Modifications of proteins by polyunsaturated fatty acid peroxidation products

Correlations of dynamic changes in lipid and protein of salted large yellow croaker during storage

Protein and lipid are two major components that undergo significant changes during processing of aquatic products. This study focused on the protein oxidation, protein conformational states, lipid oxidation and lipid molecule profiling of salted large yellow croaker during storage, and their correlations were investigated. The degree of oxidation of protein and lipid was time-dependent, leading to an increase in carbonyl content and surface hydrophobicity, a decrease in sulfhydryl groups, and an increase in conjugated diene, peroxide value and thiobarbituric acid reactive substances value. Oxidation caused protein structure denaturation and aggregation during storage. Lipid composition and content changed dynamically, with polyunsaturated phosphatidylcholine (PC) was preferentially oxidized compared to polyunsaturated triacylglycerol. Correlation analysis showed that the degradation of polyunsaturated key differential lipids (PC 18:2_20:5, PC 16:0_22:6, PC 16:0_20:5, etc.) was closely related to the oxidation of protein and lipid. The changes in protein conformation and the peroxidation of polyunsaturated lipids mutually promote each other's oxidation process.

Insights into the Synergistic Antibacterial Activity of Silver Nitrate with Potassium Tellurite against Pseudomonas aeruginosa

The constant, ever-increasing antibiotic resistance crisis leads to the announcement of "urgent, novel antibiotics needed" by the World Health Organization. Our previous works showed a promising synergistic antibacterial activity of silver nitrate with potassium tellurite out of thousands of other metal/metalloid-based antibacterial combinations. The silver-tellurite combined treatment not only is more effective than common antibiotics but also prevents bacterial recovery, decreases the risk of future resistance chance, and decreases the effective concentrations. We demonstrate that the silver-tellurite combination is effective against clinical isolates. Further, this study was conducted to address knowledge gaps in the available data on the antibacterial mechanism of both silver and tellurite, as well as to give insight into how the mixture provides synergism as a combination. Here, we defined the differentially expressed gene profile of Pseudomonas aeruginosa under silver, tellurite, and silver-tellurite combination stress using an RNA sequencing approach to examine the global transcriptional changes in the challenged cultures grown in simulated wound fluid. The study was complemented with metabolomics and biochemistry assays. Both metal ions mainly affected four cellular processes, including sulfur homeostasis, reactive oxygen species response, energy pathways, and the bacterial cell membrane (for silver). Using a Caenorhabditis elegans animal model we showed silver-tellurite has reduced toxicity over individual metal/metalloid salts and provides increased antioxidant properties to the host. This work demonstrates that the addition of tellurite would improve the efficacy of silver in biomedical applications. IMPORTANCE Metals and/or metalloids could represent antimicrobial alternatives for industrial and clinical applications (e.g., surface coatings, livestock, and topical infection control) because of their great properties, such as good stability and long half-life. Silver is the most common antimicrobial metal, but resistance prevalence is high, and it can be toxic to the host above a certain concentration. We found that a silver-tellurite composition has antibacterial synergistic effect and that the combination is beneficial to the host. So, the efficacy and application of silver could increase by adding tellurite in the recommended concentration(s). We used different methods to evaluate the mechanism for how this combination can be so incredibly synergistic, leading to efficacy against antibiotic- and silver-resistant isolates. Our two main findings are that (i) both silver and tellurite mostly target the same pathways and (ii) the coapplication of silver with tellurite tends not to target new pathways but targets the same pathways with an amplified change.

Co-encapsulation of resveratrol in fish oil microcapsules optimally stabilized by enzyme-crosslinked whey protein with gum Arabic

O/W emulsion and its spray-dried microcapsule contain the oil phase and the protein matrix, providing the potential to co-encapsulate different antioxidants. However, antioxidants were generally encapsulated in the oil phase of microcapsule, its protein matrix is rarely used. It is first to prove the possibility to encapsulate resveratrol in the emulsified oil droplets at high wall/core ratios. The optimal microcapsule with 1.75% surface oil was fabricated with 15% transglutaminase-crosslinked WPI (TGase-WPI) and 5% gum Arabic (GA). Resveratrol mainly located in the protein matrix of initial emulsion and reconstituted microcapsule. The effects of TGase-WPI/GA microcapsule and resveratrol co-encapsulation on DHA/EPA and lipid hydroperoxides/TBARS were different. The interfacial protein, the partition of resveratrol in the emulsified oil droplets and its storage stability and inhibitory effect on size change of reconstituted microcapsules increased as the polyphenol increased. These results expand the potential use of spray-dried microcapsules as co-encapsulation carriers.

Role of Oxidative Stress in Ocular Diseases: A Balancing Act

Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.

Functional and Allergenic Properties Assessment of Conalbumin (Ovotransferrin) after Oxidation

Conalbumin (CA) is an iron-binding egg protein that has various bioactivities and causes major allergenicity in humans. This study investigated how oxidation affects the multiple functional properties of CA. The lipid peroxidation method was used to prepare treated CA [2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH)-CA and acrolein-CA] complexes. CA induced structural changes through oxidation. These changes enhanced the digestibility, rate of endocytosis in dendritic cells, and emulsifying and foaming properties of CA. ELISA and immunoblot analysis showed that the complexes reduced the IgE-binding ability of CA through lipid oxidation. KU812 cell assays showed that modification by AAPH and acrolein caused the release of IL-4 and histamine to decline. In conclusion, oxidation treatment modified the functional and structural properties of CA, reducing allergenicity during processing and preservation.

Effects of ultrasonic pretreatment of soybean protein isolate on the binding efficiency, structural changes, and bioavailability of a protein-luteolin nanodelivery system

The combination of protein and flavonoids can ameliorate the problems of poor solubility and stability of flavonoids in utilization. In this study, soybean protein isolate pretreated by ultrasonication was selected as the embedding wall material, which was combined with luteolin to form a soybean protein isolate-luteolin nanodelivery system. The complexation effect and structural changes of soybean protein isolate (SPI) and ultrasonic pretreatment (100 W, 200 W, 300 W, 400 W and 500 W) of soybean protein isolate with luteolin (LUT) were compared, as well as the changes in digestion characteristics and antioxidant activity in vitro. The results showed that proper ultrasonic pretreatment increased the encapsulation efficacy, loading amount and solubility to 89.72%, 2.51 μg/mg and 90.56%. Appropriate ultrasonic pretreatment could make the particle size and the absolute value of ζ-potential of SPI-LUT nanodelivery system decrease and increase respectively. The FTIR and fluorescence results show that appropriate ultrasonic pretreatment could reduce α-helix, β-sheet and random coil, increase β-turn, and enhance fluorescence quenching. The thermodynamic evaluation results indicate that the ΔG < 0, ΔH > 0 and ΔS > 0, so the interaction of LUT with the protein was spontaneous and mostly governed by hydrophobic interactions. The XRD results show that the LUT was amorphous and completely wrapped by SPI. The DSC results showed that ultrasonic pretreatment could improve the thermal stability of SPI-LUT nanodelivery system to 112.66 ± 1.69 °C. Digestion and antioxidant analysis showed that appropriate ultrasonic pretreatment increased the LUT release rate and DPPH clearance rate of SPI-LUT nanodelivery system to 89.40 % and 55.63 % respectively. This study is a preliminary source for the construction of an SPI nanodelivery system with ultrasound pretreatment and the deep processing and utilization of fat-soluble active substances.

Glycerol-bound oxidized fatty acids: formation and occurrence in peanuts

For peanuts, roasted at 170 °C, the formation of selected glycerol-bound oxidized fatty acids (GOFAs), namely 9-oxononanoic acid (9-ONA), azelaic acid (AZA) and octanoic acid, was observed by GC-MS (EI). The content of octanoic acid as well as AZA increased with continuous roasting time (from 59 mg/kg peanut oil to 101 mg/kg peanut oil and from not detectable to 8 mg/kg peanut oil, respectively), whereas the content of 9-ONA initially decreased from 25 mg/kg peanut oil to 8 mg/kg peanut oil (20 min) and increased again up to 37 mg/kg peanut oil following roasting for 40 min. Due to its aldehyde function, 9-ONA could contribute to amino acid side chain modifications as a result of lipation, which could directly influence the functional properties of peanut proteins. Both 9-ONA and octanoic acid are potential markers of thermal processes. Furthermore, in model experiments using methyl linoleate and methyl oleate, up to 18 oxidized fatty acids could be identified as methyl esters, 9-ONA as well as octanoic acid as major components and a faster formation of GOFAs under roasting conditions (170 °C, 20 min). In addition, 9-ONA contributes to the formation of AZA and octanoic acid in both free and bound form as a result of oxidative subsequent reactions in presence of iron (III).

A nanodevice with lifetime-improved singlet oxygen for enhanced photodynamic therapy

The short lifetime of singlet oxygn reduces its accumulation in the ehdoplasmic reticulum, which limited the output of photodynamic therapy. A nanodevice with functions of singlet oxygen production, storage and...

Antioxidant and prooxidant activities of tea polyphenols in oil-in-water emulsions depend on the level used and the location of proteins

We studied the impacts of protein location (interface or aqueous phase) on the antioxidant and prooxidant activities of tea polyphenols (TP) in model oil-in-water emulsions (pH 7) at a low (0.01% w/v) or high (0.04 % w/v) concentration. TP at 0.01% reduced the levels of both lipid and protein oxidation markers in emulsions, independent of the protein location. However, TP were more potent when proteins were located at the interface. At 0.04%, TP were only weakly antioxidant towards lipids but were prooxidant towards proteins in emulsions with proteins at the interface, whereas they were still somewhat antioxidant for aqueous phase proteins. These results indicate that TP may act as either antioxidants or prooxidants depending on their concentration and also on the location of the proteins in emulsions. The level of TP should be optimized for emulsion-based foods or beverages to achieve optimum antioxidant activity.

The association of N ε-Carboxymethyllysine with polyunsaturated and saturated fatty acids in healthy individuals

Red blood cell (RBC) fatty acids status is used as a biomarker of dietary intake of fats however, there is still a paucity of evidence regarding individual fatty acids and modulation of endogenous advanced glycation end-product (AGE) levels. Due to membrane PUFA being a well-known target for peroxidation, we hypothesized that cellular PUFAs are positively associated with circulatory N ε-carboxymethyllysine (CML) that is also influenced by glyoxal (GO) levels in healthy cohorts. To test this, we investigated the association between RBC fatty acids and circulatory AGEs biomarkers in healthy individuals. The results showed a negative association between saturated fatty acids (SFA) and CML and stepwise multivariate regression analysis indicated stearic acid was negatively associated with CML levels (β = -0.200, p=0.008) after adjusting for age, BMI, and gender. In addition, stearic acid: palmitic acid ratio was also negatively correlated with plasma concentrations of CML (rp= -0.191, p = 0.012) and glucose (rp= -0.288, p = 0.0001). Polyunsaturated fatty acids (PUFA) showed a positive association with CML levels particularly, docosapentaenoic acid, γ-Linolenic acid, arachidonic acid, and docosadienoic acid. However, these associations were not evident after the multiple regression analysis adjusted for age, BMI, and gender. A strong negative correlation (rp= -0.98, p< 0.0001) between total PUFA and total SFA was observed. Furthermore, the SFA:PUFA ratio was inversely correlated with CML (rp= -0.227, p< 0.003). Overall, this study indicates that different fats and their combinations may influence the formation of AGEs and that carefully controlled interventions are required to further test this hypothesis.

Effect of periodontal disease on oxidative stress markers in patients with atherosclerosis

OBJECTIVES

The aim of this study was to investigate the effect of periodontal inflammation on oxidative stress in patients with atherosclerosis by considering serum and saliva total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI).

MATERIALS AND METHODS

In the study, there were 4 groups, with 20 individuals in each group. These groups consisted of individuals who had periodontitis with atherosclerosis (group A-P), were periodontally healthy with atherosclerosis (group A-C), were systemically healthy with periodontitis (group P), and were systemically and periodontally healthy (group C). Clinical periodontal parameters were recorded. PISA values were calculated. Atherosclerosis severity was determined by the Gensini score. The ratio of TAS/TOS resulting in the OSI levels of the serum and saliva samples was examined biochemically.

RESULTS

Group A-P serum TAS and group C saliva OSI values were lower than those of the other groups (p < 0.05). Group A-P serum TOS and OSI values were higher than those of the other groups (p < 0.05). Groups A-C and P serum TOS and OSI values were higher than those of group C (p < 0.05). In the multivariate linear regression analysis, group A-P and PISA values were independently associated with serum TOS and OSI values (p < 0.05). Group A-P, group P, and PISA values were independently associated with saliva OSI values (p < 0.05).

CONCLUSIONS

Periodontitis and atherosclerosis may have systemic oxidative stress-increasing effects. The coexistence of periodontitis and atherosclerosis increases oxidative stress beyond that seen in either condition alone. Periodontitis can be associated with increased systemic TOS and OSI values in patients with atherosclerosis.

STATEMENT OF CLINICAL RELEVANCE

Oxidative status is affected more severely when periodontitis and atherosclerosis coexist rather than when either exists alone. Periodontitis can cause increasing effect on serum TOS and OSI and decreasing effect on TAS in patients with atherosclerosis. The increase in oxidative stress markers with the presence of periodontal disease in patients with atherosclerosis emphasizes that controlling periodontal diseases, a treatable disease, may contribute to the prognosis of atherosclerosis.

Reducing the Allergenicity of α-Lactalbumin after Lipid Peroxidation

This study analyzed the effect of lipid peroxidation using 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) and acrolein on the in vitro and in vivo allergenicity of α-lactalbumin (α-La). The structure of oxidized α-La was evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, fluorescence spectroscopy, and circular dichroism, whereas the changes in the allergenic properties were evaluated. Lipid peroxidation induced changes to the structural properties that might destroy and/or mask α-La epitopes. In comparison to native α-La, oxidation complexes caused a decrease in the immunoglobulin E (IgE) binding capacity, as observed via immunoblotting. Moreover, the capacity to release mediators and cytokines from KU812 cells was also greatly reduced. In vivo, oxidation with AAPH and acrolein caused a significant reduction in IgE, IgG, IgG1, mast cell protease 1, and plasma histamine, along with the reduction of mast surface c-Kit⁺ and FcεRI⁺ expression. Therefore, these results indicate that oxidation via AAPH and acrolein can potentially reduce the allergenicity of α-La, which can help with the better understanding of the changes in allergenicity of milk allergen by lipid peroxidation.

Cu-induced mitochondrial dysfunction is mediated by abnormal mitochondrial fission through oxidative stress in primary chicken embryo hepatocytes

BACKGROUND

Excess copper (Cu) is an oxidative stress factor which associates with a variety of diseases. The aim of this study was to evaluate the effect of Cu in primary chicken embryo hepatocytes (CEHs).

METHODS

CEHs were isolated from 13 days old chicken embryos and followed by different concentration Cu (0, 10, 100, 200 μM) and/or ALC treatment (0.3 mg/mL) for 12 or 24 h. The effects of Cu exposure in CEHs were determined by detecting reactive oxygen species (ROS), malondialdehyde (MDA), mitochondrial membrane potential (MMP), and ATP levels. The expression of mitochondrial dynamics-related genes and proteins were also detected.

RESULTS

Results showed that Cu treatment (100 or 200 μM) significantly decreased CEHs viability, MMP and ATP levels, increased ROS and MDA levels in 12 or 24 h. The up-regulated mitochondrial fission genes and protein in 100 and 200 μM Cu groups suggested Cu promoted mitochondrial division but not fusion. However, the co-treatment of ALC and Cu alleviated those changes compared with the 100 or 200 μM Cu groups.

CONCLUSION

In conclusion, we speculated that Cu increased the oxidative stress and induced mitochondria dysfunction via disturbing mitochondrial dynamic balance in CEHs, and this process was not completely reversible.

A Not-So-Ancient Grease History: Click Chemistry and Protein Lipid Modifications

Protein lipid modification involves the attachment of hydrophobic groups to proteins via ester, thioester, amide, or thioether linkages. In this review, the specific click chemical reactions that have been employed to study protein lipid modification and their use for specific labeling applications are first described. This is followed by an introduction to the different types of protein lipid modifications that occur in biology. Next, the roles of click chemistry in elucidating specific biological features including the identification of lipid-modified proteins, studies of their regulation, and their role in diseases are presented. A description of the use of protein-lipid modifying enzymes for specific labeling applications including protein immobilization, fluorescent labeling, nanostructure assembly, and the construction of protein-drug conjugates is presented next. Concluding remarks and future directions are presented in the final section.

The Importance of Developing Electrochemical Sensors Based on Molecularly Imprinted Polymers for a Rapid Detection of Antioxidants

This review aims to pin out the importance of developing a technique for rapid detection of antioxidants, based on molecular imprinting techniques. It covers three major areas that have made great progress over the years in the field of research, namely: antioxidants characterization, molecular imprinting and electrochemistry, alone or combined. It also reveals the importance of bringing these three areas together for a good evaluation of antioxidants in a simple or complex medium, based on selectivity and specificity. Although numerous studies have associated antioxidants with molecular imprinting, or antioxidants with electrochemistry, but even electrochemistry with molecular imprinting to valorize different compounds, the growing prominence of antioxidants in the food, medical, and paramedical sectors deserves to combine the three areas, which may lead to innovative industrial applications with satisfactory results for both manufacturers and consumers.

Effect of High Voltage Cold Plasma on Oxidation, Physiochemical, and Gelling Properties of Myofibrillar Protein Isolate from Asian Sea Bass (Lates calcarifer)

The effects of in-bag dielectric barrier discharge high voltage cold plasma (IB-DBD-HVCP) on myofibrillar protein isolate (MPI) from Asian sea bass (ASB) and its impact on the physiochemical and gelling properties of MPI gels were elucidated. A mixture of argon (90%) and oxygen (10%) was used for generating IB-DBD-HVCP. MPI was subjected to IB-DBD-HVCP for varying times (5–15 min). Total carbonyl content was increased, while total sulfhydryl content was decreased in MPI, especially with augmenting treatment time (TT) (p < 0.05). Surface hydrophobicity initially increased when IB-DBD-HVCP TT of 5 min (DBD-HVCP5) was implemented, followed by subsequent decrease with increasing TT. Based on gel electrophoresis, lower actin and myosin heavy chain (MHC) band intensities were found for MPI subjected to IB-DBD-HVCP, particularly when a TT longer than 10 min was used, compared to those of the control. Gel made from DBD-HVCP5 had higher breaking force, deformation, and highest G′ value compared to others. A more ordered and fibrous network was found in DBD-HVCP5 treated gel. Therefore, IB-DBD-HVCP treatment, particularly for 5 min, enhanced cross-linking of proteins in ASB myofibrillar proteins, which resulted in the improved gel elasticity and strength.

Effect of Oxidation on Quality of Chiba Tofu Produced by Soy Isolate Protein When Subjected to Storage

Chiba tofu is a new type of vegetarian food prepared with soy protein isolate (SPI). According to factory feedback, the SPI stored in the factory storeroom in summer undergoes reactive oxidation, which changes the structure of SPI and further affects the quality of Chiba tofu. Consequently, the main objective of this study was to prepare Chiba tofu with SPI with different storage periods and evaluate the effect of different degrees of oxidation on structural characteristics of SPI and rheology, texture, microstructure and sensory properties of Chiba tofu. The carbonyl content and turbidity of SPI significantly increased, and the contents of free sulfhydryl (SH) and disulfide bond (S-S) simultaneously decreased with storage time. The oxidation changes the SPI conformation, leading to a transition of α-helix and β-turn to β-sheet and random coil during the storage periods. In the SDS–PAGE analysis, oxidation promoted the SPI molecules crosslinked and aggregated, which affected the quality of Chiba tofu. In short storage periods (0–12 days), SPI was relatively moderately oxidized when the carbonyl content was between 4.14 and 6.87 mmol/g. The storage and loss modulus of Chiba tofu both increased, the network was compact, and the hardness and springiness of Chiba tofu showed an increasing trend. Moreover, in longer storage periods (12–30 days), the SPI was relatively severely oxidized when the carbonyl content was between 7.24 and 9.14 mmol/g, which had an adverse effect on Chiba tofu rheological and texture properties, microstructure, and sensory properties. In sensory evaluation, Chiba tofu stored 12 days had the highest overall quality score than that stored on other days. This study is expected to provide an argument for the better industrial production of Chiba tofu.

The Advanced Lipoxidation End-Product Malondialdehyde-Lysine in Aging and Longevity

The nonenzymatic adduction of malondialdehyde (MDA) to the protein amino groups leads to the formation of malondialdehyde-lysine (MDALys). The degree of unsaturation of biological membranes and the intracellular oxidative conditions are the main factors that modulate MDALys formation. The low concentration of this modification in the different cellular components, found in a wide diversity of tissues and animal species, is indicative of the presence of a complex network of cellular protection mechanisms that avoid its cytotoxic effects. In this review, we will focus on the chemistry of this lipoxidation-derived protein modification, the specificity of MDALys formation in proteins, the methodology used for its detection and quantification, the MDA-lipoxidized proteome, the metabolism of MDA-modified proteins, and the detrimental effects of this protein modification. We also propose that MDALys is an indicator of the rate of aging based on findings which demonstrate that (i) MDALys accumulates in tissues with age, (ii) the lower the concentration of MDALys the greater the longevity of the animal species, and (iii) its concentration is attenuated by anti-aging nutritional and pharmacological interventions.

Physicochemical and Structural Characteristics of Soybean Protein Isolates Induced by Lipoxygenase-Catalyzed Linoleic Acid Oxidation during In Vitro Gastric Digestion

The effects of oxidation on the gastric digestion properties of soybean protein isolates (SPIs) in a model of lipoxygenase (LOX)-catalyzed linoleic acid (LA) oxidation system and the multiscale structural characterization of SPI hydrolysate were investigated. Results indicated that the feature of SPI hydrolysate is dependent upon the degree of oxidation. Pepsin hydrolysis caused a red shift in fluorescence intensity and a reduction in surface hydrophobicity and diminished the particle size of SPI hydrolysate during gastric digestion. Compared with the control, mild oxidation was beneficial to protein unfolding and gastric digestibility, as manifested by minimal molecular weight (MW) distribution >50 kDa (32.34%) and smaller peptide fragments under scanning electron microscopy. However, severe oxidation brought about 39.47% loss of free amino acids. It was interesting to find that glycinin was more vulnerable to pepsin hydrolysis after oxidation as compared to the native SPI. Overall, the moderately oxidized SPI appeared to be digested to a greater extent.

What Room for Two-Dimensional Gel-Based Proteomics in a Shotgun Proteomics World?

Two-dimensional gel electrophoresis was instrumental in the birth of proteomics in the late 1980s. However, it is now often considered as an outdated technique for proteomics—a thing of the past. Although this opinion may be true for some biological questions, e.g., when analysis depth is of critical importance, for many others, two-dimensional gel electrophoresis-based proteomics still has a lot to offer. This is because of its robustness, its ability to separate proteoforms, and its easy interface with many powerful biochemistry techniques (including western blotting). This paper reviews where and why two-dimensional gel electrophoresis-based proteomics can still be profitably used. It emerges that, rather than being a thing of the past, two-dimensional gel electrophoresis-based proteomics is still highly valuable for many studies. Thus, its use cannot be dismissed on simple fashion arguments and, as usual, in science, the tree is to be judged by the fruit.

Acute Cellular and Functional Changes With a Combinatorial Treatment of Ion Channel Inhibitors Following Spinal Cord Injury

Reducing the extent of secondary degeneration following spinal cord injury (SCI) is necessary to preserve function, but treatment options have thus far been limited. A combination of the ion channel inhibitors Lomerizine (Lom), YM872 and oxATP, to inhibit voltage-gated Ca²⁺ channels, Ca²⁺ permeable AMPA receptors, and purinergic P2X₇ receptors respectively, effectively limits secondary consequences of injury in in vitro and in vivo models of CNS injury. Here, we investigated the efficacy of these inhibitors in a clinically relevant model of SCI. Fischer (F344) rats were subjected to a moderate (150 kD) contusive SCI at thoracic level T10 and assessed at 2 weeks or 10 weeks post-injury. Lom was delivered orally twice daily and YM872 and oxATP were delivered via osmotic mini-pump implanted at the time of SCI until 2 weeks following injury. Open field locomotion analysis revealed that treatment with the three inhibitors in combination improved the rate of functional recovery of the hind limb (compared to controls) as early as 1-day post-injury, with beneficial effects persisting to 14 days post-injury, while all three inhibitors were present. At 2 weeks following combinatorial treatment, the functional improvement was associated with significantly decreased cyst size, increased immunoreactivity of β-III tubulin^+ve axons, myelin basic protein, and reduced lipid peroxidation by-products, and increased CC1^+ve oligodendrocytes and NG2^+ve/PDGFα^+ve oligodendrocyte progenitor cell densities, compared to vehicle-treated SCI animals. The combination of Lom, oxATP, and YM872 shows preclinical promise for control of secondary degeneration following SCI, and further investigation of long-term sustained treatment is warranted.

Effect of Dietary Microalgae on Growth Performance, Profiles of Amino and Fatty Acids, Antioxidant Status, and Meat Quality of Broiler Chickens

Simple Summary

The use of feed additives with no side effectsfor enhancing growth performance and improving meat quality in broilers chickens is an essential research topic. In these regards, this study aimed to evaluate the impact of three species of microalgae namely Chlorella vulgaris (CV), Spirulina platensis (SP) and Amphora coffeaformis (AC) on growth performance, profiles of fatty and amino acids, antioxidant status and meat quality of breast muscles. The results demonstrated that the inclusion of studied microalgae notably AC has a positive effect on performance, antioxidant status and meat quality of breast muscle in broiler chickens.

Abstract

The study used 96 broiler chickens to evaluate the impact of three species of microalgae on performance, profiles of fatty and amino acids, antioxidants, and meat quality of breast muscles. Birds were divided into four groups (24 birds/each) with 4 replicates (6 birds each). Birds in the first group were fed basal diet and served as a control (C). Birds of 2–4 groups were fed basal diet mixed with same dose (1 g/kg diet) of Chlorella vulgaris (CV), Spirulina platensis (SP), and Amphora coffeaformis (AC). At the age of 36 days, performance parameters were reported, and breast muscle samples were collected and stored frozen at −80 °C. AC shared CV in the superiority of increasing final body weight and body weight gain compared to SP and control. AC shared SP in the superiority of increasing the level of essential fatty and amino acids and decreasing the microbial growth in breast muscle compared to CV and control. All studied microalgae reduced malondialdehyde (MDA) and protein carbonyl (PC) levels, cooking loss, and aerobic plate count (APC) and increased the superoxide dismutase (SOD) activities in breast muscle compared to control. The current study indicated that studied microalgae, notably AC, can be used to enhance performance and meat quality in broilers chickens.

Chemical and Immunological Characterization of Oxidative Nonenzymatic Protein Modifications in Dialysis Fluids

← Background

Glucose degradation products (GDP) in dialysis fluids may induce nonenzymatic protein modifications, the chemical nature and biological properties of which should be better defined.

← Aims

To characterize nonenzymatic protein modifications present in glucose-based peritoneal dialysis fluids (PDF) and to evaluate the relationship between concentrations of GDP and the derived nonenzymatic modifications, and the potential of PDF for generating these modifications in vitro.

← Methods

The presence, distribution, and content of several nonenzymatic protein modifications in PDF were evaluated by immunological methods, by HPLC, and by gas chromatography-mass spectrometry (GC/MS). Peritoneal dialysis fluid-induced oxidative stress in cells was evaluated by flow cytometry. The potential of PDF for generating oxidative and glycoxidative modifications was examined by immunological and cross-linking analyses.

← Results

The albumin present in PDF is modified by carboxymethyllysine (CML). GC/MS analyses of PDF proteins confirmed the presence of CML and demonstrated the occurrence of carboxyethyllysine, malondialdehyde lysine, and oxidation-derived semialdehydes. Furthermore, their concentrations in PDF proteins were significantly higher than those in plasma proteins (in all cases, p < 0.02). The concentration of pyrraline, a non-oxidative advanced glycation end-product, increased with dwell time up to 6 hours ( p < 0.03). The PDF induced cellular free-radical production, which was partially inhibited by the Maillard reaction inhibitor aminoguanidine ( p < 0.001). The potential to generate oxidative and glycoxidative modifications demonstrated an inverse relationship with dwell time ( p < 0.05). The PDF was able to induce collagen cross-linking in a close relationship with GDP concentration.

← Conclusions

( 1 ) PDF contains non-oxidative and several oxidative nonenzymatic protein modifications in higher concentrations than plasma. ( 2 ) Peritoneal dialysis fluid induces oxidative stress in vitro, which can be partially inhibited by aminoguanidine. ( 3 ) These properties are directly related to GDP concentration. ( 4 ) Peritoneal dialysis fluid is able to generate glycoxidative and oxidative damage to proteins in vitro in a dwell-time dependent fashion.

Does Protein Glycation Impact on the Drought-Related Changes in Metabolism and Nutritional Properties of Mature Pea (Pisum sativum L.) Seeds?

Protein glycation is usually referred to as an array of non-enzymatic post-translational modifications formed by reducing sugars and carbonyl products of their degradation. The resulting advanced glycation end products (AGEs) represent a heterogeneous group of covalent adducts, known for their pro-inflammatory effects in mammals, and impacting on pathogenesis of metabolic diseases and ageing. In plants, AGEs are the markers of tissue ageing and response to environmental stressors, the most prominent of which is drought. Although water deficit enhances protein glycation in leaves, its effect on seed glycation profiles is still unknown. Moreover, the effect of drought on biological activities of seed protein in mammalian systems is still unstudied with respect to glycation. Therefore, here we address the effects of a short-term drought on the patterns of seed protein-bound AGEs and accompanying alterations in pro-inflammatory properties of seed protein in the context of seed metabolome dynamics. A short-term drought, simulated as polyethylene glycol-induced osmotic stress and applied at the stage of seed filling, resulted in the dramatic suppression of primary seed metabolism, although the secondary metabolome was minimally affected. This was accompanied with significant suppression of NF-kB activation in human SH-SY5Y neuroblastoma cells after a treatment with protein hydrolyzates, isolated from the mature seeds of drought-treated plants. This effect could not be attributed to formation of known AGEs. Most likely, the prospective anti-inflammatory effect of short-term drought is related to antioxidant effect of unknown secondary metabolite protein adducts, or down-regulation of unknown plant-specific AGEs due to suppression of energy metabolism during seed filling.

Physicochemical Changes and in Vitro Gastric Digestion of Modified Soybean Protein Induced by Lipoxygenase Catalyzed Linoleic Acid Oxidation

Protein oxidation results in structural modification which affects its digestion. The objective of this work was to investigate the influence of lipoxygenases (LOX) catalyzed linoleic acid (LA) oxidation on the structure and in vitro gastric digests of soybean protein isolate (SPI). Fluorescence recovery after photobleaching (FRAP) was used to evaluate the relationship between pepsin diffusion and gastric digestion. Results indicated that oxidation induced carbonyl formation and loss of free sulfhydryl. Increased surface hydrophobicity and zeta-potential verified the protein unfolding and thus resulted in a small particle size and low fluorescence intensity. Fourier transform infrared spectroscopy (FTIR) showed that oxidation caused the increases in β-sheets mostly at the expense of α-helix and random coils. Fluorescein isothiocyanate (FITC)-pepsin in SPI solution modified with 3 mL LA showed a faster diffusion rate with 80.51 μm²/s as well as a higher DH value of 9.11%, showing that pepsin diffusivity might play an important role in protein gastric digestion.

Hydrolysis and oxidation of protein and lipids in dry-salted grass carp (Ctenopharyngodon idella) as affected by partial substitution of NaCl with KCl and amino acids

To obtain healthier meat products with reduced Na content, the salt substitute containing l-histidine and l-lysine was compared with NaCl in the hydrolysis and oxidation of protein and lipids of dry-salted fish during processing. Compared with NaCl-treated fish (S-F), salt substitute treated fish (SS-F) had a lower Na content, higher moisture content and lower hardness. Sensory analysis showed that salt substitute didn't affect the acceptability of salted fish. The free fatty acids of SS-F treated fish had a slight tendency toward lipolysis at the end of processing. Additionally, the conjugated diene value, lipoxygenase activity and malondialdehyde value were lower in the ventral and dorsal muscles for the SS-F treatment. Meanwhile, the protein carbonyls and thiol groups were significantly decreased as cathepsin B and L activities and FAA content were increased in the ventral and dorsal muscles for the SS-F treatment. l-Histidine and l-lysine accelerated the hydrolysis (inhibit the oxidation) of protein and lipids in dry-salted grass carp, illustrating that l-histidine and l-lysine will be a positive approach to develop healthier meat products.

Taurine attenuates Cr(VI)-induced cellular and DNA damage: an in vitro study using human erythrocytes and lymphocytes

Hexavalent chromium [(Cr(VI)] is widely used in several industries, but human exposure results in multiple organ toxicity. Enhanced generation of free radicals and reactive species is thought to play a key role in Cr(VI)-induced toxicity. We have examined the effect of taurine, a simple sulphur-containing amino acid and an antioxidant, on potassium dichromate [K₂Cr₂O₇, a Cr(VI) compound]-induced cytotoxicity and genotoxicity in human blood cells. Erythrocytes were treated with K₂Cr₂O₇, either alone or after incubation with different concentrations of taurine. Treatment of erythrocytes with K₂Cr₂O₇ alone led to marked increase in generation of reactive oxygen and nitrogen species, lipid and protein oxidation. This was accompanied by decrease in total sulfhydryl and glutathione content and lowered antioxidant power of the cells. This suggests that Cr(VI) induces oxidative stress in the cells. Incubation of erythrocytes with taurine prior to addition of K₂Cr₂O₇, resulted in a concentration-dependent decrease in the generation of reactive oxygen and nitrogen species, mitigation of oxidative stress and amelioration of antioxidant power of these cells. It also restored the activities of several metabolic, antioxidant and membrane-bound enzymes. Cr(VI)-induced damage to erythrocyte membrane and lymphocyte DNA was also significantly attenuated by prior administration of taurine. These results suggest that taurine can function as a chemoprotectant against Cr(VI)-induced oxidative injury and can be potentially used to mitigate the toxic effects of this transition metal ion.

Mass Spectrometry Characterization of Thiol Conjugates Linked to Polyoxygenated Polyunsaturated Fatty Acid Species

Radical mediated oxidation of polyunsaturated fatty acids (PUFA) is known to generate a series of polyoxygenated cyclic products (PUFA-O_n, n ≥ 3). Here, we describe the characterization of glutathione (GSH) conjugates bound to polyoxygenated docosahexaenoic (DHA-O_n, n = 3-9), arachidonic (ARA-O_n, n = 3-7), α-linolenic (ALA-O₃), and linoleic (LA-O₃) acid species. Similar conjugates were also characterized for N-acetylcysteine (NAC) and Cu,Zn-superoxide dismutase (SOD1). Extensive LC-MS/MS characterization using a synthetic α-linolenic hydroxy-endoperoxide (ALA-O₃) derivative revealed at least two types of mechanisms leading to thiol adduction: a mechanism involving the nucleophilic attack by thiolate anion on 1,2-dioxolane to form a sulfenate ester-bonded conjugate and a mechanism involving cleavage of the dioxolane to form a α,β-unsaturated carbonyl followed by the Michael addition reaction. Finally, we detected a GSH conjugate with hydroxy-endoperoxide derived from linoleic acid (LA-O₃) in mice liver. In summary, our study reveals the formation of a series of thiol conjugates that are bound to highly oxygenated PUFA species. GSH conjugates described in our study may potentially play relevant roles in redox and inflammatory processes, especially under high oxygen tension conditions.

Copper-induced apoptosis and autophagy through oxidative stress-mediated mitochondrial dysfunction in male germ cells

Excess copper reduces sperm number and motility but the causes are unclear. We investigated the toxic effects of copper exposure on the immortalized male germ cell line GC-1. Copper addition to cells altered viability and morphology in a dose-dependent manner. Copper addition resulted in increased levels of reactive oxygen species (ROS), malonaldehyde (MDA) and lactate dehydrogenase (LDH) while catalase (CAT) activity and glutathione (GSH) declined. The mitochondrial transmembrane potential and ATP levels decreased in response to copper as did mitochondria fission that led to mitochondrial dysfunction. The apoptosis rate was also proportional to the level of copper in the growth medium. Copper also down-regulated Bcl2 and up-regulated Bax, Casp8 and Casp3 linking the effects of copper to increased apoptosis. The levels of mRNA for the autophagy-related genes (Atg3, Atg5, p62, Lc3b/Lc3a) and proteins (Lc3b/Lc3a, BECN1, Atg5, p62) all increased in copper-treated cells as were levels Lc3 determined by fluorescence microscopy. These results indicated that copper induces apoptosis and autophagy through oxidative stress-mediated mitochondrial dysfunction.

Lipoxidation in cardiovascular diseases

Lipids can go through lipid peroxidation, an endogenous chain reaction that consists in the oxidative degradation of lipids leading to the generation of a wide variety of highly reactive carbonyl species (RCS), such as short-chain carbonyl derivatives and oxidized truncated phospholipids. RCS exert a wide range of biological effects due to their ability to interact and covalently bind to nucleophilic groups on other macromolecules, such as nucleic acids, phospholipids, and proteins, forming reversible and/or irreversible modifications and generating the so-called advanced lipoxidation end-products (ALEs). Lipoxidation plays a relevant role in the onset of cardiovascular diseases (CVD), mainly in the atherosclerosis-based diseases in which oxidized lipids and their adducts have been extensively characterized and associated with several processes responsible for the onset and development of atherosclerosis, such as endothelial dysfunction and inflammation. Herein we will review the current knowledge on the sources of lipids that undergo oxidation in the context of cardiovascular diseases, both from the bloodstream and tissues, and the methods for detection, characterization, and quantitation of their oxidative products and protein adducts. Moreover, lipoxidation and ALEs have been associated with many oxidative-based diseases, including CVD, not only as potential biomarkers but also as therapeutic targets. Indeed, several therapeutic strategies, acting at different levels of the ALEs cascade, have been proposed, essentially blocking ALEs formation, but also their catabolism or the resulting biological responses they induce. However, a deeper understanding of the mechanisms of formation and targets of ALEs could expand the available therapeutic strategies.

Matrix-mediated distribution of 4-hydroxy-2-hexanal (nonenal) during deep-frying of chicken breast and potato sticks in vegetable oil

The distribution of HHE/HNE was mediated in different food matrices, namely, starch-based and protein-based foods, during deep-frying of vegetable oils.