Ten misconceptions about antioxidants. Trends Pharmacol Sci. 2013;34:430-436. [PMID: 23806765 DOI: 10.1016/j.tips.2013.05.010]

Iodine-Substituted Dithiocarbamic Flavanones-A Structure-Activity Relationship Study of Their Antioxidant Properties

The antioxidant properties of novel diiodo-substituted 3-dithiocarbamic flavanones were investigated. The three frameworks that proved to be the most active ones in our previous studies were selected. By varying the nature of the substituent at the para position of flavanone ring B, a structure-activity relationship study on radical scavenging properties was performed. The influence of these substituents (F, Cl, Br and H) was investigated against DPPH and ABTS+•. The results indicate that the presence of the halogen substituents induces better antioxidant properties than ascorbic acid and BHT. The highest radical scavenging activity was found in the case of morpholine carbodithioates. Regarding the ABTS+• assay, all investigated flavanones exhibited better antioxidant properties than BHT.

Evaluation of the Antioxidant Properties and Bioactivity of Koroneiki and Athinolia Olive Varieties Using In Vitro Cell-Free and Cell-Based Assays

Olive oil and table olives are considered staples of the Mediterranean diet and have been associated with various health benefits. Literature reports that the final composition of the olive drupe is greatly affected by varietal and agronomic factors, each contributing to a different degree. To that end, the objective of the study was the evaluation of the contribution of different agronomic conditions applied to two Greek olive varieties (Koroneiki, Mastoidis) using a holistic approach of in vitro methods. The findings highlight the importance of the application of a combination of agronomic techniques for each variety, as marked by the differences found in the antioxidant radical-scavenging and reducing power assays. Furthermore, the results obtained from the measurement of redox biomarkers (GSH, ROS, TBARS) in cell lines (EA.hy926, HepG2, MKN45) treated with olive samples demonstrate the capacity of the samples to induce redox imbalance, either by protecting normal cells from damage, or by inducing oxidative damage in cancer cell lines, with the Athinolia samples exhibiting greater antioxidant potential at lower concentrations. This particular finding could have further applications in possible chemo-preventive approaches facilitated by antioxidant compounds of natural origins.

Lactobionic acid matrix supramolecular complexes with enhanced bioavailability and clinical efficacy as an optimal CP system

Despite the biological activity of lactobionic acid (LBA), its low bioavailability remains a challenge in response to complex clinical needs. Aided by computer high-throughput screening and ab initio analysis, we selected betaine and mandelic acid as the right arms to synthesize supramolecular lactobionic acid (SLBA) through a proton exchange reaction, which significantly and comprehensively improved the bioavailability of LBA. Density functional theory and physicochemical characterization revealed the supramolecular characteristics and chemical stability of this coupling. The resulting SLBA has shown significant advantages over LBA in cellular, animal, and clinical trials and demonstrated enormous potential in anti-aging beauty, clinical treatment, biomedicine, and food preservation.

Antioxidants: A Hot Controversy Defused by Cool Semantics

Recent years have witnessed a rather controversial debate on what antioxidants are and how beneficial they may be in the context of human health. Despite a considerable increase in scientific evidence, the matter remains highly divisive as different pieces of new data seem to support both the pro- and the anti-antioxidant perspective. Here, we argue that the matter at the heart of this debate is not necessarily empirical but of semantics. Thus, the controversy cannot be resolved with the traditional tools of natural sciences and by the mere accumulation of new data. In fact, the term "antioxidants" has been part of the scientific language game for a few decades and is nowadays used differently in the context of different scientific disciplines active at different levels of scientific complexity. It, therefore, represents not a single expression but an entire family of words with distinctively different connotations and associations. The transcendent use of this expression from a basic to a more complex discipline, such as going from chemistry to physiology, is problematic as it assigns the term with connotations that are not corroborated empirically. This may lead to false claims and aspirations not warranted by empirical data. Initially, health claims may not even be indented, yet, on occasion, they are welcome for reasons other than scientific ones. To resolve this debate, one may need to refrain from using the term "antioxidants" in disciplines and contexts where its meaning is unclear, limit its use to disciplines where it is essential and beneficial, and, in any case, become more specific in such contexts where its use is warranted, for instance, in the case of "dietary antioxidants".

Comprehensive Strategies for Metabolic Syndrome: How Nutrition, Dietary Polyphenols, Physical Activity, and Lifestyle Modifications Address Diabesity, Cardiovascular Diseases, and Neurodegenerative Conditions

Several hallmarks of metabolic syndrome, such as dysregulation in the glucose and lipid metabolism, endothelial dysfunction, insulin resistance, low-to-medium systemic inflammation, and intestinal microbiota dysbiosis, represent a pathological bridge between metabolic syndrome and diabesity, cardiovascular, and neurodegenerative disorders. This review aims to highlight some therapeutic strategies against metabolic syndrome involving integrative approaches to improve lifestyle and daily diet. The beneficial effects of foods containing antioxidant polyphenols, intestinal microbiota control, and physical activity were also considered. We comprehensively examined a large body of published articles involving basic, animal, and human studie, as well as recent guidelines. As a result, dietary polyphenols from natural plant-based antioxidants and adherence to the Mediterranean diet, along with physical exercise, are promising complementary therapies to delay or prevent the onset of metabolic syndrome and counteract diabesity and cardiovascular diseases, as well as to protect against neurodegenerative disorders and cognitive decline. Modulation of the intestinal microbiota reduces the risks associated with MS, improves diabetes and cardiovascular diseases (CVD), and exerts neuroprotective action. Despite several studies, the estimation of dietary polyphenol intake is inconclusive and requires further evidence. Lifestyle interventions involving physical activity and reduced calorie intake can improve metabolic outcomes.

Metabolic Syndrome: A Narrative Review from the Oxidative Stress to the Management of Related Diseases

Metabolic syndrome (MS) is a growing disorder affecting thousands of people worldwide, especially in industrialised countries, increasing mortality. Oxidative stress, hyperglycaemia, insulin resistance, inflammation, dysbiosis, abdominal obesity, atherogenic dyslipidaemia and hypertension are important factors linked to MS clusters of different pathologies, such as diabesity, cardiovascular diseases and neurological disorders. All biochemical changes observed in MS, such as dysregulation in the glucose and lipid metabolism, immune response, endothelial cell function and intestinal microbiota, promote pathological bridges between metabolic syndrome, diabesity and cardiovascular and neurodegenerative disorders. This review aims to summarise metabolic syndrome's involvement in diabesity and highlight the link between MS and cardiovascular and neurological diseases. A better understanding of MS could promote a novel strategic approach to reduce MS comorbidities.

Evaluation of cinnamaldehyde derivatives as potential protective agents against oxidative-stress induced myotube atrophy using chemical, biological and computational analysis

Skeletal muscle atrophy, associated with increased morbidity, mortality and poor quality of life, is a metabolic disorder with no FDA approved drug. Oxidative stress is one of the key mediators of atrophy that influences various cell signaling molecules. The goal of this study is to identify potential antioxidant agents that could be used to treat atrophy. In this study in vitro and in situ screening of different cinnamaldehyde (CNA) derivatives for their antioxidant effects was done along with computational analysis to understand the relationship between their chemical structure and biological activity. Data show that 2-hydroxycinnamaldehyde (2HCNA) worked better than other CNA analogues at physiological pH, while 4-Fluoro-2-methoxycinnamaldehyde (4FoCNA) showed the maximum antioxidant activity under acidic conditions. However, these derivatives (2HCNA and 4FoCNA) were found to be toxic to the cultured myotubes (mature myofiber) under both physiological and pathophysiological conditions. Immunofluorescence, bright-field microscopic and biochemical studies conducted using live C2C12 cells showed that pre-incubation with other CNA analogues i.e. 2-methoxycinnamaldehyde (2MeCNA) and 2-benzyloxycinnamaldehyde (2BzCNA) not only maintained the normal morphology of myotubes but also protected them from H2O2-induced atrophy. These compounds (2MeCNA and 2BzCNA) showed higher stability and antioxidant potential, as indicated by computer simulation data analyzed by Density Functional Theory (DFT) based molecular modeling. Overall, the chemical, biological, and computational studies reveal the therapeutic potential of CNA analogues (BzCNA and MeCNA) against oxidative-stress induced muscle atrophy in C2C12 cells.

Antioxidants from different citrus peels provide protection against cancer

Cancer is one of the leading causes of death. Despite significant advancements in the discovery of medications for the treatment of cancer, these drugs are hindered by applicability and efficacy issues and frequently exhibit major side effects that can further impair patients 'quality of life. Therefore, the development of therapeutically sound anti-cancer medicines derived from natural products has gained prominence in the field of functional foods. Some of these compounds have shown efficacy in the prevention and treatment of cancer as well as low toxicity. Additionally, many recent studies have explored the recycling of agro-industrial waste to create bioactive chemicals. Citrus peels are produced in vast quantities in the food processing sector; due to their abundance of flavonoids, they may be inexpensive sources of protection against several cancers. Citrus is a common type of fruit that contains a variety of nutrients. In particular, the antioxidant chemicals found in citrus peel have been identified as potential cancer-fighting agents. Antioxidant substances such as flavonoids prevent the development of cancer by inhibiting the metastatic cascade, decreasing the mobility of cancer cells in the circulatory system, promoting apoptosis, and suppressing angiogenesis. To explore the most effective uses of citrus peel-derived antioxidants, this review presents background information, an overview of the role of citrus antioxidants in cancer therapy, and a discussion of the key underlying molecular mechanisms.

Regulatory Effects and Molecular Mechanisms of Tea and Its Active Compounds on Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease, is a multifactorial disease resulting from the interaction between environment, genetic background, and metabolic stress. Most treatments for NAFLD include dietary intervention and exercise show limited efficacy due to the complex mechanisms involved in NAFLD. Meanwhile, drug therapy is accompanied by serious side effects. The development of high-efficiency natural supplements is a sustainable strategy for the prevention and treatment of NAFLD. As the second most consumed beverage, tea has health benefits that have been widely recognized. Nevertheless, the intervention of tea active compounds in NAFLD has received limited attention. Tea contains abundant bioactive compounds with potential effects on NAFLD, such as catechins, flavonoids, theanine, tea pigments, and tea polysaccharides. We reviewed the intrinsic and environmental factors and pathogenic mechanisms that affect the occurrence and development of NAFLD, and summarized the influences of exercise, drugs, diet, and tea drinking on NAFLD. On this basis, we further analyzed the potential effects and molecular regulatory mechanisms of tea active compounds on NAFLD and proposed future development directions. This review hopes to provide novel insights into the development and application of tea active compounds in the prevention and treatment of NAFLD.

Prevention of Oxidative Stress and Diseases by Antioxidant Supplementation

Excessive and uncontrolled oxidative stress can damage biomacromolecules, such as lipids, proteins, carbohydrates, and DNA, by free radical and oxidant overproduction. In this review, we critically discuss the main properties of free radicals, their implications in oxidative stress, and specific pathological conditions. In clinical medicine, oxidative stress can play a role in several chronic noncommunicable diseases, such as diabetes mellitus, cardiovascular, inflammatory, neurodegenerative diseases, and tumours. Antioxidant supplements can theoretically prevent or stop the progression of diseases, but a careful literature analysis finds that more evidence is needed to dissect the ultimate beneficial effect of antioxidants versus reactive oxygen species in several diseases.

Maslinic Acid: A New Compound for the Treatment of Multiple Organ Diseases

Maslinic acid (MA) is a pentacyclic triterpene acid, which exists in many plants, including olive, and is highly safe for human beings. In recent years, it has been reported that MA has anti-inflammatory, antioxidant, anti-tumor, hypoglycemic, neuroprotective and other biological activities. More and more experimental data has shown that MA has a good therapeutic effect on multiple organ diseases, indicating that it has great clinical application potential. In this paper, the extraction, purification, identification and analysis, biological activity, pharmacokinetics in vivo and molecular mechanism of MA in treating various organ diseases are reviewed. It is hoped to provide a new idea for MA to treat various organ diseases.

The decylTPP mitochondria-targeting moiety lowers electron transport chain supercomplex levels in primary human skin fibroblasts

Attachment of cargo molecules to lipophilic triphenylphosphonium (TPP⁺) cations is a widely applied strategy for mitochondrial targeting. We previously demonstrated that the vitamin E-derived antioxidant Trolox increases the levels of active mitochondrial complex I (CI), the first complex of the electron transport chain (ETC), in primary human skin fibroblasts (PHSFs) of Leigh Syndrome (LS) patients with isolated CI deficiency. Primed by this finding, we here studied the cellular effects of mitochondria-targeted Trolox (MitoE10), mitochondria-targeted ubiquinone (MitoQ10) and their mitochondria-targeting moiety decylTPP (C₁₀-TPP⁺). Chronic treatment (96 h) with these molecules of PHSFs from a healthy subject and an LS patient with isolated CI deficiency (NDUFS7-V122M mutation) did not greatly affect cell number. Unexpectedly, this treatment reduced CI levels/activity, lowered the amount of ETC supercomplexes, inhibited mitochondrial oxygen consumption, increased extracellular acidification, altered mitochondrial morphology and stimulated hydroethidine oxidation. We conclude that the mitochondria-targeting decylTPP moiety is responsible for the observed effects and advocate that every study employing alkylTPP-mediated mitochondrial targeting should routinely include control experiments with the corresponding alkylTPP moiety.

Natural Antioxidant Evaluation: A Review of Detection Methods

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

Revisiting the Oxidation of Flavonoids: Loss, Conservation or Enhancement of Their Antioxidant Properties

Flavonoids display a broad range of health-promoting bioactivities. Among these, their capacity to act as antioxidants has remained most prominent. The canonical reactive oxygen species (ROS)-scavenging mode of the antioxidant action of flavonoids relies on the high susceptibility of their phenolic moieties to undergo oxidation. As a consequence, upon reaction with ROS, the antioxidant capacity of flavonoids is severely compromised. Other phenol-compromising reactions, such as those involved in the biotransformation of flavonoids, can also markedly affect their antioxidant properties. In recent years, however, increasing evidence has indicated that, at least for some flavonoids, the oxidation of such residues can in fact markedly enhance their original antioxidant properties. In such apparent paradoxical cases, the antioxidant activity arises from the pro-oxidant and/or electrophilic character of some of their oxidation-derived metabolites and is exerted by activating the Nrf2–Keap1 pathway, which upregulates the cell’s endogenous antioxidant capacity, and/or, by preventing the activation of the pro-oxidant and pro-inflammatory NF-κB pathway. This review focuses on the effects that the oxidative and/or non-oxidative modification of the phenolic groups of flavonoids may have on the ability of the resulting metabolites to promote direct and/or indirect antioxidant actions. Considering the case of a metabolite resulting from the oxidation of quercetin, we offer a comprehensive description of the evidence that increasingly supports the concept that, in the case of certain flavonoids, the oxidation of phenolics emerges as a mechanism that markedly amplifies their original antioxidant properties. An overlooked topic of great phytomedicine potential is thus unraveled.

Physical Activity vs. Redox Balance in the Brain: Brain Health, Aging and Diseases

It has been proven that physical exercise improves cognitive function and memory, has an analgesic and antidepressant effect, and delays the aging of the brain and the development of diseases, including neurodegenerative disorders. There are even attempts to use physical activity in the treatment of mental diseases. The course of most diseases is strictly associated with oxidative stress, which can be prevented or alleviated with regular exercise. It has been proven that physical exercise helps to maintain the oxidant–antioxidant balance. In this review, we present the current knowledge on redox balance in the organism and the consequences of its disruption, while focusing mainly on the brain. Furthermore, we discuss the impact of physical activity on aging and brain diseases, and present current recommendations and directions for further research in this area.

Flavonoids Seen through the Energy Perspective

In all life forms, opposing forces provide the energy that flows through networks in an organism, which fuels life. In this concept, health is the ability of an organism to maintain the balance between these opposing forces, which creates resilience, and a deranged flow of energy is the basis for diseases. Treatment should focus on adjusting the deranged flow of energy, e.g., by the redox modulating activity of antioxidants. A major group of antioxidants is formed by flavonoids, a group of polyphenolic compounds abundantly present in our diet. The objective here is to review how the redox modulation by flavonoids fits in the various concepts on the mode of action of bioactive compounds, so we can 'see' where there is overlap and where the missing links are. Based on this fundament, we should choose our research path aiming to 'understand' the redox modulating profile of specific flavonoids, so we can ultimately rationally apply the redox modulating power of flavonoids to improve our health.

Contribution of Biotransformations Carried Out by the Microbiota, Drug-Metabolizing Enzymes, and Transport Proteins to the Biological Activities of Phytochemicals Found in the Diet

The consumption of dietary phytochemicals has been associated with several health benefits and relevant biological activities. It is postulated that biotransformations of these compounds regulated by the microbiota, Phase I/II reactions, transport proteins, and deconjugating enzymes contribute not only to their metabolic clearance but also, in some cases, to their bioactivation. A number of factors (age, genetics, sex, physiopathological conditions, and the interplay with other dietary phytochemicals) modulating metabolic activities are important sources and contributors to the interindividual variability observed in clinical studies evaluating the biological activities of phytochemicals. In this review, we discuss all the processes that can affect the bioaccessibility and beneficial effects of these bioactive compounds. Herein, we argue that the role of these factors must be further studied to correctly understand and predict the effects observed following the intake of phytochemicals. This is, in particular, with regard to in vitro investigations, which have shown great inconsistency with preclinical and clinical studies. The complexity of in vivo metabolic activity and biotransformation should therefore be considered in the interpretation of results in vitro and their translation to human physiopathology.

Quantitative proteomic analysis of the effects of melatonin treatment for mice suffered from small intestinal damage induced by γ-ray radiation

PURPOSE

Intestinal damage induced by radiation exposure is a major clinic concern of radiotherapy for patients with abdominal or pelvic tumor. Melatonin (N-acetyl-5-methoxytryptamine) is likely be an ideal radioprotector to protect individuals from radiation exposure. The study aimed to define the role of melatonin in small intestinal damage caused by abdominal irradiation (ABI).

MATERIALS AND METHODS

30-day survival rate and pathological histology of the intestines from melatonin-treated mice after 13 Gy ABI exposure was first detected. Next, quantitative proteomics analysis of the small intestines tissue was examined and GO term and KEGG pathways analysis were performed.

RESULTS

Melatonin treatment before ABI exposure significantly increased 30-day survival rate to 83% and ameliorated damage to the intestinal epithelial cells. Melatonin significantly altered the proteins profile of the small intestines following irradiation. For the irradiated mice treated with melatonin in comparison with the irradiated mice, the enriched GO terms were mainly involved in defense response to other organism (BP, GO: 0098542), response to other organism (BP, GO: 0051707), anion transmembrane transporter activity (MF, GO: 0008509), and secondary active transmembrane transporter activity (MF, GO: 0015291). In the process of antioxidant activity (MF, GO: 0016209), melatonin treatment prior to radiation exhibited high protein levels of Sod3 and Gpx3. The markedly KEGG pathways for melatonin treatment prior to radiation mainly included protein digestion and absorption (ko 04974) and mineral absorption (ko 04978). p53 signaling pathway and DNA repair pathways were enriched in melatonin treated mice. The amount of radiation-induced DNA damage and the cell apoptosis of the small intestines was decreased in the melatonin-treated mice.

CONCLUSIONS

Melatonin may protect small intestines from radiation damage through increasing DNA repair and decreasing cell apoptosis of the small intestines. Our data provided perspective for the study of melatonin in mitigating ABI-caused intestinal damage.

Antioxidants: Classification, Natural Sources, Activity/Capacity Measurements, and Usefulness for the Synthesis of Nanoparticles

Natural extracts are the source of many antioxidant substances. They have proven useful not only as supplements preventing diseases caused by oxidative stress and food additives preventing oxidation but also as system components for the production of metallic nanoparticles by the so-called green synthesis. This is important given the drastically increased demand for nanomaterials in biomedical fields. The source of ecological technology for producing nanoparticles can be plants or microorganisms (yeast, algae, cyanobacteria, fungi, and bacteria). This review presents recently published research on the green synthesis of nanoparticles. The conditions of biosynthesis and possible mechanisms of nanoparticle formation with the participation of bacteria are presented. The potential of natural extracts for biogenic synthesis depends on the content of reducing substances. The assessment of the antioxidant activity of extracts as multicomponent mixtures is still a challenge for analytical chemistry. There is still no universal test for measuring total antioxidant capacity (TAC). There are many in vitro chemical tests that quantify the antioxidant scavenging activity of free radicals and their ability to chelate metals and that reduce free radical damage. This paper presents the classification of antioxidants and non-enzymatic methods of testing antioxidant capacity in vitro, with particular emphasis on methods based on nanoparticles. Examples of recent studies on the antioxidant activity of natural extracts obtained from different species such as plants, fungi, bacteria, algae, lichens, actinomycetes were collected, giving evaluation methods, reference antioxidants, and details on the preparation of extracts.

Metabolic Implications of Oxidative Stress and Inflammatory Process in SARS-CoV-2 Pathogenesis: Therapeutic Potential of Natural Antioxidants

COVID-19 is a zoonotic disease with devastating economic and public health impacts globally. Being a novel disease, current research is focused on a clearer understanding of the mechanisms involved in its pathogenesis and viable therapeutic strategies. Oxidative stress and inflammation are intertwined processes that play roles in disease progression and response to therapy via interference with multiple signaling pathways. The redox status of a host cell is an important factor in viral entry due to the unique conditions required for the conformational changes that ensure the binding and entry of a virus into the host cell. Upon entry into the airways, viral replication occurs and the innate immune system responds by activating macrophage and dendritic cells which contribute to inflammation. This review examines available literature and proposes mechanisms by which oxidative stress and inflammation could contribute to COVID-19 pathogenesis. Further, certain antioxidants currently undergoing some form of trial in COVID-19 patients and the corresponding required research gaps are highlighted to show how targeting oxidative stress and inflammation could ameliorate COVID-19 severity.

Dexmedetomidine attenuates H2O2-induced apoptosis of rat cardiomyocytes independently of antioxidant enzyme expression

INTRODUCTION AND OBJECTIVES

Dexmedetomidine is a highly selective alpha-2 adrenoceptor agonist that has sedative and analgesic properties and myocardial protective effects. However, the mechanism underlying the protective effect of dexmedetomidine on cardiomyocytes remains unknown. This study mainly aimed to investigate the effects of dexmedetomidine on the generation of reactive oxygen species (ROS) in cardiomyocytes and whether it inhibits the apoptosis of cardiomyocytes by affecting antioxidant enzyme expression.

METHODS

Neonatal rat cardiomyocytes were pretreated with dexmedetomidine (100 nM) for 24 h. The cardiomyocytes were then incubated with 200 μM hydrogen peroxide solution (H₂O₂) for 4 h. PCR assay was used to determine the mRNA expression of antioxidant enzymes. Western blot assay was used to determine the protein expression of antioxidant enzymes. Fluorescence microscopy with the MitoSOX probe was used to detect the formation of ROS in cardiomyocytes, and fluorescence-activated cell sorting with annexin V/PI was used to determine the number of apoptotic cardiomyocytes.

RESULTS

Dexmedetomidine reduced ROS generation and antioxidant enzymes levels in cardiomyocytes before H₂O₂ stimulation (p<0.05). However, ROS generation and apoptosis in cardiomyocytes were significantly increased after H₂O₂ treatment, and dexmedetomidine pretreatment markedly inhibited the changes (p<0.05).

CONCLUSION

For the first time, to the best of our knowledge, our study shows that dexmedetomidine has a protective effect on cardiomyocytes through inhibition of ROS-induced apoptosis, and more importantly, this effect is independent of antioxidant enzyme mRNA and protein expression.

Efficacy of Polyphenols in the Management of Dyslipidemia: A Focus on Clinical Studies

Polyphenols (PLPs), phytochemicals found in a wide range of plant-based foods, have gained extensive attention in view of their antioxidant, anti-inflammatory, immunomodulatory and several additional beneficial activities. The health-promoting effects noted in animal models of various non-communicable diseases explain the growing interest in these molecules. In particular, in vitro and animal studies reported an attenuation of lipid disorders in response to PLPs. However, despite promising preclinical investigations, the effectiveness of PLPs in human dyslipidemia (DLP) is less clear and necessitates revision of available literature. Therefore, the present review analyzes the role of PLPs in managing clinical DLP, notably by dissecting their potential in ameliorating lipid/lipoprotein metabolism and alleviating hyperlipidemia, both postprandially and in long-term interventions. To this end, PubMed was used for article search. The search terms included polyphenols, lipids, triglycerides, cholesterol, LDL-cholesterol and /or HDL-cholesterol. The critical examination of the trials published to date illustrates certain benefits on blood lipids along with co-morbidities in participant’s health status. However, inconsistent results document significant research gaps, potentially owing to study heterogeneity and lack of rigor in establishing PLP bioavailability during supplementation. This underlines the need for further efforts in order to elucidate and support a potential role of PLPs in fighting DLP.

Mitochondria-targeted phenolic antioxidants induce ROS-protective pathways in primary human skin fibroblasts

Phytochemical antioxidants like gallic and caffeic acid are constituents of the normal human diet that display beneficial health effects, potentially via activating stress response pathways. Using primary human skin fibroblasts (PHSFs) as a model, we here investigated whether such pathways were induced by novel mitochondria-targeted variants of gallic acid (AntiOxBEN₂) and caffeic acid (AntiOxCIN₄). Both molecules reduced cell viability with similar kinetics and potency (72 h incubation, IC50 ~23 μM). At a relatively high but non-toxic concentration (12.5 μM), AntiOxBEN₂ and AntiOxCIN₄ increased ROS levels (at 24 h), followed by a decline (at 72 h). Further analysis at the 72 h timepoint demonstrated that AntiOxBEN₂ and AntiOxCIN₄ did not alter mitochondrial membrane potential (Δψ), but increased cellular glutathione (GSH) levels, mitochondrial NAD(P)H autofluorescence, and mitochondrial superoxide dismutase 2 (SOD2) protein levels. In contrast, cytosolic SOD1 protein levels were not affected. AntiOxBEN₂ and AntiOxCIN₄ both stimulated the gene expression of Nuclear factor erythroid 2-related factor 2 (NRF2; a master regulator of the cellular antioxidant response toward oxidative stress). AntiOxBEN2 and ANtiOxCIN4 differentially affected the gene expression of the antioxidants Heme oxygenase 1 (HMOX1) and NAD(P)H dehydrogenase (quinone) 1 (NQO1). Both antioxidants did not protect from cell death induced by GSH depletion and AntiOxBEN₂ (but not AntiOxCIN₄) antagonized hydrogen peroxide-induced cell death. We conclude that AntiOxBEN₂ and AntiOxCIN₄ increase ROS levels, which stimulates NRF2 expression and, as a consequence, SOD2 and GSH levels. This highlights that AntiOxBEN₂ and AntiOxCIN₄ can act as prooxidants thereby activating endogenous ROS-protective pathways.

When It Comes to an End: Oxidative Stress Crosstalk with Protein Aggregation and Neuroinflammation Induce Neurodegeneration

Neurodegenerative diseases are characterized by a progressive loss of neurons in the brain or spinal cord that leads to a loss of function of the affected areas. The lack of effective treatments and the ever-increasing life expectancy is raising the number of individuals affected, having a tremendous social and economic impact. The brain is particularly vulnerable to oxidative damage given the high energy demand, low levels of antioxidant defenses, and high levels of metal ions. Driven by age-related changes, neurodegeneration is characterized by increased oxidative stress leading to irreversible neuronal damage, followed by cell death. Nevertheless, neurodegenerative diseases are known as complex pathologies where several mechanisms drive neuronal death. Herein we discuss the interplay among oxidative stress, proteinopathy, and neuroinflammation at the early stages of neurodegenerative diseases. Finally, we discuss the use of the Nrf2-ARE pathway as a potential therapeutic strategy based on these molecular mechanisms to develop transformative medicines.

S-allyl cysteine: A potential compound against skeletal muscle atrophy

BACKGROUND

Oxidative stress is crucial player in skeletal muscle atrophy pathogenesis. S-allyl cysteine (SAC), an organosulfur compound of Allium sativum, possesses broad-spectrum properties including immuno- and redox-modulatory impact. Considering the role of SAC in regulating redox balance, we hypothesize that SAC may have a protective role in oxidative-stress induced atrophy.

METHODS

C2C12 myotubes were treated with H₂O₂ (100 μM) in the presence or absence of SAC (200 μM) to study morphology, redox status, inflammatory cytokines and proteolytic systems using fluorescence microscopy, biochemical analysis, real-time PCR and immunoblotting approaches. The anti-atrophic potential of SAC was confirmed in denervation-induced atrophy model.

RESULTS

SAC pre-incubation (4 h) could protect the myotube morphology (i.e. length/diameter/fusion index) from atrophic effects of H₂O₂. Lower levels of ROS, lipid peroxidation, oxidized glutathione and altered antioxidant enzymes were observed in H₂O₂-exposed cells upon pre-treatment with SAC. SAC supplementation also suppressed the rise in cytokines levels (TWEAK/IL6/myostatin) caused by H₂O₂. SAC treatment also moderated the degradation of muscle-specific proteins (MHCf) in the H₂O₂-treated myotubes supported by lower induction of diverse proteolytic systems (i.e. cathepsin, calpain, ubiquitin-proteasome E3-ligases, caspase-3, autophagy). Denervation-induced atrophy in mice illustrates that SAC administration alleviates the negative effects (i.e. mass loss, decreased cross-sectional area, up-regulation of proteolytic systems, and degradation of total/specific protein) of denervation on muscles.

CONCLUSIONS

SAC exerts significant anti-atrophic effects to protect myotubes from H₂O₂-induced protein loss and myofibers from denervation-induced muscle loss, due to the prevention of elevated proteolytic systems and inflammatory/oxidative molecules.

GENERAL SIGNIFICANCE

The results signify the potential of SAC against muscle atrophy.

Luteolin inhibits melanoma growth in vitro and in vivo via regulating ECM and oncogenic pathways but not ROS

Luteolin inhibited growth of several cancer cells in vitro in previous studies, with limited in vivo studies, and no comprehensive understanding of molecular mechanisms at genomics level. This study identified luteolin as an effective agent to inhibit melanoma cell growth in vitro and in vivo. Molecular studies and genomic profiling were used to identify the mechanism of action of luteolin in melanoma cells. As a ROS (reactive oxygen species) scavenger, luteolin unexpectedly induced ROS; but co-treatment with antioxidants NAC or mito-TEMPO did not rescue cell growth inhibition, although the levels of ROS levels were reduced. Next, we profiled luteolin-induced differentially expressed genes (DEGs) in 4 melanoma cell lines using RNA-Seq, and performed pathway analysis using a combination of bioinformatics software including PharmetRx which was especially effective in discovering pharmacological pathways for potential drugs. Our results show that luteolin induces changes in three main aspects: the cell-cell interacting pathway (extracellular matrix, ECM), the oncogenic pathway and the immune response signaling pathway. Based on these results, we further validated that luteolin was especially effective in inhibiting cell proliferation when cells were seeded at low density, concomitantly with down-regulation of fibronectin accumulation. In conclusion, through extensive DEG profiling in a total of 4 melanoma cell lines, we found that luteolin-mediated growth inhibition in melanoma cells was perhaps not through ROS induction, but likely through simultaneously acting on multiple pathways including the ECM (extracellular matrix) pathway, the oncogenic signaling and the immune response pathways. Further investigations on the mechanisms of this promising compound are warranted and likely result in application to cancer patients as its safety pharmacology has been validated in autism patients.

Vitamin D Deficiency and the Risk of Cerebrovascular Disease

Vitamin D deficiency has been clearly linked to major chronic diseases associated with oxidative stress, inflammation, and aging, including cardiovascular and neurodegenerative diseases, diabetes, and cancer. In particular, the cardiovascular system appears to be highly sensitive to vitamin D deficiency, as this may result in endothelial dysfunction and vascular defects via multiple mechanisms. Accordingly, recent research developments have led to the proposal that pharmacological interventions targeting either vitamin D deficiency or its key downstream effects, including defective autophagy and abnormal pro-oxidant and pro-inflammatory responses, may be able to limit the onset and severity of major cerebrovascular diseases, such as stroke and cerebrovascular malformations. Here we review the available evidence supporting the role of vitamin D in preventing or limiting the development of these cerebrovascular diseases, which are leading causes of disability and death all over the world.

Delocalization of the Unpaired Electron in the Quercetin Radical: Comparison of Experimental ESR Data with DFT Calculations

In the antioxidant activity of quercetin (Q), stabilization of the energy in the quercetin radical (Q•) by delocalization of the unpaired electron (UE) in Q• is pivotal. The aim of this study is to further examine the delocalization of the UE in Q•, and to elucidate the importance of the functional groups of Q for the stabilization of the UE by combining experimentally obtained spin resonance spectroscopy (ESR) measurements with theoretical density functional theory (DFT) calculations. The ESR spectrum and DFT calculation of Q• and structurally related radicals both suggest that the UE of Q• is mostly delocalized in the B ring and partly on the AC ring. The negatively charged oxygen groups in the B ring (3' and 4') of Q• have an electron-donating effect that attract and stabilize the UE in the B ring. Radicals structurally related to Q• indicate that the negatively charged oxygen at 4' has more of an effect on concentrating the UE in ring B than the negatively charged oxygen at 3'. The DFT calculation showed that an OH group at the 3-position of the AC ring is essential for concentrating the radical on the C2-C3 double bond. All these effects help to explain how the high energy of the UE is captured and a stable Q• is generated, which is pivotal in the antioxidant activity of Q.

Antioxidant Defenses: A Context-Specific Vulnerability of Cancer Cells

Reactive oxygen species (ROS) are well known for their capacity to cause DNA damage, augment mutagenesis, and thereby promote oncogenic transformation. Similarly, agents that reduce ROS levels (antioxidants) are frequently thought to have anti-cancer properties given their propensity to minimize DNA damage and mutagenesis. However, numerous clinical studies focused on antioxidants suggest that this is a facile premise and that antioxidant capacity can be important for cancer cells in a similar fashion to normal cells. As a consequence of this realization, numerous laboratories have been motivated to investigate the biological underpinnings explaining how and when antioxidant activity can potentially be beneficial to cancer cells. Relatedly, it has become clear that the reliance of cancer cells on antioxidant activity in certain contexts represents a potential vulnerability that could be exploited for therapeutic gain. Here, we review some of the recent, exciting findings documenting how cancer cells utilized antioxidant activity and under what circumstances this activity could represent an opportunity for selective elimination of cancer cells.

Mitochondrial Morphofunction in Mammalian Cells

Significance: In addition to their classical role in cellular ATP production, mitochondria are of key relevance in various (patho)physiological mechanisms including second messenger signaling, neuro-transduction, immune responses and death induction. Recent Advances: Within cells, mitochondria are motile and display temporal changes in internal and external structure ("mitochondrial dynamics"). During the last decade, substantial empirical and in silico evidence was presented demonstrating that mitochondrial dynamics impacts on mitochondrial function and vice versa. Critical Issues: However, a comprehensive and quantitative understanding of the bidirectional links between mitochondrial external shape, internal structure and function ("morphofunction") is still lacking. The latter particularly hampers our understanding of the functional properties and behavior of individual mitochondrial within single living cells. Future Directions: In this review we discuss the concept of mitochondrial morphofunction in mammalian cells, primarily using experimental evidence obtained within the last decade. The topic is introduced by briefly presenting the central role of mitochondria in cell physiology and the importance of the mitochondrial electron transport chain (ETC) therein. Next, we summarize in detail how mitochondrial (ultra)structure is controlled and discuss empirical evidence regarding the equivalence of mitochondrial (ultra)structure and function. Finally, we provide a brief summary of how mitochondrial morphofunction can be quantified at the level of single cells and mitochondria, how mitochondrial ultrastructure/volume impacts on mitochondrial bioreactions and intramitochondrial protein diffusion, and how mitochondrial morphofunction can be targeted by small molecules.

Nutrition and corticosteroids in the treatment of sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a chronic disease, which is routinely treated with corticosteroids. Steroid resistance or steroid-induced adverse effects require alternatives. Other immune-modulating pharmacological treatments have been developed, and therefore expanded tremendously. Until now, the role of nutrition in the overall management of sarcoidosis has been neglected although anti-inflammatory properties of nutritional components have been known for many years now. New nutritional possibilities emerge from already existing data and offer new therapeutic avenues in the treatment of sarcoidosis.

RECENT FINDINGS

Various dietary components have been shown to reduce pulmonary inflammatory processes. It is increasingly recognized, however, that the specificity and magnitude of the effect of nutrition differs from pharmacological interventions. Conventional randomized clinical trials are less suitable to test the effect of nutrition in comparison with testing drugs. Mechanistic knowledge on the action of dietary components in conjunction with an increasing understanding of the molecular processes underlying steroid resistance (as investigated in asthma and COPD and unfortunately hardly in sarcoidosis) lead to exciting suggestions on combinations of nutrition/nutritional bioactive compounds and corticosteroids that may benefit sarcoidosis patients.

SUMMARY

In order to understand the effects of nutrition in chronic disease, it is important to elucidate mechanisms and pathways of effects. Several complementing lines of evidence should be integrated in order to be able to advise sarcoidosis patients on a healthy diet as such or in combination with prescribed anti-inflammatory therapy.

Connecting West and East

Despite their similarities, Western medicine and Eastern medicine are very different because they are built on different fundamentals. The general idea has arisen that we will benefit by connecting Western and Eastern medicine. First, both the merits as well as the limitations of both types of medicine are discussed. It was concluded that to create a bridge, we should focus on similarities that inspire the further unravelling of the molecular mechanism of the mode of action and toxicity of Traditional Chinese Medicine. It is suggested that the energy perspective provides a basis to integrate Eastern and Western medicine.

Paradoxical Roles of Oxidative Stress Response in the Digestive System before and after Carcinogenesis

Oxidative stress is recognized as a cancer-initiating stress response in the digestive system. It is produced through mitochondrial respiration and induces DNA damage, resulting in cancer cell transformation. However, recent findings indicate that oxidative stress is also a necessary anticancer response for destroying cancer cells. The oxidative stress response has also been reported to be an important step in increasing the anticancer response of newly developed molecular targeted agents. Oxidative stress might therefore be a cancer-initiating response that should be downregulated in the precancerous stage in patients at risk of cancer but an anticancer cell response that should not be downregulated in the postcancerous stage when cancer cells are still present. Many commercial antioxidant agents are marketed as “cancer-eliminating agents” or as products to improve one’s health, so cancer patients often take these antioxidant agents. However, care should be taken to avoid harming the anticancerous oxidative stress response. In this review, we will highlight the paradoxical effects of oxidative stress and antioxidant agents in the digestive system before and after carcinogenesis.

Hepatic stress associated with pathologies characterized by disturbed glucose production

The liver is an organ with many facets, including a role in energy production and metabolic balance, detoxification and extraordinary capacity of regeneration. Hepatic glucose production plays a crucial role in the maintenance of normal glucose levels in the organism i.e. between 0.7 to 1.1 g/l. The loss of this function leads to a rare genetic metabolic disease named glycogen storage disease type I (GSDI), characterized by severe hypoglycemia during short fasts. On the contrary, type 2 diabetes is characterized by chronic hyperglycemia, partly due to an overproduction of glucose by the liver. Indeed, diabetes is characterized by increased uptake/production of glucose by hepatocytes, leading to the activation of de novo lipogenesis and the development of a non-alcoholic fatty liver disease. In GSDI, the accumulation of glucose-6 phosphate, which cannot be hydrolyzed into glucose, leads to an increase of glycogen stores and the development of hepatic steatosis. Thus, in these pathologies, hepatocytes are subjected to cellular stress mainly induced by glucotoxicity and lipotoxicity. In this review, we have compared hepatic cellular stress induced in type 2 diabetes and GSDI, especially oxidative stress, autophagy deregulation, and ER-stress. In addition, both GSDI and diabetic patients are prone to the development of hepatocellular adenomas (HCA) that occur on a fatty liver in the absence of cirrhosis. These HCA can further acquire malignant traits and transform into hepatocellular carcinoma. This process of tumorigenesis highlights the importance of an optimal metabolic control in both GSDI and diabetic patients in order to prevent, or at least to restrain, tumorigenic activity during disturbed glucose metabolism pathologies.

Sources of Vascular Nitric Oxide and Reactive Oxygen Species and Their Regulation

Nitric oxide (NO) is a small free radical with critical signaling roles in physiology and pathophysiology. The generation of sufficient NO levels to regulate the resistance of the blood vessels and hence the maintenance of adequate blood flow is critical to the healthy performance of the vasculature. A novel paradigm indicates that classical NO synthesis by dedicated NO synthases is supplemented by nitrite reduction pathways under hypoxia. At the same time, reactive oxygen species (ROS), which include superoxide and hydrogen peroxide, are produced in the vascular system for signaling purposes, as effectors of the immune response, or as byproducts of cellular metabolism. NO and ROS can be generated by distinct enzymes or by the same enzyme through alternate reduction and oxidation processes. The latter oxidoreductase systems include NO synthases, molybdopterin enzymes, and hemoglobins, which can form superoxide by reduction of molecular oxygen or NO by reduction of inorganic nitrite. Enzymatic uncoupling, changes in oxygen tension, and the concentration of coenzymes and reductants can modulate the NO/ROS production from these oxidoreductases and determine the redox balance in health and disease. The dysregulation of the mechanisms involved in the generation of NO and ROS is an important cause of cardiovascular disease and target for therapy. In this review we will present the biology of NO and ROS in the cardiovascular system, with special emphasis on their routes of formation and regulation, as well as the therapeutic challenges and opportunities for the management of NO and ROS in cardiovascular disease.

Impact of Cereal Seed Sprouting on Its Nutritional and Technological Properties: A Critical Review

Sprouting induces activation and de novo synthesis of hydrolytic enzymes that make nutrients available for plant growth and development. Consumption of sprouted grains is suggested to be beneficial for human health. Positive consumer perceptions about sprouted cereals have resulted in new food and beverage product launches. However, because there is no generally accepted definition of "sprouting," it is unclear when grains are to be called sprouted. Moreover, guidelines about how much sprouted grain material food products should contain to exert health benefits are currently lacking. Accordingly, there is no regulatory base to develop appropriate food labeling for "sprouted foods." This review describes the nutritional and technological properties of sprouted grains in relation to processing conditions and provides guidelines to optimize sprouting practices in order to maximize nutritive value. Relatively long sprouting times (3 to 5 days) and/or high processing temperatures (25 to 35 °C) are needed to maximize the de novo synthesis and/or release of plant bioactive compounds. Nutrient compositional changes resulting from sprouting are often associated with health benefits. However, supportive data from clinical studies are very scarce, and at present it is impossible to draw any conclusion on health benefits of sprouted cereals. Finally, grains sprouted under the above-mentioned conditions are generally unfit for use in traditional food processing and it is challenging to use sprouted grains as ingredients without compromising their nutrient content. The present review provides a basis for better defining what "sprouting" is, and to help further research and development efforts in this field as well as future food regulations development.

Proteomic responses of carotenoid and retinol administration to Mongolian gerbils

Various health benefits of carotenoids have been described. However, while human observational studies generally suggest positive health effects, supplementation with relatively high doses of individual carotenoids (supplements) have partly produced adverse effects. In the present study, we investigated the effect of several carotenoids on the proteomic response of male Mongolian gerbils (aged 6 weeks). Five groups of gerbils (n = 6 per group) received either retinol (vitamin A/53 mg per kg bw), all-trans β-carotene (pro-vitamin A/100 mg kg-1), the non-pro vitamin A carotenoid lutein (100 mg kg-1), the acyclic carotenoid lycopene (100 mg kg-1) or vehicle (Cremophor EL), via oral single gavage. Gerbils were 12 h post-prandially sacrificed and blood plasma, liver, and white adipose tissue were collected. For liver and adipose tissue, a 2D-DIGE (difference gel electrophoresis) approach was conducted; for plasma, proteomic analyses were achieved by liquid chromatography-mass spectrometry. Compared to controls (vehicle), various proteins were showing significant abundance variations in plasma (66), liver (29) and adipose tissue (19), especially regarding structure (22), protein metabolism (15) and immune system/inflammation (19) functions, while proteins related to antioxidant effects were generally less abundant, suggesting no in vivo relevance. Surprisingly, a large overlap in protein regulation was found between lycopene and retinol exposure, while other carotenoids, including all-trans β-carotene, did not show this overlap. Mainly retinoid acid receptor co-regulated proteins may mechanistically explain this overlapping regulation. This overlapping regulation may be related to common nuclear hormone receptor mediated signalling, though further studies using synthetic ligands of retinoid receptors targeting protein regulation are needed for confirmation.

Cinnamaldehyde regulates H2 O 2 -induced skeletal muscle atrophy by ameliorating the proteolytic and antioxidant defense systems

Skeletal muscle atrophy/wasting is associated with impaired protein metabolism in diverse physiological and pathophysiological conditions. Elevated levels of reactive oxygen species (ROS), disturbed redox status, and weakened antioxidant defense system are the major contributing factors toward atrophy. Regulation of protein metabolism by controlling ROS levels and its associated catabolic pathways may help in treating atrophy and related clinical conditions. Although cinnamaldehyde (CNA) enjoys the established status of antioxidant and its role in ROS management is reported, impact of CNA on skeletal muscle atrophy and related pathways is still unexplored. In the current study, the impact of CNA on C2C12 myotubes and the possible protection of cultured cells from H ₂ O ₂ -induced atrophy is examined. Myotubes were treated with H ₂ O ₂ in the presence and absence of CNA and the changes in the antioxidative, proteolytic systems, and mitochondrial functions were scored. Morphological analysis showed significant protective effects of CNA on length, diameter, and nuclei fusion index of myotubes. The evaluation of biochemical markers of atrophy; creatine kinase, lactate dehydrogenase, succinate dehydrogenase along with the study of muscle-specific structural protein (i.e., myosin heavy chain-fast [MHCf] type) showed significant protection of proteins by CNA. CNA pretreatment not only checked the activation of proteolytic systems (ubiquitin-proteasome E3-ligases [MuRF1/Atrogin1]), autophagy [Beclin1/LC3B], cathepsin L, calpain, caspase), but also prevented any alteration in the activities of antioxidative defense enzymes (catalase, glutathione- S-transferase, glutathione-peroxidase, superoxide dismutase, glutathione reductase). The results suggest that CNA protects myotubes from H ₂ O ₂ -induced atrophy by inhibiting/resisting the amendments in proteolytic systems and maintains cellular redox-balance.

Redox regulation in regenerative medicine and tissue engineering: The paradox of oxygen

One of the biggest challenges in tissue engineering and regenerative medicine is to incorporate a functioning vasculature to overcome the consequences of a lack of oxygen and nutrients in the tissue construct. Otherwise, decreased oxygen tension leads to incomplete metabolism and the formation of the so‐called reactive oxygen species (ROS). Cells have many endogenous antioxidant systems to ensure a balance between ROS and antioxidants, but if this balance is disrupted by factors such as high levels of ROS due to long‐term hypoxia, there will be tissue damage and dysfunction. Current attempts to solve the oxygen problem in the field rarely take into account the importance of the redox balance and are instead centred on releasing or generating oxygen. The first problem with this approach is that although oxygen is necessary for life, it is paradoxically also a highly toxic molecule. Furthermore, although some oxygen‐generating biomaterials produce oxygen, they also generate hydrogen peroxide, a ROS, as an intermediate product. In this review, we discuss why it would be a superior strategy to supplement oxygen delivery with molecules to safeguard the important redox balance. Redox sensor proteins that can stimulate the anaerobic metabolism, angiogenesis, and enhancement of endogenous antioxidant systems are discussed as promising targets. We propose that redox regulating biomaterials have the potential to tackle some of the challenges related to angiogenesis and that the knowledge in this review will help scientists in tissue engineering and regenerative medicine realize this aim.

The relationship between standard reduction potentials of catechins and biological activities involved in redox control

Redox homeostasis involves factors that ensure proper function of cells. The excess reactive oxygen species (ROS) leads to oxidative stress and increased risk of oxidative damage to cellular components. In contrast, upon reductive stress, insufficient ROS abundance may result in faulty cell signalling. It may be expected that dietary antioxidants, depending on their standard reduction potentials (E°), will affect both scenarios. In our study, for the first time, we systematically tested the relationship among E°, chemical properties, and biological effects in HT29 cells for a series of structurally different catechins and a major endogenous antioxidant - glutathione (GSH), at both physiological and dietary concentrations. Among chemical antioxidant activity tests, the strongest correlation with E° was seen using a DPPH assay. The values of E° were also highly correlated with cellular antioxidant activity (CAA) values determined in HT29 cells. Our results indicated that physiological concentrations (1-10 µM) of tested catechins stabilized the redox status of cells, which was not exhibited at higher concentrations. This stabilization of redox homeostasis was mirrored by constant, dose and E° independent CAA values, uninhibited growth of HT29 cells, modulation of hydrogen peroxide-induced DNA damage, as well as effects at the genomic level, where either up-regulation of three redox-related genes (ALB, CCL5, and HSPA1A) out of 84 in the array (1 µM) or no effect (10 µM) was observed for catechins. Higher catechin concentrations (over 10 µM) increased CAA values in a dose- and E°-dependent manner, caused cell growth inhibition, but surprisingly did not protect HT29 cells against reactive oxygen species (ROS)-induced DNA fragmentation. In conclusion, dose-dependent effects of dietary antioxidants and biological functions potentially modulated by them may become deregulated upon exposure to excessive doses.

Monomeric and oligomeric flavanols maintain the endogenous glucocorticoid response in human macrophages in pro-oxidant conditions in vitro

Chronic inflammation and oxidative stress are (sub)cellular processes that enhance each other and contribute to the genesis of many systemic pathologies. The endogenous glucocorticoid cortisol plays an important role in the physiological termination of a pro-inflammatory immune response. However, in conditions of pronounced oxidative stress the anti-inflammatory action of cortisol is impaired. Since grape seed-derived monomeric and oligomeric flavan-3-ols (MOF) have been shown to attenuate both inflammation and oxidative stress in vitro and in humans, we hypothesized that these compounds are able to maintain the anti-inflammatory activity of cortisol in immune cells in a pro-oxidant environment. In a glucocorticoid resistance model using human monocytes (THP-1 cell line) differentiated into macrophage-like cells we observed that exposure to 1 mM tertiary butyl hydroperoxide (t-BuOOH) for 4 h significantly hampered the anti-inflammatory action of cortisol assessed as attenuation of the interleukin (IL)-8 production. Under these conditions, the effects of MOF were assessed on pro-inflammatory cytokines expression, cortisol's anti-inflammatory action and on the expression of 11β-hydroxysteroid dehydrogenase (11β-HSD) 1, which catalyzes intracellular conversion of cortisone to cortisol. MOF attenuated the gene expression of pro-inflammatory cytokines and prevented the decline of the anti-inflammatory effect of cortisol in the presence of t-BuOOH. MOF also maintained the activity of histone deacetylase in the cell nucleus which is essential for cortisol's molecular action to terminate the transcription of pro-inflammatory genes. Moreover, MOF prevented the down-regulation of 11β-HSD1 gene expression in this pro-oxidant cellular environment. Taken together our data suggest that MOF contribute to maintain the anti-inflammatory action of cortisol under pro-oxidant conditions via preservation of the intracellular availability of bioactive cortisol and cortisol-mediated termination of pro-inflammatory gene transcription. These findings provide novel insights in how MOF may enhance the ability to adapt, which is of particular relevance for their rational use as dietary supplement to maintain health.

Anthocyanin Biosynthesis and Degradation Mechanisms in Solanaceous Vegetables: A Review

Anthocyanins are a group of polyphenolic pigments that are ubiquitously found in the plant kingdom. In plants, anthocyanins play a role not only in reproduction, by attracting pollinators and seed dispersers, but also in protection against various abiotic and biotic stresses. There is accumulating evidence that anthocyanins have health-promoting properties, which makes anthocyanin metabolism an interesting target for breeders and researchers. In this review, the state of the art knowledge concerning anthocyanins in the Solanaceous vegetables, i.e., pepper, tomato, eggplant, and potato, is discussed, including biochemistry and biological function of anthocyanins, as well as their genetic and environmental regulation. Anthocyanin accumulation is determined by the balance between biosynthesis and degradation. Although the anthocyanin biosynthetic pathway has been well-studied in Solanaceous vegetables, more research is needed on the inhibition of biosynthesis and, in particular, the anthocyanin degradation mechanisms if we want to control anthocyanin content of Solanaceous vegetables. In addition, anthocyanin metabolism is distinctly affected by environmental conditions, but the molecular regulation of these effects is poorly understood. Existing knowledge is summarized and current gaps in our understanding are highlighted and discussed, to create opportunities for the development of anthocyanin-rich crops through breeding and environmental management.