Chemical characterization of the avenanthramide-rich extract from oat and its effect on D-galactose-induced oxidative stress in mice

The present study was to characterize the avenanthramide-rich extract (ARE) from oat bran and assess its effect on activity and gene expression of antioxidant enzymes in D-galactose-induced oxidative-stressed mice. High-performance liquid chromatography (HPLC) analysis found that ARE had 6.07% N-(3',4'-dihydroxycinnamoyl)-5-hydroxyanthranilic acid (Bc), 4.37% N-(4'-hydroxycinnamoyl)-5-hydroxyanthranilic acid (Bp), and 5.36% N-(4'-hydroxy-3'-methoxycinnamoyl)-5-hydroxyanthranilic acid (Bf). In addition, ARE was also rich in vanillic acid (0.60%), caffeic acid (0.50%), syringic acid (0.54%), p-coumaric acid (0.16%), ferulic acid (0.08%), and sinapic acid (0.03%). Administration of D-galactose markedly lowered not only the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) but also the gene expression of manganese superoxide dismutase (SOD), copper-zinc SOD, glutathione peroxidase (GPx), and lipoprotein lipase (LPL) mRNA in mice. Administration of ARE significantly reversed the D-galactose-induced oxidative stress by increasing the activity of the antioxidant enzymes and upregulating their gene expression. This was accompanied by a significant decrease in the malondialdehyde (MDA) level in mice given ARE compared to the control. The results demonstrated that ARE possessed the antioxidant activity and was effective against D-galactose-induced oxidative stress.     

Effect of diallyl sulfide on in vitro and in vivo Nrf2-mediated pulmonic antioxidant enzyme expression via activation ERK/p38 signaling pathway

Increasing oxidative stress is intimately involved in the pathogenesis of lung failure. Nuclear factor-erythroid 2 related factor 2 (Nrf2) is a key element in redox homeostasis. Nrf2 regulates antioxidant-associated genes that are often the target of phytochemicals in chemoprevention. This study evaluated the effect of diallyl sulfide (DAS), which is present in garlic, on the expression of antioxidant enzymes in the rat lung and the Nrf2 modulation in MRC-5 lung cells. DAS increased the activities of glutathione S-transferase, glutathione reductase, and catalase as well as the GSH/GSSG ratio compared with the lung of untreated control rats (p < 0.05). The pulmonic superoxide dismutase, glutathione peroxidase, NAD(P)H:quinone oxidoreductase 1, and catalase mRNA levels were also significantly increased (p < 0.05) after DAS treatment. Following DAS treatment, DAS level was measured in the plasma after 7 days of oral administration, and the C(max) value was 15 ± 4.2 μM. The total amount of pulmonic Nrf2 and the nuclear translocation of Nrf2 were elevated in DAS-treated rats, clarifying the effect of DAS on the modulation of antioxidant enzymes. Furthermore, DAS could induce nuclear translocation of Nrf2 via ERK/p38 signaling pathway in lung MRC-5 cells. This study demonstrates that DAS administration can significantly induce the activity of antioxidant enzymes in rat lungs and suggests a possible use for DAS as a dietary preventive agent against oxidative stress-induced lung injury.     

Effects of dietary sodium selenite and selenium yeast on antioxidant enzyme activities and oxidative stability of chicken breast meat

The effects of sodium selenite (SS) and selenium yeast (SY) alone and in combination (MS) on the selenium (Se) content, antioxidant enzyme activities (AEA), total antioxidant capacity (TAC), and oxidative stability of chicken breast meat were investigated. The results showed that the highest (p < 0.05) glutathione peroxidase (GSH-Px) activity was found in the SS-supplemented chicken breast meat; however, SY and MS treatments significantly increased (p < 0.05) the Se content and the activities of catalase (CAT), total superoxide dismutase (T-SOD), and TAC, but decreased (p < 0.05) the malondialdehyde (MDA) content at 42 days of age. Twelve days of storage at 4 °C decreased (p < 0.05) the activity of the GSH-Px, but CAT, T-SOD, and TAC remained stable. SY decreased the lipid oxidation more effectively in chicken breast meat. It was concluded that SY and MS are more effective than SS in increasing the AEA, TAC, and oxidative stability of chicken breast meat.     

Boron stress,oxidative damage and antioxidant protection in potato cultivars (Solanum tuberosum L.)

Six potato cultivars grown in Turkey in boron-prone areas and differing in their tolerance towards high boron were studied to reveal whether boron causes oxidative stress. To assess stress level, chlorophyll fluorescence and growth parameters were measured. Oxidative damage was assessed as malondialdehyde level, and antioxidant protection was evaluated as ascorbate (AA), dehydroascorbate, reduced glutathione (GSH) and oxidized glutathione amounts and superoxide dismutase, catalase, ascorbate peroxidase (APX) and glutathione reductase (GR) activities. High boron stress affected photosynthesis negatively in a threshold-dependent manner and inhibited growth. No pronounced changes in oxidation of lipids occurred in any cultivar. Activation of APX suggested the involvement of an ascorbic acid–reduced glutathione cycle in the protection against oxidative stress caused by high boron. Efficient work of this antioxidant system was probably hindered by boron complexation with NAD(P)⁺/NAD(P)H and resulted in the inhibition of GR and a decrease in AA and GSH. Hence, oxidative stress associated with high boron is a secondary component of boron toxicity which arises from metabolic changes caused by boron interference with major metabolites. Potato cultivars tolerate excess boron stress well and show damage only in very high boron concentrations. The potato cvs best suited for high boron soils/breeding purposes are cvs Van Gogh and Agria.

Abbreviations: AA: ascorbic acid; APX: ascorbate peroxidase; CAT: catalase; DHA: dehydroascorbic acid; DHAR: dehydroascorbate reductase; DTNB: 5; 5′-dithiobis-2-nitrobenzoic acid; DTT: dithiotreitol; F_v/F_m: photosynthetic efficiency at the dark-adapted state; GR: glutathione reductase; GSH: reduced glutathione; GSSG: oxidized glutathione; MDA: malondialdehyde; ROS: reactive oxygen species; SOD: superoxide dismutase; TCA: trichloroacetic acid     

Inhibition of induced DNA oxidative damage by beers: correlation with the content of polyphenols and melanoidins

Beers are a source of dietary flavonoids; however, there exist differences in composition, alcohol concentration, and beneficial activities. To characterize these differences, three kinds of lager beer of habitual consumption in Spain, dark, blond, and alcohol-free, were assayed for total phenolic content, antioxidant activity, superoxide and hydroxyl radical scavenging activities, and in vitro inhibitory effect on DNA oxidative damage. Furthermore, their melanoidin content and correlation with antioxidant activity were evaluated. Dark beer contained the highest total phenolic (489 +/- 52 mg/L) and melanoidin (1.49 +/- 0.02 g/L) contents with a 2-fold difference observed when compared to the alcohol-free beer. For the three kinds of beer, the antioxidant activity measured as N,N-dimethyl-p-phenylenediamine dihydrochloride concentration was strongly correlated with the total polyphenol content (R(2) = 0.91102, p < 0.005) and with the melanoidin content (R(2) = 0.7999, p < 0.05). The results support a positive effect of beers on the protection of DNA oxidative damage, by decreasing the deoxyribose degradation, DNA scission (measured by electrophoresis), and inhibition of 8-hydroxydeoxyguanosine (8-OH-dG) formation. Furthermore, a correlation between the total melanoidin content (R(2) = 0.7309, p < 0.01) and inhibition of 8-OH-dG was observed.     

Neuroprotective effect of rough aster butanol fraction against oxidative stress in the brain of mice challenged with kainic acid

The neuroprotective effect of the butanol fraction from the methanol extract of Aster scaber Thunb. (rough aster butanol fraction) on oxidative damage in the brain of mice challenged with kainic acid was examined using behavioral signs and biochemical parameters of oxidative stress. The rough aster butanol fraction (0.4-1.0 g/kg) was administered to ICR male mice, 6-8 weeks, through a gavage for 4 days consecutively, and on the third day, kainic acid (50 mg/kg) was ip administered. When compared to the vehicle-treated control, no significant changes in body and brain weight were observed in mice administered the rough aster butanol fraction. Administration of kainic acid only, causing a lethality of approximately 54%, resulted in a significant decrease of total glutathione level and an increase of the thiobarbituric acid-reactive substances (TBARS) value in brain tissue. When the rough aster butanol fraction was examined for neuroprotective action, the rough aster butanol fraction (0.4 g/kg) alleviated the lethality (25%) of kainic acid and the behavioral sign of its neurotoxicity. Moreover, administration of the rough aster butanol fraction at a dose of 0.4 g/kg restored the glutathione level in the cytosolic portion of brain homogenate to approximately 80% (p < 0.05). Also, the rough aster butanol fraction (0.4 g/kg) led to a significant reduction of kainic acid-induced increase of TBARS value. In addition, the glutathione peroxidase activity was restored significantly (p < 0.05) in the cytosolic portion of brain homogenate, whereas glutathione reductase activity was not. On the basis of these results, the rough aster butanol fraction is suggested to contain a functional agent to prevent oxidative stress in the brain of mice.     

Effect of Zinc on Cadmium Toxicity-Induced Oxidative Stress in Winter Wheat Seedlings

Two hydroponic experiments were conducted to investigate the antioxidant response of winter wheat (Triticum aestivum L.) to cadmium (Cd)-zinc (Zn) interactions, Seedlings of winter wheat (cv. Yuandong 977), were grown in modified Hoagland nutrient solution with the addition of increasing concentrations of Cd (0, 10, 25, 50 μM). In experiment 2, the seedlings of the same cultivar were treated with constant concentration of Cd (25 μM) and varying levels of Zn (0, 1, 10, 50 μM). Hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) as well as the activities of three antioxidant enzymes, catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) were monitored to estimate the amount of oxidative stress and the antioxidant ability of seedlings treated with Cd and Zn for 10 days. The results showed that levels of H₂O₂ and MDA in experiment 1 were significantly increased with increasing Cd concentrations. The data indicated that Cd could induce oxidative stress and lipid peroxidation in the plants. While H₂O₂ and MDA levels were significantly reduced by addition of Zn in experiment 2, the activities antioxidant enzymes were enhanced. A concentration of 10 μM Zn appeared to be the optimal level in this experiment for seedlings' growth, chlorophyll synthesis and antioxidant status, indicating that Zn alleviated the oxidative stress induced by Cd.     

In vivo investigation of changes in biomarkers of oxidative stress induced by plant food rich diets

It is well established that vegetables and fruit (VF) contain antioxidant phytochemicals. Consequently, it is expected that individuals who consume diets with a high content of VF should be better protected against oxidative cellular damage than individuals who do not, but not all data support this assumption. The objective of this study was to identify possible explanations for this conundrum. The effects of two diets that differed in VF content on markers of oxidative damage were studied. Sixty-four women participated in a 14-day dietary intervention. Subjects consumed on average either 3.6 or 12.1 servings of VF per day. The primary end points assessed were 8-hydroxy-2-deoxyguanosine (8-oxo-dG) in peripheral lymphocyte DNA and 8-isoprostaglandin F-2alpha (8-iso-PGF2alpha) excreted in urine. Subjects consuming the high versus low VF diet had lower concentrations of 8-oxo-dG (p < 0.01) and of 8-iso-PGF2alpha (p < 0.01). However, the reduction in oxidative end points by high VF was not uniform. Rather, an antioxidant effect was observed primarily in individuals whose oxidative end points at baseline were above the median for the study population. Using change in plasma carotenoids (end point minus baseline measurements) as an index of phytochemical intake, the reduction in oxidative markers was inversely proportional to change in plasma carotenoids; this effect was stronger for lipid peroxidation (p < 0.01) than DNA oxidation (p < 0.05). These findings imply that increasing exogenous antioxidant exposure may primarily benefit individuals with elevated levels of oxidative stress. Null findings do not necessarily indicate that an antioxidant compound lacks in vivo activity.     

Increase of the activity of phase II antioxidant enzymes in rats after a single dose of coffee

This study evaluated the acute effect of the administration of coffee brew in the activity of phase II antioxidant enzymes in the hepatic tissue of rats. A single dose of this beverage increased the activity of the enzymes SOD, CAT, and GPx; the maximum increase occurred 1 h after administration (19.1, 22.1, and 25.1%, respectively). These changes were statistically significant (p < 0.05), the response was shown to be dose-dependent (p < 0.05), and the return to basal levels took >4 h from the intervention, suggesting a long-term effect. The total antioxidant capacity of the hepatic tissue also exhibited a peak 1 h after the intervention (6.5%), but the increase was not statistically significant and the response was not dose-dependent due to the low exposure to coffee. These results indicate that coffee increases the activities of antioxidant enzymes, improving protection against oxidative stress.     

Physiological and biochemical effects of salicylic acid on Pisum sativum exposed to isoproturon

In the present study, attenuation of isoproturon (IPU) toxicity by salicylic acid (SA) was observed. Seven-day-old seedlings of pea (Pisum sativum L. cv. Azad P-1) were treated with 10 mM IPU. IPU influenced physiological and biochemical parameters. IPU significantly inhibited growth variables like shoot and root height, fresh and dry biomass of the pea. The contents of carotenoids, chlorophylls, protein and activity of nitrate reductase were inhibited significantly. IPU enhanced the accumulation of H₂O₂, ion leakage and lipid peroxidation due to induction of oxidative stress in pea. The activities of antioxidant enzymes, namely superoxide dismutase, catalase and ascorbate peroxidase increased while the activities of guaiacol peroxidase decreased. However, exogenous SA regulated the toxic effects of IPU. The indices of oxidative stress appeared to be alleviated by SA. Pigment content and activities of enzymes increased approximately up to the level of control. IPU caused non-target phytotoxicity to P. sativum. The natural growth regulator/allelochemical has potential to overcome the adverse effects caused by IPU.

Abbreviations: CAT: catalase; EL: electrolyte leakage; IPU: isoproturon; LP: lipid peroxidation; MDA: malondialdehyde; NR: nitrate reductase; POD: guaiacol peroxidase; SOD: superoxide dismutase; TCA: trichloroacetic acid     

Ca(NO3)2胁迫对嫁接番茄生长、抗氧化酶活性和活性氧代谢的影响

以“影武者”为砧木,“宝大903”为接穗,在营养液栽培条件下,对80 mmol/L Ca(NO3)2胁迫下番茄嫁接苗和自根苗的生长、叶片抗氧化酶活性、活性氧代谢以及渗透调节物质含量进行了比较。结果表明,Ca(NO3)2胁迫明显抑制植株生长,显著提高植株抗氧化酶活性,显著增加植株O2.-生成速率以及H2O2、MDA、脯氨酸和可溶性蛋白含量,但胁迫后嫁接苗的生物量显著高于自根苗,抗氧化酶活性、脯氨酸和可溶性蛋白含量均显著高于自根苗,而O2.-生成速率、H2O2和MDA含量则显著低于自根苗。以上结果表明,Ca(NO3)2胁迫下较高的抗氧化酶活性和渗透调节物质含量以及较低的氧化损伤与番茄嫁接苗耐盐性增强有关。     

Ultraviolet-B exposure induces photo-oxidative damage and subsequent repair strategies in a desert cyanobacterium Microcoleus vaginatus Gom.

Biological soil crusts are important in reversing desertification. Ultraviolet radiation, however, may be detrimental for the development of soil crusts. The cyanobacterium Microcoleus vaginatus can be a dominant species occurring in desert soil crusts all over the world. To investigate the physico-chemical consequences of ultraviolet-B radiation on M. vaginatus, eight parameters including the contents of chlorophyll a, reactive oxygen species, malondialdehyde and proline, as well as the activities of photosynthesis, superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7) and catalase (EC 1.11.1.6) were determined. As shown by the results of determinations, ultraviolet-B radiation caused decreases both in contents of chlorophyll a and in ratios of variable fluorescence over maximum fluorescence that indicate the growth and photosynthesis of M. vaginatus, besides, increases both in levels of reactive oxygen species and in contents of malondialdehyde and proline, while intensified activities of superoxide dismutase, peroxidase and catalase reflecting the abilities of enzymatic preventive substances to oxidative stress of the treated cells. Therefore, ultraviolet-B radiation affects the growth of M. vaginatus and leads to oxidative stress in cells. Under ultraviolet-B radiation, the treated cells can improve their antioxidant abilities to alleviate oxidative injury. The change trends of reactive oxygen species, superoxide dismutase, peroxidase and catalase are synchronous. These results suggest that a balance between the antioxidant system and the reactive oxygen species content may be one part of a complex stress response pathway in which multiple environmental factors including ultraviolet-B radiation affect the survival of M. vaginatus.     

Modulation of oxidative damage due to salt stress using salicylic acid in Hordeum vulgare

Oxidative status of salicylic acid (SA) treated barley (Hordeum vulgare) plants grown under saline conditions was examined in a two-year field study during 2012–2013 and 2013–2014 growing seasons. Salinity caused a marked oxidative stress which was manifested as increased concentration of hydrogen peroxide (H₂O₂) and reduced grain yield of barley. Barley plants induced antioxidant system to tolerate salt stress, so that activities of four antioxidant enzymes: peroxidase, catalase, superoxide dismutase and glutathione reductase were enhanced by 22%, 28%, 57% and 44% in the first and by 33%, 20%, 45% and 68% in the second year, respectively. Foliar application of SA in concentration over 0.5 mM enhanced the activities of all four antioxidant enzymes and reduced H₂O₂ content and so enhanced yield. However, higher concentrations of SA reduced grain yield in salt stressed plants in both years, which could be attributed to the negative interaction of antioxidant enzymes with higher concentrations of SA as a non-enzymatic antioxidant. Furthermore, SA is in benzoic acid group and at very higher concentrations can act as an herbicide. It was concluded that SA modulated the oxidative stress through enhanced activities of antioxidant enzymes and reduced the salt-induced adverse effect thereby improving grain yield.     

Black rice (Oryza sativa L. indica) pigmented fraction suppresses both reactive oxygen species and nitric oxide in chemical and biological model systems

Anthocyanins, present in fruits and vegetables as natural colorants, have been well characterized to possess bioactive properties. Anthocyanin components extracted from black rice (Oryza sativa L. indica) separated by gel filtration and identified using LC-MS were cyanidin 3-glucoside and peonidin 3-glucoside. A standardized extract of black rice pigmented fraction (BRE) containing known proportions of cyanidin 3-glucoside and peonidin 3-glucoside exhibited marked antioxidant activities and free radical scavenging capacities in a battery of in vitro model systems. Significant (p < 0.05) prevention of supercoiled DNA strand scission induced by reactive oxygen species (specifically, peroxyl radical and hydroxyl radicals) and suppression of the oxidative modification of human low-density lipoprotein was obtained with BRE. In addition, BRE reduced (p < 0.05) the formation of nitric oxide by suppressing inducible nitric oxide synthase expression in murine macrophage RAW264.7 cells, without introducing cell toxicity. The results of this study show that black rice contains anthocyanin pigments with notable antioxidant and anti-inflammatory properties for potential use in nutraceutical or functional food formulations.     

Anticarcinogenic activity of selenium-enriched green tea extracts in vivo

Both selenium and green tea have been shown to have potential antitumor effects. Here we have investigated the anticarcinogenic effect of the selenium-enriched green tea extract (Se-TE) in a Kunming mice model transplanted with human hepatoma cells HepG2. Mice were assigned to 8 groups consisting of 10 mice each after tumor cell inoculation. The control group received only water, whereas the remaining groups received regular green tea extract (RT), Se-TE which was produced by fertilization with selenite on tea leaves, selenite, and RT + selenite. After the mice were fed intragastrically with these agents for 8 days, tumor growth in RT-, Se-TE-, and selenite-fed mice was significantly suppressed, compared with that in control mice (P < 0.001). Supplementation with Se-TEs and selenite was able to elevate mice blood and liver Se concentrations, but did not significantly enhance selenoprotein glutathione peroxidase and other antioxidant enzyme superoxide dismutase activity in mice blood and liver. These results suggest that the antitumor function of Se-TEs may be attributed to the oxidative stress induced by selenium and green tea components in a suitable selenium supplementation pathway.     

Effects of Exogenous Salicylic Acid and Nitric Oxide on Peanut Seedlings Growth under Iron Deficiency

Salicylic acid (SA) and nitric oxide (NO), which are known as important signaling molecules in plants, could be promising compounds for the reduction in stress sensitivity. The aim of the present work was to study the physiological changes in peanut (Arachis hypogaea L.) seedlings grown in growth medium that contained 0.1 mM SA, 0.25 mM sodium nitroprusside (SNP, a NO donor), or in full (SA+SNP) or half [1/2 (SA+SNP)] combined strengths under iron (Fe) deficiency. After 21 days of treatment, Fe deficiency significantly inhibited peanut plant growth, destroyed photosynthetic system, and caused oxidative damages. Addition of SA, SNP, and 1/2 (SA+SNP), especially SA+SNP, alleviated the stress, increased the contents of chlorophylls, and promoted plant growth. They improved Fe uptake, transport, and availability in peanut plants by increasing the activities of H⁺-ATPase and ferric chelate reductase (FCR), and promoting Fe translocation from cell wall to cell organelle and soluble fraction in leaves. Furthermore, they also effectively mitigated oxidative damages by increasing the activities of antioxidant enzymes in peanut leaves and roots. The results from the present study indicate that application of SA, SNP, or 1/2 (SA+SNP) can overcome the adverse effect of Fe deficiency, but the combined application of SA+SNP is more effective in alleviating Fe deficiency stress.     

Dietary grape-seed procyanidins decreased postweaning diarrhea by modulating intestinal permeability and suppressing oxidative stress in rats

This study was conducted to evaluate the effects of grape-seed procyanidins in controlling weaning diarrhea using a rat model. Weaned rats were fed either the basal diet or basal diet supplemented with either 250 mg/kg grape-seed procyanidins or 2000 mg/kg ZnO. Treated rats had better performance with a reduced incidence of diarrhea (P < 0.05). Both ZnO and grape-seed procyanidins significantly reduced urinary lactulose to mannitol ratios (P < 0.05) and enhanced the mRNA and protein expression of the intestinal mucosal tight junction proteins Ocln/ZO-1 (P < 0.05). Grape-seed procyanidins increased the activities of SOD, GSH-Px, and GSH while decreasing the level of MDA in the intestinal mucosa (P < 0.05). Furthermore, an in vitro investigation revealed that supplementation with grape-seed procyanidins in IEC-6 intestinal epithelial cells significantly enhanced the expression of Ocln/ZO-1 under H(2)O(2)-induced oxidative stress. Collectively, these results indicate that grape-seed procyanidins have the potential to prevent weaning diarrhea by reducing intestinal permeability and improving antioxidant indices.     

Antioxidant activities and metal acquisition in mycorrhizal plants growing in a heavy-metal multicontaminated soil amended with treated lignocellulosic agrowaste

The plant growth, nutrient acquisition, metal translocation and antioxidant activities [ascorbate peroxidase (APX), glutatione reductase (GR), superoxide dismutase (SOD) and catalase (CAT)] were measured in plants growing in a heavy-metal (HM) multicontaminated soil inoculated with selected autochthonous microorganisms [arbuscular mycorrhizal (AM) fungus and/or plant growth promoting bacteria (PGPB)] and/or amended with an Aspergillus niger-treated agrowaste. The treated agrowaste on its own increased root growth by 296% and shoot growth by 504% compared with non-treated control plants. Both chemical and biological treatments, particularly when combined, enhanced plant shoot and root development. The stimulation effect on plant biomass was concomitant with increased AM colonization, P and K assimilation, and reduced metal translocation from soil to plant shoot. The treated residue, particularly through interactions with AM inoculation, produced the expected bioremediation effect, leading to enhanced plant development and successful rehabilitation of contaminated soil. The enhancement of CAT, APX and GR activities caused by AM inoculation suggests that AM colonization helped plants to limit oxidative damage to biomolecules in response to metal stress. The response of the plant's antioxidant activities to the amendment appears to be related to enhanced plant biomass production. The application of amendments and/or microbial inoculations to enhance plant growth and reduce metal translocation in multicontaminated soil could be a promising strategy for remediating HM pollution.     

Effects of drought stress on the seedling growth,development, and metabolic activity in different cultivars of canola

ABSTRACT

The comparative effects of drought stress on seed performance, growth parameters, free proline content, lipid peroxidation, and several antioxidative enzymes activities were studied in both cultivars of Brassica napus L. Drought stress increased mean germination rate and mean of day germination in both cultivars, and its effect was more pronounced in RGS003. The length and dry weight of root increased significantly in both cultivars under drought. RGS003 was more tolerant and obtained more biomass under drought than that of Sarigol. Proline content and pyrroline-5-carboxylate synthetase expression increased in Sarigol under drought. Measurement of malondialdehyde content in seedlings showed that lipid peroxidation was lower in RGS003 than in Sarigol. Antioxidant enzyme activities showed different trends in the two cultivars under drought stress but were higher in RGS003 than in Sarigol. These results suggest that RGS003 is better protected against drought-induced oxidative damage. Lipoxygenase activity only induced under water deficit condition in RGS003. Changes of respiratory enzymes activities of RGS003 subjected to drought stress showed a pattern different with Sarigol. Drought stress induced aconitase activity in RGS003, but it reduced fumarase and succinate dehydrogenase activity in Sarigol. This study showed that RGS003 exhibits a better protection mechanism against oxidative damage and RGS003 is more drought-tolerant than Sarigol possibly by maintaining and/or increasing growth parameters, antioxidant enzyme activities, and respiratory enzymes activities.     

Isolation and characterization of antioxidant protein fractions from melinjo (Gnetum gnemon) seeds

The protein from the seeds of melinjo ( Gnetum gnemon ) was purified using a precipitation method and ion exchange chromatographic techniques to identify the potent antioxidant and free radical scavenging activities. Two antioxidant protein fractions were isolated from G. gnemon seed with molecular weights of approximately 30 kDa (Gg-AOPI) and 12 kDa (Gg-AOPII) by SDS-PAGE. The N-terminal amino acid sequence of Gg-AOPII is Gly-Asn-Gly-Lys-Ala-Thr-Val-Ala-Ile-Leu-Val-Lys-Glu-Lys-Val-Glu-Tyr-Gly-Glu-Glu, and the result of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis showed that they were distinct from each other; no protein in database matching was found to both Gg-AOPI and Gg-AOPII. The antioxidant or free radical scavenging activities of Gg-AOPs were investigated by employing in vitro assay systems including the inhibition of linoleic acid autoxidation, scavenging effect on α,α-diphenyl-β-picrylhydrazyl free radical (DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), reducing power, chelating abilities of metal ions Cu(2+) and Fe(2+), and protections against hydroxyl radical-mediated DNA damages. The result showed that two protein fractions exhibited significant (p < 0.05) antioxidant activities against free radicals such as DPPH, ABTS, and superoxide anion and showed activities similar to those of glutathione (G-SH) and BHT in a linoleic acid emulsion assay system. Moreover, Gg-AOPI and Gg-AOPII also exhibited notable reducing power and strong chelating effect on Fe(2+) and protected hydroxyl radical induced oxidative DNA damage. The data obtained by the in vitro systems obviously established the antioxidant potency of Gg-AOPs.