Oxidative stress, free radicals and protein peroxides

Exploring enzyme inhibition and comprehensive mechanisms of antioxidant/prooxidative activity of natural furanocoumarin derivatives: A comparative kinetic DFT study

This study aimed to explore the antioxidant and prooxidative activity of two natural furanocoumarin derivatives, Bergaptol (4-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, BER) and Xanthotoxol (9-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, XAN). The collected thermodynamic and kinetic data demonstrate that both compounds possess substantial antiradical activity against HO• and CCl3OO• radicals in physiological conditions. BER exhibited better antiradical activity in comparison to XAN, which can be attributed to the enhanced deprotonation caused by the positioning of the -OH group on the psoralen ring. In contrast to highly reactive radical species, newly formed radical species BER• and XAN• exhibited negligible reactivity towards the chosen constitutive elements of macromolecules (fatty acids, amino acids, nucleobases). Furthermore, in the presence of O2•─, the ability to regenerate newly formed radicals BER• and XAN• was observed. Conversely, in physiological conditions in the presence of Cu(II) ions, both compounds exhibit prooxidative activity. Nevertheless, the prooxidative activity of both compounds is less prominent than their antioxidant activity. Furthermore, it has been demonstrated that anionic species can engage in the creation of a chelate complex, which restricts the reduction of metal ions when reducing agents are present (O2•─ and Asc─). Moreover, studies have demonstrated that these chelating complexes can be coupled with other radical species, hence enhancing their ability to inactivate radicals. Both compounds exhibited substantial inhibitory effects against enzymes involved in the direct or indirect generation of ROS: Xanthine Oxidase (XOD), Lipoxygenase (LOX), Myeloperoxidase (MPO), NADPH oxidase (NOX).

Photoreactivity of polycyclic aromatic hydrocarbons (PAHs) and their mechanisms of phototoxicity against human immortalized keratinocytes (HaCaT)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic compounds in the environment. They are produced by many anthropogenic sources of different origins and are known for their toxicity, carcinogenicity, and mutagenicity. Sixteen PAHs have been identified as Priority Pollutants by the US EPA, which are often associated with particulate matter, facilitating their dispersion through air and water. When human skin is exposed to PAHs, it might occur simultaneously with solar radiation, potentially leading to phototoxic effects. Phototoxic mechanisms involve the generation of singlet oxygen and reactive oxygen species, DNA damage under specific light wavelengths, and the formation of charge transfer complexes. Despite predictions of phototoxic properties for some PAHs, there remains a paucity of experimental data. This study examined the photoreactive and phototoxic properties of the 16 PAHs enlisted in the Priority Pollutants list. Examined PAHs efficiently photogenerated singlet oxygen and superoxide anion in simple solutions. Furthermore, singlet oxygen phosphorescence was detected in PAH-loaded HaCaT cells. Phototoxicity against human keratinocytes was evaluated using various assays. At 5 nM concentration, examined PAHs significantly reduced viability and mitochondrial membrane potential of HaCaT cells following the exposure to solar simulated light. Analyzed compounds induced a substantial peroxidation of cellular proteins after light treatment. The results revealed that a majority of the examined PAHs exhibited substantial reactive oxygen species photoproduction under UVA and violet-blue light, with their phototoxicity corresponding to their photoreactive properties. These findings improve our comprehension of the interactions between PAHs and human skin cells under environmental conditions, particularly when exposed to solar radiation.

A New Method of Extracting Polygonatum sibiricum Polysaccharide with Antioxidant Function: Ultrasound-Assisted Extraction-Deep Eutectic Solvents Method

Polygonatum sibiricum Polysaccharide (PsP) with antioxidant function is the main active component of Polygonatum sibiricum (P.sibiricum). The currently poor extraction yield and extraction methods of PsP cannot meet the application of that in food industrial production. In this research, an ultrasound-assisted extraction-deep eutectic solvents (UAE-DESs) method, which has never been used in the PsP industry, was first used to extract PsP. The extraction conditions were optimized by the response surface method (RSM). Both the extraction yield and antioxidant function were simultaneously considered during the optimization process. The indicators of PsP's level and antioxidant activity in vitro were used to present the extraction yield of the UAE-DESs method, the purity, and the antioxidant effect of PsP. Under the optimal conditions, which included a liquid-solid ratio of 26:1 (mL:g), extraction temperature of 80 °C, ultrasonic time of 51 min, and ultrasonic power of 82 W, the PsP extraction yield could reach (43.61 ± 0.09)%, which was obviously higher than single DESs (33.81%) and UAE (5.83%), respectively, and the PsP appeared favorably antioxidant function. This research proposed an efficient extraction method for PsP, filled the basic research gap, and further improved the development of PsP as a dietary supplement with antioxidant function in the food industry.

Structural characterization and antioxidant activity of processed polysaccharides PCP-F1 from Polygonatum cyrtonema Hua

Introduction

Polygonatum cyrtonema Hua. (PC) is a traditional Chinese herb with a history of use in both food and medicine. For clinical use, processed PC pieces are most commonly used, while present research has focused on crude PC polysaccharides (PCPs).

Methods

In this study, a new polysaccharide, PCP-F1, with a molecular weight of 37.46 kDa, was separated from four-time processed PCPs by column chromatography and evaluated by antioxidant activity. It was composed of glucose, mannose, galactose, rhamnose, and galacturonic acid with a molar ratio of 3.5: 2.5: 1.3: 1.8: 0.8.

Results and Discussion

The methylation analysis and two-dimensional NMR measurement revealed that the configuration of PCP-F1 contained nine residues in the primary structural unit by the chain of →3)-α-D-Glcp, →2)-α-D-Glcp (6→, →1)-ꞵ-D-Glcp (2→, →2)-α-D-GalAp (3,4→, →1) -ꞵ-D-Manp (3→, →2)-α-D-Glcp (3→, branched for →3)-α-D-Glcp, →2)-ꞵ-D-Galp (4→, →1)-ꞵ-D-Glcp (2→, →2,4)-α-D-Manp (6→, →3)-α-L-Rhap (4→. Radical scavenging assays indicated that PCP-F1 could scavenge radicals with a high scavenging rate, suggesting PCP-F1 possesses good antioxidant activity. The study confirms the importance of processed PC and offers the potential for exploiting it as a functional food.

N-acetyl-L-tryptophan (NAT) provides protection to intestinal epithelial cells (IEC-6) against radiation-induced apoptosis via modulation of oxidative stress and mitochondrial membrane integrity

BACKGROUND

Ionizing radiation generates oxidative stress in biological systems via inducing free radicals. Gastro-intestinal system has been known for its high radiosensitivity. Therefore, to develop an effective radiation countermeasure for gastrointestinal system, N-acetyl L-tryptophan was evaluated for its radioprotective efficacy using intestinal epithelial cells-6 (IEC-6) cells as the experimental model.

METHODS AND RESULTS

Cellular metabolic and lysosomal activity of L-NAT and L-NAT treated irradiated IEC-6 cells were assessed by MTT and NRU staining, respectively. ROS and mitochondrial superoxide levels along with mitochondrial disruption were detected using specific fluorescent probes.  Endogenous antioxidants (CAT, SOD, GST, GPx) activities were determined using calorimetric assay.  Apoptosis and DNA damage were assessed using flow cytometery and Comet assay, respectively. Results of the study were demonstrated that L-NAT pre-treatment (- 1 h) to irradiated IEC-6 cells significantly contribute to ensuring 84.36% to 87.68% (p < 0.0001) survival at 0.1 μg/mL concentration against LD50 radiation dose (LD50; 20 Gy). Similar level of radioprotection was observed with a clonogenic assay against γ radiation (LD50; 5 Gy). L-NAT was found to provide radioprotection by neutralizing radiation-induced oxidative stress, enhancing antioxidant enzymes (CAT, SOD, GST, and GPx), and protecting DNA from radiation-induced damage. Further, significant restoration of mitochondrial membrane integrity along with apoptosis inhibition was observed with irradiated IEC-6 cells upon L-NAT pretreatment.

Inhibition of Cancer Development by Natural Plant Polyphenols: Molecular Mechanisms

Malignant tumors remain one of the main sources of morbidity and mortality around the world. A chemotherapeutic approach to cancer treatment poses a multitude of challenges, primarily due to the low selectivity and genotoxicity of the majority of chemotherapeutic drugs currently used in the clinical practice, often leading to treatment-induced tumors formation. Highly selective antitumor drugs can largely resolve this issue, but their high selectivity leads to significant drawbacks due to the intrinsic tumor heterogeneity. In contrast, plant polyphenols can simultaneously affect many processes that are involved in the acquiring and maintaining of hallmark properties of malignant cells, and their toxic dose is typically much higher than the therapeutic one. In the present work we describe the mechanisms of the action of polyphenols on cancer cells, including their effects on genetic and epigenetic instability, tumor-promoting inflammation, and altered microbiota.

Peroxiredoxin 2: An Important Element of the Antioxidant Defense of the Erythrocyte

Peroxiredoxin 2 (Prdx2) is the third most abundant erythrocyte protein. It was known previously as calpromotin since its binding to the membrane stimulates the calcium-dependent potassium channel. Prdx2 is present mostly in cytosol in the form of non-covalent dimers but may associate into doughnut-like decamers and other oligomers. Prdx2 reacts rapidly with hydrogen peroxide (k > 10⁷ M^-1 s^-1). It is the main erythrocyte antioxidant that removes hydrogen peroxide formed endogenously by hemoglobin autoxidation. Prdx2 also reduces other peroxides including lipid, urate, amino acid, and protein hydroperoxides and peroxynitrite. Oxidized Prdx2 can be reduced at the expense of thioredoxin but also of other thiols, especially glutathione. Further reactions of Prdx2 with oxidants lead to hyperoxidation (formation of sulfinyl or sulfonyl derivatives of the peroxidative cysteine). The sulfinyl derivative can be reduced by sulfiredoxin. Circadian oscillations in the level of hyperoxidation of erythrocyte Prdx2 were reported. The protein can be subject to post-translational modifications; some of them, such as phosphorylation, nitration, and acetylation, increase its activity. Prdx2 can also act as a chaperone for hemoglobin and erythrocyte membrane proteins, especially during the maturation of erythrocyte precursors. The extent of Prdx2 oxidation is increased in various diseases and can be an index of oxidative stress.

Insights into Feruloylated Oligosaccharide Impact on Gel Properties of Oxidized Myofibrillar Proteins Based on the Changes in Their Spatial Structure

Polyphenolic compounds can protect against myofibrillar protein (MP) oxidation in meat products. In this study, the inhibitory effect of feruloyl oligosaccharides (FOs) on MP oxidation was investigated, and the gel properties of MPs were further studied. The results showed that 50–100 μmol/g protein of FOs could effectively inhibit damage to amino acid side chains by reducing carbonyl contents by 60.5% and increasing sulfhydryl and free amine contents by 89.5% and 66%, which may protect the secondary and tertiary structures of MPs. Additionally, FOs at 50 μmol/g protein had better effects on the crosslinking of MPs, leading to effective improvements in the gel properties, which can be seen in the rheology properties, scanning electron microscope (SEM) photographs, and the distribution of water in the MP gel. On the contrary, 150–200 μmol/g protein of FOs showed peroxidative effects on oxidatively stressed MPs, which were detrimental to MPs and contributed to their denaturation in the electrophoresis analysis and irregular aggregation in the SEM analysis. The concentration-dependent effects of FOs depended on MP-FOs interactions, indicating that an appropriate concentration of FOs has the potential to protect MPs from oxidation and enhance the gelation ability of pork meat during processing.

Sericin Ser3 Ectopic Expressed in Posterior Silk Gland Affects Hemolymph Immune Melanization Response via Reducing Melanin Synthesis in Silkworm

The transgenesis of silkworms is an important way to innovate genetic resources and silk function. However, the silk-gland (SG) of transgenic silkworms, which is the most concerned target tissue of sericulture, often suffers from low vitality, stunting and other problems, and the reasons are still unknown. This study trans engineered recombinant Ser3, a middle silk gland (MSG) specific expression gene, in the posterior silk gland (PSG) of the silkworm, and studied hemolymph immune melanization response changes in mutant pure line SER (Ser3^+/+). The results showed that although the mutant had normal vitality, the melanin content and phenoloxidase (PO) activity in hemolymph related to humoral immunity were significantly reduced, and caused significantly slower blood melanization and weaker sterilization ability. The mechanism investigation showed that the mRNA levels and enzymatic activities of phenylalanine hydroxylase (PAH), tyrosine hydroxylase (TH) and dopamine decarboxylase (DDC) in the melanin synthesis pathway in mutant hemolymph, as well as the transcription levels of the PPAE, SP21 and serpins genes in the serine protease cascade were significantly affected. Moreover, the total antioxidant capacity, superoxide anion inhibition capacity and catalase (CAT) level related to the redox metabolic capacity of hemolymph were significantly increased, while the activities of superoxide dismutase (SOD) and glutathione reductase (GR), as well as the levels of hydrogen peroxide (H₂O₂) and glutathione (GSH), were significantly decreased. In conclusion, the anabolism of melanin in the hemolymph of PSG transgenic silkworm SER was inhibited, while the basic response level of oxidative stress was increased, and the hemolymph immune melanization response was decreased. The results will significantly improve the safe assessment and development of genetically modified organisms.

Comparison of the Effects of Constraint-Induced Movement Therapy and Unconstraint Exercise on Oxidative Stress and Limb Function-A Study on Human Patients and Rats with Cerebral Infarction

Most conventional post-stroke rehabilitation treatments do not involve imposed constraints of the unaffected limb. In contrast, Constraint-Induced Movement Therapy (CIMT) is comprised of massed task practice with the affected limb and constraint of the unaffected limb. CIMT is a promising rehabilitation technique used for motor recovery of affected limbs after stroke, but its effectiveness and mechanism are not fully understood. We compared the effects of the two exercise modes on limb function post-stroke in animal models and human subjects, and investigated whether oxidative stress response was involved in regulating the effects. We first conducted a randomized controlled trial (RCT), in which 84 subjects with cerebral infarction were assigned to dose-matched constraint-induced movement therapy (CIMT), or unconstraint exercise (UE), or conventional rehabilitation treatment. Motor functions of the limb are primary outcomes of the RCT measured using Brief Fugl-Meyer upper extremity score (FMA-UE), Ashworth score, and Barthel scale. Psychological influence of CIMT and UE was also examined using Self-Rating Depression Scale (SDS). Next, we investigated the effects of CIMT and UE in rats undergoing middle cerebral artery occlusion and reperfusion (MCAO/R). Motor function, infarct volume, and pathohistological changes were investigated by mNSS, MRI, and histological studies. The role of Keap1-Nrf2-ARE was investigated using qRT-PCR, Western blot, immunochemistry, immunofluorescence, and ELISA experiments. In RCT, patients taking CIMT had a higher score in FMA-UE, Barthel index, and SDS, and a lower score in modified Ashworth, compared to those taking UE. In rats receiving CIMT, motor function was increased, and infarct volume was decreased compared to those receiving UE. The expression of Keap1 protein and mRNA in the peri-infarct tissue was decreased, and Nrf2 and ARE protein and mRNA were increased in rats receiving CIMT compared with UE. Nrf2 agonist t-BHQ increased the benefits of CIMT. In conclusion, CIMT is more effective than UE in improving upper limb motor function, reducing muscle spasm in patients with cerebral infarction compared to UE, but patients receiving CIMT may feel depressed. Moreover, both CIMT and UE are beneficial to limb function recovery and limit the infarct expansion in MCAO/R rats, but CIMT was more effective than UE. Oxidative stress reaction has an essential role in regulating the CIMT induced benefits.

Spectroscopic Analysis of an Antimalarial Drug’s (Quinine) Influence on Human Serum Albumin Reduction and Antioxidant Potential

Quinine (Qi) is a well-known drug used in malaria therapy; it is also a potential anti-arrhythmic drug used in the treatment of calf cramps, rheumatoid arthritis, colds, and photodermatitis. Moreover, it is used in the food industry for the production of tonics. This study aimed to analyze the interaction between quinine and a transporting protein—human serum albumin (HSA)—as well as the influence of Qi on both protein reduction and antioxidant potential. It was found that Qi (via spectrofluorometric measurements and circular dichroism spectroscopy) binds to HSA with a low affinity and slightly affects the secondary structure of albumin. As demonstrated by the use of ABTS and FRAP assays, HSA has a higher antioxidant and reduction potential than Qi, while their mutual interaction results in a synergistic effect in antioxidant activity and reduction potential.

The Use of Nanoparticles in Otoprotection

The inner ear can be insulted by various noxious stimuli, including drugs (cisplatin and aminoglycosides) and over-acoustic stimulation. These stimuli damage the hair cells giving rise to progressive hearing loss. Systemic drugs have attempted protection from ototoxicity. Most of these drugs poorly reach the inner ear with consequent ineffective action on hearing. The reason for these failures resides in the poor inner ear blood supply, the presence of the blood-labyrinthine barrier, and the low permeability of the round window membrane (RWM). This article presents a review of the use of nanoparticles (NPs) in otoprotection. NPs were recently used in many fields of medicine because of their ability to deliver drugs to the target organs or cells. The studies included in the review regarded the biocompatibility of the used NPs by in vitro and in vivo experiments. In most studies, NPs proved safe without a significant decrease in cell viability or signs of ototoxicity. Many nano-techniques were used to improve the drugs' kinetics and efficiency. These techniques included encapsulation, polymerization, surface functionalization, and enhanced drug release. In such a way, it improved drug transmission through the RWM with increased and prolonged intra-cochlear drug concentrations. In all studies, the fabricated drug-NPs effectively preserved the hair cells and the functioning hearing from exposure to different ototoxic stimuli, simulating the actual clinical circumstances. Most of these studies regarded cisplatin ototoxicity due to the wide use of this drug in clinical oncology. Dexamethasone (DEX) and antioxidants represent the most used drugs in most studies. These drugs effectively prevented apoptosis and reactive oxygen species (ROS) production caused by ototoxic stimuli. These various successful experiments confirmed the biocompatibility of different NPs and made it successfully to human clinical trials.

Curcumin and Intestinal Oxidative Stress of Pigs With Intrauterine Growth Retardation: A Review

Intrauterine growth restriction (IUGR) refers to the slow growth and development of a mammalian embryo/fetus or fetal organs during pregnancy, which is popular in swine production and causes considerable economic losses. Nutritional strategies have been reported to improve the health status and growth performance of IUGR piglets, among which dietary curcumin supplementation is an efficient alternative. Curcumin is a natural lipophilic polyphenol derived from the rhizome of Curcuma longa with many biological activities. It has been demonstrated that curcumin promotes intestinal development and alleviates intestinal oxidative damage. However, due to its low bioavailability caused by poor solubility, chemical instability, and rapid degradation, the application of curcumin in animal production is rare. In this manuscript, the structural-activity relationship to enhance the bioavailability, and the nutritional effects of curcumin on intestinal health from the aspect of protecting piglets from IUGR associated intestinal oxidative damage were summarized to provide new insight into the application of curcumin in animal production.

Oxidative Stress in the Protection and Injury of the Lacrimal Gland and the Ocular Surface: are There Perspectives for Therapeutics?

Oxidative stress (OS) is a major disruption in the physiology of the lacrimal functional unit (LFU). Antioxidant enzymes have dual protective activities: antioxidant and antimicrobial activities. Peroxidases have been indistinctly used as markers of the secretory activity of the LFU and implicated in the pathophysiology, diagnosis and treatment of dry eye disease (DED), even though they comprise a large family of enzymes that includes lactoperoxidase (LPO) and glutathione peroxidase (GPO), among others. Assays to measure and correlate OS with other local LFU phenomena have methodological limitations. Studies implicate molecules and reactions involved in OS as markers of homeostasis, and other studies identify them as part of the physiopathology of diseases. Despite these conflicting concepts and observations, it is clear that OS is influential in the development of DED. Moreover, many antioxidant strategies have been proposed for its treatment, including calorie restriction to nutritional supplementation. This review offers a critical analysis of the biological mechanisms, diagnostic outcomes, drug use, dietary supplements, and life habits that implicate the influence of OS on DED.

Reactive Oxygen Species in the Adverse Outcome Pathway Framework: Toward Creation of Harmonized Consensus Key Events

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are formed as a result of natural cellular processes, intracellular signaling, or as adverse responses associated with diseases or exposure to oxidizing chemical and non-chemical stressors. The action of ROS and RNS, collectively referred to as reactive oxygen and nitrogen species (RONS), has recently become highly relevant in a number of adverse outcome pathways (AOPs) that capture, organize, evaluate and portray causal relationships pertinent to adversity or disease progression. RONS can potentially act as a key event (KE) in the cascade of responses leading to an adverse outcome (AO) within such AOPs, but are also known to modulate responses of events along the AOP continuum without being an AOP event itself. A substantial discussion has therefore been undertaken in a series of workshops named "Mystery or ROS" to elucidate the role of RONS in disease and adverse effects associated with exposure to stressors such as nanoparticles, chemical, and ionizing and non-ionizing radiation. This review introduces the background for RONS production, reflects on the direct and indirect effects of RONS, addresses the diversity of terminology used in different fields of research, and provides guidance for developing a harmonized approach for defining a common event terminology within the AOP developer community.

Inhibition mechanism of melanin formation based on antioxidant scavenging of reactive oxygen species

The production of reactive oxygen species (ROS) leads to the generation of oxidative stress, which will result in the excessive production and accumulation of melanin in the body and even the occurrence of some skin diseases.

A New Insight into an Alternative Therapeutic Approach to Restore Redox Homeostasis and Functional Mitochondria in Neurodegenerative Diseases

Neurodegenerative diseases are accompanied by oxidative stress and mitochondrial dysfunction, leading to a progressive loss of neuronal cells, formation of protein aggregates, and a decrease in cognitive or motor functions. Mitochondrial dysfunction occurs at the early stage of neurodegenerative diseases. Protein aggregates containing oxidatively damaged biomolecules and other misfolded proteins and neuroinflammation have been identified in animal models and patients with neurodegenerative diseases. A variety of neurodegenerative diseases commonly exhibits decreased activity of antioxidant enzymes, lower amounts of antioxidants, and altered cellular signalling. Although several molecules have been approved clinically, there is no known cure for neurodegenerative diseases, though some drugs are focused on improving mitochondrial function. Mitochondrial dysfunction is caused by oxidative damage and impaired cellular signalling, including that of peroxisome proliferator-activated receptor gamma coactivator 1α. Mitochondrial function can also be modulated by mitochondrial biogenesis and the mitochondrial fusion/fission cycle. Mitochondrial biogenesis is regulated mainly by sirtuin 1, NAD⁺, AMP-activated protein kinase, mammalian target of rapamycin, and peroxisome proliferator-activated receptor γ. Altered mitochondrial dynamics, such as increased fission proteins and decreased fusion products, are shown in neurodegenerative diseases. Due to the restrictions of a target-based approach, a phenotype-based approach has been performed to find novel proteins or pathways. Alternatively, plasma membrane redox enzymes improve mitochondrial function without the further production of reactive oxygen species. In addition, inducers of antioxidant response elements can be useful to induce a series of detoxifying enzymes. Thus, redox homeostasis and metabolic regulation can be important therapeutic targets for delaying the progression of neurodegenerative diseases.

Exploring the binding mechanism and adverse toxic effects of persistent organic pollutant (dicofol) to human serum albumin: A biophysical, biochemical and computational approach

The organochlorine pesticide dicofol (DCF), a persistent organic pollutant, is used as acaricide worldwide. Considering its large consumption in the agriculture sector and potential toxic effects such as endocrine disruption, carcinogenicity, and environmental persistence are detrimental to human health. To take an extensive evaluation of its potential toxicity, the current study was aimed to explore the binding mechanism and adverse effect of DCF on human serum albumin (HSA) by using an array of biophysical techniques (UV-visible, fluorescence, 3D fluorescence, and circular dichroism spectroscopy), isothermal titration calorimetric (ITC), computational methods and biochemical approaches. Fluorescence quenching and UV-Visible spectra of the HSA-DCF system confirmed static quenching mechanism and complex formation between HSA and DCF. The thermodynamics results from ITC revealed DCF-HSA interaction was exothermic and spontaneous and involved hydrophobic interactions and hydrogen bonding. The esterase activity of HSA displayed constant V_max and elevated K_m values confirming DCF-HSA competitive interaction. Circular dichroism spectra results revealed structural changes in HSA protein on interaction with DCF. Furthermore, molecular-specific site marker and molecular modelling results affirmed that the binding Site of DCF is Site I of HSA. A significant carbonyl content level in DCF-HSA system suggested protein structure damage. This work is likely to add a better understanding of DCF toxicity in human health and helpful in fortifying the check on food safety.

Review on oxidative stress relation on COVID-19: Biomolecular and bioanalytical approach

COVID-19 disease has put life of people in stress worldwide from many aspects. Since the virus has mutated in absolutely short period of time the challenge to find a suitable vaccine has become harder. Infection to COVID-19, especially at severe life threatening states is highly dependent on the strength of the host immune system. This system is partially dependent on the balance between oxidative stress and antioxidant. Besides, this virus still has unknown mechanism of action companied by a probable commune period. From another hand, some reactive oxygen species (ROS) levels can be helpful on the state determination of the disease. Thus it could be possible to use modern bioanalytical techniques for their detection and determination, which could indicate the disease state at the golden time window since they have the potential to show whether specific DNA, RNA, enzymes and proteins are affected. This also could be used as a preclude study or a reliable pathway to define the best optimized time of cure beside effective medical actions. Herein, some ROS and their relation with SARS-CoV-2 virus have been considered. In addition, modern bioelectroanalytical techniques on this approach from quantitative and qualitative points of view have been reviewed.

Role of Mitochondria in Radiation Responses: Epigenetic, Metabolic, and Signaling Impacts

Until recently, radiation effects have been considered to be mainly due to nuclear DNA damage and their management by repair mechanisms. However, molecular biology studies reveal that the outcomes of exposures to ionizing radiation (IR) highly depend on activation and regulation through other molecular components of organelles that determine cell survival and proliferation capacities. As typical epigenetic-regulated organelles and central power stations of cells, mitochondria play an important pivotal role in those responses. They direct cellular metabolism, energy supply and homeostasis as well as radiation-induced signaling, cell death, and immunological responses. This review is focused on how energy, dose and quality of IR affect mitochondria-dependent epigenetic and functional control at the cellular and tissue level. Low-dose radiation effects on mitochondria appear to be associated with epigenetic and non-targeted effects involved in genomic instability and adaptive responses, whereas high-dose radiation effects (>1 Gy) concern therapeutic effects of radiation and long-term outcomes involving mitochondria-mediated innate and adaptive immune responses. Both effects depend on radiation quality. For example, the increased efficacy of high linear energy transfer particle radiotherapy, e.g., C-ion radiotherapy, relies on the reduction of anastasis, enhanced mitochondria-mediated apoptosis and immunogenic (antitumor) responses.

NF-E2-Related Factor 2 (Nrf2) Ameliorates Radiation-Induced Skin Injury

Radiation-induced skin injury (RISI) commonly occur in cancer patients who received radiotherapy and is one of the first clinical symptoms after suffering from nuclear exposure. Oxidative damage is the major causes of RISI. Nuclear factor erythroid 2-related factor 2 (Nrf2) is considered as a key mediator of the cellular antioxidant response. However, whether Nrf2 can alleviate RISI after high-dose irradiation remains unknown. In this study, we demonstrated that Nrf2-deficient (Nrf2^-/-) mice were susceptible to high-dose irradiation and adenovirus-mediated overexpression of Nrf2 (ad-Nrf2) protected against radiation in skin cells. Overexpression of Nrf2 attenuated the severity of skin injury after high-dose electron beam irradiation. To uncover the mechanisms of Nrf2 involved in RISI, mRNA sequencing technology was performed to analyze the mRNA expression profiles of Ad-Nrf2 skin cells following radiation. The results revealed that a total of 127 genes were significantly changed, 55 genes were upregulated, and 72 genes were downregulated after Nrf2 overexpression. GSEA showed that Nrf2 was associated with positive regulation of genes involved in the reactive oxygen species pathway after radiation. Taken together, this study illustrated the role of Nrf2 in RISI and provided potentially strategies for ameliorating RISI.

Deciphering Differential Life Stage Radioinduced Reproductive Decline in Caenorhabditis elegans through Lipid Analysis

Wildlife is chronically exposed to various sources of ionizing radiations, both environmental or anthropic, due to nuclear energy use, which can induce several defects in organisms. In invertebrates, reproduction, which directly impacts population dynamics, has been found to be the most radiosensitive endpoint. Understanding the underlying molecular pathways inducing this reproduction decrease can help in predicting the effects at larger scales (i.e., population). In this study, we used a life stage dependent approach in order to better understand the molecular determinants of reproduction decrease in the roundworm C. elegans. Worms were chronically exposed to 50 mGy·h⁻¹ external gamma ionizing radiations throughout different developmental periods (namely embryogenesis, gametogenesis, and full development). Then, in addition to reproduction parameters, we performed a wide analysis of lipids (different class and fatty acid via FAMES), which are both important signaling molecules for reproduction and molecular targets of oxidative stress. Our results showed that reproductive defects are life stage dependent, that lipids are differently misregulated according to the considered exposure (e.g., upon embryogenesis and full development) and do not fully explain radiation induced reproductive defects. Finally, our results enable us to propose a conceptual model of lipid signaling after radiation stress in which both the soma and the germline participate.

Curcumin reduces enteric isoprostane 8-iso-PGF2α and prostaglandin GF2α in specific pathogen-free Leghorn chickens challenged with Eimeria maxima

The purpose of this pilot study was to evaluate and determine the concentration of prostaglandin GF2α (PGF2α) and isoprostane 8‐iso‐PGF2α in plasma and intestine of specific pathogen-free (SPF) Leghorn chickens challenged with Eimeria maxima, with or without dietary supplementation of curcumin using solid‐phase microextraction and ultra‐performance liquid chromatography/tandem mass spectrometry. Eighty 1-day-old male SPF chickens were randomly allocated to one of four groups with four replicates (n = 5 chickens/replicate). Groups consisted of: (1) Control (no challenge), (2) Curcumin (no challenge), (3) Eimeria maxima (challenge), and (4) Eimeria maxima (challenge) + curcumin. At day 28 of age, all chickens in the challenge groups were orally gavaged with 40,000 sporulated E. maxima oocysts. No significant differences (P > 0.05) were observed in the groups regardless of the treatment or challenge with E. maxima. Enteric levels of both isoprostane 8‐iso‐PGF2α and PGF2α at 7 days and 9 days post-challenge were significantly increased (P < 0.01) compared to the non-challenge control chickens. Interestingly, the enteric levels of both isoprostane 8‐iso‐PGF2α and PGF2α at 7 days post-challenge were significantly reduced in chickens fed curcumin, compared to control chickens challenge with E. maxima. At 9 days post-challenge, only levels of isoprostane 8‐iso‐PGF2α in the enteric samples were significantly reduced in chickens challenged with E. maxima supplemented with curcumin, compared with E. maxima challenge chickens. No differences of isoprostane 8‐iso‐PGF2α or PGF2α were observed in plasma at both days of evaluation. Similarly, no significant differences were observed between the challenge control or chickens challenge with E. maxima and supplemented with curcumin at both times of evaluation. The results of this pilot study suggests that the antioxidant anti-inflammatory properties of curcumin reduced the oxidative damage and subsequent intestinal mucosal over-production of lipid oxidation products. Further studies to confirm and extend these results in broiler chickens are required.

Impact of binding to the multidrug resistance regulator protein LmrR on the photo-physics and -chemistry of photosensitizers

Light activated photosensitizers generate reactive oxygen species (ROS) that interfere with cellular components and can induce cell death, e.g., in photodynamic therapy (PDT). The effect of cellular components and especially proteins on the photochemistry and photophysics of the sensitizers is a key aspect in drug design and the correlating cellular response with the generation of specific ROS species. Here, we show the complex range of effects of binding of photosensitizer to a multidrug resistance protein, produced by bacteria, on the formers reactivity. We show that recruitment of drug like molecules by LmrR (Lactococcal multidrug resistance Regulator) modifies their photophysical properties and their capacity to induce oxidative stress especially in 1O2 generation, including rose bengal (RB), protoporphyrin IX (PpIX), bodipy, eosin Y (EY), riboflavin (RBF), and rhodamine 6G (Rh6G). The range of neutral and charged dyes with different exited redox potentials, are broadly representative of the dyes used in PDT.

Active Peptide KF-8 from Rice Bran Attenuates Oxidative Stress in a Mouse Model of Aging Induced by d-Galactose

This study investigated the effects of a physiologically active peptide derived from rice bran (KF-8) on oxidative stress in d-galactose (d-gal)-induced aging mice and the underlying molecular mechanisms. The aging model was developed by subcutaneously injecting Institute of Cancer Research mice with 250 mg/kg d-gal daily for 12 weeks and simultaneously treating them with 30 mg/kg KF-8. The relative expression levels of Nrf2 and NF-κB in the liver were determined by the western blot. The regulation of Nrf2 and NF-κBp65 by KF-8 was further validated in NIH/3T3 cells. Compared with the control mice, the aging mice had significantly decreased body weights as well as superoxide dismutase and GSH-Px levels (p < 0.05); however, they had increased serum reactive oxygen species and malondialdehyde and 8-hydroxydeoxyguanosine levels accompanied by aortic and brain injuries. They also had elevated RAGE, TLR4, IκB, Bax, and caspase-8 expressions and NF-κB/p65 phosphorylation but reduced BcL-2 expression in the liver. Moreover, in vitro experiments demonstrated that the pretreatment of H₂O₂-treated NIH/3T3 cells with KF-8 significantly mitigated the NF-κB signaling and attenuated the Nrf2 nuclear transport (both p < 0.05). In conclusion, KF-8 treatment inhibited aging-induced oxidative stress-related organ injury in mice by attenuating NF-κB/p38 signaling and preserving Nrf2 activity.

Developing [60]Fullerene Nanomaterials for Better Photodynamic Treatment of Non-Melanoma Skin Cancers

Skin cancer is the most common cancer in the U.S.A. and Europe. Its subtype, squamous skin carcinoma (SCC), if allowed to grow, has the potential to metastasize and can become deadly. Currently, carbon nanomaterials are being developed to treat cancer due to their attractive physicochemical and biological properties such as an enhanced permeability effect and their ability to produce reactive oxygen species. Here, we describe the synthesis of two water-soluble aminofullerenes (MonoaminoC₆₀ and HexakisaminoC₆₀), which were evaluated as novel [60]fullerene based photosentizers exhibiting anticancer properties. Moreover, the previously described neutral glycofullerene GF1 and its peracetylated lipophilic precursor MMS48 were compared with the aminofullerenes for their ability to generate reactive oxygen species and oxidize lipids. Remarkably, the generation of singlet oxygen and a superoxide radical by HexakisaminoC₆₀ was found to be markedly elevated in the presence of bovine serum albumin and NADH, respectively. Mechanistic studies of lipid peroxidation using cholesterol as a unique reporter molecule revealed that although all four fullerene nanomaterials primarily generated singlet oxygen, superoxide anion was also formed, which suggest a mixed mechanism of action (in which Type I and Type II photochemistry is involved). The [60]fullerene derivative HexakisaminoC₆₀ was also studied for its phototoxicity in squamous skin cancer cell line (A431) using the MTT test and propidium iodide staining.

Metabolism and biological activity of α-tocopherol derived from vitamin E-enriched transgenic maize in broilers

BACKGROUND

The aim of this study was to investigate the metabolism of α-tocopherol derived from vitamin E-enriched transgenic maize (VER) and its effects on antioxidant and immune functions in broilers aged 1-42 days. A total of 360 1-day-old male broilers were randomly divided into three groups containing six replicates with 20 broilers per replicate. The negative control (NC) group and the positive control (PC) group were given non-GM maize and non-GM maize plus exogenous vitamin E (VE), respectively, and the VER group was given VER, replacing the non-GM maize given to the NC group. Between days 1 and 21 and days 22 and 42, VE levels were 4.38 and 4.63 mg kg^-1 in the NC group, and 14.11 and 14.91 mg kg^-1 in the PC and VER group, respectively.

RESULTS

The results showed that α-tocopherol from both VER and additives increased α-tocopherol transfer protein and cytochrome P450 concentrations. Serum α-tocopherol and α-tocopherylquinone levels of broilers in the PC and VER groups were also significantly higher than those in the NC group (P < 0.05). Compared with the NC group, broilers in both groups that received α-tocopherol had reduced NF-κB p65 concentrations, significantly decreased serum prostaglandin E₂ , interleukin-6, malondialdehyde, and hydrogen peroxide levels (P < 0.05), and significantly increased glutathione, glutathione peroxidase, and total antioxidant capacity (P < 0.05).

CONCLUSION

In summary, both VER and non-GM maize fortified with exogenous VE showed similar effects on broilers, indicating that the α-tocopherol in VER has sufficient biological activity. © 2020 Society of Chemical Industry.

Ionizing Radiation as a Source of Oxidative Stress-The Protective Role of Melatonin and Vitamin D

Ionizing radiation (IR) has found widespread application in modern medicine, including medical imaging and radiotherapy. As a result, both patients and healthcare professionals are exposed to various IR doses. To minimize the negative side effects of radiation associated with oxidative imbalance, antioxidant therapy has been considered. In this review, studies on the effects of melatonin and vitamin D on radiation-induced oxidative stress are discussed. According to the research data, both substances meet the conditions for use as agents that protect humans against IR-induced tissue damage. Numerous studies have confirmed that melatonin, a hydro- and lipophilic hormone with strong antioxidant properties, can potentially be used as a radioprotectant in humans. Less is known about the radioprotective effects of vitamin D, but the results to date have been promising. Deficiencies in melatonin and vitamin D are common in modern societies and may contribute to the severity of adverse side effects of medical IR exposure. Hence, supporting supplementation with both substances seems to be of first importance. Interestingly, both melatonin and vitamin D have been found to selectively radiosensitise cancer cells, which makes them promising adjuvants in radiotherapy. More research is needed in this area, especially in humans.

Antioxidants as Molecular Probes: Structurally Novel Dihydro-m-Terphenyls as Turn-On Fluorescence Chemodosimeters for Biologically Relevant Oxidants

One interesting aspect of antioxidant organic molecules is their use as probes for the detection and quantitation of biologically relevant reactive oxidant species (ROS). In this context, a small library of dihydroterphenyl derivatives has been synthesised and studied as fluorescent chemodosimeters for detecting reactive oxygen species and hypochlorite. The fluorescence quantum yields of these molecules are negligible, while the corresponding aromatized compounds formed upon oxidation show moderate to high native fluorescence, depending on their structures. The fluorescence signal is quickly developed in the presence of trace amounts of the probe and the analytes in acetonitrile media at room temperature, with good analytical figures. ROS detection in aqueous media required incubation at 37 °C in the presence of horseradish peroxidase, and was applied to glucose quantitation by coupling glucose oxidation by O₂ to fluorescence detection of H₂O₂. The mild reaction conditions and sensitive fluorescent response lead us to propose dihydroterphenyls with an embedded anthranilate moiety as chemosensors/chemodosimeters for ROS detection.

Metal body burden and tissue oxidative status in the bivalve Venerupis decussata from Tunisian coastal lagoons

Coastal transitional waters are exposed to many anthropogenic threats. This study aims to assess the trace metals' pollution status of transitional waters by evaluating its biological effects in the clam Venerupis decussata. Among the studied sites along the Tunisian littoral, South Tunis and Boughrara were the most impacted, since clams from these two lagoons presented significant differences in: (i) trace metal contents, (ii) in-cell hydrogen peroxide, (iii) enzymatic and non-enzymatic defenses, (iv) damage to lipids and proteins, and (v) protein post-translational modifications. These changes related to evident histopathological traits. PCA showed a clear separation between the digestive gland and gills tissues and illustrated an impact gradient in Tunisian coastal lagoons. Water temperature was revealed as an added natural stressor that, when concurring with high pollution, may jeopardize an ecosystem's health and contribute to the accumulation of hazardous metals in organisms.

Effect of Curcumin on Protein Damage Induced by Rotenone in Dopaminergic PC12 Cells

Oxidative stress is considered to be a key factor of the pathogenesis of Parkinson's disease, a multifactorial neurodegenerative disorder characterized by reduced dopaminergic neurons in the substantia nigra pars compacta and accumulated protein aggregates. Rotenone is a worldwide-used pesticide that induces the most common features of Parkinson's by direct inhibition of the mitochondrial complex I. Rotenone-induced Parkinson's models, as well as brain tissues from Parkinson's patients, are characterized by the presence of both lipid peroxidation and protein oxidation markers resulting from the increased level of free radical species. Oxidation introduces several modifications in protein structure, including carbonylation and nitrotyrosine formation, which severely compromise cell function. Due to the link existing between oxidative stress and Parkinson's disease, antioxidant molecules could represent possible therapeutic tools for this disease. In this study, we evaluated the effect of curcumin, a natural compound known for its antioxidant properties, in dopaminergic PC12 cells treated with rotenone, a cell model of Parkinsonism. Our results demonstrate that the treatment of PC12 cells with rotenone causes severe protein damage, with formation of both carbonylated and nitrotyrosine-derived proteins, whereas curcumin (10 µM) co-exposure exerts protective effects by reducing the levels of oxidized proteins. Curcumin also promotes proteasome activation, abolishing the inhibitory effect exerted by rotenone on this degradative system.

Stability of the Meat Protein Type I Collagen: Influence of pH, Ionic Strength, and Phenolic Antioxidant

The water-holding capacity (WHC) is among the key factors in determining the quality of meat and its value, which is strongly influenced by the content and quality of the connective tissue proteins like collagen. Therefore, the factors that influence the proteins’ stability, e.g., pH, ionic strength, and the antioxidants which are used to increase the meat shelf-life, also affect the WHC. The interaction of collagen, whose structure is strongly influenced by the interaction with water molecules, can be studied following the behavior of water diffusion by low-resolution ¹H NMR experiments. The present study is addressed to study the collagen stability as a function of pH, ionic strength, and phenolic antioxidants like catechin. The experimental study demonstrated how the ¹H NMR time domain (TD) experiments are able to evaluate the hydration properties of collagen, not only as a function of ionic strength and pH, but also in determining the ability of catechin to interact both on the surface of the collagen fibrils and inside the fibrillar domain.

Velvet antler methanol extracts (MEs) protects against oxidative stress in Caenorhabditis elegans by SKN-1

Velvet antler is one of the most important animal medicines or functional foods widely used in East Asia for many centuries, which has several biological activities including anti-ageing and health promotion. To date, the mechanism underlying these effects of velvet antler is widely studied by its protein or polypeptide components. Few studies have been reported for the function of the other components in velvet antler. Herein, C. elegans is used as the model animal to dissect how none protein components of velvet antler affect in vivo oxidative stress. Methanol extracts (MEs) from velvet antler which has few protein components extends the maximum lifespan of C. elegans compared to the control under oxidative stress, while water extracts (WEs) which is protein-rich component has no apparent function. The activity of MEs is mediated by clk-1 signaling pathway, but not via daf-2, eat-2 or glp-1 pathway. Further investigations show MEs decrease endogenous ROS by promoting SKN-1 nuclei translocation, subsequently up-regulating the expression of its target genes gst-4, gst-7 and gst-10 in C. elegans. In all, MEs, the none protein components of velvet antler, protects against oxidative stress in C. elegans, which indicates it might be a product with potential of being a curative medicine.

Evaluation of the effects of the green nanoparticles zinc oxide on monosodium glutamate-induced toxicity in the brain of rats

Background

Monosodium glutamate (MSG) is used extensively as a food additive in the diets of many countries around the world.

Aim of the study

Our aim was to determine the effects of green zinc oxide nanoparticles on MSG-induced oxidative damage, neurotransmitter changes, and histopathological alternation in the cerebral cortexes of rats.

Methods

MSG was administered orally at two doses of 6 and 17.5 mg/kg body weight. The higher dose was associated with a significant decline in the activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as the levels of brain-derived neurotrophic factor (BDNF) and glutathione (GSH) in the cerebral cortex of rats.

Results

The administration of zinc oxide nanoparticles/green tea extract (ZnO NPs/GTE) to 17.5 mg/kg MSG-treated rats was associated with significant improvements in all parameters previously shown to be altered by MSG. The higher dose of MSG induced significant histopathological variation in brain tissue. Co-treatment of rats with ZnO NPs/GTE and MSG-HD inhibited the reduction of neurotransmitters and acetylcholinesterase by MSG.

Conclusions

ZnO NPs/GTE have the potential to protect against oxidative stress and neuronal necrosis induced by MSG-HD. ZnO NPs/GTE conferred a greater benefit than the control treatment or ZnO NPs or GTE administered separately.

Screening of Duck Tembusu Virus NS3 Interacting Host Proteins and Identification of Its Specific Interplay Domains

NS3 protein is a member of the non-structural protein of duck Tembusu virus (DTMUV), which contains three domains, each of which has serine protease, nucleotide triphosphatase, and RNA helicase activities, respectively. It performs a variety of biological functions that are involved in the regulation of the viral life cycle and host immune response. Based on the yeast two-hybrid system, we successfully transformed pGBKT7-NS3 bait plasmid into Y2H Gold, tested it to prove that it has no self-activation and toxicity, and then hybridized it with the prey yeast strain of the duck embryo fibroblast cDNA library for screening. After high-stringency selection, positive alignment with the National Center for Biotechnology Information database revealed nine potential interactive proteins: MGST1, ERCC4, WIF1, WDR75, ACBD3, PRDX1, RPS7, ND5, and LDHA. The most interesting one (PRDX1) was selected to be verified with full-length NS3 protein and its three domains S7/DEXDc/HELICc using yeast regressive verification and GST Pull-Down assay. It denoted that PRDX1 does indeed interact with HELICc domains of NS3. NS3 is involved in the RNA uncoiling process of viral replication, which may cause mitochondrial overload to create oxidative stress (OS) during DTMUV attack. We deduced that the HELICc domain binding partner PRDX1, which regulates the p38/mitogen-activated protein kinase pathway (p38/MAPK) to avert OS, causing apoptosis, making it possible for viruses to escape host immune responses.

Comparative Examination of Antioxidant Capacity and Fingerprinting of Unfractionated Extracts from Different Plant Parts of Quinoa (Chenopodium quinoa) Grown under Greenhouse Conditions

Integrated surveys of metabolic profiles and antioxidant capacity from Chenopodium quinoa have been limited and have particularly focused on an examination of seeds and leaves. According to this, the main aim of the present study was to address an evaluation of the antioxidant activity of crude ethanolic extracts from different plant parts (leaves, stems, roots, flowers, and seeds) harvested at different times during growth and processed by two distinct drying methods: Air-drying and freeze-drying. In order to characterize the resulting extracts, the total content of phenolics (TPC) and flavonoids (TFC) was then measured through the Folin–Ciocalteu method, while antioxidant capacity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) free radical scavenging and ferric-reducing antioxidant power (FRAP) methods. Parallel to this evaluation, extracts were profiled by LC-DAD-ESI-MS. Data analysis was supported by statistics. Most of the extracts obtained from freeze-dried samples showed higher TPC values ranging from 6.02 to 43.47 milligram of gallic acid equivalents per gram of plant material and a TFC between 1.30 and 12.26 milligram of quercetin equivalents per gram of plant material. After statistical analysis, a low correlation between TPC and TFC values was observed regarding antioxidant capacity from DPPH and FRAP measurements of both drying methods. A multivariate analysis showed that antioxidant components and antioxidant capacity in C. quinoa changed during growth and between plant parts and drying methods. These changes need to be taken into consideration when comparing the production/accumulation of beneficial bioactive compounds in this pseudocereal.

Intensification of serum albumin amyloidogenesis by a glycation-peroxidation loop (GPL)

The interaction of reducing sugars with proteins leads to the formation of advanced glycation end products (AGE) and reactive oxidative species (ROS). ROS peroxidise free or membrane included unsaturated fatty acids, leading to generate reactive aldehydes as advanced lipid peroxidation end products (ALE). Aldehydes from lipid peroxidation (LPO) react with proteins to cause alteration of protein structure to exacerbate complication of diseases. Here we studied serum albumin glycation in the presence and absence of liposomes as a bio-membrane model to investigate protein structural changes using various techniques including intrinsic and extrinsic fluorescence spectroscopies and electron microscopy analysis. Accordingly, serum albumin glycation and fibrillation were accelerated and intensified in the presence of liposomes through a hypothesized glycation-peroxidation loop (GPL). Together, our results shed light on the necessity of reconsidering diabetic protein glycation to make it close to physiological conditions mimicry, more importantly, proteins structural change due to diabetic glycation is intensified in the proximity of cell membranes which probably potentiates programmed cell death distinct from apoptosis.

Plasma membrane redox enzymes: new therapeutic targets for neurodegenerative diseases

Mitochondrial dysfunction caused by oxidative stress appears at early stages of aging and age-related diseases. Plasma membrane redox enzymes act in a compensatory manner to decrease oxidative stress and supply reductive capacity to ensure cell survival. Plasma membrane redox enzymes transfer electrons from NAD(P)H to oxidized ubiquinone and α-tocopherol, resulting in inhibition of further oxidative damage. Plasma membrane redox enzymes and their partners are affected by aging, leading to progression of neurodegenerative disease pathogenesis. Up-regulating plasma membrane redox enzymes via calorie restriction and phytochemicals make cells more resistant to oxidative damage under stress conditions by maintaining redox homeostasis and improving mitochondrial function. Investigation into plasma membrane redox enzymes can provide mechanistic details underlying the relationships between plasma membrane redox enzymes and mitochondrial complexes and provide a good therapeutic target for prevention and delay of neurodegenerative disorders.

Role of catechin on collagen type I stability upon oxidation: a NMR approach

The study focuses on the understanding, at molecular level, the mechanism of interaction between protein and flavonoids. Collagen and catechin interactions were investigated by NMR in solution and solid state. The effect of catechin on the stability of collagen to oxidation was also explored. Collagen was treated with two concentrations of catechin solutions. Oxidation was carried out by incubation of collagen solution with three oxidation systems: Fe(II)/H₂O₂, Cu(II)/H₂O₂, and NaOCl/H₂O₂. The effects of oxidation systems were evaluated by high resolution 1 D and 2 D proton spectroscopy and solid state NMR (¹³C CP MAS) experiments. Interactions between collagen and catechin preferentially occur between catechin B ring and the amino acids Pro and Hyp of collagen. Results showed that both iron and copper oxidation systems were able to interact with collagen by site specific attack. Moreover, catechin protects collagen proline from oxidation by metal/H₂O₂ systems, preventing copper and iron approach to collagene molecule;this behaviour was more evident for the copper/H₂O₂ system.