Lipid peroxidation: physiological levels and dual biological effects

Effect of storage temperature and time on the fatty acids and nutritional quality of the commercial mussel (Mytilus galloprovincialis)

The effect of storage time (5, 10 and 15 days) and temperature (- 20 °C and + 4 °C) on the biochemical composition of the Tunisian mussel (Mytilus galloprovincialis) was evaluated by investigating changes in proximate composition, fatty acids, minerals and nutritional quality indices. Lipid and protein degradations were also evaluated through several markers of oxidative damage. Results showed a significant decrease in the biochemical compounds in mussel tissues after both refrigeration and freezing processes (p < 0.01). As regards the fatty acid composition, saturated fatty acids increased significantly after both storage processes. However, polyunsaturated and monounsaturated decreased, especially after 10 and 15 days of storage. The reduction of nutritional quality and mineral contents were detected after both storage processes. Markers of oxidative damage varied remarkably between fresh and stored tissues, revealing that both processes greatly influenced the nutritional quality of mussels. Overall, it is well recommended to consume fresh and stored mussels for no more than 5 days in the refrigerator (+ 4 °C) in order to preserve the better quality of this product and provide more benefits for human health.

Effects of insulin treatment on hepatic CYP1A1 and CYP2E1 activities and lipid peroxidation levels in streptozotocin-induced diabetic rats

Reactive oxygen species (ROS) and lipid peroxidation (LPO) levels may increase in diabetic state and lead to oxidative stress, which plays a critical role in the progression of diabetes. There are various sources of ROS, including cytochrome P450 monooxygenases (CYP450s), which may be modulated in terms of their activities and expressions under diabetic conditions. This study is aimed to investigate the effects of streptozotocin-induced diabetes and insulin treatment on hepatic cytochrome P450 1A1 (CYP1A1) and cytochrome P450 2E1 (CYP2E1) activities and LPO levels. Methods: CYP1A1 and CYP2E1 activities were measured with ethoxyresorufin O-deethylase and p-nitrophenol hydroxylase activities, respectively. LPO levels were then corroborated via thiobarbituric acid reactive substances. Results: In diabetic rats, a marked 2.1- and 2.4-fold increase in hepatic CYP1A1 activity and 1.8- and 1.6-fold increase in hepatic CYP2E1 activity were observed compared to controls and insulin-treated diabetic rats, respectively. Hepatic LPO levels in diabetic rats did not significantly change compared to controls. However, in insulin-treated diabetic rats, LPO levels are 0.92- and 0.89-fold remarkably decrease compared to controls and diabetics, respectively. Conclusion: The present study suggests that insulin might have a useful role in the modulation of CYP1A1 and CYP2E1 activities as well as LPO levels in the liver of diabetic rats.

Dibenzazepine combats acute liver injury in rats via amendments of Notch signaling and activation of autophagy

Paracetamol is a commonly used over-the-counter analgesic and antipyretic drug. Nevertheless, an overdose of paracetamol leads to hepatic necrosis that can be lethal. This study aimed to assess the potential hepatoprotective effects of dibenzazepine, a Notch inhibitor, against acute liver injury in rats via interfering with oxidative stress, inflammation, apoptosis, autophagy, and Notch signaling. Silymarin (200 mg/kg, p.o.) or dibenzazepine (2 mg/kg, i.p.) were administered to rats for 5 days before a single hepatotoxic dose of paracetamol (800 mg/kg, i.p.). Pretreatment with silymarin and dibenzazepine significantly mitigated oxidative stress, inflammatory and apoptotic markers induced by paracetamol hepatotoxicity where dibenzazepine showed greater repression of inflammation. Furthermore, dibenzazepine was found to be significantly more efficacious than silymarin in inhibiting Notch signaling as represented by expression of Notch-1 and Hes-1. A significantly greater response was also demonstrated with dibenzazepine pretreatment with regard to the expression of autophagic proteins, Beclin-1 and LC-3. The aforementioned biochemical results were confirmed by histopathological examination. Autophagy and Notch signaling seem to play a significant role in protection provided by dibenzazepine for paracetamol-induced hepatotoxicity in rats, which could explain its superior results relative to silymarin. Graphical abstract.

Phase separation liquid-liquid extraction for the quantification of 8-iso-Prostaglandin F2 Alpha in human plasma by LC-MS/MS

BACKGROUND

Reactive oxygen species (ROS) are produced in the body during normal metabolism by means of enzymes and non-enzymatic chemical reduction of molecular oxygen. In case of the prevalence of ROS formation over their elimination, highly reactive free radicals can be accumulated and can cause multiple damages to the biomolecules and cells. Determination of isoprostanes in biological matrices is most often used to register free radical damage and requires selective, sensitive and specific techniques.

METHODS

This study presents the development and validation of the LC-MS/MS method for the determination of 8-iso-Prostaglandin F2α in human plasma utilising a modified liquid-liquid extraction procedure with phase separation.

RESULTS

Modified sample preparation procedure assured higher extraction yield, clear separation of organic layer from the plasma water phase and protein precipitates, and better-purified product for instrumental analysis. Linearity was validated in the range 0.1-5.0 µg/L with R2 > 0.996; normalised matrix varied between 86.0% and 108.3%, accuracy ranged from 90.4 % to 113.9% and precision both within runs and between runs was less than 7%. With a run time of 10 min, a throughput of over 50 samples per working day could be performed.

CONCLUSIONS

The method meets all the current industrial validation criteria and allows the accurate and precise determination of 8-iso-PGF2α in human plasma at diagnostically significant concentration range.

OH radical reactions with the hydrophilic component of sphingolipids

In this work, using the example of model compounds, we studied the reactions resulting from the interaction of OH radicals with the hydrophilic part of sphingolipids. We compared the stopped-flow EPR spectroscopy and pulse radiolysis with optical detection methods to characterize radical intermediates formed in the reaction of OH radicals with glycerol, serinol and N-boc-serinol. Quantum chemical calculations were also performed to help interpret the observed experimental data. It was shown that H-abstraction from the terminal carbon atom is the main process that is realized for all the studied compounds. The presence of the unsubstituted amino group (-NH2) is seen to completely change the reaction properties of serinol in comparison with those observed in glycerol and N-boc serinol.

Nitric Oxide-elicited Resistance to Antitumor Photodynamic Therapy via Inhibition of Membrane Free Radical-mediated Lipid Peroxidation

This review focuses on the ability of nitric oxide (NO) to antagonize antitumor photodynamic therapy (PDT). NO's anti-PDT effects were recognized relatively recently and require a better mechanistic understanding for developing new strategies to improve PDT efficacy. Many PDT sensitizers (PSs) are amphiphilic and tend to localize in membrane compartments of tumor cells. Unsaturated lipids in these compartments can undergo peroxidative degradation after PS photoactivation. Primary Type I (free radical) vs. Type II (singlet oxygen) photochemistry of lipid peroxidation is discussed, along with light-independent turnover of primary lipid hydroperoxides to free radical species. Chain lipid peroxidation mediated by the latter exacerbates membrane damage and cytotoxicity after a PDT challenge. Our studies have shown that NO from chemical donors can suppress chain peroxidation by intercepting lipid-derived free radical intermediates, thereby protecting cancer cells against photokilling. More recent evidence has revealed that inducible NO synthase (iNOS) is dramatically upregulated in several cancer cell types after a photodynamic challenge, and that iNOS-derived NO enhances resistance as well as growth and migratory aggressiveness of surviving cells. Chain breaking by NO and other possible NO-based resistance mechanisms are discussed, along with novel pharmacologic approaches for overcoming these negative effects.

Age-related alteration in HNE elimination enzymes

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

Mammals to membranes: A reductionist story

This is the story of a series of reductionist studies that started with an attempt to explain what underpins the high-level of aerobic metabolism in mammals (i.e. associated with the evolution of endothermy) and almost forty years later had led to investigations into the role of membrane lipids in determining metabolism. Initial studies showed that the increase in aerobic metabolism in mammals was driven by a combination of increases in mitochondrial volume and membrane densities, organ size and changes in the molecular activity of enzymes. The increase in the capacity to produce energy was matched by an increase in energy use, notably driven by increases in H⁺, Na⁺ and K⁺ fluxes. In the case of increased Na⁺ flux, it was found this was matched by increases in Na⁺-dependent metabolism at the tissue level and increases in enzyme activity at a cellular level but not by an increase in the number of sodium pumps. To maintain Na⁺ gradient across cell membranes, increased Na⁺ flux is not controlled by an increase in sodium pump number but rather by an increase in sodium pump molecular activity (i.e. an increase the substrate turnover rate of each sodium pump) in tissues of endotherms. This increase in molecular activity is coupled to an increase in the level of highly unsaturated polyunsaturated fatty acids (PUFA) in membranes, a mechanism similar to that used by ectotherms to ameliorate decreasing activities of metabolic processes in the cold. Determination of how changes in membrane fatty acid composition can change the activities of proteins in membranes will be the next step in this story.

Effect of aqueous extracts of Ficus vogeliana Miq and Tieghemella africana Pierre in 7,12-Dimethylbenz(a)anthracene -induced skin cancer in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Skin cancer is the most common form of cancer responsible for considerable morbidity and mortality. Tieghemella africana and Ficus vogeliana are used in traditional medicine to treat cancers.

AIM OF THE STUDY

Therefore, the aim of this study was to investigate the antioxidant, antiangiogenic and anti-tumor activities of these plant extracts.

MATERIALS AND METHODS

To achieve it, phytochemical screening, antioxidant activity and antiangiogenic activity were assessed. Thereafter, the anti-tumor activity was determined using skin tumorigenesis induced by 7,12-dimethylbenz[a]anthracene.

RESULTS

The phytochemical result analysis showed that both plant extracts were rich in polyphenols, alkaloids and terpene compounds and possessed good antioxidant activity based on DPPH radical scavenging (IC₅₀ = 9.70 μg/mL and 4.60 μg/mL and AAI values of 5.20 and 10.88) and strong total antioxidant capacity (115.44 VtCE (mg)/g of dry plant extract and 87.37 VtCE (mg)/g of dry plant extract, respectively). Additionally, both plant extracts possessed antiangiogenic activities (IC₅₀ = 53.43 μg/mL and 92.68 μg/mL, respectively), which correlated with significant antitumor activities when using 35 mg/kg (65.02% and 77.54%) and 70 mg/kg of extracts (81.07% and 88.18%).

CONCLUSIONS

In summary, this study illustrates the promising usage of Tieghemella africana and Ficus vogeliana plant extracts in treating skin cancer. However, further characterization of the extracts must be performed to isolate the most active anticancer compound.

Not All Stressors Are Equal: Mechanism of Stressors on RPE Cell Degeneration

Age-related macular degeneration (AMD) is a major cause of irreversible blindness among the elderly population. Dysfunction and degeneration of the retinal pigment epithelial (RPE) layer in the retina underscore the pathogenesis of both dry and wet AMD. Advanced age, cigarette smoke and genetic factors have been found to be the prominent risk factors for AMD, which point to an important role for oxidative stress and aging in AMD pathogenesis. However, the mechanisms whereby oxidative stress and aging lead to RPE cell degeneration are still unclear. As cell senescence and cell death are the major outcomes from oxidative stress and aging, here we review the mechanisms of RPE cell senescence and different kinds of cell death, including apoptosis, necroptosis, pyroptosis, ferroptosis, with an aim to clarify how RPE cell degeneration could occur in response to AMD-related stresses, including H₂O₂, 4-Hydroxynonenal (4-HNE), N-retinylidene-N-retinyl-ethanolamine (A2E), Alu RNA and amyloid β (Aβ). Besides those, sodium iodate (NaIO₃) induced RPE cell degeneration is also discussed in this review. Although NaIO₃ itself is not related to AMD, this line of study would help understand the mechanism of RPE degeneration.

Cellular compartments challenged by membrane photo-oxidation

The lipid composition impacts directly on the structure and function of the cytoplasmic as well as organelle membranes. Depending on the type of membrane, specific lipids are required to accommodate, intercalate, or pack membrane proteins to the proper functioning of the cells/organelles. Rather than being only a physical barrier that separates the inner from the outer spaces, membranes are responsible for many biochemical events such as cell-to-cell communication, protein-lipid interaction, intracellular signaling, and energy storage. Photochemical reactions occur naturally in many biological membranes and are responsible for diverse processes such as photosynthesis and vision/phototaxis. However, excessive exposure to light in the presence of absorbing molecules produces excited states and other oxidant species that may cause cell aging/death, mutations and innumerable diseases including cancer. At the same time, targeting key compartments of diseased cells with light can be a promising strategy to treat many diseases in a clinical procedure called Photodynamic Therapy. Here we analyze the relationships between membrane alterations induced by photo-oxidation and the biochemical responses in mammalian cells. We specifically address the impact of photosensitization reactions in membranes of different organelles such as mitochondria, lysosome, endoplasmic reticulum, and plasma membrane, and the subsequent responses of eukaryotic cells.

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

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

Exploitation of long-lasting ultraweak photon emission to estimate skin photodamage after ultraviolet exposure

BACKGROUND

Establishing a noninvasive method to estimate skin damage immediately after ultraviolet (UV) exposure is required to minimize the anticipated severe symptoms triggered by early phase UV-induced reactions in the skin. To develop a suitable method, we focused on ultraweak photon emission (UPE) immediately after UV exposure to characterize the relationship of UPE to skin photodamage caused by the UV exposure.

MATERIALS AND METHODS

Analysis of the correlation between UV-induced UPE and erythema formation characterized by skin redness was conducted in a clinical study. To clarify the source of UPE, time-dependent lipid oxidation was analyzed in human epidermal keratinocytes in vitro using a fluorescence indicator as well as the lipid hydroperoxide (LPO) assay.

RESULTS

The average amount of UV-induced long-lasting UPE per second, especially from 1 to 3 minutes compared to other time periods after the UV radiation, increased in a dose-dependent manner and was highly correlated with the intensity of cutaneous redness 24 hours after UV exposure. In addition, cellular examinations elucidated that both the long-lasting UPE signals and the increased amounts of LPO 2 minutes after UV radiation were significantly suppressed by Trolox (a vitamin E derivative), which has been shown to inhibit UV-induced erythema formation in human skin.

CONCLUSION

Long-lasting UPE generated between 1 and 3 minutes immediately after UV exposure, which is associated with LPO production, is a valuable indicator to estimate and/or avoid severe cutaneous photodamage.

Increased Oxidative Stress, Altered Trace Elements, and Macro-Minerals Are Associated with Female Obesity

Generally female individuals are more prone to obesity due to their lifestyle and physiology. However, female individuals have got little attention in this aspect. This pioneering study designed to find the level of serum malondialdehyde (MDA), non-enzymatic antioxidant (vitamin C), other trace elements (zinc and iron), and macro-minerals (sodium, potassium, and calcium) for female obesity determining its role and action in disease diagnosis along with propagation. For this prospective case-control study, 70 female obese and 70 healthy individuals were evaluated. Serum lipid peroxidation product malondialdehyde (MDA) concentration was measured to determine the level of lipid peroxidation. UV spectrophotometric method was implemented for vitamin C concentration to measure serum ascorbic acid. Atomic absorption spectroscopy (AAS) was implemented to determine serum macro-minerals (Na, K, and Ca), and trace elements (Zn and Fe) were estimated. For statistical analysis, student's t-test and Pearson's correlation test were executed. A significantly higher concentration of serum MDA (p < 0.001) and low concentration of antioxidants (vitamin C) (p < 0.001) are observed in patient than control group. We found a lower concentration of trace elements (zinc, iron) and macro-minerals (sodium, potassium, and calcium) in patients compared to control except sodium. The mean concentrations for serum Zn, Fe, Na, K, and Ca were 0.34 ± 0.01, 0.25 ± 0.01, 3828.91 ± 205.09, 90.42 ± 6.45, and 43.04 ± 2.38 mg/L and 0.78 ± 0.08, 0.84 ± 0.08, 2600.97 ± 99.79, 223.79 ± 14.64, and 86.43 ± 2.78 mg/L, respectively, for female obese patients and control subjects (p < 0.001). We can suggest from our study that there is a strong association of female obesity with increased serum concentrations of MDA and reduced non-enzymatic antioxidant vitamin C and different serum trace metals and macro-minerals.

Proteomic analysis of liver in diet-induced Hyperlipidemic mice under Fructus Rosa roxburghii action

Fructus Rosae Roxburghii (FRR) has been considered as edible and medicinal fruit possessing antiatherosclerotic effect, but the mechanism is still unclear. HLP is material basis for AS formation. Under FRR action, TC, TG, LDL, HDL and ASI in serum were regulated to control level. Differentially expressed proteins in liver were analyzed by using TMT labeling and LC-MS/MS for better understanding the effect and molecular mechanism of FRR on diet-induced hyperlipidemic mice. In total, 4460 proteins were quantified, of which 469 proteins showed dramatic changes between each group. According to molecular functions, 25 differentially co-expressed proteins were divided into five categories: substance metabolism, energy transformation and signal transduction, transcription and translation, immune defense. 15 key proteins involved lipids metabolism, which were identified as Cyp7a1, Cyp3a11, Tm7sf2, COAT2, CSAD, RBP3, Lpin1, Dhrs4, Aldh1b1, GK, Acot 4, TSC22D1, PGFS, EHs, GSTM1. This suggested that FRR could maintain metabolic homeostasis by regulating the metabolism of fatty acids, biosynthesis of BAs and steroids, and production of LPOs. 20 oxidative lipids further confirmed their importance regulating lipids metabolism. It's first time potential antiatherosclerotic mechanism of FRR regulating blood lipids was explored from protein level, which is of great significance to explore new drug targets for AS. SIGNIFICANCE: Under the action of FRR juice, the blood lipids in mice were regulated to control level. By TMT proteomic analysis, the effect and molecular mechanism of FRR on diet-induced hyperlipidemic mice were further explored. 25 differentially co-expressed proteins obtained in three diet groups might cooperatively regulate the lipids metabolism and hepatic function of mice, thus maintaining the metabolism homeostasis. By lipidomics analysis, 20 oxidative lipids further confirmed the importance of ω-3 and ω-6 PUFAs in regulating the lipids metabolism. These findings provide an improved understanding for the regulation of FRR on the blood lipids and explores potential metabolic targets for AS prevention.

Near-Infrared Light-Triggered Chlorine Radical (. Cl) Stress for Cancer Therapy

Free radicals with reactive chemical properties can fight tumors without causing drug resistance. Reactive oxygen species (ROS) has been widely used for cancer treatment, but regrettably, the common O₂ and H₂ O₂ deficiency in tumors sets a severe barrier for sufficient ROS production, leading to unsatisfactory anticancer outcomes. Here, we construct a chlorine radical (^. Cl) nano-generator with SiO₂ -coated upconversion nanoparticles (UCNPs) on the inside and Ag⁰ /AgCl hetero-dots on the outside. Upon near-infrared (NIR) light irradiation, the short-wavelength emission UCNP catalyzes ^. Cl generation from Ag⁰ /AgCl with no dependence on O₂ /H₂ O₂ . ^. Cl with strong oxidizing capacity and nucleophilicity can attack biomolecules in cancer cells more effectively than ROS. This ^. Cl stress treatment will no doubt broaden the family of oxidative stress-induced antitumor strategies by using non-oxygen free radicals, which is significant in the development of new anticancer agents.

Oxygen administration in patients recovering from cardiac arrest: a narrative review

High oxygen tension in blood and/or tissue affects clinical outcomes in several diseases. Thus, the optimal target PaO₂ for patients recovering from cardiac arrest (CA) has been extensively examined. Many patients develop hypoxic brain injury after the return of spontaneous circulation (ROSC); this supports the need for oxygen administration in patients after CA. Insufficient oxygen delivery due to decreased blood flow to cerebral tissue during CA results in hypoxic brain injury. By contrast, hyperoxia may increase dissolved oxygen in the blood and, subsequently, generate reactive oxygen species that are harmful to neuronal cells. This secondary brain injury is particularly concerning. Although several clinical studies demonstrated that hyperoxia during post-CA care was associated with poor neurological outcomes, considerable debate is ongoing because of inconsistent results. Potential reasons for the conflicting results include differences in the definition of hyperoxia, the timing of exposure to hyperoxia, and PaO₂ values used in analyses. Despite the conflicts, exposure to PaO₂ > 300 mmHg through administration of unnecessary oxygen should be avoided because no obvious benefit has been demonstrated. The feasibility of titrating oxygen administration by targeting SpO₂ at approximately 94% in patients recovering from CA has been demonstrated in pilot randomized controlled trials (RCTs). Such protocols should be further examined.

Surviving Reactive Chlorine Stress: Responses of Gram-Negative Bacteria to Hypochlorous Acid

Sodium hypochlorite (NaOCl) and its active ingredient, hypochlorous acid (HOCl), are the most commonly used chlorine-based disinfectants. HOCl is a fast-acting and potent antimicrobial agent that interacts with several biomolecules, such as sulfur-containing amino acids, lipids, nucleic acids, and membrane components, causing severe cellular damage. It is also produced by the immune system as a first-line of defense against invading pathogens. In this review, we summarize the adaptive responses of Gram-negative bacteria to HOCl-induced stress and highlight the role of chaperone holdases (Hsp33, RidA, Cnox, and polyP) as an immediate response to HOCl stress. We also describe the three identified transcriptional regulators (HypT, RclR, and NemR) that specifically respond to HOCl. Besides the activation of chaperones and transcriptional regulators, the formation of biofilms has been described as an important adaptive response to several stressors, including HOCl. Although the knowledge on the molecular mechanisms involved in HOCl biofilm stimulation is limited, studies have shown that HOCl induces the formation of biofilms by causing conformational changes in membrane properties, overproducing the extracellular polymeric substance (EPS) matrix, and increasing the intracellular concentration of cyclic-di-GMP. In addition, acquisition and expression of antibiotic resistance genes, secretion of virulence factors and induction of the viable but nonculturable (VBNC) state has also been described as an adaptive response to HOCl. In general, the knowledge of how bacteria respond to HOCl stress has increased over time; however, the molecular mechanisms involved in this stress response is still in its infancy. A better understanding of these mechanisms could help understand host-pathogen interactions and target specific genes and molecules to control bacterial spread and colonization.

Role of Melanin Chemiexcitation in Melanoma Progression and Drug Resistance

Melanoma is the deadliest type of skin cancer. Human melanomas often show hyperactivity of nitric oxide synthase (NOS) and NADPH oxidase (NOX), which, respectively, generate nitric oxide (NO ^· ) and superoxide (O₂ ^·- ). The NO ^· and O₂ ^- react instantly with each other to generate peroxynitrite (ONOO^-) which is the driver of melanin chemiexcitation. Melanoma precursors, the melanocytes, are specialized skin cells that synthesize melanin, a potent shield against sunlight's ultraviolet (UV) radiation. However, melanin chemiexcitation paradoxically demonstrates the melanomagenic properties of melanin. In a loop, the NOS activity regulates melanin synthesis, and melanin is utilized by the chemiexcitation pathway to generate carcinogenic melanin-carbonyls in an excited triplet state. These carbonyl compounds induce UV-specific DNA damage without UV. Additionally, the carbonyl compounds are highly reactive and can make melanomagenic adducts with proteins, DNA and other biomolecules. Here we review the role of the melanin chemiexcitation pathway in melanoma initiation, progression, and drug resistance. We conclude by hypothesizing a non-classical, positive loop in melanoma where melanin chemiexcitation generates carcinogenic reactive carbonyl species (RCS) and DNA damage in normal melanocytes. In parallel, NOS and NOX regulate melanin synthesis generating raw material for chemiexcitation, and the resulting RCS and reactive nitrogen species (RNS) regulate cellular proteome and transcriptome in favor of melanoma progression, metastasis, and resistance against targeted therapies.

Lipid Hydroperoxidation Effect on the Dynamical Evolution of the Conductance Process in Bilayer Lipid Membranes: A Condition Toward Criticality

Cell membranes are one of the main targets of oxidative processes mediated by reactive oxygen species (ROS). These chemical species interact with unsaturated fatty acids of membrane lipids, triggering an autocatalytic chain reaction, producing lipid hydroperoxides (LOOHs) as the first relatively stable product of the ROS-mediated lipid peroxidation (LPO) process. Numerous biophysical and computational studies have been carried out to elucidate the LPO impact on the structure and organization of lipid membranes. However, although LOOHs are the major primary product of LPO of polyunsaturated fatty acids (PUFAs), to the best of our knowledge, there is no experimental evidence on the effects of the accumulation of these LPO byproducts on the electrical properties and the underlying dynamics of lipid membranes. In this work, bilayer lipid membranes (BLMs) containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocoline (POPC) with increasing hydroperoxidized POPC (POPC-OOH) molar proportions (BLM_PC/PC-OOH) are used as model membranes to investigate the effect of LOOH-mediated LPO propagation on the electrical behavior of lipid bilayers. Voltage-induced ion current signals are analyzed by applying the fractal method of power spectrum density (PSD) analysis. We experimentally prove that, when certain LOOH concentration and energy threshold are overcome, oxidized membranes evolve toward a critical state characterized by the emergence of non-linear electrical behavior dynamics and the pore-type metastable structures formation. PSD analysis shows that temporal dynamics exhibiting "white" noise (non-time correlations) reflects a linear relationship between the input and output signals, while long-term correlations (β > 0.5) begin to be observed closely to the transition (critical point) from linear (Ohmic) to nonlinear (non-Ohmic) behavior. The generation of lipid pores appears to arise as an optimized energy dissipation mechanism based on the system's ability to self-organize and generate ordered structures capable of dissipating energy gradients more efficiently under stressful oxidative conditions.

4-Hydroxynonenal induces Cx46 hemichannel inhibition through its carbonylation

Hemichannels formed by connexins mediate the exchange of ions and signaling molecules between the cytoplasm and the extracellular milieu. Under physiological conditions hemichannels have a low open probability, but in certain pathologies their open probability increases, which can result in cell damage. Pathological conditions are characterized by the production of a number of proinflammatory molecules, including 4-hydroxynonenal (4-HNE), one of the most common lipid peroxides produced in response to inflammation and oxidative stress. The aim of this work was to evaluate whether 4-HNE modulates the activity of Cx46 hemichannels. We found that 4-HNE (100 μM) reduced the rate of 4',6-diamino-2-fenilindol (DAPI) uptake through hemichannels formed by recombinant human Cx46 fused to green fluorescent protein, an inhibition that was reversed partially by 10 mM dithiothreitol. Immunoblot analysis showed that the recombinant Cx46 expressed in HeLa cells becomes carbonylated after exposure to 4-HNE, and that 10 mM dithiothreitol reduced its carbonylation. We also found that Cx46 was carbonylated by 4-HNE in the lens of a selenite-induced cataract animal model. The exposure to 100 μM 4-HNE decreased hemichannel currents formed by recombinant rat Cx46 in Xenopus laevis oocytes. This inhibition also occurred in a mutant expressing only the extracellular loop cysteines, suggesting that other Cys are not responsible for the hemichannel inhibition by carbonylation. This work demonstrates for the first time that Cx46 is post-translationally modified by a lipid peroxide and that this modification reduces Cx46 hemichannel activity.

Lipid peroxidation inhibition study: A promising case of 1,3-di([1,1'-biphenyl]-3-yl)urea

In the present study eighteen inhibitors of the hydrolytic enzymes of the endocannabinoid system were investigated for antioxidant activity using lipid peroxidation (LP) method. Among the assayed compounds ten belong to carbamates with phenyl [1,1'-biphenyl]-3-ylcarbamate (6), reported for the first time, and eight are retro-amide derivatives of palmitamine. Interestingly, results indicated that most of the tested compounds have good antioxidant properties. In particular, 1,3-di([1,1'-biphenyl]-3-yl)urea (3) shows IC₅₀ = 26 ± 6 μM comparable to ones obtained for standard antioxidants trolox and quercetin (IC₅₀ = 22 ± 6 μM and 23 ± 6 μM, respectively). Compound 3 was investigated further by means of DFT calculations, to clarify a possible mechanism of the antioxidant action. In order to estimate the capability of 3 to act as radical scavenger the structure was optimized at B3LYP/6-311++G** level and the respective bond dissociation enthalpies were calculated. The calculations in non-polar medium predicted as favorable mechanism a donation of a hydrogen atom to the free radical and formation of N-centered radical, while in polar solvents the mechanism of free radical scavenging by SPLET dominates over HAT H-abstraction. The possible radical scavenging mechanisms of another compound with potent antioxidant properties (IC₅₀ = 53 ± 12 μM), the retro-amide derivative of palmitamine (compound 18), was estimated computationally based on the reaction enthalpies of a model compound (structural analogue to 18). The computations indicated that the most favorable mechanisms are hydrogen atom transfer from the hydroxyl group in meta-position of the benzamide fragment in nonpolar medium, and proton transfer from the hydroxyl group in ortho-position of the benzamide fragment in polar medium.

Supplementation with omega-3 fatty acids potentiates oxidative stress in human airway epithelial cells exposed to ozone

BACKGROUND

Dietary intake of the omega-3 family of polyunsaturated fatty acids (ω-3 FA) is associated with anti-inflammatory effects. However, unsaturated fatty acids are susceptible to oxidation, which produces pro-inflammatory mediators. Ozone (O₃) is a tropospheric pollutant that reacts rapidly with unsaturated fatty acids to produce electrophilic and oxidative mediators of inflammation.

OBJECTIVE

Determine whether supplementation with ω-3 FA alters O₃-induced oxidative stress in human airway epithelial cells (HAEC).

METHODS

16-HBE cells expressing a genetically encoded sensor of the reduced to oxidized glutathione ratio (GSH/GSSG, E_GSH) were supplemented with saturated, monounsaturated, or ω-3 FA prior to exposure to 0, 0.08, 0.1, or 0.3 ppm O₃. Lipid peroxidation was measured in cellular lipid extracts and intact cells following O₃ exposure.

RESULTS

Relative to cells incubated with the saturated or monounsaturated fatty acids, cells supplemented with ω-3 FA containing 5 or 6 double bonds showed a marked increase in E_GSH during exposure to O₃ concentrations as low as 0.08 ppm. Consistent with this finding, the concentration of lipid hydroperoxides produced following O₃ exposure was significantly elevated in ω-3 FA supplemented cells.

DISCUSSION

Supplementation with polyunsaturated ω-3 FA potentiates oxidative responses, as indicated by E_GSH, in HAEC exposed to environmentally relevant concentrations of O₃. This effect is mediated by the increased formation of lipid hydroperoxides produced by the reaction of O₃ with polyunsaturated fatty acids. Given the inflammatory activity of lipid hydroperoxides, these findings have implications for the potential role of ω-3 FA in increasing human susceptibility to the adverse health effects of O₃ exposure.

ADAM17-triggered TNF signalling protects the ageing Drosophila retina from lipid droplet-mediated degeneration

Animals have evolved multiple mechanisms to protect themselves from the cumulative effects of age‐related cellular damage. Here, we reveal an unexpected link between the TNF (tumour necrosis factor) inflammatory pathway, triggered by the metalloprotease ADAM17/TACE, and a lipid droplet (LD)‐mediated mechanism of protecting retinal cells from age‐related degeneration. Loss of ADAM17, TNF and the TNF receptor Grindelwald in pigmented glial cells of the Drosophila retina leads to age‐related degeneration of both glia and neurons, preceded by an abnormal accumulation of glial LDs. We show that the glial LDs initially buffer the cells against damage caused by glial and neuronally generated reactive oxygen species (ROS), but that in later life the LDs dissipate, leading to the release of toxic peroxidated lipids. Finally, we demonstrate the existence of a conserved pathway in human iPS‐derived microglia‐like cells, which are central players in neurodegeneration. Overall, we have discovered a pathway mediated by TNF signalling acting not as a trigger of inflammation, but as a cytoprotective factor in the retina.

Simultaneous analysis of saturated and unsaturated oxylipins in 'ex vivo' cultured peripheral blood mononuclear cells and neutrophils

Oxylipins are a family of saturated and unsaturated fatty acids peroxidation products with bioactive properties. We have developed an improved method for the measurement of ex vivo oxylipin production by peripheral blood mononuclear cells (PBMCs) and neutrophils. We aimed to develop an analytical method to determine the production rates of polyunsaturated fatty acids (PUFAs), PUFA-oxylipin, and saturated-oxylipins by stimulated PBMCs and neutrophils based on solid phase extraction and HPLC-MS/MS technology. A UHPLC system coupled to a Q-Exactive Hybrid Quadrupole-Orbitrap mass spectrometer was used to identify and quantify oxylipin production. For each oxylipin and PUFA their differential response was calculated with respect to a deuterated internal standard factor (ISF). To calculate oxylipin and PUFAs in the culture samples, the individual ISF was used for each oxylipin and PUFA with respect to the deuterated internal standard. PBMCs and neutrophils showed a different pattern of oxylipin production and fatty acid secretion. Lipopolysaccharide (LPS) did not stimulate oxylipin production or fatty acids secretion in PBMCs, whereas phorbol myristate acetate (PMA) stimulation increased the production rate of 5-HETE, 15-HETE, 15-HEPE, 17-DoHE, PGE2, AA, and DHA. LPS stimulation decreased 16-hydroxyl-palmitatte (16-OHPAL) production and DHA secretion in neutrophils, while PMA stimulation increased the production rate of AA and its derivate oxylipins, 5-HETE, 15-HETE, and PGE2. In conclusion, we have developed a new method to determine oxylipins derived from both saturated and unsaturated fatty acids in culture cell media. This method has enough sensitivity, and accuracy, to determine oxylipin production and fatty acid secretion by PBMCs and neutrophils.

The role of medical gas in stroke: an updated review

Medical gas is a large class of bioactive gases used in clinical medicine and basic scientific research. At present, the role of medical gas in neuroprotection has received growing attention. Stroke is a leading cause of death and disability in adults worldwide, but current treatment is still very limited. The common pathological changes of these two types of stroke may include excitotoxicity, free radical release, inflammation, cell death, mitochondrial disorder, and blood-brain barrier disruption. In this review, we will discuss the pathological mechanisms of stroke and the role of two medical gases (hydrogen and hydrogen sulfide) in stroke, which may potentially provide a new insight into the treatment of stroke.

Acquired Traits Contribute More to Drought Tolerance in Wheat Than in Rice

Drought tolerance is governed by constitutive and acquired traits. Combining them has relevance for sustaining crop productivity under drought. Mild levels of stress induce specific mechanisms that protect metabolism when stress becomes severe. Here, we report a comparative assessment of "acquired drought tolerance (ADT)" traits in two rice cultivars, IR64 (drought susceptible) and Apo (tolerant), and a drought-tolerant wheat cultivar, Weebill. Young seedlings were exposed to progressive concentrations of methyl viologen (MV), a stress inducer, before transferring to a severe concentration. "Induced" seedlings showed higher tolerance and recovery growth than seedlings exposed directly to severe stress. A novel phenomic platform with an automated irrigation system was used for precisely imposing soil moisture stress to capture ADT traits during the vegetative stage. Gradual progression of drought was achieved through a software-controlled automated irrigation facility. This facility allowed the maintenance of the same level of soil moisture irrespective of differences in transpiration, and hence, this platform provided the most appropriate method to assess ADT traits. Total biomass decreased more in IR64 than in Apo. The wheat cultivar showed lower levels of damage and higher recovery growth even compared to Apo. Expression of ROS-scavenging enzymes and drought-responsive genes was significantly higher in Apo than in IR64, but differences were only marginal between Apo and Weebill. The wheat cultivar showed significantly higher stomatal conductance, carbon gain, and biomass than the rice cultivars, under drought. These differences in ADT traits between cultivars as well as between species can be utilised for improving drought tolerance in crop plants.

Growth Temperature Influence on Lipids and Photosynthesis in Lepidium sativum

Temperature has a major impact on plant development and growth. In temperate climates, the seasonal temperature displays large variations that can affect the early stages of plant growth and development. Sessile organisms need to be capable of responding to these conditions, so that growth temperature induces morphological and physiological changes in the plant. Besides development, there are also important molecular and ultrastructural modifications allowing to cope with different temperatures. The chloroplast plays a crucial role in plant energetic metabolism and harbors the photosynthetic apparatus. The photosynthetic light reactions are at the interface between external physical conditions (light, temperature) and the cell biochemistry. Therefore, photosynthesis requires structural flexibility to be able to optimize its efficiency according to the changes of the external conditions. To investigate the effect of growth temperature on the photosynthetic apparatus, we followed the photosynthetic performances and analyzed the protein and lipid profiles of Lepidium sativum (cress) grown at three different temperatures. This revealed that plants developing at temperatures above the optimum have a lower photosynthetic efficiency. Moreover, plants grown under elevated and low temperatures showed a different galactolipid profile, especially the amount of saturated galactolipids decreased at low temperature and increased at high temperature. From the analysis of the chlorophyll a fluorescence induction, we assessed the impact of growth temperature on the re-oxidation of plastoquinone, which is the lipidic electron carrier of the photosynthetic electron transport chain. We show that, at low temperature, along with an increase of unsaturated structural lipids and plastochromanol, there is an increase of the plastoquinone oxidation rate in the dark. These results emphasize the importance of the thylakoid membrane composition in preserving the photosynthetic apparatus under non-optimal temperatures.

Hydrolysis of oxidized phosphatidylcholines by crude enzymes from chicken, pork and beef muscles

Crude enzymes were extracted from beef, pork and chicken and were employed to hydrolyze 1-palmitoyl-2-linoleoyl-phosphatidylcholine (PLPC) and oxidized PLPC, i.e. hydroperoxide of PLPC (PLPC-OOH) and hydroxide of PLPC (PLPC-OH). HPLC-ELSD and ESI-MS were used to characterize and determinate hydrolytic products. After hydrolysis at 37 °C for 180 min, 26.8 ~ 27.4%, 21.6 ~ 22.8% and 17.8 ~ 19.0% of substrates were hydrolyzed by crude enzymes from beef, pork and chicken, respectively. Phospholipase A₂ (PLA₂) was the major contributor to hydrolysis, which accounted for 47.8 ~ 49.6%, 45.8 ~ 48.7% and 46.6 ~ 46.8% of hydrolysis of PLPC, PLPC-OOH and PLPC-OH, respectively. Crude enzymes demonstrated almost same specificities towards PLPC, PLPC-OOH and PLPC-OH. Under actions of crude enzymes, hydroperoxyoctadecadienoic acids (HpODE) and hydroxyoctadecadienoic acids (HODE) were yielded as hydrolytic products of PLPC-OOH and PLPC-OH, respectively. These finding would be helpful to better understand the fate of hydroperoxides of phospholipids and formation of HODE during meat products manufacturing.

Evaluation of oxidant/antioxidant status, metabolic profile and milk production in cows with metritis

Background

The aim of the study was to evaluate oxidant/antioxidant status in 21 Holstein dairy cows with metritis compared to 8 healthy controls. Blood samples were taken during the first 21 days postpartum. Malondialdehyde (MDA), a marker of oxidative stress, total antioxidant status (TAS) and antioxidant parameters such as glutathione peroxidase (GPx), selenium (Se), vitamins A and E and beta-carotene were determined from all cows. The differences in beta-hydroxybutyrate (BHB), non-esterified fatty acids (NEFA), calcium, bilirubin concentrations and aspartate aminotransferase (AST) activity were also monitored, as were milk production and milk composition. Metritis was defined by an unpleasant discharge of varying color (milky-grey/brown/sanguineous) and consistency (muco-purulent/purulent/watery) and by the presence of increased temperature (> 38.5 °C) in cows within 21 days postpartum. Rectal examination revealed increased uterine size, thickened uterine wall and increased uterine tone. The affected cows had significantly reduced daily milk production. Additionally, hematological parameters and haptoglobin concentration were also measured in metritic cows.

Results

Higher MDA concentration (P <  0.001) was recorded in cows with metritis, while vitamin A and vitamin E concentrations were lower (P <  0.01) compared to healthy cows. Higher BHB (P <  0.05), NEFA (P <  0.05), AST (P <  0.05) and bilirubin (P <  0.001) concentrations was recorded in cows with metritis as compared to the control group. Significant differences in beta-carotene concentration, GPx activity, and Se, TAS and Ca concentrations in cows with metritis compared to control group were not observed in the present study (P >  0.05). Milk production was decreased in the cows with metritis (P <  0.001) and alterations in milk composition were also observed in metritic cows as compared to healthy cows.

Conclusions

The results of the study showed that cows with metritis in early postpartum are exposed to a higher degree of oxidative stress and that the incidence of metritis can negatively affect milk production in dairy cows.

Potent Oxidation of DNA by Haloquinoid Disinfection Byproducts to the More Mutagenic Imidazolone dIz via an Unprecedented Haloquinone-Enoxy Radical-Mediated Mechanism

Halogenated quinones are a class of carcinogenic intermediates and newly identified chlorination disinfection byproducts in drinking water. We found recently that halogenated quinones could enhance the decomposition of hydroperoxides independent of transition-metal ions and formation of the novel quinone enoxy/ketoxy radicals. Here, we show that the major oxidation product was 2-amino-5-[(2-deoxy-β-d-erythro-pentofuranosyl)amino]-4H-imidazol-4-one (dIz) when the nucleoside 2'-deoxyguanosine (dG) was treated with tetrachloro-1,4-benzoquinone (TCBQ) and t-butyl hydroperoxide (t-BuOOH). The formation of dIz was markedly inhibited by typical radical spin-trapping agents. Interestingly and unexpectedly, we found that the generated quinone enoxy radical played a critical role in dIz formation. Using [¹⁵N₅]-8-oxodG, dIz was found to be produced either directly from dG or through the transient formation of 8-oxodG. Based on these data, we proposed that the production of dIz might be through an unusual haloquinone-enoxy radical-mediated mechanism. Analogous results were observed in the oxidation of ctDNA by TCBQ/t-BuOOH and when t-BuOOH was substituted by the endogenously generated physiologically relevant hydroperoxide 13S-hydroperoxy-9Z,11E-octadecadienoic acid. This is the first report that halogenated quinoid carcinogens and hydroperoxides can induce potent oxidation of dG to the more mutagenic product dIz via an unprecedented quinone-enoxy radical-mediated mechanism, which may partly explain their potential carcinogenicity.

The processes associated with lipid peroxidation in human embryonic lung fibroblasts, treated with polycyclic aromatic hydrocarbons and organic extract from particulate matter

Polycyclic aromatic hydrocarbons (PAHs) may cause lipid peroxidation via reactive oxygen species generation. 15-F2t-isoprostane (IsoP), an oxidative stress marker, is formed from arachidonic acid (AA) by a free-radical induced oxidation. AA may also be converted to prostaglandins (PG) by prostaglandin-endoperoxide synthase (PTGS) induced by NF-κB. We treated human embryonic lung fibroblasts (HEL12469) with benzo[a]pyrene (B[a]P), 3-nitrobenzanthrone (3-NBA) and extractable organic matter (EOM) from ambient air particulate matter <2.5 µm for 4 and 24 h. B[a]P and 3-NBA induced expression of PAH metabolising, but not antioxidant enzymes. The concentrations of IsoP decreased, whereas the levels of AA tended to increase. Although the activity of NF-κB was not detected, the tested compounds affected the expression of prostaglandin-endoperoxide synthase 2 (PTGS2). The levels of prostaglandin E2 (PGE2) decreased following exposure to B[a]P, whereas 3-NBA exposure tended to increase PGE2 concentration. A distinct response was observed after EOM exposure: expression of PAH-metabolising enzymes was induced, IsoP levels increased after 24-h treatment but AA concentration was not affected. The activity of NF-κB increased after both exposure periods, and a significant induction of PTGS2 expression was found following 4-h treatment. Similarly to PAHs, the EOM exposure was associated with a decrease of PGE2 levels. In summary, exposure to PAHs with low pro-oxidant potential results in a decrease of IsoP levels implying 'antioxidant' properties. For such compounds, IsoP may not be a suitable marker of lipid peroxidation.

Black Chokeberry Fruit Polyphenols: A Valuable Addition to Reduce Lipid Oxidation of Muffins Containing Xylitol

The study aimed at assessing effects of black chokeberry polyphenol extract (ChPE) added (0.025-0.075%) to xylitol-containing muffins to reduce lipid oxidation, especially in preventing degradation of hydroperoxides throughout the storage period. Among polyphenolic compounds (3092 mg/100 g in total) in ChPE, polymeric procyanidins were the most abundant (1564 mg/100 g). ChPE addition resulted in a significantly increased capacity of scavenging free radicals and markedly inhibited hydroperoxides decomposition, as reflected by low anisidine values (AnV: 3.25-7.52) throughout the storage. On the other hand, sucrose-containing muffins had increased amounts of primary lipid oxidation products and differed significantly from other samples in conjugated diene hydroperoxides (CD values), which was in accordance with the decrease of C18:2 9c12c in those muffins after storage. In addition, sucrose-containing muffins were found to be those with the highest level of contamination with toxic carbonyl lipid oxidation products. Throughout the storage, no yeast or moulds contamination were found in higher enriched muffins. The incorporation of polyphenols to xylitol-containing muffins resulted in preventing decomposition of polyunsaturated fatty acids (PUFAs), and in reducing the content of some toxic aldehydes. ChPE could be regarded as a possible solution to xylitol-containing muffins to extend their shelf life. The results support the use of xylitol in muffin manufacture as being favourable in terms of suitability for diabetics.

Reaction targets of antioxidants in azo-initiator or lipid hydroperoxide induced lipid peroxidation

Lipid peroxidation (LPO) is reported to be involved in the pathogenesis of several oxidative diseases, and several therapeutic approaches using antioxidants have been proposed. LPO is thought to progress via a complicated series of multistep reactions suggesting that the activity of each antioxidant may be different, and depends on the reacting molecules. Hence, in this study, we evaluated the inhibitory mechanisms of several antioxidants toward arachidonic acid (AA) peroxidation induced by the azo initiator 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) or a lipid hydroperoxide, hydroperoxyoctadecadienoic acid (HpODE)/hemin. Edaravone, ferrostatin-1, TEMPO and trolox effectively inhibited the production of malondialdehyde (MDA) and several oxidised AAs generated in the AAPH-induced LPO because of their scavenging ability toward lipid peroxyl radicals. In contrast, ebselen and ferrostatin-1 showed strong antioxidative activity in the HpODE/hemin-induced peroxidation. Under this condition, ebselen and ferrostatin-1 were thought to reduce HpODE and its derived alkoxyl radicals to the corresponding lipid alcohols. In conclusion, we found that each antioxidant had different antioxidative activities that prevented the progression of LPO. We expect that these findings will contribute to the design of novel therapeutic strategies using an appropriate antioxidant targeted to each step of the development of oxidative stress diseases.

Sphingomyelins Prevent Propagation of Lipid Peroxidation-LC-MS/MS Evaluation of Inhibition Mechanisms

Free radical driven lipid peroxidation is a chain reaction which can lead to oxidative degradation of biological membranes. Propagation vs. termination rates of peroxidation in biological membranes are determined by a variety of factors including fatty acyl chain composition, presence of antioxidants, as well as biophysical properties of mono- or bilayers. Sphingomyelins (SMs), a class of sphingophospholipids, were previously described to inhibit lipid oxidation most probably via the formation of H-bond network within membranes. To address the “antioxidant” potential of SMs, we performed LC-MS/MS analysis of model SM/glycerophosphatidylcholine (PC) liposomes with different SM fraction after induction of radical driven lipid peroxidation. Increasing SM fraction led to a strong suppression of lipid peroxidation. Electrochemical oxidation of non-liposomal SMs eliminated the observed effect, indicating the importance of membrane structure for inhibition of peroxidation propagation. High resolution MS analysis of lipid peroxidation products (LPPs) observed in in vitro oxidized SM/PC liposomes allowed to identify and relatively quantify SM- and PC-derived LPPs. Moreover, mapping quantified LPPs to the known pathways of lipid peroxidation allowed to demonstrate significant decrease in mono-hydroxy(epoxy) LPPs relative to mono-keto derivatives in SM-rich liposomes. The results presented here illustrate an important property of SMs in biological membranes, acting as “biophysical antioxidant”. Furthermore, a ratio between mono-keto/mono-hydroxy(epoxy) oxidized species can be used as a marker of lipid peroxidation propagation in the presence of different antioxidants.

Mitochondrial damage & lipid signaling in traumatic brain injury

Mitochondria are essential for neuronal function because they serve not only to sustain energy and redox homeostasis but also are harbingers of death. A dysregulated mitochondrial network can cascade until function is irreparably lost, dooming cells. TBI is most prevalent in the young and comes at significant personal and societal costs. Traumatic brain injury (TBI) triggers a biphasic and mechanistically heterogenous response and this mechanistic heterogeneity has made the development of standardized treatments challenging. The secondary phase of TBI injury evolves over hours and days after the initial insult, providing a window of opportunity for intervention. However, no FDA approved treatment for neuroprotection after TBI currently exists. With recent advances in detection techniques, there has been increasing recognition of the significance and roles of mitochondrial redox lipid signaling in both acute and chronic central nervous system (CNS) pathologies. Oxidized lipids and their downstream products result from and contribute to TBI pathogenesis. Therapies targeting the mitochondrial lipid composition and redox state show promise in experimental TBI and warrant further exploration. In this review, we provide 1) an overview for mitochondrial redox homeostasis with emphasis on glutathione metabolism, 2) the key mechanisms of TBI mitochondrial injury, 3) the pathways of mitochondria specific phospholipid cardiolipin oxidation, and 4) review the mechanisms of mitochondria quality control in TBI with consideration of the roles lipids play in this process.

Relation between redox homeostasis blood parameters in cirrhotic patients and endothelial dysfunction development

BACKGROUND

Liver is one of the first organs to be exposed to reactive oxygen species (ROS). But the data about the levels of redox homeostasis parameters in the patients with liver cirrhosis (LC) are contradictory. We hypothesized that the levels of malondialdehyde and catalase should change in accordance with the LC severity causing the endothelial dysfunction.

METHODS

In a randomized way with the preliminary stratification by the presence of LC 81 patients and 20 healthy volunteers were examined. To determine the contents of catalase, malondialdehyde, cyclic guanosine monophosphate, endothelin-1, renin, aldosterone, natriuretic peptide, the routine standardized methods were used.

RESULTS

Patients with LC revealed the statistically significant increase of malondialdehyde and decrease of catalase levels in parallel with the increase of cyclic guanosine monophosphate, endothelin-1, renin, aldosterone, natriuretic peptide contents and disease course worsening according to the Child-Pugh criteria. It testifies the huge oxidative stress impact on the organism. Initially, at the stage of LC compensation, it slightly stimulates the activation of antioxidant system, followed by its gradual suppression at the stages of sub- and decompensation. Disorders of redox homeostasis lead to the endothelial dysfunction that becomes the background of extrahepatic comorbid disorders.

CONCLUSIONS

Cirrhotic patients have significant abnormalities in the redox homeostasis, which become the background of the endothelial dysfunction - common trigger mechanism for the syntrophic comorbid diseases and early pathophysiologic symptom of the unfavorable prognosis for such patients.

Redox basis of exercise physiology

Redox reactions control fundamental processes of human biology. Therefore, it is safe to assume that the responses and adaptations to exercise are, at least in part, mediated by redox reactions. In this review, we are trying to show that redox reactions are the basis of exercise physiology by outlining the redox signaling pathways that regulate four characteristic acute exercise-induced responses (muscle contractile function, glucose uptake, blood flow and bioenergetics) and four chronic exercise-induced adaptations (mitochondrial biogenesis, muscle hypertrophy, angiogenesis and redox homeostasis). Based on our analysis, we argue that redox regulation should be acknowledged as central to exercise physiology.

The Role of Selenium in Oxidative Stress and in Nonthyroidal Illness Syndrome (NTIS): An Overview

Selenium is a trace element, nutritionally classified as an essential micronutrient, involved in maintaining the correct function of several enzymes incorporating the selenocysteine residue, namely the selenoproteins. The human selenoproteome including 25 proteins is extensively described here. The most relevant selenoproteins, including glutathione peroxidases, thioredoxin reductases and iodothyronine deiodinases are required for the proper cellular redox homeostasis as well as for the correct thyroid function, thus preventing oxidative stress and related diseases. This review summarizes the main advances on oxidative stress with a focus on selenium metabolism and transport. Moreover, thyroid-related disorders are discussed, considering that the thyroid gland contains the highest selenium amount per gram of tissue, also for future possible therapeutic implication.

Atomic-scale modeling of the effect of lipid peroxidation on the permeability of reactive species

Biomembranes and lipid systems are rich in unsaturated lipid components and are subject to photo-induced lipid peroxidation. The peroxidized lipid products in cellular systems are known to affect the structural organization and function of the biomembrane. We employed molecular dynamics simulations to study the effects of phospholipid peroxidation on membrane properties and the permeability of different reactive species. The results suggest that when the lipids are peroxidized, the peroxide group moves toward the membrane surface, which causes the membrane system to expand laterally and increase in area. The permeability profile revealed that nitrogen species can easily permeate through the native and peroxidized system in comparison to oxygen species, suggesting its importance in plasma-based treatment. Thus, by breaching the energy barrier with lower energy, they can traverse the cell membrane and induce oxidative stress, which leads to apoptosis.Communicated by Ramaswamy H. Sarma.

In silico Prediction of Protein-Protein Interaction Network Induced by Manganese II in Meyerozyma guilliermondii

Recently, there has been an increasing interest in the use of yeast to produce biosorbent materials, because yeast is economical to use, adaptable to a variety of conditions, and amenable to morphological manipulations to yield better raw biomaterials. Previous studies from our laboratory have shown that Meyerozyma guilliermondii, a non-pathogenic haploid yeast (ascomycete), exhibits excellent biosorption capacity for Mn²⁺, as demonstrated by kinetic analyses. Shotgun/bottom-up analyses of soluble fractions revealed a total of 1257 identified molecules, with 117 proteins expressed in the absence of Mn²⁺ and 69 expressed only in the presence of Mn²⁺. In this article, we describe the first in silico prediction and screening of protein–protein interactions (PPIs) in M. guilliermondii using experimental data from shotgun/bottom-up analyses. We also present the categorization of biological processes (BPs), molecular functions (MFs), and metabolic pathways of 71 proteins upregulated in the M. guilliermondii proteome in response to stress caused by an excess of Mn²⁺ ions. Most of the annotated proteins were related to oxidation–reduction processes, metabolism, and response to oxidative stress. We identified seven functional enrichments and 42 metabolic pathways; most proteins belonged to pathways related to metabolic pathways (19 proteins) followed by the biosynthesis of secondary metabolites (10 proteins) in the presence of Mn²⁺. Using our data, it is possible to infer that defense mechanisms minimize the impact of Mn²⁺ via the expression of antioxidant proteins, thus allowing adjustment during the defense response. Previous studies have not considered protein interactions in this genus in a manner that permits comparisons. Consequently, the findings of the current study are innovative, highly relevant, and provide a description of interactive complexes and networks that yield insight into the cellular processes of M. guilliermondii. Collectively, our data will allow researchers to explore the biotechnological potential of M. guilliermondii in future bioremediation processes.

Radioiodinated Nitroxide Derivative for the Detection of Lipid Radicals

Thus far, no accurate measurement technology has been developed to detect lipid alkyl radicals (lipid radicals), which cause lipid peroxidation. Therefore, we aimed to develop a nuclear medical imaging probe that can be taken up in the lipophilic site in cells such as biological membranes, by reacting specifically with the lipid radicals generated there. We designed and synthesized 4-(4-[¹²⁵I]iodobenzamido)-2,2,6,6-tetramethylpiperidine-1-oxyl, which shows high reactivity to lipid radicals with a high radiochemical yield and purity. Intracellular retention was found to increase significantly when lipid radicals were produced.

The Role of Lipoxidation in the Pathogenesis of Diabetic Retinopathy

Lipids can undergo modification as a result of interaction with reactive oxygen species (ROS). For example, lipid peroxidation results in the production of a wide variety of highly reactive aldehyde species which can drive a range of disease-relevant responses in cells and tissues. Such lipid aldehydes react with nucleophilic groups on macromolecules including phospholipids, nucleic acids, and proteins which, in turn, leads to the formation of reversible or irreversible adducts known as advanced lipoxidation end products (ALEs). In the setting of diabetes, lipid peroxidation and ALE formation has been implicated in the pathogenesis of macro- and microvascular complications. As the most common diabetic complication, retinopathy is one of the leading causes of vision loss and blindness worldwide. Herein, we discuss diabetic retinopathy (DR) as a disease entity and review the current knowledge and experimental data supporting a role for lipid peroxidation and ALE formation in the onset and development of this condition. Potential therapeutic approaches to prevent lipid peroxidation and lipoxidation reactions in the diabetic retina are also considered, including the use of antioxidants, lipid aldehyde scavenging agents and pharmacological and gene therapy approaches for boosting endogenous aldehyde detoxification systems. It is concluded that further research in this area could lead to new strategies to halt the progression of DR before irreversible retinal damage and sight-threatening complications occur.