Exogenous melatonin enhances heat stress tolerance in sweetpotato by modulating antioxidant defense system,osmotic homeostasis and stomatal traits

Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular membranes.Therefore,the development of efficient approaches for mitigating heat-related impairments is essential for the long-term production of sweetpotatoes.Melatonin has been recognised for its capacity to assist plants in dealing with abiotic stress conditions.This research aimed to investigate how different doses of exogenous melatonin influence heat damage in sweetpotato plants.Heat stress drastically affected shoot and root fresh weight by 31.8 and 44.5%,respectively.This reduction resulted in oxidative stress characterised by increased formation of hydrogen peroxide(H_(2)O_(2))by 804.4%,superoxide ion(O_(2)^(·-))by 211.5%and malondialdehyde(MDA)by 234.2%.Heat stress also reduced chlorophyll concentration,photosystemⅡefficiency(F_v/F_m)by 15.3%and gaseous exchange.However,pre-treatment with 100μmol L^(-1)melatonin increased growth and reduced oxidative damage to sweetpotato plants under heat stress.In particular,melatonin decreased H_(2)O_(2),O_(2)^(·-)and MDA by 64.8%,42.7%and 38.2%,respectively.Melatonin also mitigated the decline in chlorophyll levels and improved stomatal traits,gaseous exchange and F_(v)/F_(m)(13%).Results suggested that the favorable outcomes of melatonin treatment can be associated with elevated antioxidant enzyme activity and an increase in non-enzymatic antioxidants and osmo-protectants.Overall,these findings indicate that exogenous melatonin can improve heat stress tolerance in sweetpotatoes.This stu dy will assist re searchers in further investigating how melatonin makes sweetpotatoes more resistant to heat stress.

Exogenous Alpha-Ketoglutarate(AKG)Modulate Physiological Characteristics,Photosynthesis,Secondary Metabolism and Antioxidant Defense System in Peganum Harmala L.under Nickel Stress

Nickel(Ni)toxicity significantly impairs plant growth,photosynthesis,and metabolism by inducing oxidative stress.This study evaluates the potential of exogenous Alpha-Ketoglutarate(AKG)in mitigating Ni-induced stress in Peganum harmala L.Seedlings were exposed to 0,200,500,and 750μM NiCl2,with or without AKG supplementation.Under 750μM Ni stress,dry weight(DW)decreased by 33.7%,tissue water content(TWC)by 39.9%,and chlorophyll a and total chlorophyll levels were reduced by 17%and 15%,respectively.Ni exposure also significantly increased secondary metabolite production,with leaf anthocyanin content rising by 131%,and superoxide dismutase(SOD)and catalase(CAT)activities increasing by 228%and 53%,respectively,in roots at 500μM Ni.AKG treatment alleviated Ni toxicity by enhancing TWC by 39%and promoting root and shoot growth.Additionally,AKG treatment boosted the synthesis of phenolic compounds and flavonoids,contributing to improved tolerance against Ni stress.These findings demonstrate the potential of AKG in enhancing Ni tolerance in P.harmala,suggesting its promising role in bioremediation of metal-contaminated soils.This is the first study to report the beneficial effects of exogenous AKG in alleviating nickel toxicity in P.harmala L.,offering a new approach for improving plant resilience to heavy metal stress.

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.

Hydroxyethyl starch conjugates co-assembled nanoparticles promote photodynamic therapy and antitumor immunity by inhibiting antioxidant systems

Photodynamic therapy(PDT)can produce high levels of reactive oxygen species(ROS)to kill tumor cells and induce antitumor immunity.However,intracellular antioxidant systems,including glutathione(GSH)system and thioredoxin(Trx)system,limit the accumulation of ROS,resulting in compromised PDT and insufficient immune stimulation.Herein,we designed a nanomedicine PtHPs co-loading photosensitizer pyropheophorbide a(PPa)and cisplatin prodrug Pt-COOH(Ⅳ)(Pt(Ⅳ))based on hydroxyethyl starch(HES)to inhibit both GSH and Trx antioxidant systems and achieve potent PDT as well as antitumor immune responses.Specifically,HES-PPa and HES-Pt were obtained by coupling HES with PPa and Pt(Ⅳ),and assembled into nanoparticle PtHPs by emulsification method to achieve the purpose of co-delivery of PPa and Pt(Ⅳ).PtHPs improved PPa photostability while retaining PPa photodynamic properties.In vitro experiments showed that PtHPs reduced GSH,inhibited Trx system and had better cell-killing effect and ROS generation ability.Subcutaneous tumormodels showed that PtHPs had good safety and tumor inhibition effect.Bilateral tumor models suggested that PtHPs promoted the release of damage-associated molecular patterns and the maturation of dendritic cells,induced T cell-mediated immune responses,and thus suppressed the growth of both primary and distal tumors.This study reports a novel platinum-based nanomedicine and provides a newstrategy for boosting PDT therapy-mediated antitumor immunity by overcoming intrinsic antioxidant systems.

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.

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.

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.

Antioxidant and lipoxygenase inhibitory properties of a novel flavonoid from Pistacia chinensis Bunge and its molecular docking analysis

Background:Pistacia chinensis Bunge has been traditionally used to manage various conditions,including asthma,pain,inflammation,hepatoprotection,and diabetes.The study was conducted to investigate the antioxidant and anti-lipoxygenase(LOX)properties of the isolated compound 2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4H-chromen-4-one from Pistacia chinensis.Methods:LOX assay and antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl(DPPH)assay were performed.Molecular docking studies were conducted using a molecular operating environment.Results:The LOX assay revealed significant inhibitory effects at 0.2µM concentration,with an IC50 value of 37.80µM.The antioxidant effect demonstrated dose-dependency across 5 to 100µg/mL concentrations,reaching 93.09%at 100µg/mL,comparable to ascorbic acid’s 95.43%effect.Molecular docking studies highlighted strong interactions with the lipoxygenase enzyme,presenting an excellent docking score of-10.98 kcal/mol.Conclusion:These findings provide valuable insights into Pistacia chinensis’chemical components and biological effects,reinforcing its traditional medicinal applications.

Response surface optimization of preparation parameters and evaluation of the antioxidant and antihypertensive activities of Spirulina protein hydrolysates

Safety,high protein content,and the numerous health benefits make Spirulina an outstanding source of bioactive peptides.Peptides from Spirulina,which exhibit antioxidant,anti-inflammatory,and antihypertensive effects,may assist in the management of cardiovascular diseases(CVDs).Here,we present the optimization of enzyme-digested hydrolysates derived from Spirulina sp.by using response surface methodology(RSM).We also evaluated the biological activity of Spirulina protein hydrolysates(SPHs)in contributing to the amelioration of hypertension and associated cardiovascular diseases.Our findings suggest that Spirulina protein extracts contain a complex proteinaceous composition with phycocyanin being the dominant protein,as evidenced by both SDS-PAGE and LC-MS/MS profiling.Alkaline protease,protease K,andα-chymotrypsin exhibited a substantial hydrolytic effect on Spirulina protein,taking into account their degree of hydrolysis(DH),peptide yield,and molecular weight distribution.Single-factor experiments identified pH,temperature,and enzyme/substrate ratio as the key factors influencing DH.Moreover,optimal hydrolysis conditions for the proteases were determined via RSM,leading to a considerable enhancement of the actual DH.Bioassays showed that SPHs have strong antioxidant activity against various free radicals,with a higher ability to scavenge hydroxyl radicals.Furthermore,SPHs inhibited macrophage nitric oxide secretion and significantly inhibited angiotensin I-converting enzyme in vitro at 400μg/mL.It is worth noting that SPHs prepared with protease K exhibited a potent anti-hypertensive effect in vivo.The findings indicate the potential usefulness of including dietary SPHs in preventing hypertension and associated CVDs.This research could be valuable in guiding the development of health-promoting foods within the Spirulina industry.

Understanding Investigational Perspective of Antioxidant and Antibacterial Properties of Rice

Whole-grain rice has gained significant attention for its potential health benefits,particularly because of its antioxidant and antibacterial properties.Despite this growing interest,there remains a pressing need for a comprehensive evaluation of the methods used to analyze these bioactive compounds,considering the diversity of rice types and the influence of environmental factors.This review aims to provide an in-depth overview of recent analytical methods,particularly those employed over the last five years,to assess the antioxidant and antibacterial properties of rice.It focuses on commonly used antioxidant assays,such as the 2,2-diphenyl-1-picrylhydrazyl(DPPH)radical scavenging activity assay,which encompasses both single electron transfer and hydrogen atom transfer mechanisms.Other antioxidant assays are also discussed,alongside methods used to evaluate antibacterial properties,including disc diffusion,well diffusion,broth or agar dilution,and advanced techniques such as flow cytofluorometric and bioluminescent assays.The review further explores the bacterial strains most frequently studied,including Bacillus cereus,Listeria monocytogenes,Escherichia coli,and Salmonella species.It highlights the key techniques and parameters employed to ascertain and quantify the antioxidant and antibacterial potential of rice,while critically analysing the strengths and limitations of these approaches.By synthesizing current methods and offering insights into their application,this review can be served as a guide for future research aimed at standardizing and improving the assessment of rice’s bioactive properties,paving the way for broader scientific and practical applications.

Effects of Relative Soil Water Content on Antioxidant Enzyme System in Malus sieversii(Lebed.) Roem

By pot experiment under artificially simulated water stress conditions, soluble protein content, MDA content and SOD, POD, CAT and APX activities in Malus sieversfi leaves were determined to reveal the response mechanism of M. sieversii to changes of relative soil water content. According to the results, with the decrease of relative soil water content, MDA content in M. sieversii leaves increased by mem- brane lipid peroxidation. Cells resist water stress-induced membrane lipid peroxidation and clear the increased reactive oxygen species by improving soluble protein content and SOD, POD, CAT and APX activities. However, various enzymes were involved in the response to water stress under different moisture conditions. In addition, the results indicated that M. sieversii had a good adaptability to higher relative soil water contents.

Effect of Botryosphaeria berengeriana f.sp.piricola and Biocontrol Bacteria on the System of Antioxidant Enzymes in Pears

[Objective] The aim was to understand defense mechanism of pear after inoculated Botryosphaeria berengeriana f. sp. piricolan and mechanism of antioxidant enzymes of biocontrol bacteria. [Method] Pears were treated by Botryosphaeria berengeriana f. sp. piricolan and bio control bacteria, and the change of antioxidant enzymes were determined. [Result] The biocontrol bacteria had little effect on MDA;the content of MDA treated by B. berengeriana reached high peak in 48 h, was 10.22nmol/g which was 1.86 times of CK; the content of MDA treated by B. berengeriana and biocontrol bacteria reached high peak in 24 h, was 8.92 nmol/g which was1.62 times of CK. The content of SOD treated by biocontrol bacteria reached high peak in 48 h, was 126.69 U/[g（FW）·min] which was 1.54 times of CK; the contents of SOD treated by B. berengeriana as well as B. berengeriana and biocontrol bacteria reached high peak in 24 h, were 122.10 and 135.32 U/[g（FW）·min] which were 1.48 and 1.65 times of CK respectively; the contents of POD on biocontrol bacteria treatment, B. ana treatment as well as B. berengeriana and biocontrol bacteria treatment reached high peak in 24 h, were 385.34, 342.50 and 290.00 U/[g（FW）·min] which were 1.83, 1.62 and 1.38 times of CK respectively. The contents of CAT on biocontrol bacteria treatment, B. rengeriana treatment as well as B. berengeriana and biocontrol bacteria treatment reached high peak in 6 h, were 133.33,114.17 and 113.35 U/[g（FW）·min] which were 1.33, 1.14 and 1.13 times of CK respectively. The biocontrol bacteria had little difference in CK; the content of PPO of B. berengeriana treatment reached high peak in 12 h, was 81.86 U/[g（FW）·min]which was 1.76 times of CK; B. berengeriana and biocontrol bacteria treatment reached high peak in 24 h, was 70.00 U/[g（FW）·min] which was 1.50 times of CK.[Conclusion] B. berengeriana and biocontrol bacteria had more effect on MDA; both B. berengeriana and biocontrol bacteria could increase the excitation of SOD enzyme activity; both B. berengeriana and biocontrol bacteria could increase the excitation of POD enzyme activity; both B. berengeriana and biocontrol bacteria could increase the excitation of CAT enzyme activity; using biocontrol bacteria alone had not obvious effect on PPO, B. berengeriana could increase the excitation of PPO enzyme activity.

Antioxidant System of the Intertidal Mollusk Littorina kurila in Its Natural Habitat

Based on the theory of oxidative stress, it is believed that the induction of antioxidant components of the cellular defense system reflects the adaptive compensatory response of an organism aimed at overcoming stressful conditions. Therefore, this work concentrated on investigating the effect of the low and high tides on the antioxidant system of L. （Littorina） kurila and also compared the antioxidant parameters of two species of gastropods： intertidal--L, kurila and subtidal--L, squalida. The following parameters were evaluated in the hepatopancreas of mollusks： the activity of the antioxidant enzymes SOD （superoxide dismutase）, CAT （catalase）, and GR （glutathione reductase）, the production of ROS （reactive oxygen species）, and the levels of GSH （glutathione） and the lipid peroxidation product-MDA （malondialdehyde）. The results of this work indicate that the state of the antioxidant system of L. kurila reflected the adaptive capacity of the species in the changing environmental conditions.

Effects of Drought Stress on Antioxidant System of Leaves from Different Citrus Rootstocks

[Objective] The paper aims to study the effects of drought stress on antioxidation system of different Citrus rootstock leaves. [Method] Potted plant experiments were carried out to control the water content of soil in pots,in order to investigate the effects of drought stress on antioxidation system activity （SOD,POD and CAT） and the content of protein,GSH,MDA and O-·2 from the leaves of Shandong Zhike,Ningminju,Yangshuojinbaosuanju,Huapijinju and Guizhi No.1. [Result] The content of chlorophyll a,chlorophyll b and chlorophyll （a＋b） from the test 5 breeds decreased with the enhancement of drought stress,and there were significant differences between them and the control under the severe stress; the activities of SOD,POD and CAT from the 5 breeds increased as the drought stress strengthened; the content of soluble protein declined while that of GSH,MDA and O-·2 rose because of the drought stress. [Conclusion] This research provided a good reference to choose the breeds of citrus rootstocks in arid and semi-arid areas.

Effect of Soil Drought Stress on Leaf Water Status, Membrane Permeability and Enzymatic Antioxidant System of Maize

A simulation experiment on the responses of maize (Zea mays L.) from the third leaf stage to maturity for different soil water levels (well-watered, moderately stressed, and severely stressed) was conducted by controlling irrigation and using a mobile rain shelter in a neutral loam, meadow soil to determine the effects on leaf water status, membrane permeability and enzymatic antioxidant system for different growth stages. The results indicated that drought stress relied on drought intensity and duration, with more severe drought stress creating more serious effects on maize. Compared with well-watered conditions, during the silking and blister stages moderate stress did not significantly change the relative water content (RWC) and did change significantly the relative conductivity (RC) (P < 0.05) of the leaves; however, severe stress did significantly decrease (P < 0.01) the leaf RWC and increase (P < 0.01) membrane permeability (leaf relative conductivity). Furthermore, under severe drought stress antioxidant enzyme activities declined significantly (P < 0.01) in later stages, namely for superoxide dismutase (SOD) the tasseling and blister stages, for peroxidase (POD) the milk stage, and for catalase (CAT) during the tasseling, blister, and milk stages. Meanwhile, membrane lipid peroxidation (measured as malondialdehyde content) significantly increased (P < 0.01) in all stages.

Effect of methoxychlor on antioxidant system of goat epididymal sperm in vitro

Aim: To evaluate the effect of methoxychlor on the antioxidant system of goat epididymal sperm. Methods:Epididymis of adult goat was obtained from local slaughter houses and sperm were collected by chopping the epididymisin modified Ringer's phosphate solution (RPS). After several washings, the sperm samples were dispersed in RPS andincubated with methoxychlor (1μmol/L, 10μmol/L and 100μmol/L) and methoxychlor + vitamin C (100μmol/Leach) for 3 h at 32℃. After incubation, the sperm motility and viability were assessed. An aliquot of sperm samplewas homogenized, centrifuged and used for the assay of superoxide dismutase, glutathione peroxidase, glutathione re-ductase and lipid peroxidation. Results; In methoxychlor-incubated sperm and in sperm co-incubated with methoxy-chlor and vitamin C, the sperm motility and viability showed no significant changes as compared to the correspondingcontrols. In methoxychlor-incubated sperm the activity of superoxide dismutase, glutathione reductase and glutathioneperoxidase were decreased while lipid peroxidation was increased in a dose-dependent manner. Co-incubation of spermwith methoxychlor and vitamin C showed no changes in the activity of superoxide dismutase, glutathione reductase andglutathione peroxidase and in the level of lipid peroxidation. Conclusion; Methoxychlor induced oxidative stress inepididymal sperm of goats by decreasing the levels of antioxidant enzymes. Co-incubation of sperm with methoxychlorand vitamin C, a natural antioxidant, reversed the effect of methoxychlor. (Asian J Androl 2001 Dec; 3; 285 - 288)

Antioxidant therapy in the management of acute,chronic and post-ERCP pancreatitis:A systematic review

We systematically reviewed the clinical trials which recruited antioxidants in the therapy of pancreatitis and evaluated whether antioxidants improve the outcome of patients with pancreatitis. Electronic bibliographic databases were searched for any studies which investigated the use of antioxidants in the management of acute pancreatitis （AP） or chronic pancreatitis （CP） and in the prevention of post-endoscopic retrograde cholangio-pancreatography （post-ERCP） pancreatitis （PEP） up to February 2009. Twenty-two randomized, placebo-controlled, clinical trials met our criteria and were included in the review. Except for a cocktail of antioxidants which showed improvement in outcomes in three different clinical trials, the results of the administration of other antioxidants in both AP and CP clinical trials were incongruent and heterogeneous.Furthermore, antioxidant therapy including allopurinol and N-acetylcysteine failed to prevent the onset of PEP in almost all trials. In conclusion, the present data do not support a benefit of antioxidant therapy alone or in combination with conventional therapy in the management of AP, CP or PER Further double blind, randomized, placebo-controlled clinical trials with large sample size need to be conducted.

Effect of lindane on testicular antioxidant system and steroidogenic enzymes in adult rats

Aim: To find out the effect of lindane on testicular antioxidant system and testicular steroidogenesis in adult malerats. Methods: Adult male rats were orally administered with lindane at a dose of 5.0 mg/kg body weight per dayfor 30 days. Twenty-four hours after the last treatment the rats were killed using anesthetic ether. Testes, epididymis,seminal vesicles and ventral prostate were removed and weighed. A 10% testicular homogenate was prepared and cen-trifuged at 4℃. The supernatant was used for various biochemical estimations. Results; The body weight and theweights of testes, epididymis, seminal vesicles and ventral prostate were reduced in lindane-treated rats. There was asignificant decline in the activities of antioxidant enzymes superoxide dismutase (SOD), catalase and glutathione reduc-tase while an increase in hydrogen peroxide (H_2O_2) generation was observed. The specific activities of testicularsteroidogenic enzymes 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase were decreased. Thelevels of DNA, RNA and protein were also decreased in lindane-treated rats. Conclusion: Lindane induces oxida-tive stress and decreases antioxidant enzymes in adult male rats.

Free radicals and antioxidant systems in reflux esophagitis and Barrett's esophagus

AIM: Experimental studies suggest that free radicals are involved in acid and pepsin-induced damage of esophageal mucosa. The profile and balance between free radicals and antioxidant systems in human esophagitis are unknown. METHODS: Superoxide anion and its powerful oxidant reaction with nitric oxide (peroxynitrite) generation were determined in esophageal mucosal biopsies from 101 patients with different gastro-esophageal reflux diseases and 28 controls. Activity of both superoxide dismutase (SOD) and catalase, and reduced glutathione (GSH) levels, were also assessed. Expression of Cu,ZnSOD, MnSOD and tyrosine-nitrated MnSOD were analyzed by Western blot and/or immunohistochemistry. RESULTS: The highest levels of superoxide anion generation were found in patients with severe lesions of esophagitis. Peroxynitrite generation was intense in Barrett's biopsies, weaker in esophagitis and absent/weak in normal mucosa. Expression of Cu,ZnSOD and MnSOD isoforms were present in normal mucosa and increased according to the severity of the lesion, reaching the highest level in Barrett's esophagus. However, SOD mucosal activity significantly decreased in patients with esophagitis and Barrett's esophagus, which was, at least in part, due to nitration of its tyrosine residues. Catalase activity and GSH levels were significantly increased in mucosal specimens from patients with esophagitis and/or Barrett's esophagus. CONCLUSION: A decrease in SOD antioxidant activity leading to increased mucosal levels of superoxide anion and peroxynitrite radicals may contribute to the development of esophageal damage and Barrett's esophagus in patients with gastroesophageal reflux. Administration of SOD may be a therapeutic target in the treatment of patients with esophagitis and Barrett's esophagus.

Hepatoprotective effects of Nigella sativa L and Urtica dioica L on lipid peroxidation, antioxidant enzyme systems and liver enzymes in carbon tetrachloride-treated rats

AIM： To investigate the effects of Nigella sativa 1 （NS） and Urtica dioica 1 （UD） on lipid peroxidation, antioxidant enzyme systems and liver enzymes in CCl4-treated rats. METHODS： Fifty-six healthy male Wistar albino rats were used in this study. The rats were randomly allotted into one of the four experimental groups： A （CCl4-only treated）, B （CCl4＋UD treated）, C （CCl4＋NS treated） and D （CCl4＋UD＋NS treated）, each containing 14 animals. All groups received CCl4 （0.8 mL/kg of body weight, sc, twice a week for 60 d）. In addition, B, C and D groups also received daily i.p. injections of 0.2 mL/kg NS or/and 2 mL/kg UD oils for 60 d. Group A, on the other hand, received only 2 mL/kg normal saline solution for 60 d. Blood samples for the biochemical analysis were taken by cardiac puncture from randomly chosen-seven rats in each treatment group at beginning and on the 60th d of the experiment. RESULTS： The CCl4 treatment for 60 d increased the lipid peroxidation and liver enzymes, and also decreased the antioxidant enzyme levels. NS or UD treatment （alone or combination） for 60 d decreased the elevated lipid peroxidation and liver enzyme levels and also increased the reduced antioxidant enzyme levels. The weight of rats decreased in group A, and increased in groups B, C and D. CONCLUSION： NS and UD decrease the lipid peroxidation and liver enzymes, and increase the antioxidant defense system activity in the CCl4-treated rats.