Molecular Mechanism and Molecular Design of Lubricating Oil Antioxidants

To overcome the limitations of traditional experimental“trial and error”methods in lubricant additive design,a new molecular design method based on molecular structure parameters is established here.The molecular mechanism of the antioxidant reaction of hindered phenol,diphenylamine,and alkyl sulfide are studied via molecular simulations.Calculation results show that the strong electron-donating ability and high hydrogen-donating activity of the antioxidant molecule and the low hydrogen-abstracting activity of free radicals formed after dehydrogenation are the internal molecular causes of the shielding of phenol and diphenylamine from scavenging peroxy free radicals,and the strong electron-donating ability is the internal molecular cause of the high activity of thioether in decomposing alkyl hydrogen peroxide.Based on this antioxidant molecular mechanism,a molecular design rule of antioxidant is proposed,namely“high EHOMO,large Q(S),low bond dissociation energy BDE(O—H)and BDE(N—H)”.Two new antioxidants,PAS-I and PAS-II,are designed and prepared by chemical bonding of hindered phenol,diphenylamine,and sulfur atoms.Experimental results show that these antioxidants both have excellent antioxidant effects in lubricating oil,and that PAS-II is the superior antioxidant,consistent with theoretical predictions.

Maternal supplementation with n-3 fatty acids affects placental lipid metabolism, inflammation, oxidative stress, the endocannabinoid system, and the neonate cytokine concentrations in dairy cows

Background The placenta plays a crucial role in supporting and influencing fetal development.We compared the effects of prepartum supplementation with omega-3(n-3)fatty acid(FA)sources,flaxseed oil(FLX)and fish oil(FO),on the expression of genes and proteins related to lipid metabolism,inflammation,oxidative stress,and the endocannabinoid system(ECS)in the expelled placenta,as well as on FA profile and inflammatory response of neonates.Late-pregnant Holstein dairy cows were supplemented with saturated fat(CTL),FLX,or FO.Placental cotyledons(n=5)were collected immediately after expulsion,and extracted RNA and proteins were analyzed by RTPCR and proteomic analysis.Neonatal blood was assessed for FA composition and concentrations of inflammatory markers.Results FO increased the gene expression of fatty acid binding protein 4(FABP4),interleukin 10(IL-10),catalase(CAT),cannabinoid receptor 1(CNR1),and cannabinoid receptor 2(CNR2)compared with CTL placenta.Gene expression of ECS-enzyme FA-amide hydrolase(FAAH)was lower in FLX and FO than in CTL.Proteomic analysis identified 3,974 proteins;of these,51–59 were differentially abundant between treatments(P≤0.05,|fold change|≥1.5).Top canonical pathways enriched in FLX vs.CTL and in FO vs.CTL were triglyceride metabolism and inflammatory processes.Both n-3 FA increased the placental abundance of FA binding proteins(FABPs)3 and 7.The abundance of CNR1 cannabinoid-receptor-interacting-protein-1(CNRIP1)was reduced in FO vs.FLX.In silico modeling affirmed that bovine FABPs bind to endocannabinoids.The FLX increased the abundance of inflammatory CD44-antigen and secreted-phosphoprotein-1,whereas prostaglandin-endoperoxide synthase 2 was decreased in FO vs.CTL placenta.Maternal FO enriched neonatal plasma with n-3 FAs,and both FLX and FO reduced interleukin-6 concentrations compared with CTL.Conclusion Maternal n-3 FA from FLX and FO differentially affected the bovine placenta;both enhanced lipid metabolism and modulated oxidative stress,however,FO increased some transcriptional ECS components,possibly related to the increased FABPs.Maternal FO induced a unique balance of pro-and anti-inflammatory components in the placenta.Taken together,different sources of n-3 FA during late pregnancy enhanced placental immune and metabolic processes,which may affect the neonatal immune system.

Application of Polygonum minus Extract in Enhancing Drought Tolerance in Maize by Regulating Osmotic and Antioxidant System

Drought stress is a major factor affecting plant growth and crop yield production.Plant extracts as natural biostimulants hold great potential to strengthen plants to overcome drought impacts.To explore the effect of Polygonum minus extract(PME)in enhancing drought tolerance in plants,a study was set up in a glasshouse environment using 10 different treatment combinations.PME foliar application were designed in CRD and effects were closely observed related to the growth,physiology,and antioxidant system changes in maize(Zea mays L.)under well-watered and drought conditions.The seaweed extract(SWE)was used as a comparison.Plants subjected to drought stress exhibited a significant reduction in fresh weight,dry weight,relative water content(RWC),and soluble sugar,but they stimulated the phenolic,flavonoid,proline,glutathione(GSH),malondialdehyde(MDA)and antioxidant enzyme(catalase,CAT;peroxidase,POD;superoxide dismutase,SOD)activities.Foliar application of PME improved fresh and dry weight(FW:33.1%~41.4%;DW:48.0%~43.1%),chlorophyll content(Chl b:87.9%~100.76%),soluble sugar(23.6%~49.3%),and soluble protein(48.6%~56.9%)as well as antioxidant enzyme activities(CAT and POD)compared to CK under drought conditions.while decreasing the level of MDA.Notably,the mitigating effect of PME application with high concentration was more effective than those of SWE.Our study reveals that PME could alleviate drought stress by regulating osmoprotectant content and antioxidant defense system and can be used as an economical and environmentally friendly biostimulants for promoting maize growth under drought stress.

Distribution of antioxidants and phenolic compounds in flour milling fractions from hard red winter wheat

Mature wheat kernels contain three main parts:endosperm,bran,and germ.Flour milling results in multiple streams that are chemically different;however,the distribution of antioxidants and phenolic compounds has not been well documented in terms of conventional milling by-product streams.In this study,multiple analytical methods were used to investigate antioxidant activity and phenolic compound compositions of hard red winter wheat(whole ground wheat),the parts of a wheat kernel(bran,flour,germ),and wheat by-product streams(mill feed,red dog,shorts)for the first time.For each mill stream,phenolic compounds(total,flavonoid,and anthocyanin contents)were determined and antioxidant activities were evaluated with 1,1-diphenyl-2-picrylhydrazyl(DPPH)radical-scavenging activity,ferric reducing/antioxidant power(FRAP),and total antioxidant capacity assays.Significant differences(P<0.05)were observed in phenolic concentrations among fractions of bran,flour,and germ milled from the same kernels and noted that germ accounts for the majority of antioxidant properties,whereas bran contains a substantial portion of phenolic compounds and anthocyanins.Mill feed was high in phenolic content(5.29 mg FAE/g),total antioxidant capacity(866 mg/g),and antioxidant activity(up to 75% DPPH inhibition and 20.26μmol FeSO_(4)/g).The comprehensive information on distribution of antioxidants and phenolic compounds provides insights for future human consumption of commonly produced co-products from flour milling,and for selecting and using different milling fractions to make foods with improved nutritional properties.

Effect of antioxidants on the efficiency of jet milling and the powder characteristics of Sm2Co17 permanent magnets

This study investigated the effect of antioxidants on the grinding efficiency,magnetic powder characteristics,microstructure,and magnetic properties of 2:17 type SmCo permanent magnet materials.The results show that adding antioxidants helps improve the dispersion among magnetic powders,leading to a 33.3%decrease in jet milling time and a 15.8%increase in magnet powder production yield.Additionally,adding antioxidants enhances the oxidation resistance of the magnetic powders.After being stored in a constant temperature air environment at 25C for 48 h,the O content in the powder decreased by 33%compared to samples without antioxidants.While in the magnet body,the O content decreased from 0.21 wt.%to 0.14 wt.%,which helps increase the effective Sm content and domain wall pinning uniformity in the magnet.Excellent magnetic properties were obtained in the magnet with added antioxidants:B_(r)=11.6 kGs,SF=79.6%,H_(cj)=16.8 kOe,and(BH)_(max)=32.5 MGOe.

Melatonin Alleviates Abscisic Acid Deficiency Inhibition on Photosynthesis and Antioxidant Systems in Rice under Salt Stress

Melatonin and abscisic acid,as major plant hormones,play important roles in the physiological and biochemical activities of crops,but the interaction between the two under salt stress is not yet clear.This study investigated the endogenous levels of melatonin and abscisic acid in rice by using exogenous melatonin,abscisic acid,and their synthetic inhibitors,and examined their interactions under salt stress.The research results indicate that melatonin and abscisic acid can improve rice salt tolerance.Melatonin alleviated the salt sensitivity caused by abscisic acid deficiency,increased antioxidant enzyme activity and antioxidant content in rice treated with abscisic acid synth-esis inhibitors,and reduced total reactive oxygen species content and thiobarbituric acid reactive substance accu-mulation.Melatonin also increased the activity of key photosynthetic enzymes and the content of photosynthetic pigments,maintaining the parameters of photosynthetic gas exchange and chlorophyllfluorescence.In summary,melatonin alleviated the effects of abscisic acid deficiency on photosynthesis and antioxidant systems in rice and improved salt tolerance.This study is beneficial for expanding the understanding of melatonin regulation of crop salt tolerance.

Ellagic Acid Enhances Antioxidant System Activity and Maintains the Quality of Strawberry Fruit during Storage

Ellagic acid(EA)is a natural antioxidant,widely present in a lot of forms’soft fruits,nuts,and other plant tissues,and helpful for promoting human health;however,its protective effect on postharvest fruit and improving the quality index of postharvest fruit have rarely been studied.In this experiment,the strawberries were soaked in 0,100,200,300,400,and 500 mg L^(−1) EA,respectively,and the influential EA on fruit quality and the antioxidant system of strawberries were studied.Compared with the control,EA treatment can reduce the browning degree and rotting rate of strawberry fruit during storage and augment the soluble solid content(SSC).EA treatment can also increase the content of related stuff and enzyme activity in antioxidant systems;the gene expression level of polyphenol oxidase(PPO)in strawberries treated with EA was always down-regulated,correspondingly,the expression of other antioxidant enzyme genes was enhanced.Among the strawberry fruits treated with EA of different concentrations,300 mg L^(−1) EA had the best effect in the process of strawberry preservation.The results suggested that the proper concentration of exogenous EA at 300 mg L−1 could maintain strawberries’quality and enhance the antioxidant system by improving the activities of antioxidative enzymes and the ascorbateglutathione(AsA-GSH)cycle during storage.

Sodium nitroprusside as a signal molecule for up-regulating membrane characteristics,antioxidant defense system to improve flax productivity under water stress

Water stress is a critical environmental adversity that significantly impacts the growth,development,and yield of flax plants.In this study,flax seeds were cultivated under different water irrigation requirements(WIR)(100%,75%,and 50%)to investigate the effects of exogenously supplied nitric oxide(NO)donor sodium nitroprusside(SNP)as foliar treatments at concentrations of 0.0 mmol/L,0.5 mmol/L,1.0 mmol/L,and 2.0 mmol/L.Drought stress led to a significant decrease in plant growth,photosynthetic pigments,yield components such as oil and total carbohydrate percentage.It also resulted in an increase in leaf H2O2 production,lipid peroxidation levels and activities of enzymatic antioxidants including polyphenol oxidase,superoxide dismutase,and nitrate reductase enzymes.However,foliar application of SNP improved photosynthetic pigments and antioxidant defense system which mitigated the negative impact of water stress on growth and yield productivity by reducing oxidative damage caused by reactive oxygen species accumulation.The use of SNP also decreased H_(2)O_(2) accumulation levels,lipid peroxidation levels,and improved membrane stability.SNP treatment at concentration of 2 mmol/L showed superior results compared to other concentrations with extremely significant increases observed in yield characteristics such as oil content,total carbohydrate percentages,and unsaturated fatty acids to saturated fatty acids ratio.

A Systematic Review of Contrast-Induced Acute Kidney Injury

Background: Contrast-induced acute kidney injury (CI-AKI) is the third most common cause of AKI in hospitalized patients. Contrast agents mainly cause acute kidney injury through hypoxic damage to renal parenchyma and toxic effects on renal capillaries and tubules. Patients with CI-AKI are more likely to experience adverse events, including longer hospital stay and costs, longer ICU stay, and higher mortality rates. This article elaborates on the definition, epidemiology, risk factors, pathogenesis, and prevention strategies of CI-AKI. Methods: We conducted an extensive literature search using contrast agents and AKI as keywords to identify relevant studies on CI-AKI. Conclusion: CI-AKI is a significant clinical challenge that requires a multifaceted approach to prevention and management. Understanding the risk factors, pathophysiology, and current best practices is essential for healthcare providers to optimize patient care and improve outcomes in those undergoing contrast-enhanced imaging procedures. Hydration therapy is currently the main prevention method, but antioxidants may also become a new strategy.

Relationships between a Thiol-Disulfide System and Liposoluble Antioxidants with Cytogenetic Indices in Humans Exposed to Low Doses Radiation

This work presents the results of biochemical examination of people exposed to irradiation as a result of the Chernobyl catastrophe. In remote period ( in 4, 5, 6 and 7 years) after Chernobyl accident we studied the state of the redox system of glutathione(GSH, GSSG) and the response of the system of essential lipid antioxidants (vitamin E, A) in blood plasma of people of various ages. An analysis of correlations between cytogenetic indices in lymphocytes and levels of reduced glutathione and liposoluble antioxidants in the plasma of peripheral blood in children born after the Chernobyl accident and liquidators is presented. The cumulative doses for the examined group of children received by their mothers from 0.8 to 70 cSv and liquidators received, on average, the highest irradiation doses from 0.1 to 150 cSv. A complex relationship between lipo-and water-soluble antioxidants level in plasma in human population (children living in radionuclide-contaminated regions and the Chernobyl liquidators) exposed to chronic low-level radiation after the Chernobyl accident was demonstrated. The obtained experimental data indicate different responses of the human population water-and fat-soluble antioxidants system to low (from 0.1 to 20 cSv) and high (from 20 to 150 cSv) doses of ionizing radiation.

Transcriptomes of Litopenaeus vannamei reveal modulation of antioxidant system induced by dietary archaeal carotenoids

Oxidative stress induced by factors such as ammonia nitrogen has become a major issue in shrimp farming.The effects of carotenoids on the growth and antioxidant capability of Litopenaeus vannamei juveniles were investigated in this study using dietary archaeal carotenoids supplementation.For four weeks,shrimp were given diets containing 0 mg/kg(Ctrl)and 55.98 mg/kg(Car)archaeal carotenoids.Dietary archaeal carotenoids significantly enhanced the astaxanthin content in shrimp muscles and carapaces,as well as the superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activity(P<0.05).The malonaldehyde(MDA)content in Car group significantly decreased(P<0.05).The transcriptome analysis was conducted to determine the molecular processes in response to archaeal carotenoids supplementation.A total of 1536 differentially expressed genes(DEGs)were detected,including 538 upregulated DEGs and 998 downregulated DEGs.GO functional enrichment analysis between Ctrl and Car indicated that 26 GO terms including extracellular region,metabolic process,and proteolysis were enriched.The KEGG pathway enrichment analysis revealed that the amino sugar and nucleotide sugar metabolism,cysteine and methionine metabolism,glycine serine and threonine metabolism,and amino acid biosynthesis were enriched.Archaeal carotenoids influenced the expression of several important genes involved in reactive oxygen species(ROS)generation,Nrf2 signaling,and antioxidant enzymes.Seven DEGs were chosen to confirm the RNA-Seq data using qRT-PCR.The genes and pathways discovered in this work assist to elucidate the molecular processes through which archaeal carotenoid enhances L.vannamei antioxidative system.

Hydrogen Sulfide Improves Rice Seed Germination by Regulating Aluminum Absorption,Internal Antioxidant Enzyme System and Osmotic Balance under Aluminum Toxicity Conditions

Uncovering the mechanism of hydrogen sulfide(H2S)in improving rice seed germination under aluminum(Al)toxicity conditions is important for rice production in acidic soil.In the present study,an Al sensitive rice variety Kasalath was used.Pretreatment with 0.1 mmol/L sodium hydrosulfide(NaHS,H2S donor)under 70 mmol/L AlCl3(indicated as Al+NaHS treatment)increased rice seed germination by 27.95%,germination potential by 474.16%,and the germination index by 43.44%,compared with Al treatment.The treatment of Al+NaHS reduced the Al content in rice seeds by 16.31%and 32.11%and increased the internal H2S content by 3.82%and 8.90%at 3 and 5 d of treatment,respectively,compared with Al treatment.Al+NaHS treatment significantly increased the activities of superoxide dismutase(SOD)。

Effect of powdery mildew on interleaf microbial communities and leaf antioxidant enzyme systems

Chinese peony(Paeonia lactiflora Pall.)is both medicinally and aesthetically beneficial.Powdery mildew is a common fungal disease that seriously jeopardizes the value of numerous species,including peonies as a crop.In order to provide a basis for the prevention and treatment of peony powdery mildew,we examined the microbial diversity,the malondialdehyde(MDA)concentrations and antioxidant enzyme activities of peony leaves infected with three levels of powdery mildew to determine any modifications to the leaf's antioxidant enzyme systems and microbial community structure following the onset of disease.The results show that the MDA content rose as the degree of infection became worse.Antioxidant enzyme activity rose and then declined.Following the initiation of powdery mildew,fungal community diversity decreased,whereas there was not any appreciable change in bacterial communities according to microbial diversity sequencing.The relative abundance of more than half of fungal species decreased,with the bacterial genera displaying both abundant and diminished communities with less pronounced alterations in their community structure after the disease spread.Significant different taxa that were critical to the organization of each microbiome were found.Correlation analysis showed that the relative abundance of powdery mildew pathogenic fungal genus Erysiphe was correlated with those of 11 fungal genera and one bacterial genus.Among them,Aureobasidium,Neosetophoma and Sclerostagonospora showed significant positive correlations with Erysiphe and MDA.

Endophytic Bacteria Promote the Growth of Suaeda glauca in Saline-Alkali Stress:Regulation of Osmotic Pressure and Antioxidative Defense System

Endophytic bacteria are promising bacterial fertilizers to improve plant growth under adverse environment.For ecological remediation of coastal wetlands,it was necessary to investigate the effect and interaction of endophytes on halophytes under saline-alkali stress.In this study,an endophytic bacterium strain HK1 isolated from halophytes was selected to infect Suaeda glauca under pH(7 and 8)and salinity gradient(150,300 and 450mmolL^(-1)).Strain HK1 was identified as Pantoea ananatis and it had ability to fix nitrogen,dissolve inorganic phosphorus and produce indole-3-aceticacid(IAA).The results showed that strain HK1 could promote the growth of S.glauca seedings when the salinity was less than 300mmolL^(-1),in view of longer shoot length and heavier fresh weight.The infected plants could produce more proline to decrease the permeability of cells,which content increased by 26.2%–61.1%compared to the non-infected group.Moreover,the oxidative stress of infected plants was relieved with the malondialdehyde(MDA)content decreased by 16.8%–32.9%,and the peroxidase(POD)activity and catalase(CAT)activity increased by 100%–500%and 6.2%–71.4%,respectively.Statistical analysis revealed that increasing proline content and enhancing CAT and POD activities were the main pathways to alleviate saline-alkali stress by strain HK1 infection,and the latter might be more important.This study illustrated that endophytic bacteria could promote the growth of halophytes by regulation of osmotic substances and strengthening antioxidant activities.This finding would be helpful for the bioremediation of coastal soil.

Terpenes extracted from marine sponges with antioxidant activity:a systematic review

Marine biodiversity has emerged as a very promising resource of bioactive compounds and secondary metabolites from different sea organisms.The sponge’s secondary metabolites demonstrated various bioactivities and potential pharmacological properties.This systematic review of the literature focuses on the advances achieved in the antioxidant potential of marine sponges in vitro.The review was performed in accordance with PRISMA guidelines.The main inclusion criterion for analysis was articles with identification of compounds from terpene classes that demonstrate antioxidant activity in vitro.Searching in three different databases,two hundred articles were selected.After screening abstracts,titles and evaluating for eligibility of manuscripts 14 articles were included.The most performed analyzes to detect antioxidant activity were scavenging activity 2,2-diphenyl-1-picrylhydrazyl(DPPH)and measurement of intracellular reactive oxygen species(ROS).It was possible to identify 17 compounds of the terpene class with pronounced antioxidant activity in vitro.Scientific evidence of the studies included in this review was accessed by the GRADE analysis.Terpenes play an important ecological role,moreover these molecules have a pharmaceutical and industrial application.

Inoculation of Chlorella and Food Waste Improves the Physio-Morphological Features of Red Pepper by Regulating Activating Antioxidant Defense System

Food waste is recognized as a valuable source for potential agricultural applications to supply organic matter and nutrients to arable soil.However,the information on the combined application of food waste and the plant growth-promoting bacterial strain,Chlorella,related to plant metabolic features and sodium chloride content in arable soil is limited.The present study was conducted to investigate the exogenous application of food waste along with Chlorella,which improved the physio-morphological features of red pepper.Our results revealed that this combination enhanced the organic matter in the soil,ultimately improving the fertility rate of the soil,and the physio-morphological features,such as chlorophyll a content(24.5±0.7),root(7.8±0.7)cm and shoot length(12.1±0.7)cm,fresh weight(2.1±0.05)g,dry weight(0.19±0.05)g,mineral contents,and hormonal concentration(ABA by up to 2 folds).The combined treatment also minimized free radicals via the activation of the intrinsic antioxidant series cascade and electrolyte leakage.Our findings showed that adding Chlorella and food wastes improved growth characteristics and can be used as a green bio-fertilizer for sustainable agriculture.

Dual Role of Plant Phenolic Compounds as Antioxidants and Prooxidants

Natural phenolic compounds are secondary metabolites found in a wide range of plants including food crops. As many of them are known to be antioxidants and can prevent several chronic and degenerative diseases in humans, they are a part of a healthy diet. However, these antioxidants can act as prooxidants under high phenolic concentration, high pH, or in the presence of transition metal ions such as Cu2+ or Fe3+, producing reactive oxygen species (ROS) including hydroxyl radicals resulting in oxidative stress and cell toxicity. While this can lead to pathogenesis including the development of various types of cancers, elevated levels of ROS are beneficial to kill malignant cells and foodborne pathogens to improve food safety. Thus, the dual nature of phenolic compounds allows them to act as antioxidants and prooxidants. Similarly, depending on the level of prooxidant activity, ROS can induce either pathogenesis or serve as a potential agent to kill malignant cells and foodborne pathogens.

Drought-Mediated Modulation in Metabolomic Profiling of Nigella Sativa Leaf, Growth, Ecophysiology and Antioxidants

Abiotic stresses,including drought,have been found to affect the growth and medicinal quality of numerous herbs.The proposed study aims to study the effects of different drought regimes on the metabolic profile,growth,ecophysiology,cellular antioxidants,and antioxidant potential of Nigella sativa(Black cumin)leaf.Forty-day-old seedlings of N.sativa were exposed to three regimes of drought(control,moderate and high)for a week.UPLCMS/MS metabolic profile of the leaf reveals the presence of more than a hundred metabolites belonging to anthocyanins,chalcones,dihydro flavonoids,flavonoids,flavanols,flavones,flavonoid carbonoside,isoflavones,etc.Drought was found to alter the contents of identified metabolites.Drought stress-induced oxidative stress and increased production of hydrogen peroxide and superoxide anions.Physiological changes,activities of antioxidant enzymes,contents of antioxidants,and proline were significantly high under drought to protect against the low water regimes.Furthermore,stressed leaf extract had higher antioxidant potential.Thus,N.sativa leaf bears multiple metabolic pathways and can tolerate a higher degree of drought or osmotic stress.

Silicon and Nitric Oxide-Mediated Regulation of Growth Attributes, Metabolites and Antioxidant Defense System of Radish (Raphanus sativus L.) under Arsenic Stress

Arsenic(As)contaminated food chains have emerged as a serious public concern for humans and animals and are known to affect the cultivation of edible crops throughout the world.Therefore,the present study was designed to investigate the individual as well as the combined effects of exogenous silicon(Si)and sodium nitroprusside(SNP),a nitric oxide(NO)donor,on plant growth,metabolites,and antioxidant defense systems of radish(Raphanus sativus L.)plants under three different concentrations of As stress,i.e.,0.3,0.5,and 0.7 mM in a pot experiment.The results showed that As stress reduced the growth parameters of radish plants by increasing the level of oxidative stress markers,i.e.,malondialdehyde and hydrogen peroxide.However,foliar application of Si(2 mM)and pretreatment with SNP(100μM)alone as well as in combination with Si improved the plant growth parameters,i.e.,root length,fresh and dry weight of plants under As stress.Furthermore,As stress also reduced protein,and metabolites contents(flavonoids,phenolic and anthocyanin).Activities of antioxidative enzymes such as catalase(CAT),ascorbate peroxidase(APX),guaiacol peroxidase(POD),and polyphenol oxidase(PPO),as well as the content of non-enzymatic antioxidants(glutathione and ascorbic acid)decreased under As stress.In most of the parameters in radish,As III concentration showed maximum reduction,as compared to As I and II concentrations.However,the individual and combined application of Si and NO significantly alleviated the As-mediated oxidative stress in radish plants by increasing the protein,and metabolites content.Enhancement in the activities of CAT,APX,POD and PPO enzymes were recorded.Contents of glutathione and ascorbic acid were also enhanced in response to co-application of Si and NO under As stress.Results obtained were more pronounced when Si and NO were applied in combination under As stress,as compared to their individual application.In short,the current study highlights that Si and NO synergistically regulate plant growth through lowering the As-mediated oxidative stress by upregulating the metabolites content,activity of antioxidative enzymes and non-enzymatic antioxidants in radish plants.

Effects of Manganese on the Antioxidant System and Related Gene Expression Levels in the “Hong Yang” Kiwifruit Seedlings

To explore how manganese affects the antioxidant system and the expression levels of related genes of“Hong yang”seedlings,the leaves of its tissue cultured seedlings were taken as test materials,and single factor treatment was performed by changing the manganese chloride(MnCl_(2)·4H_(2)O)solution concentration when spraying the leaves.The expression levels of Mn-SOD,POD64 and POD27 genes in leaves were quantitatively analyzed by real-time quantitative PCR(qRT-PCR)at different determination times.Meanwhile,the contents of malondial-dehyde(MDA),hydrogen peroxide(H_(2)O_(2)),the activities of antioxidant enzymes,including catalase(CAT),peroxidase(POD),and superoxide dismutase(SOD).The results showed that the SOD,CAT,POD,ascorbate peroxidase(APX),and reduced glutathione(GSH)activities in leaves were the highest at 12 h post-treatment with 50μM MnCl_(2)·4H_(2)O.Furthermore,the contents of MDA and H_(2)O_(2) in leaves also peaked when the concentration of H_(2)O_(2) is 50μM,which is the minimum value.Additionally at 50μM Mn^(2+),the Mn-SOD and POD27 expression was up-regulated as compared to the control,which promoted the expression of their respective enzyme activities.However,POD64 expression increased with the increasing Mn^(2+) concentration.Therefore,50μM is the optimal concentration of Mn when exogenously applied on“Hong yang”,which improve the antioxidant enzyme activity and regulate the plant’s physiological and biochemical functions.