness is due to its chemical composition and the health beneficial properties that rise from its composition. This review is a detailed analytical picture of the current state of knowledge currently available regarding the Hippophaë plant, providing an overview of the qualities of sea buckthorn. This article summarizes data on sea buckthorn’s nutritional value, health beneficial properties, and its applications.

Analytical Capabilities of Coulometric Sensor Systems in the Antioxidants Analysis

The definition of antioxidants (AOs), their classification and properties as well as electrochemical sensor systems for AOs analysis are briefly discussed. The analytical capabilities of coulometric titration with electrogenerated titrants as sensor systems for AOs determination have been considered in detail. The attention focused on the individual AO quantification that was mainly used in the pharmaceutical analysis and estimation of total antioxidant parameters (total antioxidant capacity (TAC), ferric reducing power (FRP) and ceric reducing/antioxidant capacity (CRAC)) allowing the fast screening of the target samples including their quality control. The main advantages of coulometric sensor systems are pointed out. The selective quantification of individual AO in a complex matrix using a combination of chromatography with coulometric or coulometric array detection under potentiostatic mode is discussed. The future development of coulometric sensor systems for AOs analysis is focused on the application of novel coulometric titrants and the application of coulometric detection in flow injection analysis.

Linking biomarkers of oxidative stress and disease with flavonoid consumption: From experimental models to humans

Identification of the links among flavonoid consumption, mitigation of oxidative stress and improvement of disease in humans has significantly advanced in the last decades. This review used (−)-epicatechin (EC) as an example of dietary flavonoids, and inflammation, endothelial dysfunction/hypertension and insulin resistance/diabetes as paradigms of human disease. In these pathologies, oxidative stress is part of their development and/or their perpetuation. Evidence from both, rodent studies and characterization of mechanisms in cell cultures are encouraging and mostly support indirect antioxidant actions of EC and EC metabolites in endothelial dysfunction and insulin resistance. Human studies also show beneficial effects of EC on these pathologies based on biomarkers of disease. However, there is limited available information on oxidative stress biomarkers and flavonoid consumption to allow establishing conclusive associations. The evolving discovery of metabolites that could serve as reliable markers of intake of specific flavonoids constitutes a powerful tool to link flavonoid consumption to disease and prevention of oxidative stress in human populations.

•

Flavonoid’s metabolism and concentration determine their antioxidant mechanisms.

•

Except for the GI tract, flavonoids are relevant indirect antioxidants in organs and tissues.

•

Flavonoid's health effects are not always linked to biomarkers of oxidative stress.

•

(‒)-Epicatechin mitigates the redox deregulation involved in hypertension/T2D pathogenesis.

•

More human studies will strength links among flavonoids, oxidative stress, and disease.

Burn injury induces elevated inflammatory traffic: the role of NF-κB

A burn insult generally sustains a hypovolemic shock due to a significant loss of plasma from the vessels. The burn injury triggers the release of various mediators, such as reactive oxygen species (ROS), cytokines, and inflammatory mediators. Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs), stemming from foreign microbial discharge and damaged tissue or necrotic cells from the burn-injured site, enter the systemic circulation, activate toll-like receptors (TLRs), and trigger the excessive secretion of cytokines and inflammatory mediators. Inflammation plays a vital role in remodeling an injured tissue, detoxifying toxins, and helps in the healing process. A transcription factor, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), contributes to a variety of physiological and pathological conditions, including immune response, cell death, cell survival, and inflammatory processes. During the pathogenesis of a burn wound, upregulation of various cytokines and growth factors lead to undesirable tissue inflammation. Thus, NF-κB, a dominant moderator of inflammation, needs to be altered to prove beneficial to the treatment of burns or other inflammation-associated diseases. This review addresses the relationship between NF-κB and elevated inflammation in a burn condition that could potentially be altered to induce an early wound-healing mechanism of burn wounds.

Redox Homeostasis and Inflammation Responses to Training in Adolescent Athletes: a Systematic Review and Meta-analysis

Background

Several studies have highlighted the substantial role of the athlete’s redox and inflammation status during the training process. However, many factors such as differences in testing protocols, assays, sample sizes, and fitness levels of the population are affecting findings and the understanding regarding how exercise affects related biomarkers in adolescent athletes.

Objectives

To search redox homeostasis variables’ and inflammatory mediators’ responses in juvenile athletes following short- or long-term training periods and examine the effect size of those variations to training paradigms.

Methods

A PRISMA-compliant systematic review and meta-analysis were conducted. The entire content of PubMed (MEDLINE), Scopus, and Science Direct were systematically searched until December 2019. Studies with outcomes including (1) a group of adolescent athletes from any individual or team sport, (2) the assessment of redox and/or inflammatory markers after a short- (training session or performance testing) or longer training period, and (3) variables measured in blood were retained. The literature search initially identified 346 potentially relevant records, of which 36 studies met the inclusion criteria for the qualitative synthesis. From those articles, 27 were included in the quantitative analysis (meta-analysis) as their results could be converted into common units.

Results

Following a short training session or performance test, an extremely large increase in protein carbonyls (PC) (ES 4.164; 95% CI 1.716 to 6.613; Z = 3.333, p = 0.001), a large increase in thiobarbituric acid reactive substances (TBARS) (ES 1.317; 95% CI 0.522 to 2.112; Z = 3.247, p = 0.001), a large decrease in glutathione (GSH) (ES − 1.701; 95% CI − 2.698 to − 0.705; Z = − 3.347, p = 0.001), and a moderate increase of total antioxidant capacity (TAC) level (ES 1.057; 95% CI − 0.044 to 2.158; Z = 1.882, p = 0.060) were observed. Following more extended training periods, GSH showed moderate increases (ES 1.131; 95% CI 0.350 to 1.913; Z = 2.839, p = 0.005) while TBARS displayed a small decrease (ES 0.568; 95% CI − 0.062 to 1.197; Z = 1.768, p = 0.077). Regarding cytokines, a very large and large increase were observed in IL-6 (ES 2.291; 95% CI 1.082 to 3.501; Z = 3.713, p = 0.000) and IL-1 receptor antagonist (ra) (ES 1.599; 95% CI 0.347 to 2.851; Z = 2.503, p = 0.012), respectively, following short-duration training modalities in juvenile athletes.

Conclusions

The results showed significant alterations in oxidative stress and cytokine levels after acute exercise, ranging from moderate to extremely large. In contrast, the variations after chronic exercise ranged from trivial to moderate. However, the observed publication bias and high heterogeneity in specific meta-analysis advocate the need for further exploration and consistency when we deal with the assessed variables to ascertain the implications of structured training regimes on measured variables in order to develop guidelines for training, nutritional advice, and wellbeing in young athletes.

Trial Registration

PROSPERO CRD42020152105

Role of Mitochondria in the Redox Signaling Network and Its Outcomes in High Impact Inflammatory Syndromes

Inflammation is associated with the release of soluble mediators that drive cellular activation and migration of inflammatory leukocytes to the site of injury, together with endothelial expression of adhesion molecules, and increased vascular permeability. It is a stepwise tightly regulated process that has been evolved to cope with a wide range of different inflammatory stimuli. However, under certain physiopathological conditions, the inflammatory response overwhelms local regulatory mechanisms and leads to systemic inflammation that, in turn, might affect metabolism in distant tissues and organs. In this sense, as mitochondria are able to perceive signals of inflammation is one of the first organelles to be affected by a dysregulation in the systemic inflammatory response, it has been associated with the progression of the physiopathological mechanisms. Mitochondria are also an important source of ROS (reactive oxygen species) within most mammalian cells and are therefore highly involved in oxidative stress. ROS production might contribute to mitochondrial damage in a range of pathologies and is also important in a complex redox signaling network from the organelle to the rest of the cell. Therefore, a role for ROS generated by mitochondria in regulating inflammatory signaling was postulated and mitochondria have been implicated in multiple aspects of the inflammatory response. An inflammatory condition that affects mitochondrial function in different organs is the exposure to air particulate matter (PM). Both after acute and chronic pollutants exposure, PM uptake by alveolar macrophages have been described to induce local cell activation and recruitment, cytokine release, and pulmonary inflammation. Afterwards, inflammatory mediators have been shown to be able to reach the bloodstream and induce a systemic response that affects metabolism in distant organs different from the lung. In this proinflammatory environment, impaired mitochondrial function that leads to bioenergetic dysfunction and enhanced production of oxidants have been shown to affect tissue homeostasis and organ function. In the present review, we aim to discuss the latest insights into the cellular and molecular mechanisms that link systemic inflammation and mitochondrial dysfunction in different organs, taking the exposure to air pollutants as a case model.

Understanding diversity in oxidative status and oxidative stress: the opportunities and challenges ahead

Oxidative stress may be of profound biological relevance. In this Commentary, I discuss some key issues faced by the emerging field of oxidative stress ecology, and seek to provide interpretations and solutions. First, I show that the way in which we define oxidative stress has far-reaching implications for the interpretation of results, and that we need to distinguish between (1) a biochemical definition in terms of the molecular outcomes of oxidative stress (e.g. generation of oxidative damage) and (2) a biological definition in terms of the fitness consequences for the organism (e.g. effects on fertility). Second, I discuss the dangers of comparing different tissues and markers. Third, I highlight the need to pay more attention to the cross-talk between oxidative stress and other important physiological costs and functions; this will allow us to better understand the mechanistic basis of fitness costs. Fourth, I propose the 'redox signalling hypothesis' of life history to complement the current 'oxidative stress hypothesis' of life history. The latter states that oxidative damage underlies trade-offs because it affects traits like growth, reproduction or cell senescence. By contrast, the redox signalling hypothesis states that a trade-off between signalling and biochemical oxidative stress underlies the regulation of reactive oxygen species production and their subsequent control. Finally, I critically appraise our current knowledge of oxidative stress ecology, highlighting key research themes and providing an optimistic overview of future opportunities for the discipline to yield considerable insight into the ecological and evolutionary meaning of oxidative stress.

Redox Biology in Transition Periods of Dairy Cattle: Role in the Health of Periparturient and Neonatal Animals

Dairy cows undergo various transition periods throughout their productive life, which are associated with periods of increased metabolic and infectious disease susceptibility. Redox balance plays a key role in ensuring a satisfactory transition. Nevertheless, oxidative stress (OS), a consequence of redox imbalance, has been associated with an increased risk of disease in these animals. In the productive cycle of dairy cows, the periparturient and neonatal periods are times of increased OS and disease susceptibility. This article reviews the relationship of redox status and OS with diseases of cows and calves, and how supplementation with antioxidants can be used to prevent OS in these animals.

Treatment of NASH with Antioxidant Therapy: Beneficial Effect of Red Cabbage on Type 2 Diabetic Rats

Aims

Oxidative stress (OS) plays a major role in type 2 diabetes and its vascular and hepatic complications, and novel therapeutic approaches include natural antioxidants. Our previous chemical and biological studies demonstrated the antioxidant activities of red cabbage (RC), and here, we aimed to determine the in vivo effects of 2-month long RC consumption using a high-fat/high-fructose model of diabetic rats.

Results

This vegetable, associated with lifestyle measurement, was shown to decrease OS and increase vascular endothelial NO synthase expression, ensuring vascular homeostasis. In the liver, RC consumption decreased OS by inhibiting p22phox expression and Nrf2 degradation and increasing catalase activity. It inhibited the activation of SREBP (1c, 2), ChREBP, NF-κB, ERK1/2, PPARγ, and GS and SIRT1 decrease, as observed in diabetic rats.

Conclusion/innovation

RC consumption led to metabolic profile improvement, together with hepatic function improvements. Although lifestyle changes are not sufficient to prevent diabetic complications, enrichment with RC avoids progression hepatic complications. This antioxidant strategy using RC does not only able to increase antioxidant defense, such as classical antioxidant, but also able to assure a metabolic and energetic balance to reverse complications. Whereas traditional medical therapy failed to reverse NASH in diabetic patients, consumption of RC should be a natural therapy to treat it.

Seed-mediated growth of Au@Ag core-shell nanorods for the detection of ellagic acid in whitening cosmetics

Seed-mediated growth has been employed as a simple and powerful means to the shape-controlled synthesis of metal nanocrystals. In this work, we apply the principle of seed-mediated growth in analytical chemistry, and achieve improved sensitivity due to the low energy barrier in the target-induced formation of bimetallic nanoparticles with core-shell structure. As a result, a simple, reliable, highly sensitive and selective method for the detection of ellagic acid (EA), a naturally occurring polyphenolic antioxidant, has been developed. With the aid of EA in alkaline solution, Ag⁺ ions can be transformed to Ag atoms and deposit on the surfaces of Au nanorods (AuNRs, act as seeds here) to generate Au@Ag core-shell nanorods, accompanied by blue shift of the longitudinal localized surface plasmon resonance (LSPR) band of AuNRs from near-infrared region to shorter wavelengths. Based on the linear relationship between the wavelength change of longitudinal LSPR band and the concentration of EA, our method achieves a detectable range of 0.2-20 μM and a limit of detection as low as 40 nM toward EA. This approach is highlighted by its high sensitivity for EA assay, which benefits from the viewpoint of thermodynamics in the nucleation/growth mode of metal nanoparticles. Moreover, this method shows high selectivity for EA detection when potential species coexist, and thus has been successfully applied in the detection of EA in skin-whitening cosmetics. The proposed strategy of seed-mediated growth herein can also be extended to other systems for sensing.

Antioxidants: Wonder drugs or quackery?

An answer to the question posed by the title must be simple not to disturb in his tomb Albert Einstein, who wrote "Man muß die Dinge so einfach wie möglich machen. Aber nicht einfacher". A simple answer (not simpler) can be: Antioxidants are not antioxidants, they are not wonder drugs and they are not all quackery; but they are not nothing. The arguments in support of this conundrumic statement will be developed below. © 2017 BioFactors, 43(6):785-788, 2017.

Polyphenols reported to shift APAP-induced changes in MAPK signaling and toxicity outcomes

Due to its widespread availability, acetaminophen (APAP) is the leading cause for drug-induced liver injury in many countries including United States and United Kingdom. When used as recommended, APAP is relatively safe. However, in overdose cases, increased metabolism of APAP to N-acetyl-para-benzoquinoneimine (NAPQI), a reactive metabolite, leads to glutathione (GSH) depletion, oxidative stress, and cellular injury. Throughout this process, a variety of factors play important roles in propagating toxicity, including c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family. Because of its involvement in multiple cellular processes, biomarkers associated with MAPK signaling have generated interest as a mechanistic target for protecting against APAP-induced liver injury and hepatocellular injury, in general. This review summarizes mechanistic details by which natural products, specifically those containing polyphenolic moieties, are capable of attenuating APAP-induced toxicity, at least in part through an ability to modulate MAPKs. These compounds include carnosic acid, chlorogenic acid, davallialactone, extracts from Hibiscus sabdariffa, quercetin-based compounds, and resveratrol. Despite variations in the experimental designs across these studies, common pathways and biomarkers were implicated in cytoprotection when polyphenolic compounds were given with APAP, such as enhanced antioxidant gene expression and reversal of APAP-induced changes in oxidative stress markers and MAPK signaling. Overall, an emphasis should be placed on method standardization for future studies if we are to gain a more in-depth understanding of how polyphenolic moieties contribute to cytoprotection during an APAP overdose event.

Oxidative Stress

Oxidative stress is two sided: Whereas excessive oxidant challenge causes damage to biomolecules, maintenance of a physiological level of oxidant challenge, termed oxidative eustress, is essential for governing life processes through redox signaling. Recent interest has focused on the intricate ways by which redox signaling integrates these converse properties. Redox balance is maintained by prevention, interception, and repair, and concomitantly the regulatory potential of molecular thiol-driven master switches such as Nrf2/Keap1 or NF-κB/IκB is used for system-wide oxidative stress response. Nonradical species such as hydrogen peroxide (H₂O₂) or singlet molecular oxygen, rather than free-radical species, perform major second messenger functions. Chemokine-controlled NADPH oxidases and metabolically controlled mitochondrial sources of H₂O₂ as well as glutathione- and thioredoxin-related pathways, with powerful enzymatic back-up systems, are responsible for fine-tuning physiological redox signaling. This makes for a rich research field spanning from biochemistry and cell biology into nutritional sciences, environmental medicine, and molecular knowledge-based redox medicine.

Insecticides induced stress response and recuperation in fish: Biomarkers in blood and tissues related to oxidative damage

The present research investigated the growth, blood, antioxidant response (liver), AChE (brain and muscle) and Na+/K + ATPase in gills of Clarias batrachus exposed to 0 (control), two insecticides, 1.65 mg L^-1 chlorpyrifos (CPF) and 2.14 mg L^-1 monocrotophos (MCP) for a fixed interval time of 3, 6, 9, 12 and 15 days and follow up depuration process in fresh water for 30 days (at an interval of 7, 15 and 30 days). The toxicants exposed fish indicated significantly (P < 0.05) lower weight gain and HSI. The RBC, Hb, Hct, plasma total protein, glucose, albumin, globulin and respiratory burst activity was reduced. However, WBC, plasma glucose, serum creatinine, and triglycerides were enhanced. The weight gain, HSI and all haematological parameters were reversed following depuration of CPF and MCP exposed fish. Hepatic superoxide dismutase, catalase, lipid peroxidation, reduced glutathione, and glutathione S-transferase activities were significantly activated whereas glutathione peroxidase was inhibited in both tested groups. All the antioxidant enzymes were reversed on day 15 in MCP concentration, whereas CPF on day 30 of depuration process. The inhibition of acetylcholinesterase (brain, muscle) and gill Na+/K + ATPase activities were more in CPF exposure and early recovery in MCP. The results indicated that depuration process might help in detoxification of fish and improve growth, haematological conditions, oxidative stress and AChE, Na+/K + ATPase activity. However, further studies are needed in different fish species with different toxicants to support this strategy of depuration process in order to detoxify polluted fish.

Polyphenols in Regulation of Redox Signaling and Inflammation During Cardiovascular Diseases

Cardiovascular diseases remain one of the major health problems worldwide. The worldwide research against cardiovascular diseases as well as genome wide association studies were successful in indentifying the loci associated with this prominent life-threatening disease but still a substantial amount of casualty remains unexplained. Over the last decade, the thorough understanding of molecular and biochemical mechanisms of cardiac disorders lead to the knowledge of various mechanisms of action of polyphenols to target inflammation during cardiac disorders. The present review article summarizes major mechanisms of polyphenols against cardiovascular diseases.

The effect of conjugated linoleic acid supplements on oxidative and antioxidative status of dairy cows

Dairy cows develop frequently negative energy balance around parturition and in early lactation, resulting in excessive mobilization of body fat and subsequently in increased risk of ketosis and other diseases. Dietary conjugated linoleic acid (CLA) supplements are used in dairy cows mainly for their depressing effect on milk fat content, but are also proposed to have antioxidative properties. As negative energy balance is associated with oxidative stress, which is also assumed to contribute to disease development, the present study was conducted to examine effects of CLA on oxidative and antioxidative status of lactating dairy cows. German Holstein cows (primiparous n=13, multiparous n=32) were divided into 3 dietary treatment groups receiving 100g/d of control fat supplement, containing 87% stearic acid (CON; n=14), 50g/d of control fat supplement and 50g/d of CLA supplement (CLA 50; n=15), or 100g/d of CLA supplement (CLA 100; n=16). The CLA supplement was lipid-encapsulated and contained 12% of trans-10,cis-12 CLA and cis-9,trans-11 CLA each. Supplementation took place between d1 and 182 postpartum; d 182 until 252 postpartum served as a depletion period. Blood was sampled at d -21, 1, 21, 70, 105, 140, 182, 224, and 252 relative to calving. The antioxidative status was determined using the ferric-reducing ability of plasma, α-tocopherol, α-tocopherol-to-cholesterol mass ratio, and retinol. For determination of oxidative status concentrations of hydroperoxides, thiobarbituric acid-reactive substances (TBARS), N'-formylkynurenine, and bityrosine were measured. Mixed models of fixed and random effects with repeated measures were used to evaluate period 1 (d -21 to 140) and 2 (d182-252) separately. Cows showed increased oxidative stress and lipid peroxidation during the periparturient period in terms of increased serum concentrations of hydroperoxides and TBARS, which decreased throughout lactation. During period 1, the supplemented cows had lower TBARS concentrations, which was not detectable in period 2. The other determined parameters were not affected by CLA supplementation. The obtained results show that dietary CLA supplementation in the chosen dosage, formulation, and application period had a marginal antioxidative effect in terms of lipid peroxidation in lactating dairy cows.

Polyphenol compounds and PKC signaling

BACKGROUND

Naturally occurring polyphenols found in food sources provide huge health benefits. Several polyphenolic compounds are implicated in the prevention of disease states, such as cancer. One of the mechanisms by which polyphenols exert their biological actions is by interfering in the protein kinase C (PKC) signaling pathways. PKC belongs to a superfamily of serine-threonine kinase and are primarily involved in phosphorylation of target proteins controlling activation and inhibition of many cellular processes directly or indirectly.

SCOPE OF REVIEW

Despite the availability of substantial literature data on polyphenols' regulation of PKC, no comprehensive review article is currently available on this subject. This article reviews PKC-polyphenol interactions and its relevance to various disease states. In particular, salient features of polyphenols, PKC, interactions of naturally occurring polyphenols with PKC, and future perspective of research on this subject are discussed.

MAJOR CONCLUSIONS

Some polyphenols exert their antioxidant properties by regulating the transcription of the antioxidant enzyme genes through PKC signaling. Regulation of PKC by polyphenols is isoform dependent. The activation or inhibition of PKC by polyphenols has been found to be dependent on the presence of membrane, Ca(2+) ion, cofactors, cell and tissue types etc. Two polyphenols, curcumin and resveratrol are in clinical trials for the treatment of colon cancer.

GENERAL SIGNIFICANCE

The fact that 74% of the cancer drugs are derived from natural sources, naturally occurring polyphenols or its simple analogs with improved bioavailability may have the potential to be cancer drugs in the future.

Evaluation of Radical Scavenging Activity of Sempervivum tectorum and Corylus avellana Extracts with Different Phenolic Composition

Sempervivum tectorum L. and Corylus avellana L. are traditional herbal remedies exhibiting antioxidant activity and representing diverse phenolic composition. The aim of this study was to reveal the contribution of certain compounds to total radical scavenging activity by studying S. tectorum and C. avellana extracts prepared with solvents of different selectivity for diverse classes of phenolics. Antioxidant activity of S. tectorum and C. avellana samples was determined in the ABTS and DPPH radical scavenging assays, and phenolic composition was evaluated by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Correlations between antioxidant activity and phenolic content of houseleek extracts have been revealed. Significant differences regarding antioxidant activity have been shown between S. tectorum 80% (v/v) methanol extract and its fractions. Additionally, synergism among the constituents present together in the whole extract was assumed. Significantly higher radical scavenging activity of hazel extracts has been attributed to the differences in phenolic composition compared with houseleek extracts.

Anemia in the frail, elderly patient

Anemia and frailty are two common findings in geriatric patients and have been shown to be associated with poor outcomes in this patient group. Recent studies have contributed to the growing evidence of a possible association with the age-related chronic inflammatory status known as “inflammaging”. These findings do not only give a better insight into the pathogenesis of anemia in frailty, but also offer new treatment options. The present article focuses on this assumed association between anemia, frailty, and inflammaging and summarizes current management options for anemia in frail patients.

Exercise-induced oxidative stress: past, present and future

The existence of free radicals in living cells was first reported in 1954 and this important finding helped launch the field of free radical biology. However, the discovery that muscular exercise is associated with increased biomarkers of oxidative stress did not occur until 1978. Following the initial report that exercise promotes oxidative stress in humans, many studies have confirmed that prolonged or short-duration high intensity exercise results in increased radical production in active skeletal muscles resulting in the formation of oxidized lipids and proteins in the working muscles. Since these early descriptive studies, the investigation of radicals and redox biology related to exercise and skeletal muscle has grown as a discipline and the importance of this research in the biomedical sciences is widely recognized. This review will briefly summarize the history of research in exercise-induced oxidative stress and will discuss the major paradigm shifts that the field has undergone and continues to experience. We conclude with a discussion of future directions in the hope of stimulating additional research in this important field.

Emulsions Made of Oils from Seeds of GM Flax Protect V79 Cells against Oxidative Stress

Polyunsaturated fatty acids, sterols, and hydrophilic phenolic compounds are components of flax oil that act as antioxidants. We investigated the impact of flax oil from transgenic flax in the form of emulsions on stressed Chinese hamster pulmonary fibroblasts. We found that the emulsions protect V79 cells against the H2O2 and the effect is dose dependent. They reduced the level of intracellular reactive oxygen species and protected genomic DNA against damage. The rate of cell proliferation increased upon treatment with the emulsions at a low concentration, while at a high concentration it decreased significantly, accompanied by increased frequency of apoptotic cell death. Expression analysis of selected genes revealed the upregulatory impact of the emulsions on the histones, acetylases, and deacetylases. Expression of apoptotic, proinflammatory, and anti-inflammatory genes was also altered. It is thus suggested that flax oil emulsions might be useful as a basis for biomedical products that actively protect cells against inflammation and degeneration. The beneficial effect on fibroblast resistance to oxidative damage was superior in the emulsion made of oil from transgenic plants which was correlated with the quantity of antioxidants and squalene. The emulsions from transgenic flax are promising candidates for skin protection against oxidative damage.

Amelioration of Cadmium-Induced Nephropathy using Polyphenol-rich Extract of Vernonia amygdalina (Del.) Leaves in Rat Model

AIM

To determine the effects of polyphenol-rich extract of the leaves of Vernonia amygdalina (PEVA) in rats with Cd-induced nephropathy.

MATERIALS AND METHODS

Sixty five male Wistar rats were divided into five groups as follows; Group 1 received distilled water throughout the period of study. Group 2 received 5 mg/kg body weight of cadmium (Cd), in the form of CdSO4, for five consecutive days via intraperitoneal route. Groups 3, 4 and 5 were pretreated with Cd as group 2 and thereafter received oral treatment of PEVA for 4 weeks at 100 mg/kg, 200 mg/kg and 400 mg/kg body weight, respectively.

RESULTS

Exposure to Cd toxicity significantly induced deleterious alterations in plasma and urine levels of creatinine, urea and glucose as well as creatinine and urea clearance (p < 0.05) in the rat model. There was a significant disturbance in the antioxidant system as revealed by the levels of thiobarbituric acid reactive substance (TBARS) and reduced glutathione (GSH) (p < 0.05) in the kidney tissue of the rats. With marked improvements in renal histoarchitecture, PEVA treatment showed a duration and non dose-dependent ameliorative potential.

CONCLUSION

PEVA treatment reversed the compromise of renal function that was induced by Cd toxicity in rat model.

Oxidative stress, the term and the concept

The 30th birthday of a central concept in biomedicine, such as oxidative stress (OS) is a good time for re-evaluation of its contribution to science and particularly to the field of redox biology. In his recent communication, Sies described the history of the concept as well as the benefits and pitfalls of the term OS. In this mini-review, we discuss the problems associated with the still common perception of "bad OS, good antioxidants". Specifically, the term OS is an intuitively understood term originally used to describe an imbalance between pro-oxidative factors and anti-oxidative factors. It has no units, its level is dependent on the way it is measured and there is no correlation between various criteria of OS, which indicates that there are sub-classes (types) of OS (other than the classifications presented by Sies). In spite of these limitations, it is commonly regarded a measure of a person's probability to suffer from oxidative damages and is being held responsible for many diseases and antioxidants are predicted to be good to us. In fact, a "Basal OS" is vital and antioxidants may interfere with the mechanisms responsible for maintaining the oxidative status. We also discuss the linkage of OS to the outcome of antioxidant supplementation and comment on the importance of kinetic studies in evaluation of OS and on the ranking of antioxidants.

Digitoflavone provokes mitochondrial biogenesis in PC12 cells: A protective approach to oxidative stress

CONTEXT

Reactive oxygen species (ROS) are known to be one of the main causes of neurodegenerative disorders, and flavonoids play characteristic roles in a variety of biological activities, and specially are known to be antioxidant reagents.

OBJECTIVE

In this study, we investigated neuroprotective effects of digitoflavone to suppress H2O2 -induced cell death in neuron-like PC12 cells.

MATERIAL AND METHODS

PC12 cells were pre-treated with digitoflavone for 2 h and then cells were exposed to H2O2 for 18 h. The cells' viability was evaluated by MTT assay. Rhodamine 123 staining was used for the determination of mitochondrial membrane potential (ΔΨm). The intracellular ROS aggregation was determined by using 2',7'-dichlorofluorescein diacetate. Also, the level of mitochondrial biogenesis factors was measured by western blot. The antioxidant capacity of digitoflavone was also determined by measuring reduced glutathione (GSH) level and catalase (CAT) activity quantification.

RESULTS

Digitoflavone significantly elevated cells' viability at concentrations of 10 and 20 µM. Also, digitoflavone attenuated intracellular level of ROS, and stabilized ΔΨm. Moreover, digitoflavone increased phosphorylation of AMP-activated protein kinase (AMPK) and, consequently, elevated mitochondrial biogenesis factors which were reduced after H2O2 exposure. We emphasized on the protective effect of digitoflavone through increasing mitochondrial biogenesis by specifically inhibiting AMPK. Antioxidant ability of digitoflavone was indicated by the elevation of GSH level and CAT activity.

CONCLUSION

As a result, digitoflavone stabilize ΔΨm, enhanced cell viability through inducing mitochondrial biogenesis pathway, and increased antioxidant capacity of the cells which lead to better combating the oxidative stress.

Responses of the hepatic glutathione antioxidant defense system and related gene expression in juvenile common carp after chronic treatment with tributyltin

Recently, residual organotin compounds have generally been recognised as relevant sources of aquatic environmental pollutants. However, the effects of these contaminants on the glutathione (GSH)-antioxidant system of fishes have not been adequately studied. In the current study, the chronic effects of tributyltin (TBT) found within antifouling paints for ships, on the GSH antioxidant system and related gene expression in the liver of juvenile common carp (Cyprinus carpio) were investigated. Fishes were exposed to sub-lethal concentrations of TBT (75 ng/L, 0.75 and 7.5 μg/L) for 15, 30 and 60 days. GSH levels and GSH-related enzymes activities, including glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST), were quantified in the fish liver. The levels of malondialdehyde were also measured as a marker of oxidative damage. In addition, the expression levels of gstp1, gr and gpx1 in common carp chronically exposed to TBT were determined. The results of the current study indicate that chronic exposure of TBT results in reactive oxygen species stress in the liver of common carp, and mRNA expression levels are more sensitive than related enzyme levels. In short, the measured GSH-related indices could potentially be used as molecular indicators for monitoring organotin compounds in the aquatic environment.

Oxidative stress: a concept in redox biology and medicine

"Oxidative stress" as a concept in redox biology and medicine has been formulated in 1985; at the beginning of 2015, approx. 138,000 PubMed entries show for this term. This concept has its merits and its pitfalls. Among the merits is the notion, elicited by the combined two terms of (i) aerobic metabolism as a steady-state redox balance and (ii) the associated potential strains in the balance as denoted by the term, stress, evoking biological stress responses. Current research on molecular redox switches governing oxidative stress responses is in full bloom. The fundamental importance of linking redox shifts to phosphorylation/dephosphorylation signaling is being more fully appreciated, thanks to major advances in methodology. Among the pitfalls is the fact that the underlying molecular details are to be worked out in each particular case, which is bvious for a global concept, but which is sometimes overlooked. This can lead to indiscriminate use of the term, oxidative stress, without clear relation to redox chemistry. The major role in antioxidant defense is fulfilled by antioxidant enzymes, not by small-molecule antioxidant compounds. The field of oxidative stress research embraces chemistry, biochemistry, cell biology, physiology and pathophysiology, all the way to medicine and health and disease research.

Insights on antioxidant assays for biological samples based on the reduction of copper complexes-the importance of analytical conditions

Total antioxidant capacity assays are recognized as instrumental to establish antioxidant status of biological samples, however the varying experimental conditions result in conclusions that may not be transposable to other settings. After selection of the complexing agent, reagent addition order, buffer type and concentration, copper reducing assays were adapted to a high-throughput scheme and validated using model biological antioxidant compounds of ascorbic acid, Trolox (a soluble analogue of vitamin E), uric acid and glutathione. A critical comparison was made based on real samples including NIST-909c human serum certified sample, and five study samples. The validated method provided linear range up to 100 µM Trolox, (limit of detection 2.3 µM; limit of quantification 7.7 µM) with recovery results above 85% and precision <5%. The validated developed method with an increased sensitivity is a sound choice for assessment of TAC in serum samples.

Comparative study on the antioxidant and anti-Toxoplasma activities of vanillin and its resorcinarene derivative

A resorcinarene derivative of vanillin, resvan, was synthesized and characterized by spectroscopic techniques. We measured the cytotoxicity (in vivo and in vitro), antioxidant and anti-Toxoplasma activities of vanillin and the resorcinarene compound. Here we show that vanillin has a dose-dependent behavior with IC₅₀ of 645 µg/mL through an in vitro cytotoxicity assay. However, we could not observe any cytotoxic response at higher concentrations of resvan (IC₅₀ > 2,000 µg/mL). The in vivo acute toxicity assays of vanillin and resvan exhibited a significant safety margin indicated by a lack of systemic and behavioral toxicity up to 300 mg/kg during the first 30 min, 24 h or 14 days after administration. The obtained derivative showed greater antioxidative activity (84.9%) when comparing to vanillin (19.4%) at 1,000 μg/mL. In addition, vanillin presents anti-Toxoplasma activity, while resvan does not show that feature. Our findings suggest that this particular derivative has an efficient antioxidant activity and a negligible cytotoxic effect, making it a potential target for further biological investigations.

Effect of ibuprofen exposure on blood, gill, liver, and brain on common carp (Cyprinus carpio) using oxidative stress biomarkers

Although trace concentrations of ibuprofen (IBP) have been detected in diverse water bodies, there is currently insufficient information on the potentially deleterious effects of this xenobiotic. The present study aimed to determine whether IBP induces oxidative stress in brain, liver, gill, and blood of the common carp Cyprinus carpio. To this end, the median lethal concentration at 96 h (96-h LC50) was determined and the lowest observed adverse effect level was established. Carp were exposed to the latter concentration (17.6 mg L(-1)) for 12, 24, 48, 72, and 96 h, and the following biomarkers were evaluated: lipid peroxidation (LPX) and activity of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. Results indicated that LPX and antioxidant enzymes' activity increased significantly (p < 0.05) with respect to the control group in liver, gill, and blood, while no significant differences occurred in brain. In conclusion, IBP induced oxidative stress on C. carpio, the liver being the organ most affected by this damage.

Identification of Phenolic Compounds and Evaluation of Antioxidant and Antimicrobial Properties of Euphorbia Tirucalli L

Bioactive compounds extracted from natural sources can benefit human health. The aim of this work was to determine total phenolic content and antioxidant activity in extracts of Euphorbia tirucalli L. followed by identification and quantification of the phenolic compounds, as well as their antibacterial activities. Antioxidant activities were determined by DPPH and ABTS^•+ assay. Identification of phenolic compounds was performed using high-performance liquid chromatography (HPLC), and antimicrobial activities were verified by agar dilution methods and MIC values. Total phenolic content ranged from 7.73 to 30.54 mg/100 g gallic acid equivalent. Extracts from dry plants showed higher antioxidant activities than those from fresh ones. The DPPH EC₅₀ values were approximately 12.15 μg/mL and 16.59 μg/mL, respectively. Antioxidant activity measured by the ABTS method yielded values higher than 718.99 μM trolox/g for dry plants, while by the Rancimat^® system yielded protection factors exceeding 1 for all extracts, comparable to synthetic BHT. Ferulic acid was the principal phenolic compound identified and quantified through HPLC-UV in all extracts. The extracts proved effective inhibitory potential for Staphylococcus epidermidis and Staphylococcus aureus. These results showed that extracts of Euphorbia tirucalli L. have excellent antioxidant capacity and moderate antimicrobial activity. These can be attributed to the high concentration of ferulic acid.

In vitro measurements and interpretation of total antioxidant capacity

BACKGROUND

One of the strategies most commonly used to assess a free radical-antioxidant balance in chemical and biological systems is the determination of the total antioxidant capacity (TAC). A large amount of research has been published using TAC. However, it remains unclear which is the significance of these investigations for understanding the biological importance of free radical reactions.

SCOPE OF REVIEW

This review discusses the relevance and limitations of TAC for the assessment of the antioxidant activities present in food and food derivatives, and in body tissues and fluids.

MAJOR CONCLUSIONS

TAC determinations are simple, inexpensive, and able to evaluate the capacity of known and unknown antioxidants and their additive, synergistic and/or antagonistic actions, in chemical and biological systems. However, different TAC assays correlate poorly with each other, since each TAC assay is sensitive to a particular combination of compounds, but exclude many others. The TAC values for foods cannot be translated to the in vivo (human) antioxidant defenses, and furthermore, to health effects provided by that food.

GENERAL SIGNIFICANCE

Up to date, conclusions that can be drawn from the extensive amount of research done using TAC of foods or populations should not be considered when used for making decisions affecting population health. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.

Loranthus pulverulentus: A Potent Source of Natural Antioxidants and Alternative Medicine

This study was designed to evaluate the antioxidant potential ofLoranthus pulverulentus. Stem bark, leaves, and seeds ofLoranthus pulverulentuswere extracted in methanol:water (90 : 10) and partitioned with n-hexane, chloroform, ethyl acetate, and n-butanol successively using partition chromatography. Total phenolic contents and antioxidant potential were checked using standard protocols. Total phenolic contents of all extracts were determined, using Folin–Ciocalteu reagent, and ranged between 151 ± 2.1 and 396 ± 1.6 for stem bark, 137 ± 0.9 and 430 ± 2.2 for, and 39 ± 0.6 and 231 ± 1.7 for seeds. The antioxidant potential of extracts was evaluated; namely, DPPH, FRAP, and total antioxidant models. The ethyl acetate extract of stem-bark, leaves, and seeds showed the highest activity in DPPH (94.5 ± 2.1%, 96.30 ± 0.9%, and 92.30 ± 1.1%, IC5015.9 ± 0.5 μg, 14.5 ± 0.8, and 102.7 ± 1.3, resp.), FRAP (7.7 ± 0.6, 7.5 ± 0.7 and 6.6 ± 0.7, resp.), and total antioxidant (0.95 ± 0.09, 1.19 ± 0.09, and 0.686 ± 0.08, resp.). Strong correlations were observed between total phenols versus total antioxidant activity, DPPH, and FRAP withR2values ranging from 0.8185 to 0.9951 (stem-bark), 0.6728 to 0.8648 (leaves), and 0.8658 to 0.9910 (seed) which indicated that phenolic contents are the major constituents responsible for antioxidant activity.