Antioxidant mechanism of potato protein hydrolysates against in vitro oxidation of reduced glutathione

The Role of Life Stages in the Sensitivity of Hediste diversicolor to Nanoplastics: A Case Study with Poly(Methyl)Methacrylate (PMMA)

The presence of plastic particles in oceans has been recognized as a major environmental concern. The decrease in particle size increases their ability to directly interact with biota, with particles in the nanometer size range (nanoplastics-NPs) displaying a higher ability to penetrate biological membranes, which increases with the decrease in particle size. This study aimed to evaluate the role of life stages in the effects of poly(methyl)methacrylate (PMMA) NPs on the polychaete Hediste diversicolor, a key species in the marine food web and nutrient cycle. Thus, behavioral (burrowing activity in clean and spiked sediment) and biochemical endpoints (neurotransmission, energy reserves, antioxidant defenses, and oxidative damage) were assessed in juvenile and adult organisms after 10 days of exposure to spiked sediment (between 0.5 and 128 mg PMMA NPs/Kg sediment). Overall, the results show that H. diversicolor is sensitive to the presence of PMMA NPs. In juveniles, exposed organisms took longer to burrow in sediment, with significant differences from the controls being observed at all tested concentrations when the test was performed with clean sediment, whereas in PMMA NP-spiked sediment, effects were only found at the concentrations 8, 32, and 128 mg PMMA NPs/Kg sediment. Adults displayed lower sensitivity, with differences to controls being found, for both sediment types, at 8, 32, and 128 mg PMMA NPs/Kg sediment. In terms of Acetylcholinesterase, used as a marker of effects on neurotransmission, juveniles and adults displayed opposite trends, with exposed juveniles displaying increased activity (suggesting apoptosis), whereas in adults, overall decreased activity was found. Energy-related parameters revealed a generally similar pattern (increase in exposed organisms) and higher sensitivity in juveniles (significant effects even at the lower concentrations). NPs also demonstrated the ability to increase antioxidant defenses (higher in juveniles), with oxidative damage only being found in terms of protein carbonylation (all tested NPs conditions) in juveniles. Overall, the data reveal the potential of PMMA NPs to affect behavior and induce toxic effects in H. diversicolor, with greater effects in juveniles.

Effects of polymethylmethacrylate nanoplastics on the polychaete Hediste diversicolor: Behavioural, regenerative, and biochemical responses

Plastics, particularly microplastics (MPs) and nanoplastics (NPs), have been regarded as pollutants of emerging concern due to their effects on organisms and ecosystems, especially considering marine environments. However, in terms of NPs, there is still a knowledge gap regarding the effects of size and polymer on marine invertebrates, such as benthic organisms. Therefore, this study aimed to understand, regarding behavioural, physiological, and biochemical endpoints (neurotransmission, energy metabolism, antioxidant status, and oxidative damage), the effects of 50 nm waterborne polymethylmethacrylate (PMMA) NPs (0.5 to 500 µg/L) on the marine benthic polychaete Hediste diversicolor, a key species in estuarine and coastal ecosystems. Results demonstrated that worms exposed to PMMA NPs had a shorter burrowing time than control organisms. Nevertheless, worms exposed to PMMA NPs (0.5 and 500 µg/L) decreased cholinesterase activity. Energy metabolism was decreased at 50 and 500 µg/L, and glycogen content decreased at all concentrations of PMMA NPs. Enzymes related to the antioxidant defence system (superoxide dismutase and glutathione peroxidase) displayed increased activities in H. diversicolor specimens exposed to concentrations between 0.5 and 500 µg/L, which led to no damage at the cell membrane and protein levels. In this study, polychaetes also displayed a lower regenerative capacity when exposed to PMMA NPs. Overall, the data obtained in this study emphasize the potential consequences of PMMA NPs to benthic worms, particularly between 0.5 and 50 µg/L, with polychaetes exposed to 50 µg/L being the most impacted by the analysed NPs. However, since sediments are considered to be sinks and sources of plastics, further studies are needed to better understand the impacts of different sizes and polymers on marine organisms, particularly benthic species.

In vitro screening of imidazolium and pyrrolidinium based ionic liquids toxicity on subcellular fractions of the Mediterranean mussel Mytilus galloprovincialis

Ionic liquids (ILs) have been considered eco-friendly alternatives to conventional organic solvents. However, several studies have reported that ILs exert toxicity towards aquatic invertebrates. Applying in vitro methodology, the aim of the present study was to evaluate the potential effect of three ILs on the biochemical performance of exposed Mytilus galloprovincialis digestive gland and gills cellular fractions. Carboxylesterase might be involved in the derived toxicity mechanism of ILs as activity levels increased significantly in digestive gland exposed fractions. This group of ILs did not seem to induce genotoxicity, except in gills cellular fractions exposed to 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. In the literature, in vitro methodology has been suggested as an important complement to animal testing and in silico studies. The present research underlines its efficacy as a quick pre-screening before in vivo testing, particularly with heterogenic groups of substances with high variability in composition, such as ILs and deep eutectic solvents.

Antioxidant Properties and Prediction of Bioactive Peptides Produced from Flixweed (sophia, Descurainis sophia L.) and Camelina (Camelina sativa (L.) Crantz) Seed Meal: Integrated In Vitro and In Silico Studies

Flixweed (sophia) seed meal and camelina, both by-products of oil processing, were employed to generate protein hydrolysates by applying Flavourzyme and Alcalase. This study aimed to integrate in vitro and in silico methods to analyze sophia and camelina protein hydrolysates for releasing potent antioxidative, dipeptidyl peptidase IV (DPP IV) inhibitors and angiotensin-converting enzyme (ACE) inhibitory peptides. In vitro methods were used to investigate the antioxidant potential of sophia/camelina protein hydrolysates. Bioinformatics techniques, including Peptideranker, BIOPEP, Toxinpred, AlgPred, and SwissADME, were employed to obtain the identification of bioactive peptides produced during the hydrolysis process. Protein hydrolysates produced from sophia and camelina seed meal exhibited higher ABTS and DPPH radical scavenging activities Ithan their protein isolates. Among the produced protein hydrolysates, Alcalase-treated samples showed the highest oxygen radical absorbance capacity and hydroxyl radical scavenging activity. In addition, sophia/camelina hydrolysates prevented hydroxyl and peroxyl radical-induced DNA scission and LDL cholesterol oxidation. In silico proteolysis was conducted on Alcalase-treated samples, and resultant peptides showed potential DPP IV and ACE-inhibitory activities. Identified peptides were further assessed for their toxicity and medicinal properties. Results indicate that all digestive-resistant peptides were non-toxic and had desirable drug-like properties. The findings of this study suggest that sophia/camelina protein hydrolysates are promising candidates for functional foods, nutraceuticals, and natural therapeutics.

Exogenous glutathione maintains the postharvest quality of mango fruit by modulating the ascorbate-glutathione cycle

Background

Mango fruit is prone to decay after harvest and premature senescence, which significantly lowers its quality and commercial value.

Methods

The mango fruit (Mangifera indica L.cv. Guixiang) was treated with 0 (control), 2, 5, and 8 mM of reduced glutathione (GSH) after harvest. The fruit was stored at 25 ± 1 °C for 12 days to observe the changes in the antioxidant capacity and postharvest quality.

Results

Compared with the control, the 5 mM GSH treatment significantly decreased the weight loss by 44.0% and 24.4%, total soluble solids content by 25.1% and 4.5%, and soluble sugar content by 19.0% and 27.0%. Conversely, the 5 mM GSH treatment increased the firmness by 25.9% and 30.7% on days 4 and 8, respectively, and the titratable acidity content by 115.1% on day 8. Additionally, the 5 mM GSH treatment decreased the malondialdehyde and hydrogen peroxide contents and improved the antioxidant capacity of mango fruit by increasing the superoxide dismutase and peroxidase activities and upregulating the expression of the encoding genes. Meanwhile, the higher levels of monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase enzyme activities and gene expressions accelerated the AsA-GSH cycle, thereby increasing the accumulation of AsA and GSH and maintaining the redox balance.

Conclusions

Overall, the experimental results suggest that 5 mM GSH maintains high antioxidant capacity and postharvest quality of mangoes and can use as an effective preservation technique for postharvest mangoes.

Antioxidant and ACE-Inhibitory Activity of Protein Hydrolysates Produced from Atlantic Sea Cucumber (Cucumaria frondosa)

Atlantic sea cucumber is a benthic marine echinoderm found in Northwest Atlantic waters and is harvested mainly for its body wall. The body wall, along with internal organs and aquaphyrangeal bulb/flower, is a rich source of proteins, where the latter parts are often considered as processing discards. The objective of this research was to produce protein hydrolysates from sea cucumber tissues (body wall, flower, and internal organs) with bioactive properties associated with antioxidants, DNA and LDL cholesterol oxidation inhibition, and angiotensin-I-converting enzyme (ACE) inhibitory effects. The protein hydrolysates were prepared using food-grade commercial enzymes, namely Alcalase, Corolase, and Flavourzyme, individually and in combination, and found that the combination of enzymes exhibited stronger antioxidant potential than the individual enzymes, as well as their untreated counterparts. Similar trends were also observed for the DNA and LDL cholesterol oxidation inhibition and ACE-inhibitory properties of sea cucumber protein hydrolysates, mainly those that were prepared from the flower. Thus, the findings of this study revealed potential applications of sea cucumber-derived protein hydrolysates in functional foods, nutraceuticals, and dietary supplements, as well as natural therapeutics.

Effects of Graphene Oxide Nanosheets in Freshwater Biofilms

Graphene oxide (GO) properties make it a promising material for graphene-based applications in areas such as biomedicine, agriculture, and the environment. Thus, its production is expected to increase, reaching hundreds of tons every year. One GO final destination is freshwater bodies, possibly affecting the communities of these systems. To clarify the effect that GO may impose in freshwater communities, a fluvial biofilm scraped from submerged river stones was exposed to a range (0.1 to 20 mg/L) of GO concentrations during 96 h. With this approach, we hypothesized that GO can: (1) cause mechanical damage and morphological changes in cell biofilms; (2) interfere with the absorption of light by biofilms; (3) and generate oxidative stress, causing oxidative damage and inducing biochemical and physiological alterations. Our results showed that GO did not inflict mechanical damage. Instead, a positive effect is proposed, linked to the ability of GO to bind cations and increase the micronutrient availability to biofilms. High concentrations of GO increased photosynthetic pigment (chlorophyll a, b, and c, and carotenoids) content as a strategy to capture the available light more effectively as a response to the shading effect. A significant increase in the enzymatic (SOD and GSTs activity) and low molecular weight (lipids and carotenoids) antioxidant response was observed, that efficiently reduced oxidative stress effects, reducing the level of peroxidation, and preserving membrane integrity. Being complex entities, biofilms are more similar to environmental communities and may provide more accurate information to evaluate the impact of GO in aquatic systems.

Antioxidant Potential of Glutathione and Crosstalk with Phytohormones in Enhancing Abiotic Stress Tolerance in Crop Plants

Glutathione (GSH) is an abundant tripeptide that can enhance plant tolerance to biotic and abiotic stress. Its main role is to counter free radicals and detoxify reactive oxygen species (ROS) generated in cells under unfavorable conditions. Moreover, along with other second messengers (such as ROS, calcium, nitric oxide, cyclic nucleotides, etc.), GSH also acts as a cellular signal involved in stress signal pathways in plants, directly or along with the glutaredoxin and thioredoxin systems. While associated biochemical activities and roles in cellular stress response have been widely presented, the relationship between phytohormones and GSH has received comparatively less attention. This review, after presenting glutathione as part of plants' feedback to main abiotic stress factors, focuses on the interaction between GSH and phytohormones, and their roles in the modulation of the acclimatation and tolerance to abiotic stress in crops plants.

Application of Plant Growth-Promoting Bacteria from Cape Verde to Increase Maize Tolerance to Salinity

Salinity constitutes a major abiotic factor that negatively affects crop productivity. Inoculation with plant growth-promoting bacteria (PGPB) is proven to increase plant tolerance to abiotic stresses and enhance plant growth, development and productivity. The present study aims to increase the resilience of crops to salinity using bacteria from the microbiome of plants growing in saline environments. For that, the halotolerance of bacteria present in the roots of natural plants growing on Sal Island, which is characterized by its arid environment and maritime influence, was determined, with some strains having extreme halotolerance. Their ability to produce plant growth-promoting traits was evaluated, with most strains increasing indole acetic acid (26-418%), siderophore (>300%) and alginate (2-66%) production and phosphate solubilization (13-100%) under salt stress. The strains evidencing the best performance were inoculated in maize (Zea mays L.) plants and their influence on plant growth and biochemical status was evaluated. Results evidenced bacterial ability to especially increase proline (55-191%), whose osmotic, antioxidant and protein-protecting properties reduced protein damage in salt-stressed maize plants, evidencing the potential of PGPB to reduce the impact of salinity on crops. Enhanced nutrition, phytohormone production and osmolyte synthesis along with antioxidant response all contribute to increasing plant tolerance to salt stress.

Biochemical and Behavioural Alterations Induced by Arsenic and Temperature in Hediste diversicolor of Different Growth Stages

Contamination with Arsenic, a toxic metalloid, is increasing in the marine environment. Additionally, global warming can alter metalloids toxicity. Polychaetes are key species in marine environments. By mobilizing sediments, they play vital roles in nutrient and element (including contaminants) cycles. Most studies with marine invertebrates focus on the effects of metalloids on either adults or larvae. Here, we bring information on the effects of temperature increase and arsenic contamination on the polychaete Hediste diversicolor in different growth stages and water temperatures. Feeding activity and biochemical responses-cholinesterase activity, indicators of cell damage, antioxidant and biotransformation enzymes and metabolic capacity-were evaluated. Temperature rise combined with As imposed alterations on feeding activity and biochemical endpoints at different growth stages. Small organisms have their antioxidant enzymes increased, avoiding lipid damage. However, larger organisms are the most affected class due to the inhibition of superoxide dismutase, which results in protein damage. Oxidative damage was observed on smaller and larger organisms exposed to As and temperature of 21 °C, demonstrating higher sensibility to the combination of temperature rise and As. The observed alterations may have ecological consequences, affecting the cycle of nutrients, sediment oxygenation and the food chain that depends on the bioturbation of this polychaete.

Do Volatiles Affect Bacteria and Plants in the Same Way? Growth and Biochemical Response of Non-Stressed and Cd-Stressed Arabidopsis thaliana and Rhizobium E20-8

Plant roots are colonized by rhizobacteria, and these soil microorganisms can not only stimulate plant growth but also increase tolerance to stress through the production of volatile organic compounds. However, little is known about the effect that these plant beneficial volatiles may have on bacteria. In this study, the effects on growth and oxidative status of different concentrations of three volatiles already reported to have a positive influence on plant growth (2-butanone, 3-methyl-1-butanol, and 2,3-butanediol) were determined in A. thaliana and Rhizobium sp. strain E20-8 via airborne exposure in the presence and absence of Cd. It was expected to ascertain if the plant and the bacterium are influenced in the same way by the volatiles, and if exposure to stress (Cd) shifts the effects of volatiles on plants and bacteria. Results showed the antioxidant activity of the volatiles protecting the plant cell metabolism from Cd toxicity and increasing plant tolerance to Cd. Effects on bacteria were less positive. The two alcohols (3-methyl-1-butanol and 2,3-butanediol) increased Cd toxicity, and the ketone (2-butanone) was able to protect Rhizobium from Cd stress, constituting an alternative way to protect soil bacterial communities from stress. The application of 2-butanone thus emerges as an alternative way to increase crop production and crop resilience to stress in a more sustainable way, either directly or through the enhancement of PGPR activity.

Does parental exposure to nanoplastics modulate the response of Hediste diversicolor to other contaminants: A case study with arsenic

Plastic pollution is a serious problem in aquatic systems throughout the world. Despite the increasing number of studies addressing the impact of macro- and microplastics on biota, there is still a significant knowledge gap regarding the effects of nanoplastics alone and in combination with other contaminants. Among the aquatic contaminants that may interact with nanoplastics is arsenic (As), a metalloid found in estuarine and coastal ecosystems, pernicious to benthic organisms. This study aimed to understand how a parental pre-exposure to 100 nm polystyrene nanoplastics (PS NPs) would influence the response of Hediste diversicolor to exposure to arsenic in terms of behaviour, neurotransmission, antioxidant defences and oxidative damage, and energy metabolism. The obtained data revealed an increase in burrowing time and a significant inhibition in cholinesterase activity in all polychaetes exposed to As, regardless of the pre-exposure to PS NPs. Oxidative status was altered particularly in parentally exposed organisms, with damage detected in terms of lipid peroxidation at 50 μg/L and protein carbonylation at 50 and 250 μg As/L exposed organisms when compared to control. Overall, data shows that parental pre-exposure to plastics influences the response of aquatic organisms, increasing their susceptibility to other contaminants. Thus, more studies should be performed with other environmental contaminants, to better understand the potential increased risk associated with the presence of nanoplastics to aquatic ecosystems.

Bioprospecting Soil Bacteria from Arid Zones to Increase Plant Tolerance to Drought: Growth and Biochemical Status of Maize Inoculated with Plant Growth-Promoting Bacteria Isolated from Sal Island, Cape Verde

Climate change and anthropogenic activities are responsible for extensive crop yield losses, with negative impact on global agricultural production. The occurrence of extreme weather events such as drought is a big challenge for agriculture, negatively impacting crops. Thus, methodologies reducing crop dependence on water will be a great advantage. Plant roots are colonized by soil bacteria, that can establish beneficial associations with plants, increasing crop productivity and plant tolerance to abiotic stresses. The aim of this study was to promote plant growth and to increase crop tolerance to drought by inoculation with osmotolerant bacterial strains. For that, bacteria were isolated from plants growing in Sal Island (Cape Verde) and identified. The osmotolerance and plant-growth promotion (PGP) abilities of the strains were determined. A maize seed cultivar tolerant to drought was inoculated with the strains evidencing best PGP capacity and osmo-tolerance. Results evidenced the ability of some bacterial strains increasing the development and inducing osmotolerance in plants. These results evidence the potential of osmotolerant bacteria to further increase the level of tolerance of maize varieties tolerant to drought, decreasing the dependence of this crop on irrigation, and open new perspectives to growth maize in drought affected areas and to use water more efficiently.

In Silico Analysis of Bioactive Peptides Produced from Underutilized Sea Cucumber By-Products-A Bioinformatics Approach

Bioinformatic tools are widely used in predicting potent bioactive peptides from food derived materials. This study was focused on utilizing sea cucumber processing by-products for generating antioxidant and ACE inhibitory peptides by application of a range of in silico techniques. Identified peptides using LC-MS/MS were virtually screened by PepRank technique followed by in silico proteolysis simulation with representative digestive enzymes using BIOPEP-UWMTM data base tool. The resultant peptides after simulated digestion were evaluated for their toxicity using ToxinPred software. All digestive resistance peptides were found to be non-toxic and displayed favorable functional properties indicating their potential for use in a wide range of food applications, including hydrophobic and hydrophilic systems. Identified peptides were further assessed for their medicinal characteristics by employing SwissADME web-based application. Our findings provide an insight on potential use of undervalued sea cucumber processing discards for functional food product development and natural pharmaceutical ingredients attributed to the oral drug discovery process.

Interplay of Seasonality, Major and Trace Elements: Impacts on the Polychaete Diopatra neapolitana

Simple Summary

Coastal systems often serve as sinks for toxic elements, and seasonality has been responsible for many changes in the physical and chemical parameters of waters and sediments, leading to geochemical alterations in aquatic systems and the alteration of element uptake rates in organisms. Diopatra neapolitana worms were collected from five sites of the Ria de Aveiro lagoon in the autumn, winter, spring, and summer of 2018/2019 and were tested to check for differences in the biochemical responses (cell damage, antioxidant enzymes, biotransformation enzymes, and energy-related parameters) among seasons and sites. In general, the results demonstrated that enzyme activities were higher in spring and summer due to high temperatures and element bioaccumulation. Energy-related parameters presented with higher levels in spring and autumn, which was mainly due to element bioaccumulation. Oxidative damage was higher during winter and was related to salinity and decreases in temperature. This study demonstrated that abiotic factors influence the geochemistry of elements and that both significantly affect organism performance in low-contamination systems, such as the Ria de Aveiro lagoon. This knowledge is important to understand how ecological and economically relevant species such as D. neapolitana respond to environmental changes.

Abstract

Polychaetes are known to be good bioindicators of marine pollution, such as inorganic contamination. Major and trace elements are commonly present in sediment and may be accumulated by polychaetes such as the tubiculous Diopatra neapolitana. In this study, D. neapolitana individuals were collected in the autumn, winter, spring, and summer of 2018/2019 from the Ria de Aveiro lagoon (western Portugal) to understand how seasonality influences element accumulation. The impact of the interaction of seasonality and elements on oxidative status, energy metabolism, and oxidative damage was also assessed. The obtained results showed that the activity of the antioxidant enzymes catalase, glutathione S-transferases, and non-protein thiol levels were higher in summer and that superoxide dismutase, lipid peroxidation, and electron transport system activity increased in winter. The lowest glycogen levels were observed during spring, and protein carbonylation was the highest during autumn. These results could mainly be related to high temperatures and the bioaccumulation of Al, As, Mn, and Zn. Energy-related parameters increased during spring and autumn, mainly due to the bioaccumulation of the same elements during spring and summer. Lipid damage was higher during winter, which was mainly due to salinity and temperature decreases. Overall, this study demonstrates that seasonality plays a role in element accumulation by polychaetes and that both impact the oxidative status of D. neapolitana.

Dipeptide IF and Exercise Training Attenuate Hypertension in SHR Rats by Inhibiting Fibrosis and Hypertrophy and Activating AMPKα1, SIRT1, and PGC1α

Bioactive peptides are physiologically active peptides produced from proteins by gastrointestinal digestion, fermentation, or hydrolysis by proteolytic enzymes. Bioactive peptides are resorbed in their whole form and have a preventive effect against various disease conditions, including hypertension, dyslipidemia, inflammation, and oxidative stress. In recent years, there has been a growing body of evidence showing that physiologically active peptides may have a function in sports nutrition. The present study aimed to evaluate the synergistic effect of dipeptide (IF) from alcalase potato protein hydrolysates and exercise training in hypertensive (SHR) rats. Animals were divided into five groups. Bioactive peptide IF and swimming exercise training normalized the blood pressure and decreased the heart weight. Cardiac, hepatic, and renal functional markers also normalized in SHR rats. The combined administration of IF peptide and exercise offer better protection in SHR rats by downregulating proteins associated with myocardial fibrosis, hypertrophy, and inflammation. Remarkably, peptide treatment alongside exercise activates the PI3K/AKT cell survival pathway in the myocardial tissue of SHR animals. Further, the mitochondrial biogenesis pathway (AMPKα1, SIRT1, and PGC1α) was synergistically activated by the combinatorial treatment of IF and exercise. Exercise training along with IF administration could be a possible approach to alleviating hypertension.

TNKPVI, a Putative Bioaccessible Pharmacophore of Anti-Inflammatory Potato Patatin-Derived Decapeptide DIKTNKPVIF

Potato protein-derived decapeptide DIKTNKPVIF exerted anti-inflammatory activity in animal models when delivered via intragastric gavage and intraperitoneal injection. However, DIKTNKPVIF is susceptible to hydrolysis in the digestive tract, which will decrease its bioaccessibility and possibly bioactivity. In this study, the anti-inflammatory activity of fragments generated from in silico gastrointestinal enzymatic hydrolysis of DIKTNKPVIF was investigated using the human monocytic (THP-1) cell line. The simulated digestion by pepsin and trypsin released four fragments, DIKTNKPVI, TNKPVIF, DIK and TNKPVI. The peptides lacked the cleavage sites of chymotrypsin. All five peptides were predicted to be non-toxic, which was validated using cytotoxicity assay at 0.25–1 mM peptide concentration. However, the peptides were predicted to possess poor pharmacokinetic profiles, including low passive gastrointestinal absorption and blood–brain barrier permeability. TNKPVIF, DIK and TNKPVI significantly reduced the amount of pro-inflammatory interleukin (IL)-6, IL-8 and tumor necrosis factor in lipopolysaccharide-activated THP-1 cells. Notably, the anti-inflammatory activity of fragment TNKPVI was comparable to that of the parent decapeptide while peptide fragment DIKTNKPVI had no apparent effect on the pro-inflammatory cytokines. This highlights the important role of the C-terminal phenylalanine residue of the parent peptide in the bioactivity. Furthermore, given its activity and the absence of cleavage sites of major digestive proteases, TNKPVI could be the biostable and bioaccessible pharmacophore of potato patatin-derived anti-inflammatory decapeptide DIKTNKPVIF.

Graphene oxide influence in soil bacteria is dose dependent and changes at osmotic stress: growth variation, oxidative damage, antioxidant response, and plant growth promotion traits of a Rhizobium strain

Climate change events, such as drought, are increasing and soil bacteria can be severely affected. Moreover, the accumulation of emerging pollutants is expected to rapidly increase, and their impact on soil organisms, their interactions, and the services they provide is poorly known. The use of graphene oxide (GO) has been increasing due to its enormous potential for application in several areas and it is expected that concentration in soil will increase in the future, potentially causing disturbances in soil microorganisms not yet identified.Here we show the effects that GO nanosheets can cause on soil bacteria, in particular those that promote plant growth, in control and 10% polyethylene glycol (PEG) conditions. Low concentrations of GO nanosheets did not affect the growth of Rhizobium strain E20-8, but under osmotic stress (PEG) GO decreased bacterial growth even at lower concentrations. GO caused oxidative stress, with antioxidant mechanisms being induced to restrain damage, effectively at lower concentrations, but less effective at higher concentrations, and oxidative damage overcame. Under osmotic stress, alginate and glycine betaine osmoregulated the bacteria. Simultaneous exposure to PEG and GO induced oxidative damage. Plant growth promotion traits (indole acetic acid and siderophores production) were increased by osmotic stress and GO did not disturb these abilities. In the context of climate change, our findings might be relevant as they can form the premises for the implementation of crop production methodologies adapted to the new prevailing conditions, which include the presence of nanoparticles in the soil and more frequent and severe drought.

Effects of graphene oxide nanosheets in the polychaete Hediste diversicolor: Behavioural, physiological and biochemical responses

Numerous applications exist for graphene-based materials, such as graphene oxide (GO) nanosheets. Increased concentrations of GO nanosheets in the environment have the potential to have a large negative effect on the aquatic environment, with consequences for benthic organisms, such as polychaetes. The polychaete Hediste diversicolor mobilises the sediments, hence altering the availability of contaminants and the nutrients biogeochemical cycle. As such, this study proposes to assess the effects of different GO nanosheet concentrations on the behaviour, feeding activity, mucus production, regenerative capacity, antioxidant status, biochemical damage and metabolism of H. diversicolor. This study evidenced that H. diversicolor exposed to GO nanosheets had a significantly lower ability to regenerate their bodies, took longer to feed and burrow into the sediment and produced more mucus. Membrane oxidative damage (lipid peroxidation) increased in exposed specimens. The increased metabolic rate (ETS) evidenced a higher energy expenditure in exposed organisms (high use of ready energy sources - soluble sugars) to fight the toxicity induced by GO nanosheets, such as SOD activity. The increase in SOD activity was enough to reduce reactive oxygen species (ROS) induced by GO on cytosol at the lowest concentrations, avoiding the damage on proteins (lower PC levels), but not on membranes (LPO increase). This study revealed that the presence of GO nanosheets, even at the lower levels tested, impaired behavioural, physiological, and biochemical traits in polychaetes, suggesting that the increase of this engineered nanomaterial in the environment can disturb these benthic organisms, affecting the H. diversicolor population. Moreover, given the important role of this group of organisms in coastal and estuarine food webs, the biogeochemical cycle of nutrients, and sediment oxygenation, there is a real possibility for repercussions into the estuarine community.

Potato protein: current review of structure, technological properties, and potential application on spray drying microencapsulation

Studies regarding spray drying microencapsulation are aplenty available; especially focusing on processing parameters, microparticle characteristics and encapsulation efficiency. Hence, there is a rising interest in tailoring wall materials aiming to improve the process's effectiveness. Reflecting a market trend in the food industry, plant-based proteins are emerging as alternative protein sources, and their application adaptability is an increasing research of interest related to consumers' demand for healthy food, product innovation, and sustainability. This review presents a perspective on the investigation of potato protein as a technological ingredient, considering it a nonconventional source obtained as by-product from starch industry. Furthermore, this piece emphasizes the potential application of potato protein as wall material in spray drying encapsulation, considering that this purpose is still limited for this ingredient. The literature reports that vegetal-based proteins might present compromised functionality due to processing conditions, impairing its technological application. Structural modification can offer a potential approach to modify potato protein configuration aiming to improve its utilization. Studies reported that modified proteins can perform as better emulsifiers and antioxidant agents compared to intact proteins. Hence, it is expected that their use in microencapsulation would improve process efficiency and protection of the core material, consequently delivering superior encapsulation performance.

Effects of volatile sulfur compounds on growth and oxidative stress of Rhizobium leguminosarum E20-8 exposed to cadmium

Volatile sulfur compounds (VSCs) have been reported to be produced by many bacterial species. Depending on the compound, they can negatively influence some organisms (fungi, nematodes and insects) or promote plant growth. Some of these compounds have also been hypothesized to play a role in bacterial response to cadmium (Cd) induced stress. This study aimed to assess the potential effects of four VSCs (dimethyl sulfide - DMS, dimethyl disulfide - DMDS, dimethyl trisulfide - DMTS and methyl thioacetate - MTA) on the growth and oxidative status of Rhizobium sp. strain E20-8 via airborne exposure, in order to test the hypothesis that these volatile compounds can influence growth and tolerance to cadmium. Our results show that, overall, the tested compounds triggered similar antioxidant mechanisms in Rhizobium in the presence of Cd. The protective effect at the membrane level by DMDS and DMTS particularly demonstrates the antioxidant effect of these volatiles, with reductions of up to 50% (DMS) and 80% (DMTS) in lipid peroxidation levels. Due to the volatile nature of these compounds, the low concentrations tested (1 nM to 100 mM), and considering that they are released by bacteria and other organisms such as plants, it is possible that these effects also occur in the soil ecosystem.

Effects of the antineoplastic drug cyclophosphamide on the biochemical responses of the mussel Mytilus galloprovincialis under different temperatures

Cyclophosphamide (CP) is an antineoplastic drug widely used in chemotherapy treatments with high consumption rates and that has been detected in the aquatic environment. After being released into the aquatic environment, CP may cause adverse effects on aquatic organisms since antineoplastics are well-known cytotoxic, genotoxic, mutagenic and teratogenic drugs. Moreover, predicted environmental changes, such as the temperature rising, may alter the impacts caused by CP on organisms. Thus, the present study aimed to assess the effects caused by CP chronic exposure in the mussel Mytilus galloprovincialis, under actual and predicted warming scenarios. Organisms were exposed for 28 days to different concentrations of CP (10, 100, 500 and 1000 ng/L) at control (17 ± 1.0 °C) and increased (21 ± 1.0 °C) temperatures. Biochemical responses related to metabolic capacity, energy reserves, oxidative stress and neurotoxicity were assessed. The results showed that the organisms were able to maintain their metabolic capacity under all exposure conditions. However, their antioxidant defense mechanisms were activated mostly at higher CP concentrations being able to prevent cellular damage, even under the warming scenario. Overall, the present findings suggest that temperature rise may not alter the impacts of CP towards M. galloprovincialis.

A Concise Review of Current In Vitro Chemical and Cell-Based Antioxidant Assay Methods

Antioxidants remain interesting molecules of choice for suppression of the toxic effects of free radicals in foods and human systems. The current practice involves the use of mainly synthetic molecules as potent antioxidant agents. However, due to the potential negative impact on human health, there is an intensive effort within the research community to develop natural alternatives with similar antioxidant efficacy but without the negative side effects of synthetic molecules. Still, the successful development of new molecules depends on the use of reliable chemical or cell culture assays to screen antioxidant properties. Chemical antioxidant assays include the determination of scavenging ability against free radicals such as DPPH, superoxide anion radicals, hydroxyl radicals, hydrogen peroxide, and nitric oxide. Other antioxidant tests include the ability of compounds to bind and sequester prooxidant metal cations, reduce ferric iron, and attenuate the rate of lipid oxidation. Ex vivo tests utilize cell cultures to confirm entry of the molecules into cells and the ability to quench synthetic intracellular free radicals or to stimulate the increased biosynthesis of endogenous antioxidants. In order to assist researchers in their choice of antioxidant evaluation methods, this review presents background scientific information on some of the most commonly used antioxidant assays with a comparative discussion of the relevance of published literature data to food science and human nutrition applications.

Antioxidative Activity of Soy, Wheat and Pea Protein Isolates Characterized by Multi-Enzyme Hydrolysis

Hydrolysis of protein by proteases produces small molecular weights (MWs) peptides as nanomaterials that are easily absorbed. This study investigated the physicochemical properties and antioxidant activity of three plant protein isolates (PIs) including soy, wheat and pea after multi-enzyme hydrolysis. The MWs, particle size and microstructure of PI hydrolysate (PIH) were determined by SDS-PAGE and MALDI-TOF-MS mass spectrometry, dynamic light scattering and transmission electron microscopy, respectively. Cell viability was determined in vitro using a mouse skeletal muscle cell line (C2C12) and crystal violet staining. The MWs and particle sizes of the three plant PIs were reduced after hydrolysis by three proteases (bromelain, Neutrase and Flavourzyme). The MWs of soy, wheat and pea PIH were 103.5–383.0 Da, 103.5–1146.5 Da and 103.1–1937.7 Da, respectively, and particle size distributions of 1.9–2.0 nm, 3.2–5.6 nm and 1.3–3.2 nm, respectively. All three plant PIHs appeared as aggregated nanoparticles. Soy PIH (100 μg/mL) provided better protection against H₂O₂-induced oxidative damage to C2C12 than wheat or pea PIH. In summary, soy PIH had the best antioxidant activity, and particle size than wheat PIH and pea PIH. Therefore, soy PIH might be a dietary supplement for healthy diet and medical applications.

Non-animal proteins as cutting-edge ingredients to reformulate animal-free foodstuffs: Present status and future perspectives

Consumer interest in protein rich diets is increasing, with more attention being paid to the protein source. Despite the occurrence of animal proteins in the human diet, non-animal proteins are gaining popularity around the world due to their health benefits, environmental sustainability, and ethical merit. These sources of protein qualify for vegan, vegetarian, and flexitarian diets. Non-animal proteins are versatile, derived mainly from cereals, vegetables, pulses, algae (seaweed and microalgae), fungi, and bacteria. This review's intent is to analyze the current and future direction of research and innovation in non-animal proteins, and to elucidate the extent (limitations and opportunities) of their applications in food and beverage industries. Prior knowledge provided relevant information on protein features (processing, structure, and techno-functionality) with particular focus on those derived from soy and wheat. In the current food landscape, beyond conventionally used plant sources, other plant proteins are gaining traction as alternative ingredients to formulate animal-free foodstuffs (e.g., meat alternatives, beverages, baked products, snack foods, and others). Microbial proteins derived from fungi and algae are also food ingredients of interest due to their high protein quantity and quality, however there is no commercial food application for bacterial protein yet. In the future, key points to consider are the importance of strain/variety selection, advances in extraction technologies, toxicity assessment, and how this source can be used to create food products for personalized nutrition.

Antioxidant potential and physicochemical properties of protein hydrolysates from body parts of North Atlantic sea cucumber (Cucumaria frondosa)

Abstract

Protein hydrolysates were prepared from North Atlantic sea cucumber (Cucumaria frondosa) body wall (BW), and processing by-product flower (FL) and internal organs (IN). Sea cucumber proteins from these three tissues were hydrolysed with selected endopeptidases and exopeptidases. The enzymes used were Alcalase (A), and Corolase (C) as endopeptidases and Flavourzyme (F) with both endo- and exopeptidase functions. These were employed individually or in combination under controlled conditions. The hydrolysates so prepared were subsequently analysed for their antioxidant potential and functionalities in food systems for the first time. Hydrolysates treated with the combination of A and F exhibited the highest radical scavenging activity against DPPH and ABTS radicals. The highest metal chelation activity was observed for samples hydrolysed with the combination of enzymes (C + F and A + F). All treatments inhibited beta-carotene bleaching in an oil-in-water emulsion and TBARS production in a meat model system. In addition, sea cucumber protein hydrolysates were more than 75% soluble over a pH range of 2–12. Hydrolysed proteins were also effective in enhancing water holding capacity in a meat model system compared to their untreated counterparts. The amino acids of sea cucumber protein hydrolysates had desirable profiles with glutamic acid as the predominant component in samples analysed. These findings demonstrate the desirable functionalities of hydrolysates from North Atlantic sea cucumber and their potential for use as functional food ingredients.

Graphical abstract

Physicochemical and Antioxidative Characteristics of Potato Protein Isolate Hydrolysate

This study investigated the physicochemical characteristics of potato protein isolate hydrolysate (PPIH) and its antioxidant activity. Potato protein isolate (PPI) was hydrolyzed into PPIH by the proteases bromelain, Neutrase, and Flavourzyme. Compared with PPI, the resulting PPIH had a lower molecular weight (MW, from 103.5 to 422.7 Da) and smaller particle size (<50 nm), as well as a higher solubility rate (>70%) under acidic conditions (pH 3–6). PPIH presented good solubility (73%) across the tested pH range of 3–6. As the pH was increased, the zeta potential of PPIH decreased from −7.4 to −21.6. Using the 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical-scavenging assay, we determined that the half-maximal effective concentration (EC₅₀) values of ascorbic acid, PPIH, and PPI were 0.01, 0.89, and >2.33 mg/mL, respectively. Furthermore, PPIH (50 μg/mL) protected C2C12 cells from H₂O₂ oxidation significantly better than PPI (10.5% higher viability rate; p < 0.01). These findings demonstrated the possible use of PPIH as an antioxidant in medical applications.

Can Palythoa cf. variabilis biochemical patterns be used to predict coral reef conservation state in Todos Os Santos Bay?

Coral reefs are one of the most diverse, complex and productive marine ecosystems on the planet. Global climate change and other anthropogenic impacts have had a strong impact on the equilibrium of these ecosystems and causing the denominated "coral reef crisis". One consequence of coral reef crisis is the phase shift in reef communities, where scleractinian corals responsible for the bioconstruction of the coralline building are replaced by macroalgae or soft corals. In Todos os Santos Bay (TSB) there is a rare case of phase shift caused by the soft coral Palythoa cf. variabilis. When in population outbreak, this coral species becomes dominant and leads to loss of scleractinian coral cover. Palythoa genus establishes a symbiotic relationship with dinoflagellate algae of the genus Symbiodinium, that is changed in phase shift coral reefs, but other alterations remain unknown. In this study, the metabolism (oxidative damage, antioxidant and biotransformation enzymes, electron transport chain activity and photosynthetic pigments) of P. cf. variabilis from reefs in different conservation states was studied to identify and relate if changes that may occur in the biochemical and metabolism of the coral might trigger the population outbreak, identify parameters recognizing if corals are in stress and assess if one or more parameters can reflect the level of stress organisms are experiencing. The results obtained evidenced a clear distinction in the biochemistry and metabolism of corals from conserved sites and sites in phase shift, and these changes may be the trigger for population outbreak. Some of the parameters were able to discriminate the level of stress corals are experiencing and may allow to recognize the most at-risk coral reefs that need immediate intervention and prevent the entry into or revert P. cf. variabilis outbreak and phase shift in coral reefs. Actions like these can be of vital importance for the preservation of TSB coral reefs and possibly for other threatened reefs worldwide.

Preparation and characterization of potato protein-based microcapsules with an emphasis on the mechanism of interaction among the main components

BACKGROUND

Potato protein (PP) has promising potential for utilization in food applications due to its high nutritive value and functional properties. Grapeseed oil (GO) is rich in unsaturated fatty acids and antioxidant active ingredients. However, its application is limited because of low stability and high volatility. In order to overcome such problems, PP-based microcapsules encapsulating GO were produced by complex coacervation, and characterized using optical, thermodynamic and spectroscopic analyses.

RESULTS

Results indicated that a ratio of GO/PP of 1:2 led to the best encapsulation effect with the maximum microencapsulation efficiency and yield. Intact and nearly spherical microcapsules were observed from scanning electron microscopy images. Results of thermogravimetry demonstrated that thermal resistance was increased in the microencapsulated GO, indicating that PP-based microcapsules could be a good way to protect the thermal stability of GO. Fourier transform infrared spectra indicated that hydrogen bonding and covalent crosslinking might occur among wall materials, but a physical interaction between GO and wall materials.

CONCLUSIONS

PP can be successfully used to encapsulate GO when combined with chitosan, indicating that PP-based microcapsules have potential for application in encapsulating liquid oils with functional properties. A schematic diagram of possible interactions was constructed to better understand the mechanism of formation of the microcapsules. © 2020 Society of Chemical Industry.

Rhizobium response to sole and combined exposure to cadmium and the phytocompounds alpha-pinene and quercetin

Soils can be contaminated with substances arising from anthropogenic sources, but also with natural bioactive compounds produced by plants, such as terpenes and flavonoids. While terpenes and flavonoids have received much less attention from research studies than metals, the effects that phytocompounds can have on soil organisms such as beneficial microorganisms should not be neglected. Herein we report the sole and combined exposure of Rhizobium to cadmium, to the monoterpene alpha-pinene and to the flavanol quercetin. A range of environmentally relevant concentrations of the phytocompounds was tested. Physiological (growth, protein content and intracellular Cd concentration), oxidative damage (lipid peroxidation, protein carbonylation) and antioxidant mechanisms (superoxide dismutase, catalase, glutathione, glutathione-S-transferases, protein electrophoretic profiles) were assessed. Results suggest that exposure to both phytocompounds do not influence Rhizobium growth, but for combined exposure to phytocompounds and Cd, different responses are observed. At low concentrations, phytocompounds seem to relieve the stress imposed by Cd by increasing antioxidant responses, but at high concentrations this advantage is lost and membrane damage may even be exacerbated. Thus, the presence of bioactive phytocompounds in soil may influence the tolerance of microorganisms to persistent toxicants, and may change their impact on the environment.

Neuroprotective effect from Salvia hispanica peptide fractions on pro-inflammatory modulation of HMC3 microglial cells

Neuroinflammation plays a critical role in the neurodegenerative disease's development, where microglia's act an important role in the mechanisms of response to neuronal damage. In the present research, the neuroprotective effect from Salvia hispanica peptide fractions on the proinflammatory modulation on HMC3 microglial cells was evaluated. From the enzymatic hydrolysis of a protein-rich fraction from S. hispanica seeds, three peptide fractions (<1, 1-3 and 3-5 kDa) were obtained, from which its neuroprotective and anti-inflammatory effect was determined on the production of proinflammatory mediators on HMC3 cells. The F1-3 kDa exhibited the greatest protective effect (79.04%), associated with the decrease in ROS cell production (51.3 ± 2.3%). Likewise, F1-3 kDa at 50 µg/ml, presented the highest reduction percentages of NO (33.1 ± 2.30%), TNFα (26.4 ± 1.1%) and IL6 (17.36 ± 1.6%). F1-3 kDa exhibited a neuroprotective effect in HMC3 cells associated with its antioxidant and anti-inflammatory effect. PRACTICAL APPLICATIONS: Currently, neurodegenerative diseases represent a global health problem, so the search for bioactive compounds with neuroprotective effect is useful in the prevention and treatment of this group of diseases. Peptide research with an effect on the proinflammatory and prooxidant mediator's reduction presents a potential application in the functional food's development aimed at the treatment of chronic diseases, that have oxidative stress and inflammation as their etiological factor. The present research adds to the scientific evidence of the potential benefits of bioactive peptides obtained from chia seeds. The results correlate with the main health benefits of whole chia seed in humans, such as antioxidant, anti-inflammatory, hypoglycemic and hypotensive capacity. This relationship is associated with the protein and peptide composition of chia, which increases its added value as food.

Behavior and biochemical responses of the polychaeta Hediste diversicolor to polystyrene nanoplastics

Plastic debris has been reaching the world's oceans since it started being used. Multiple studies have been addressing the effects of microplastics in various organisms but, despite the increased scientific awareness, there is still a significant gap in knowledge when it comes to small-sized plastic particles of sizes below 100 nm. The aim of this study was to understand the effect of waterborne 100 nm polystyrene nanoplastics (PS NPs) on the marine polychaeta Hediste diversicolor, a keystone species in intertidal and coastal environments, in terms of behavior, neurotransmission, oxidative status, energy metabolism and oxidative damage. Results of PS NPs characterization showed an aggregation along the time and with increasing concentrations. Results also revealed a considerable impact of PS NPs on ecologically relevant endpoints like cholinesterase (ChE) and burrowing, but no increases in most of the parameters associated with oxidative stress. Protein carbonylation was found to be more sensitive to PS NPs effects than lipid peroxidation. Behavioral alterations induced by PS NPs may affect nutrient cycling and (endo-)benthic fauna. The data revealed in this study highlighted the potential consequences of NPs to benthic organisms and the need for further studies.

The role of volatiles in Rhizobium tolerance to cadmium: Effects of aldehydes and alcohols on growth and biochemical endpoints

Rhizobia have a significant agronomic and environmental role and are eminent contributors to soil fertility. However, this group of microorganisms are affected by various environmental stresses, such as Cd contamination. High Cd concentrations change bacterial metabolism. During this metabolic shift, bacteria alter their volatilome (the set of volatile metabolites synthesized by an organism). In the presence of Cd, peak areas of saturated aldehydes and alcohols were previously reported to increase, and the consequences of this increase to cells are poorly known. In this study, Rhizobium sp. strain E20-8 cells were exposed to Cd and aldehydes or their conjugated alcohols. Exposure to Cd (100 μM) inhibited cell growth and induced several biomarkers of oxidative stress. The present study also evidenced the higher toxicity of most aldehydes relatively to the corresponding alcohol in the presence of Cd, suggesting that reduction of aldehydes into alcohols may be an effective mechanism to restrain aldehydes toxicity in Rhizobium cells under Cd toxicity. Nonetheless, the protective effect was dependent on the pair aldehyde-respective alcohol considered and it differed between Cd stressed and non-stressed cells. Differences in the ability to convert aldehydes to alcohols may emerge as a new feature helping explain the oxidative tolerance variability among bacteria.

Enzymatic release of dipeptidyl peptidase-4 inhibitors (gliptins) from pigeon pea (Cajanus cajan) nutrient reservoir proteins: In silico and in vitro assessments

In silico and in vitro parameters were used to assess the potential of pigeon pea (Cajanus cajan) nutrient reservoir proteins as sources of dipeptidyl peptidase (DPP)-4 inhibitors. In silico, 40 pigeon pea proteins evaluated had 46% of amino acids associated with DPP-4 inhibition. After virtual hydrolysis, pepsin had the highest frequency of release and bioactivity of released DPP-4 inhibiting peptides, compared to papain and thermolysin. In vitro, thermolysin released the most active DPP-4 inhibitors. The protein hydrolysates contained similar amino acids but different particle sizes. Thus, the bioactivity patterns are attributable to the different nature and behavior of proteins/peptides under actual and virtual conditions. Using eight physicochemical variables, a random forest model with moderate prediction accuracy was developed for predicting DPP-4 inhibitory activity of papain hydrolysates. The findings demonstrate that proteins from pigeon pea are precursors of DPP-4 inhibitors, with potential use in formulating functional food for managing type 2 diabetes. PRACTICAL APPLICATIONS: The emerging use of in silico simulations to predict bioactivity of peptides can provide a framework to direct further wet lab assessments. This pattern can enhance focusing on factors relevant to the bioactive properties of interest. However, there is still limited evidence to confirm the reliability and accuracy of this tool. This study therefore provides insight into the practical use of in silico simulations to predict bioactivity of food peptides by assessing the factors relevant to the enzymatic release of dipeptidyl peptidase-4 inhibitors from pigeon pea seed storage proteins and validating the findings with wet lab assessment. This work also provides important information that can enhance the utilization of pigeon pea, which is an orphan crop, in developing functional food products for managing type 2 diabetes mellitus in developing countries.

Antifungal and antimicrobial proteins and peptides of potato (Solanum tuberosum L.) tubers and their applications

Potato proteins are well known for their nutritional, emulsifying, foaming, gel forming or antioxidant properties that all make from them valuable protein source for food industry. Antifungal, antimicrobial and also antiviral properties, described for potato proteins in the review, enrich the possibilities of potato protein usage. Potato proteins were divided into patatin, protease inhibitors and fraction of other proteins that also included, besides others, proteins involved in potato defence physiology. All these proteins groups provide proteins and peptides with antifungal and/or antimicrobial actions. Patatins, obtained from cultivars with resistance to Phytophthora infestans, were able to inhibit spore germination of this pathogen. Protease inhibitors represent the structurally heterogeneous group with broad range of antifungal and antimicrobial activities. Potato protease inhibitors I and II reduced the growth of Phytophthora infestans, Rhizoctonia solani and Botrytis cinerea or of the fungi of Fusarium genus. Members of Kunitz family (proteins Potide-G, AFP-J, Potamin-1 or PG-2) were able to inhibit serious pathogens such as Staphylococcus aureus, Listeria monocytogenes, Escherichia coli or Candida albicans. Potato snakins, defensins and pseudothionins are discussed for their ability to inhibit serious potato fungi as well as bacterial pathogens. Potato proteins with the ability to inhibit growth of pathogens were used for developing of pathogen-resistant transgenic plants for crop improvement. Incorporation of potato antifungal and antimicrobial proteins in feed and food products or food packages for elimination of hygienically risk pathogens brings new possibility of potato protein usage.

Evidence that Nitric Oxide is Involved in the Blood Pressure Lowering Effect of the Peptide AVFQHNCQE in Spontaneously Hypertensive Rats

AVFQHNCQE is an antihypertensive nonapeptide obtained from a chicken foot protein hydrolysate. The present study aims to investigate the mechanisms involved in its blood pressure (BP)-lowering effect. Male (17⁻20 weeks old) spontaneously hypertensive rats (SHR) were used in this study. Rats were divided into two groups and orally administered water or 10 mg/kg body weight (bw) AVFQHNCQE. One hour post-administration, animals of both groups were intra-peritoneally treated with 1 mL of saline or with 1 mL of saline containing 30 mg/kg bw Nω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthesis, or with 1 mL of saline containing 5 mg/kg bw indomethacin, which is an inhibitor of prostacyclin synthesis (n = 6 per group). Systolic BP was recorded before oral administration and six hours after oral administration. In an additional experiment, SHR were administered water or 10 mg/kg bw AVFQHNCQE (n = 6 per group) and sacrificed six hours post-administration to study the mechanisms underlying the peptide anti-hypertensive effect. Moreover, the relaxation caused by AVFQHNCQE in isolated aortic rings from Sprague-Dawley rats was evaluated. The BP-lowering effect of the peptide was not changed after indomethacin administration but was completely abolished by L-NAME, which demonstrates that its anti-hypertensive effect is mediated by changes in endothelium-derived NO availability. In addition, AVFQHNCQE administration downregulated aortic gene expression of the vasoconstrictor factor endothelin-1 and the endothelial major free radical producer NADPH. Moreover, while no changes in plasma ACE activity were observed after its administration, liver GSH levels were higher in the peptide-treated group than in the water group, which demonstrates that AVFQHNCQE presents antioxidant properties.

Protective effects of farnesol on a Rhizobium strain exposed to cadmium

Soil acts as a repository for many metals that human activity releases into the environment. Cadmium enters agricultural soils primarily from application of phosphate fertilizers and sewage sludge. Among soil bacteria, rhizobia have a great agronomic and environmental significance and are major contributors to a sustainable maintenance of soil fertility. However, the services that this group of microorganisms provides are affected by environmental constraints, such as Cd contamination. Bioactive compounds also influence soil microorganisms. Farnesol is a phytocompound with recognized bioactivity, inducing both beneficial and harmful effects. In this study, Rhizobium sp. strain E20-8 was exposed to sole or combined exposure to Cd and farnesol. Results showed that farnesol (25 and 200 µM) did not affect rhizobia; exposure to Cd (µM) inhibited rhizobia growth and induced several biomarkers of oxidative stress; exposure to the combination of farnesol and Cd reduced oxidative damage, and the highest concentration of farnesol tested reduced Cd accumulation and allowed a significant growth recovery. Farnesol protective effects on rhizobia exposed to Cd is novel information which can be used in the development of microbe-based environmental engineering strategies for restoration of metal contaminated areas.

Photoinactivation of Pseudomonas syringae pv. actinidiae in kiwifruit plants by cationic porphyrins

The studied cationic porphyrins formulation allows an effective photoinactivation of Pseudomonas syringae pv. actinidiae in kiwifruit leaves under sunlight irradiation, without damaging the plant. Pseudomonas syringae pv. actinidiae (Psa) is a Gram-negative phytopathogenic bacterium responsible for canker on kiwifruit plant. Over the last decade, this bacterium dramatically affected the production of this fruit worldwide, causing significant economic losses. In general, Psa control consists in the application of copper which are toxic and persist in the environment. The application of antimicrobial photodynamic therapy (aPDT) as an alternative to inactivate Psa has already been demonstrated in recent studies that showed a 4 log Psa reduction using the cationic porphyrin Tetra-Py⁺-Me as photosensitizer (PS) and 3 consecutive cycles of treatment with a light irradiance of 150 mW cm^-2. The present work aimed to evaluate the photodynamic efficiency of a new formulation constituted with five cationic porphyrins as PS in Psa inactivation. This new formulation was prepared to have as main component the tri-cationic porphyrin which is considered one of the most efficient photosensitizers in the photoinactivation of microorganisms. The in vitro study with a PS concentration of 5.0 µM and low irradiance, showed a 7.4 log photoinactivation after 60 min. Posteriorly, several assays were performed with the PS at 50 µM on kiwifruit leaves (ex vivo), under different conditions of light and inoculation. The ex vivo assays with artificially contaminated leaves showed a 2.8 and 4.5 log inactivation with low irradiance and sunlight, respectively, after 90 min. After a second treatment with sunlight, a 6.2 log inactivation was achieved. The photoinactivation on naturally contaminated leaves was about 2.3 log after 90 min sunlight irradiation. Ten consecutive cycles of phototreatment in sub-lethal conditions showed that Psa does not develop resistance, nor recover viability. The results suggest that aPDT can be an alternative to the current methods used to control Psa, since it was possible to inactivate this bacterium under sunlight, without damaging the leaves.

N-Acetyl-tryptophan glucoside (NATG) protects J774A.1 murine macrophages against gamma radiation-induced cell death by modulating oxidative stress

Immune system is amongst the most radiosensitive system to radiation-induced cellular and molecular damage. Present study was focused on the evaluation of radioprotective efficacy of a novel secondary metabolite, N-acetyl tryptophan glucoside (NATG), isolated from a radioresistant bacterium Bacillus sp. INM-1 using murine macrophage J774A.1 cells experimental model. Radioprotective efficacy of NATG against radiation-induced DNA damage and apoptosis was estimated using phosphatidyl-serine-externalization Annexin V-PI and Comet assay analysis. Radiation-induced cell death is the outcome of oxidative stress caused by free radicals. Therefore, perturbations in antioxidant enzymes i.e., superoxide dismutase (SOD), catalase, glutathione-s-transferase (GST) and GSH activities in irradiated and NATG pre-treated irradiated J774A.1 cells were studied. Results of the present study demonstrated that NATG pre-treated (0.25 µg/ml) irradiated (20 Gy) cells showed significant (p < 0.05) reduction in apoptotic cells index at 4-48 h as compared to radiation alone cells. Comet assay exhibited significant protection to radiation-induced DNA damage in J774A.1 cells. Significantly shortened DNA tail length, increased % Head DNA contents and lower olive tail moment was observed in NATG pre-treated irradiated cells as compared to radiation alone cells. Further, significant increase in catalase (~ 3.9 fold), SOD (67.52%), GST (~ 1.9 fold), and GSH (~ 2.5 fold) levels was observed in irradiated cells pre-treated with NATG as compared to radiation-alone cells. In conclusion, current study suggested that NATG pre-treatment to irradiated cells enhanced antioxidant enzymes in cellular milieu that may contribute to reduce oxidative stress and decrease DNA damage which resulted to significant reduction in the cell death of irradiated macrophages.