Reduced Protein Oxidation Research Articles

P099 EXERCISE TRAINING FURTHER ATTENUATES BLOOD PRESSURE VARIABILITY AND RENAL DAMAGE IN HYDROCHLOROTHIAZIDE TREATED-HYPERTENSIVE AND POSTMENOPAUSAL RATS

Background and Objective: Considering that blood pressure variability (BPV) has been associated with damage to target organs such as the kidney, this study aimed to investigate the effects of hydrochlorothiazide (HCTZ) combined with exercise training (CET) on BPV, as well as renal tissue morphology, function, inflammation, and oxidative stress. Methods: Female spontaneously hypertensive rats (SHR) were divided into 4 ovariectomized groups (n=5-6/group): sedentary (OS), sedentary + HCTZ (OSH), trained (OT), and trained + HCTZ (OTH). Both HCTZ (3 mg/kg) and CET (3 days/week) were administered for 8 weeks. Blood pressure was directly recorded for BPV analysis. Results: Renal function, morphology, inflammation and oxidative stress were assessed. The OSH, OT, and OTH groups had lower systolic BP (OSH: 189±13; OT: 179±5; OTH: 174±15 mmHg) compared to the OS group (208±15 mmHg). Only the combination of the drug with CET promoted a reduction in BPV variance. The HCTZ-treated groups showed lower plasma creatinine levels and increased creatinine clearance compared to the OS group. Treated groups showed a reduction in fields of 51–100% of interstitial tubule fibrosis when compared to the OS group; and the OTH group also showed reduction in fields in the range of 26–50% vs. other groups. The HCTZ-treated groups showed a reduction in protein oxidation. Renal catalase and IL10/TNF-alpha ratio were increased in the OTH group. Positive correlations were obtained between SBP variance and SBP (r=0.72), plasma creatinine (r=0.58), and levels of TNF-α (r=0.69), hydrogen peroxide (r=0.61), and protein oxidation (r=0.66) in renal tissue. Conclusions: Our results highlight the enhanced efficacy of the combination of HCTZ and CET compared to the use of either drug alone in the model studied. This combination effectively reduced BPV, resulting in beneficial changes in renal inflammatory and redox profiles, inducing morphological and functional benefits in hypertensive ovariectomized rats. Financial support: FAPESP (2022/04050-1), CNPq, CAPES-PROSUP, UNINOVE.

Arabinoxylan from pearl millet bran: Optimized extraction, structural characterization, and its bioactivities

Arabinoxylan (AX) from cereals and millets have garnered attention due to the myriad of their bioactivities. Pearl millet (Pennisetum glaucum) bran, an underexplored milling by-product was used to extract AX (PMAX) by optimized alkali-assisted extraction using Response Surface Methodology and Central Composite Design, achieving a yield of 15.96 ± 0.39 % (w/w) under optimal conditions (0.57 M NaOH, 1:17 g/mL solid-to-liquid ratio, 60 °C, 4 h). Structural analysis revealed that PMAX was primarily composed of arabinose, xylose, glucose, galactose, and mannose (molar ratio 45.1:36.1:10.4:7.1:1.8), with a highly substituted (1 → 4)-linked β-D-xylopyranose backbone and a molecular weight of 794.88 kDa. PMAX displayed a significant reducing power of 0.617, metal chelating activity of 51.72 %, and DPPH, and ABTS radical scavenging activities (64.43 and 75.4 %, respectively at 5 mg/mL). It also demonstrated anti-glycation effects by inhibiting fructosamine (52.5 %), protein carbonyl (53.6 %), and total advanced glycation end products (77.0 %) formation, and reduced protein oxidation products such as dityrosine (84.7 %), kynurenine (80.2 %), and N′-formyl-kynurenine (50.0 %) at 5 mg/mL. PMAX induced the growth of Lactobacillus spp. in vitro and modulate gut microbiota in male Wistar rats by increasing Bacteroidetes and decreasing Firmicutes. These results provide a basis for further research on pearl millet arabinoxylan and its possible nutraceutical application.

Exploring the therapeutic potential of plasma from intermittent fasting and untreated rats on aging-induced liver damage.

This research aims to investigate the effects of plasma from 12-month-old intermittently fasting rats (IFpls) and untreated rats (Npls) on the liver biomolecules and histological changes in 24-month-old male Sprague-Dawley rats. Fasting rats underwent an 18-h daily fasting period and a 6-h feeding window for 35 days. The plasma was administered bi-daily, and blood samples were examined for specific liver biomolecules. Fourier transform infrared (FTIR) spectroscopy and linear discriminant analysis (LDA) was used to identify molecular profiles. Liver sections were stained for histopathological evaluation, and the expression levels of Notch signalling pathway components were assessed. Distinct molecular profiles were identified across liver biomolecules, lipids, proteins and nucleic acids with high accuracy. Notably, IFpls was found to protect against hepatic instability, microvesicular steatosis and liver fibrosis by decreasing lymphatic infiltration density and Notch pathway expression levels. Both treatments reduced protein oxidation and carbonylation, with Npls showing a pronounced decrease in protein oxidation. Furthermore, Npls increased protein conformation and glycogen/phosphate content, while IFpls increased glucose/protein content. Both IFpls and Npls induce substantial and unique alterations in liver biomolecules. IFpls offers a protective effect on various liver conditions, while Npls exhibits promising results in reducing protein oxidation and altering biomolecule content. These findings offer valuable insights for future research and potential therapeutic approaches.

Characterization of the Effects of Low-Sodium Salt Substitution on Sensory Quality, Protein Oxidation, and Hydrolysis of Air-Dried Chicken Meat and Its Molecular Mechanisms Based on Tandem Mass Tagging-Labeled Quantitative Proteomics.

The effects of low-sodium salt mixture substitution on the sensory quality, protein oxidation, and hydrolysis of air-dried chicken and its molecular mechanisms were investigated based on tandem mass tagging (TMT) quantitative proteomics. The composite salt formulated with 1.6% KCl, 0.8% MgCl2, and 5.6% NaCl was found to improve the freshness and texture quality scores. Low-sodium salt mixture substitution significantly decreased the carbonyl content (1.52 nmol/mg), surface hydrophobicity (102.58 μg), and dimeric tyrosine content (2.69 A.U.), and significantly increased the sulfhydryl content (74.46 nmol/mg) and tryptophan fluorescence intensity, suggesting that protein oxidation was inhibited. Furthermore, low-sodium salt mixture substitution significantly increased the protein hydrolysis index (0.067), and cathepsin B and L activities (102.13 U/g and 349.25 U/g), suggesting that protein hydrolysis was facilitated. The correlation results showed that changes in the degree of protein hydrolysis and protein oxidation were closely related to sensory quality. TMT quantitative proteomics indicated that the degradation of myosin and titin as well as changes in the activities of the enzymes, CNDP2, DPP7, ABHD12B, FADH2A, and AASS, were responsible for the changes in the taste quality. In addition, CNDP2, ALDH1A1, and NMNAT1 are key enzymes that reduce protein oxidation. Overall, KCl and MgCl2 composite salt substitution is an effective method for producing low-sodium air-dried chicken.

Inhibiting post-harvest perishability of edible beetle grubs (Oryctes spp) by blanching and pre-treatment with sodium metabisulphite and ascorbic acid

Although edible beetle grubs (Oryctes spp) are highly nutritious, post-harvest perishability limits their utilization in food processing. This study investigated the effects of blanching singly or in combination with either ascorbic acid or sodium metabisulphite or a blend of the two chemicals, on colour, microbial quality, protein quality, total phenol content and amino acid composition of the grubs after harvest. All the pretreatments effectively preserved the colour of the grubs, reduced protein oxidation and inhibited most harmful microbes to food safety limits. The treatments had insignificant effect on amino acid profiles of the larvae. Combining blanching with ascorbic acid eliminated Staphylococcus aureus from the larvae and outperformed the other treatments in enhancing the content of total phenols. The findings provide prospects for preservation of the edible beetle grubs using the affordable, readily available, and easy-to-apply heat and chemical pretreatments prior to processing into other palatable food products.

Targeted screening of baicalein inhibitor with controlling lipid and protein oxidation for quality preservation of grass carp fillets

In this study, targeted screening of candidate polyphenols was conducted by docking methods and inhibition assay. Baicalein (BCL) was identified as the target polyphenol, with IC50 value and docking score of 27.16 μmol/L and −7 kcal/mol, respectively. During the chilled storage of grass carp fillets at 4 °C, baicalein has been shown to reduce the degree of lipid oxidation by inhibiting the activity of lipase and lipoxygenase effectively and enhancing the activity of antioxidant enzymes, which is manifested by a decrease in thiobarbituric acid values and peroxide value. Baicalein has also been proved to have the ability to reduce protein oxidation by decreasing carbonyl content and sulfhydryl content of grass carp protein. Furthermore, baicalein can significantly eliminate the degree of protein hydrolysis of grass carp fillets by regulating the activity of cathepsin B and cathepsin L. The results suggest that baicalein expects to become a potential natural fresh-keeping agent for aquatic product industry and provides some new insights into understanding of the mechanism of fish quality preservation.

Effect of plasma-activated organic acids against Salmonella Typhimurium and Escherichia coli O157:H7 inoculated on pork loin and its quality characteristics

This study investigated the effectiveness of plasma-activated organic acid (PAOA) on pork loin's bactericidal impact and quality. Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes were used to inoculate the pork loins, revealing that PAOA achieved approximately 1.0 log CUF/g greater reduction than plasma-activated water. This was attributed to PAOA's lower pH, elevated oxidation-reduction potential, and increased reactive oxygen species concentrations. Notably, 0.5% plasma-activated acetic acid (PAA) showed 1.5 and 0.6 log CFU/g higher synergistic bactericidal effect against S. Typhimurium and E. coli O157:H7, respectively, compared to acetic acid. PAA also outperformed other PAOA treatments in terms of pork quality with similar meat color to deionized water, no adverse effect on lipid oxidation, and significantly reduced protein oxidation. Sensory analysis revealed PAA's highest umami taste. Thus, PAA is a promising method for microbial control in the meat industry while enhancing the oxidative stability and umami taste of pork loin. Industrial relevanceThis study demonstrated the industrial potential of combining plasma and organic acid treatments to control microorganisms in meat production and processing, while improving storage quality and sensory attributes. By using plasma- activated acetic acid, the oxidative stability of meat was enhanced during storage and umami taste was improved. This innovative technology offers advantages such as ease of operation and large-scale production, and it may help to overcome consumer concerns regarding the overuse of chlorine-based disinfectants, as organic acids are commonly used food additives.

Stress response of European seabass (Dicentrarchus labrax) fed plant-based diets supplemented with swine blood hydrolysates

To improve fish welfare, it is essential that aquafeeds are designed to help fish cope with the stressful conditions of fish farms. One effective strategy to achieve this goal is to supplement the diet with bioactive hydrolysates. Here, diet supplementation to modulate oxidative stress after air exposure was investigated in European seabass, using swine blood hydrolysates (BH), obtained either by autohydrolysis (AH) or enzymatically. The enzymatically produced BH were further submitted to a micro- (RMF) and nanofiltration (RNF). Four isolipidic, isoproteic and isoenergetic diets were developed: a plant-based diet with low (12.5%) fishmeal levels (control, CTRL) and three diets where 3% of each BH (RMF, RNF and AH) was added to the CTRL. Diets were assigned to triplicate groups of 71 European seabass juveniles (initial weight 12.3 ± 1.4 g). After 12 weeks, 9 fish per treatment were either immediately sampled or air-exposed for 1 min and let to recover in a new system for 6 h prior to sampling. Stress response increased cortisol levels, followed by an increment in plasma lactate. The challenge increased liver lipid peroxidation (LPO) due to reactive oxygen species (ROS) accumulation. Carbonyls decreased post-stress, maybe due to a possible interaction with the LPO radicals, reducing protein oxidation. None of the BH improved plasma stress response. By reducing catalase levels without increasing LPO, the RNF treatment appears to adjust European seabass' antioxidant defences, indicating its potential to supply exogenous antioxidants to combat oxidative stress induced by ROS. However, this impact was not sufficient to lower LPO levels compared to a control plant-based diet. The tested diets seemed to affect the fish oxidative stress response in the liver, possibly due to the presence of bioactive peptides, which aided in the non-enzymatic modulation of stress response, as observed by the total antioxidant capacity values in the liver.

Effect of lentinan on gelling properties and structural changes of goose myofibrillar protein under oxidative stress.

The reduction of protein oxidation is important for maintaining the product quality of reconstituted meat. In this study, the dose-dependent effects of lentinan (LNT) on gelling properties and chemical changes in oxidatively stressed goose myofibrillar protein were investigated. Myofibrillar protein (MP) with 200 μmol g-1 protein LNT increased gel strength by 87.90 ± 9.26% in comparison with LNT-free myofibrillar protein after oxidation. Scanning electron microscopy analysis revealed that the gel network containing LNT was compact, with small pores and uniform distribution. The absolute value of the zeta potential reduced significantly following oxidation of LNT with 200 μmol g-1 protein at 4 °C for 12 h compared with the zeta potential without LNT, according to the laser particle size analyzer. The incorporation of LNT increased protein solubility and -SH content, inhibited carbonyl formation, enhanced α-helix content and tryptophan intrinsic fluorescence intensity, and reduced exposure of hydrophobic groups and protein aggregation. The results indicated that adding LNT to myofibrillar protein could improve gel. This is related to its protective effect on conformational changes in the oxidation system. Lentinan is therefore recommended for oxidatively stressed goose meat processing to enhance the MP gelling potential. © 2023 Society of Chemical Industry.

Effects of kojic acid on changes in the microstructure and myofibrillar protein of duck meat during superchilled storage.

This study investigated the effect of 0.8% (m/v) kojic acid treatment on changes in the microstructure and myofibrillar protein of duck meat covered with oxygen-permeable polyvinylchloride (PVC) film (9±0.5µM) during superchilled storage (-1.65±0.5°C). The superchilled samples exhibited wider gaps between muscle fibers at 5 weeks storage compared with kojic acid-treated groups. Based on the variation of water status, the water-holding capacity decreased significantly (p<0.05), and bound water and immobilized water were gradually converted into free water during superchilled storage. For kojic acid-treated samples, however, no major changes were observed with respect to muscle structure, water status, and protein degradation at 6 weeks. The 0.8% (m/v) kojic acid treatment increased the water-holding capacity, reduced carbonyl content and protein degradation, and decreased the α-helix contents loss of myofibrillar proteins. Kojic acid treatment effectively protected myofibrillar protein structure from being destroyed during superchilled storage, suggesting that this method was a good way to reduce protein oxidation and prolonged its shelf life.

Mitoquinone mesylate attenuates pathological features of lean and obese allergic asthma in mice.

Obesity is associated with severe, difficult-to-control asthma, and increased airway oxidative stress. Mitochondrial reactive oxygen species (mROS) are an important source of oxidative stress in asthma, leading us to hypothesize that targeting mROS in obese allergic asthma might be an effective treatment. Using a mouse model of house dust mite (HDM)-induced allergic airway disease in mice fed a low- (LFD) or high-fat diet (HFD), and the mitochondrial antioxidant MitoQuinone (MitoQ), we investigated the effects of obesity and ROS on HDM-induced airway inflammation, remodeling, and airway hyperresponsiveness (AHR). Obese allergic mice showed increased lung tissue eotaxin, airway tissue eosinophilia, and AHR compared with lean allergic mice. MitoQ reduced airway inflammation, remodeling, and hyperreactivity in both lean and obese allergic mice, and tissue eosinophilia in obese-allergic mice. Similar effects were observed with decyl triphosphonium (dTPP+), the hydrophobic cationic moiety of MitoQ lacking ubiquinone. HDM-induced oxidative sulfenylation of proteins was increased particularly in HFD mice. Although only MitoQ reduced sulfenylation of proteins involved in protein folding in the endoplasmic reticulum (ER), ER stress was attenuated by both MitoQ and dTPP+ suggesting the anti-allergic effects of MitoQ are mediated in part by effects of its hydrophobic dTPP+ moiety reducing ER stress. In summary, oxidative signaling is an important mediator of allergic airway disease. MitoQ, likely through reducing protein oxidation and affecting the UPR pathway, might be effective for the treatment of asthma and specific features of obese asthma.

Effects of tetrasodium pyrophosphate coupled with soy protein isolate on the emulsion gel properties of oxidative myofibrillar protein

The effects of protein oxidation on the emulsion gel properties of myofibrillar protein (MP) in the presence of tetrasodium pyrophosphate (TSPP) and soybean protein isolate (SPI) were investigated from the perspective of interfacial protein interactions. The results showed that the emulsifying activity and emulsion stability of MP increased by 35.2 %–181.6 % with elevated H2O2 concentrations (1–20 mM), while the gel strength and water holding capacity of MP emulsions first increased to a maximum at 5 mM H2O2 and then decreased. TSPP and SPI further reinforced the effects caused by oxidation. The emulsifying properties of MP and its emulsion gel properties were closely related to surface hydrophobicity/hydrogen bonds/hydrophobic interactions and disulfide bonds among interfacial proteins, respectively. However, these correlations became difficult to define when TSPP and SPI were introduced. The study provides a theoretical basis for the strategy development to reduce protein oxidation damage on meat product quality.

Effect of different postmortem ageing conditions on physicochemical properties, structure and water‐holding capacity of pork

SummaryThis study aimed to determine the effects of postmortem ageing temperatures on protein–water interactions and muscle water‐holding capacity (WHC) of pork. The oxidation degree, solubility and secondary structure of myofibrillar protein (MP) were also studied. Porcine longissimus lumborum muscles were aged at −6 ± 1, 4 ± 1, and 10 ± 1°C for 3, 12, 24, 72, 120 and 168 h, respectively. The results showed the lower ageing temperature is conducive to decrease the protein oxidation and the transformation of protein conformation from ordered structures (α‐helices and β‐sheets) to disordered structures (β‐turns and random coils). These physicochemical changes favoured protein–water interactions, thus the muscle samples aged at −6 ± 1°C for 120 h had the highest protein solubility and WHC. This work revealed that ageing at sub‐freezing temperature (−6 ± 1°C) is beneficial to reduce protein oxidation and improve muscle water‐holding capacity.

Evaluation of the Efficacy and Safety of Blue Fenugreek Kale Extract on Skin Health and Aging: In-vitro and Clinical Evidences.

BackgroundThe skin is primarily affected by aging, especially when it is exposed to particulate matter present in the environment. It has been hypothesized that consumption of products with known antioxidant properties would help combat factors associated with both intrinsic and extrinsic aging factors.ObjectiveThe aim of the present study was to evaluate the effect of the formulation Blue Fenugreek Kale Extract (BFKE) on skin aging.MethodsIn this study, the effect of BFKE on protein oxidation was determined in human dermal fibroblasts by analysis of the level of protein carbonylation after cells were stressed with either H2O2 or urban pollution consisting of particulate matter and UV-A. Furthermore, a randomized, double-blind, placebo-controlled clinical study that evaluated the effect of BFKE consumption over a period of 56 days in 59 volunteers was performed. The major parameter studied was skin barrier dysfunction through the assessment of Transepidermal Water Loss (TEWL). Additional parameters analyzed clinically include skin moisture content, participant self-assessment of skin parameters, wrinkle severity, skin sagging and elasticity. Furthermore, low grade and allergic inflammatory biomarker levels were measured at the start and end of the treatment period, along with oxidative stress assessment using blood malondialdehyde levels.ResultsBFKE significantly reduced protein carbonylation in human dermal fibroblasts stressed with urban pollution. In the clinical study, the TEWL level reduced significantly and at the same time the skin moisture content levels increased by end of the treatment period. No significant changes were observed in wrinkle severity, skin sagging, elasticity, inflammatory and oxidative stress biomarker levels. Participant and investigator perception of treatment was significantly greater after product consumption, as was the improvement in skin parameters based on participant self-assessment.ConclusionBFKE reduces protein oxidation induced by H2O2 and restores skin barrier function and skin hydration, while also combating early signs of aging.

Utilization of fermented and enzymatically hydrolyzed soy press cake as ingredient for meat analogues

The aim of the present study was to improve the properties of soy press cake to be utilized as an ingredient of meat analogues. Soy press cakes were fermented with lactobacillus strains, and separately hydrolyzed by cellulase/xylanase mixture and α-amylase. Meat analogues were produced with 10% fermented or hydrolyzed soy press cakes. The effect of applied processes on protein oxidation, physical and functional properties of soy press cakes were analyzed, as well as sensory and textural properties of meat analogues. The results indicated that soy press cake was a suitable source of fibre and energy with low content of saturated fatty acids, and provided plant-based proteins and essential amino acids. The study demonstrated the potential of lactic acid fermentation, and enzymatic hydrolysis to improve water- and oil-holding capacity and reduce protein oxidation in soy press cakes. L. acidophilus 336 and cellulase/xylanase mixture were recommended for fermentation and hydrolysis of soy press cakes, respectively, regarding reduction of protein oxidation. Fermentation of soy press cakes with L. plantarum P1 improved the texture of meat analogues. Press cakes fermentation reduced bitterness, increased juiciness, and balanced the taste of meat analogues. Fermented soy press cake was recommended for the production of meat analogues.

Promising Efficacy of Nanocurcumin in Comparison to Curcumin Against Nicotine-induced Complications

Long-term exposure to nicotine severely affects the immune system. Nicotine-addicted women suffer more to diseases because of their history to several disorders or susceptibility to nicotine-related morbidity and mortality. The beneficial uses of nano-curcumin in nicotine-addicted women are still unknown, possibly due to its poor pharmacokinetics and limited bioavailability. Nanocurcumin is administered to study the immune-protective effects in nicotine exposed female rats. Female albino rats of Wistar strain (Rattus norvegicus) are nicotine injected (2.5 mg/kg bodyweights s.c., daily) for 21 days. Three hours later nanocurcumin is administered by oral gavages (4 mg/kg bodyweights/day). The dose and period of nanocurcumin is adopted from our earlier publications elsewhere. Animals are eradicated after the treatment period and immune-related cytokines, apoptotic markers, sex hormones and other parameters are measured from individual serum. Molecular docking, as well as, in vitro interactions of nanocurcumin with nicotine and some specific cellular proteins are measured for understanding the mechanism of action of nanocurcumin. Nanocurcumin reduced protein oxidation, augmented the immune system by regulating the expression of immunity-related cytokines and apoptotic markers. It helps maintaining the healthy levels of sex hormones and protein content of cells under nicotine-stressed condition. Molecular docking and in vitro interactions reveal that nanocurcumin possesses higher binding ability to nicotine and several cellular proteins. Cytokines, apoptotic markers and steroidogenic hormones are severely affected by nicotine exposure. Bio-soluble nanocurcumin acts as significant immune-modulator, which offers better protection than curcumin to female rats from nicotine-induced complications. Heightened therapeutic effects of nanocurcumin are discussed.

PILATES METHOD IMPROVES PHYSICAL CAPACITY AND ANTI-OXIDATIVE SYSTEM IN ELDERLY WOMEN

Objective: The decline in physical capacity in humans occurs as a consequence of ageing. It is well established that oxidative mechanisms play a role in ageing process, leading to oxidative accumulation in tissue damage. Regular physical exercise can minimize the physiological changes that occur during aging and also contribute to improving the individual’s health and well-being. The aim of the present study is to verify the effects of resistance physical training on oxidative damage and physical capacity in elderly women who practice Pilates (P) or Strength Training (ST). Design and method: Elderly volunteer were evaluated and divided into P (68 ± 4 years age) or ST (66 ± 3 years age) groups (n = 20 per group), according to individual choice for the modality. The training protocol (moderate intensity) lasted 12 weeks, with 2 sessions of 60 minutes per week. All volunteers underwent dual-energy x-ray absorptiometry (DXA) and handgrip strength (HGS) for physical and functional assessment. Blood sample was collected for the analysis of oxidative stress markers (TBARS, Carbonilated proteins, NOX and SOD activities and Frap). Results: The results show that resistance exercises in P and ST modalities are effective in inducing changes in physical composition (body weight, fat percentage and bone density did not change). On the other hand, ST was effective in reducing fat mass in upper and lower limbs and increasing HGS (+40%), while P increased lean mass in limbs and trunk. Pilates method was more efficient in increasing muscle mass throughout the body, while strength training was more efficient in allowing fat loss. Finally, Pilates method was effective in increasing SOD activity (+20%), reducing protein oxidation (17%). On the other hand, strength training implemented an increase in the antioxidant system at the end of the ROS production cascade, which seems not to have been effective in reducing lipid oxidation (Frap increased 37%, while TBARS and NOX maintained 50% and 30% higher compared to Pilates, respectively). Conclusions: The results allow us to conclude that Pilates method, for a period of 12 weeks, is effective in bringing anti-oxidative capacity and in the quality of life of sedentary elderly women.

Hydrogen sulfide manages hexavalent chromium toxicity in wheat and rice seedlings: The role of sulfur assimilation and ascorbate-glutathione cycle

The role of hydrogen sulfide (H2S) is well known in the regulation of abiotic stress such as toxic heavy metal. However, mechanism(s) lying behind this amelioration are still poorly known. Consequently, the present study was focused on the regulation/mitigation of hexavalent chromium (Cr(VI) toxicity by the application of H2S in wheat and rice seedlings. Cr(VI) induced accumulation of reactive oxygen species and caused protein oxidation which negatively affect the plant growth in both the cereal crops. We noticed that Cr(VI) toxicity reduced length of wheat and rice seedlings by 21% and 19%, respectively. These reductions in length of both the cereal crops were positively related with the down-regulation in the ascorbate-glutathione cycle, and were recovered by the application NaHS (a donor of H2S). Though exposure of Cr(VI) slightly stimulated sulfur assimilation but addition of H2S further caused enhancement in sulfur assimilation, suggesting its role in the H2S-mediated Cr(VI) stress tolerance in studied cereal crops. Overall, the results revealed that H2S renders Cr(VI) stress tolerance in wheat and rice seedlings by stimulating sulfur assimilation and ascorbate-glutathione which collectively reduce protein oxidation and thus, improved growth was observed.

Effects of freeze-thaw cycles of Pacific white shrimp (Litopenaeus vannamei) subjected to radio frequency tempering on melanosis and quality

This study was conducted to investigate the effects of different tempering methods and freeze-thaw cycles on melanosis and quality parameters of pacific white shrimp. Frozen pacific white shrimps tempered with radio frequency tempering (RFT) were compared to that in water tempering (WT) and refrigerator tempering (RT) in terms of temper loss, total volatile base nitrogen (TVBN), polyphenol oxidase (PPO) activity, melanosis, total sulfhydryl contents, differential scanning calorimetry (DSC), and texture properties after 0, 1, 3, 5 freeze-thaw cycles. Results showed that crushed ice was effective as an effective surrounding medium for six layers of frozen shrimp reaching −2 °C within 6 min in RFT. For quality attributes, the temper loss of samples tempered with radio frequency is lower than that of RT and WT after all freeze-thaw cycles, and RFT resulted in the lowest TVBN value (9.17 mgN/100 g) of shrimps after the 5th freeze-thaw cycle. The PPO activity and melanosis of samples increased as the number of freeze-thaw cycles increased, and RFT effectively inhibited the development of melanosis. After the 3rd freeze-thaw cycle, the enthalpy change (△H) and the sulfhydryl content (0.16 mmol/gprot) of radio frequency tempered samples was significantly higher (p < 0.05) than that of WT and RT. RFT retained the hardness and chewiness of shrimp samples in all freeze-thaw cycles. Therefore, RFT effectively inhibited melanosis and reduce protein oxidation in Pacific white shrimp during freeze-thaw cycles with its fast and uniform heating characteristics.

Effects of low voltage electrostatic field on the microstructural damage and protein structural changes in prepared beef steak during the freezing process

AbstractThis study investigated the effect of low voltage electrostatic field (LVEF) on the microstructure damage and protein structure changes of prepared beef steak during freezing. The scanning electron microscopy results showed that LVEF-assisted freezing (LVEFF) minimized the gaps in the cross section between muscle fibers induced by freezing and thus improved fiber compactness. Furthermore, LVEFF reduced the length of the enlarged sarcomere, repaired the Z-line fractures, and intensified the dismission of the A band in the air-blast freezing (AF) process. The decreased carbonyl content and increased total sulfhydryl content indicated that LVEFF reduced protein oxidation in the freezing process. In addition, the results of Raman spectroscopy and fluorescence spectroscopy revealed that LVEFF minimized the changes in protein secondary and tertiary structures during freezing. In conclusion, utilization of LVEF in the freezing of prepared beef steak could reduce both the microstructure damage and protein structure changes in the freezing process.