Electron transfer from all-trans β-carotene to the t-butyl peroxyl radical at low oxygen pressure (an EPR spectroscopy and computational study)

Several lines of antioxidant defense against oxidative stress: antioxidant enzymes, nanomaterials with multiple enzyme-mimicking activities, and low-molecular-weight antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well recognized for playing a dual role, since they can be either deleterious or beneficial to biological systems. An imbalance between ROS production and elimination is termed oxidative stress, a critical factor and common denominator of many chronic diseases such as cancer, cardiovascular diseases, metabolic diseases, neurological disorders (Alzheimer's and Parkinson's diseases), and other disorders. To counteract the harmful effects of ROS, organisms have evolved a complex, three-line antioxidant defense system. The first-line defense mechanism is the most efficient and involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This line of defense plays an irreplaceable role in the dismutation of superoxide radicals (O2•-) and hydrogen peroxide (H2O2). The removal of superoxide radicals by SOD prevents the formation of the much more damaging peroxynitrite ONOO- (O2•-  + NO• → ONOO-) and maintains the physiologically relevant level of nitric oxide (NO•), an important molecule in neurotransmission, inflammation, and vasodilation. The second-line antioxidant defense pathway involves exogenous diet-derived small-molecule antioxidants. The third-line antioxidant defense is ensured by the repair or removal of oxidized proteins and other biomolecules by a variety of enzyme systems. This review briefly discusses the endogenous (mitochondria, NADPH, xanthine oxidase (XO), Fenton reaction) and exogenous (e.g., smoking, radiation, drugs, pollution) sources of ROS (superoxide radical, hydrogen peroxide, hydroxyl radical, peroxyl radical, hypochlorous acid, peroxynitrite). Attention has been given to the first-line antioxidant defense system provided by SOD, CAT, and GPx. The chemical and molecular mechanisms of antioxidant enzymes, enzyme-related diseases (cancer, cardiovascular, lung, metabolic, and neurological diseases), and the role of enzymes (e.g., GPx4) in cellular processes such as ferroptosis are discussed. Potential therapeutic applications of enzyme mimics and recent progress in metal-based (copper, iron, cobalt, molybdenum, cerium) and nonmetal (carbon)-based nanomaterials with enzyme-like activities (nanozymes) are also discussed. Moreover, attention has been given to the mechanisms of action of low-molecular-weight antioxidants (vitamin C (ascorbate), vitamin E (alpha-tocopherol), carotenoids (e.g., β-carotene, lycopene, lutein), flavonoids (e.g., quercetin, anthocyanins, epicatechin), and glutathione (GSH)), the activation of transcription factors such as Nrf2, and the protection against chronic diseases. Given that there is a discrepancy between preclinical and clinical studies, approaches that may result in greater pharmacological and clinical success of low-molecular-weight antioxidant therapies are also subject to discussion.

Reuse of treated urban wastewater on the growth and physiology of Medicago sativa L. cv. Gea and Petroselinum crispum L. cv. Commun: correlation with oxydative stress and DNA damage

The freshwater scarcity is one of the major environmental problems, which is why the water reuse has become a possible remedy to cope with the shortage of water needed for agriculture irrigation. This study focuses on the evaluation of the irrigation effect with treated effluent from wastewater treatment plant in Tunisia on parsley (Petroselinum crispum L. cv. Commun) used as human food and alfalfa (Medicago sativa L. cv. Gea) as animal food. In vitro germination test was conducted at different dilution levels of wastewater as rejected into the environment (25, 50, and 100%) and wastewater with further treatment (TWW). Results have shown that wastewater with dilution of 25% as well as TWW positively affected the physiological parameters in comparison with the dilutions 50 and 100%. However, the tap water (TW) applied as control treatment has shown the best effects. Oxidative stress evaluated by malondialdehyde (MDA) content was in agreement with the physiological results and showed that the most stressed seeds were those treated with the dilutions 50 and 100%. A pot trial was also conducted to evaluate the suitability of WW and TWW in comparison to TW. Results have shown that TWW is more adapted than WW for irrigation as an improvement of growth and physiological parameters was recorded. Oxidative stress assessed with MDA and proline content has shown that plants irrigated with WW significantly accumulate MDA and proline compared to TWW. The TW has shown the lowest values. DNA damage was evaluated by extraction and agarose gel electrophoresis. It has revealed degradation of DNA for plants irrigated with WW. According to these results, it can be concluded that TWW can be used for irrigation of plants destined for human or animal foods. So, it can be a hydric alternative to resolve the problem of water deficit in semi-arid countries.

Association of Different ABO and Rh Blood Groups with the Erythroprotective Effect of Extracts from Navicula incerta and Their Anti-Inflammatory and Antiproliferative Properties

Previous studies have reported that different blood groups are associated with the risk of chronic degenerative diseases that mainly involve inflammation and neoplastic processes. We investigate the relationship between blood groups and the erythroprotective effect of extracts from Navicula incerta against oxidative damage as a proposal to develop drugs designed for people with a specific blood type related to chronic pathology. The study was carried out through the elucidation of the erythroprotective potential, anti-inflammatory and antiproliferative activity of Navicula incerta. Research suggests that the presence or absence of certain blood groups increases or decreases the abilities of certain phytochemicals to inhibit oxidative stress, which is related to the systemic inflammatory response involved in the development of different types of cancer. The pigment-rich extracts from Navicula incerta inhibit ROO•- induced oxidative stress in human erythrocytes on the A RhD+ve antigen without compromising the structure of the cell membrane. This result is very important, since the A antigen is related to the susceptibility of contracting prostate cancer. Similarly, it was possible to inhibit the proliferation of cervical (HeLa) and prostate (PC-3) carcinoma. The combinatorial analysis of different biological activities can help design phytochemicals as new candidates for preventive drugs treating the chronic degenerative diseases associated with a specific blood group.

Carotenoids and Chlorophylls as Antioxidants

Chlorophylls and carotenoids are natural pigments that are present in our daily diet, especially with the increasing tendency towards more natural and healthy behaviors among consumers. As disturbed antioxidant homeostasis capacities seem to be implicated in the progress of different pathologies, the antioxidant properties of both groups of lipophilic compounds have been studied. The objective of this review was to analyze the state-of-the-art advances in this field. We conducted a systematic bibliographic search (Web of Science™ and Scopus®), followed by a comprehensive and critical description of the results, with special emphasis on highly cited and more recently published research. In addition to an evaluative description of the methodologies, this review discussed different approaches used to obtain a physiological perspective, from in vitro studies to in vivo assays using oxidative biomarkers. From a chemical viewpoint, many studies have demonstrated how a pigment's structure influences its antioxidant response and the underlying mechanisms. The major outcome is that this knowledge is essential for interpreting new data in a metabolic networks context in the search for more direct applications to health. A promising era is coming where the term "antioxidant" is understood in terms of its broadest significance.

Esculetin Neutralises Cytotoxicity of t-BHP but Not of H2O2 on Human Leukaemia NB4 Cells

The coumarin esculetin shows antioxidant action on some cell types, both by scavenging ROS and by decreasing ROS production. We have previously demonstrated the induction of apoptosis by esculetin on NB4 human leukaemia cells by an ill-defined mechanism related to ROS levels. In this work, we analyze the effect of the simultaneous treatment with esculetin and two oxidants to observe the early events in the mechanism of esculetin-induced apoptosis. Our results show that, from the early time of 15 min, esculetin acts synergistically with H₂O₂ to decrease cell viability and metabolic activity and to increase apoptosis in NB4 cells. In contrast, the early oxidative effects of t-BHP are neutralised by esculetin, protecting human leukaemia NB4 cells from apoptosis. Esculetin seems to restrict the increase in peroxides caused by H₂O₂ or t-BHP in the time interval analyzed. These results contribute to a better understanding of the cytotoxic effect caused by esculetin on NB4 cells. At the same time, the early neutralisation of exogenous oxidants could be of interest to prevent diseases related to oxidative stress imbalance.

Carotenoids as a Source of Antioxidants in the Diet

Carotenoids, widely distributed fat-soluble pigments, are responsible for the attractive colorations of several fruits and vegetables commonly present in our daily diet. They are particularly abundant in yellow-orange fruits (carrots, tomatoes, pumpkins, peppers, among others) and, although masked by chlorophylls, in dark green leafy vegetables. Several health benefits have been attributed to carotenoids or to foods rich in these pigments, by means of different mechanisms-of-action, including the role as provitamin A of almost 50 different carotenoids and the antioxidant activity that protects cells and tissues from damage of free radicals and singlet oxygen, providing enhancement of the immune function, protection from sunburn reactions and delaying the onset of certain types of cancer. Common food sources and the efficiency of the absorption of carotenoids, analytical approaches used for measurement of their antioxidant effect and an overview of some epidemiological studies that have been performed to assess the beneficial impact of carotenoids in human health are outlined in this chapter.

Health protective effects of carotenoids and their interactions with other biological antioxidants

Carotenoids are natural pigments attracting attention of physicists, chemists and biologists due to their multiple functions in the nature. While carotenoids have unusually high extinction coefficients, they do not exhibit adequate emission. This fact has resulted in detailed studies of photophysical and photochemical properties of carotenoids and their role as light-harvesting pigments in photosynthesis. Carotenoids are abundantly present in fruits and vegetables and are considered as important species with beneficial effect on human health by decreasing the risk of various diseases, particularly decreasing the incidence of cancers and eye disease. More trials are needed to ascertain the role of carotenoids in prevention of cardiovascular disease and metabolic disease. Carotenoids effectively scavenge peroxyl radicals and act predominantly as antioxidants. However, under conditions of increased concentration of oxygen and carotenoid concentration, beta-carotene was found to exhibit prooxidant behaviour. Photophysical properties of carotenoids and conditions affecting a switch between antioxidant and prooxidant behaviour of carotenoids are the main aims of this review. In addition, the localization of carotenoids in biological membranes, their interactions and reactions with ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E) as well as their redox potentials are discussed in view of their antioxidant properties as beneficial species in preventing various diseases.

Carotenoids and phenolic compounds from Solanum sessiliflorum, an unexploited Amazonian fruit, and their scavenging capacities against reactive oxygen and nitrogen species

The composition of carotenoids and phenolic compounds from mana-cubiu (Solanum sessiliflorum), a fruit native to Amazonia, was determined by high-performance liquid chromatography coupled to diode array and mass spectrometry detectors (HPLC-DAD-MS(n)). The antioxidant capacities of the hydrophilic and carotenoid extracts against some reactive oxygen (ROO(•), H(2)O(2), HOCl, and HO(•)) and nitrogen (ONOO(-)) species were also determined. Seventeen carotenoids and three phenolic compounds were found in mana-cubiu. The major carotenoids were (all-E)-β-carotene (7.15 μg/g of dry weight) and (all-E)-lutein (2.41 μg/g of dry weight). The 5-caffeoylquinic acid (1351 μg/g of dry weight) was the major phenolic compound, representing more than 78% (w/w) of the total phenolic compounds. Moreover, two dihydrocaffeoyl spermidines were found in the hydrophilic extract. Both mana-cubiu extracts were able to scavenge all the tested reactive species. The carotenoid extract was shown to be a potent scavenger of peroxyl radical, while the hydrophilic extract was a potent hydrogen peroxide and hypochlorous acid scavenger.

Microcapsules containing antioxidant molecules as scavengers of reactive oxygen and nitrogen species

The antioxidant capacities of gum arabic and maltodextrin microcapsules containing antioxidant molecules (trolox, α-tocopherol, β-carotene, apo-8'-carotenal and apo-12'-carotenal) against reactive oxygen and nitrogen species were evaluated. The scavenging capacities were influenced by the wall material, the reactive species, namely ROO(), H(2)O(2), HO(), HOCl and ONOO(-), and the antioxidant molecule. In general, a more pronounced enhancement of the antioxidant capacity due to incorporation of antioxidant molecules was observed in gum arabic microcapsules. The empty microcapsules showed capacity to scavenge all the studied ROS and RNS, being gum arabic a more potent antioxidant than maltodextrin. Apo-8'-carotenal incorporation promoted the highest increase in the scavenging capacities among the evaluated antioxidants, varying from 50% to 132% and from 39% to 85% for gum arabic and maltodextrin microcapsules, respectively, suggesting that this carotenoid presented the best balance between the molecule localization inside the microcapsules and the reactivity against the specific reactive species.

Application of ESR spin label oximetry in food science

Lipid oxidation attributed to the presence of oxygen has long been a focal area for food science research due in early years mainly to its broad impact on the quality and shelf stability. The need to effectively strategize interventions to detect and eventually eliminate lipid oxidation in food remains as evidence on nutritional and health implications continue to accumulate. Electron spin resonance (ESR) spin label oximetry has been shown capable of detecting dissolved oxygen concentration in both liquid and gaseous phases based on the collision between oxygen and stable free radicals. This review aimed to summarize not just the principles and rationale of ESR spin label oximetry but also the wide spectrum of ESR spin label oximetry applications to date. The feasibility to identify in very early stage oxygen generation and consumption offers a promising tool for controlling lipid oxidation in food and biological systems.