Specific Activities Of Antioxidant Enzymes Research Articles

Oxidoreductase activity of soybeen seedlings at the early stage of ontogenesis

The results of analysis of specific activity and multiple forms of oxidoreductase class enzymes are presented: antioxidant complex (catalase and peroxidase) and dehydrogenases (alcohol dehydrogenase, NAD+-malate dehydrogenase, glucose-6-phosphate dehydrogenase). Seven varieties of soybean (Glycine max (L.) Merrill) served as the object of the study. Dormant seeds and 3- and 7-day-old soybean seedlings were used for the analysis. Protein content was determined by the Lowry method, peroxidase activity was determined by colorimetric, catalase and the studied dehydrogenases – by spectrophotometric methods, electrophoretic spectra of enzymes – by electrophoresis on 7.5% polyacrylamide gel columns. Identification of the zones with enzymatic activity on the gel was performed by appropriate histochemical methods. Analysis of specific activity of antioxidant enzymes in dormant soybean seeds revealed increased activity of peroxidase and low activity of catalase. During seed germination, the inverse relationship of the specific activity of these enzymes is observed. On the 7th day the specific activity of catalase increases, that of peroxidase decreases to a minimum. In soybean germination, 5 forms of catalase were detected, indicating low polymorphism and stability of the enzyme, and 18 forms of peroxidase, which confirm high polymorphism and the possibility of using this enzyme as a marker of biochemical processes. Alcohol dehydrogenase and glucose-6-phosphate dehydrogenase were found to be of low heterogeneity, with the specific activity of these enzymes decreasing during germination compared to the dormant period of soybean seeds. The specific activity of NAD+-malate dehydrogenase increases slightly during germination. Eight forms of this enzyme were detected in the soybean varieties studied indicating increased polymorphism. In dormant soybean seeds, the electrophoretic spectra of NAD+-malate dehydrogenase exhibited varietal diversity allowing the enzyme to be used as a marker for further studies.

Dietary supplementation with Lippia sidoides essential oil improves organ integrity but the specific activity of antioxidant enzymes is dose-dependent in Danio rerio.

The nutritional quality of food can affect the health of animals. This study examined the effects of dietary supplementation with Lippia sidoides essential oil (LSEO) on the physiology of Danio rerio. Four hundred fourty-eight fish were divided into 28 tanks and subjected to different dietary treatments: a control group with no supplementation, a group with grain alcohol supplementationand five groups with LSEO at concentrations of 0.25%, 0.50%, 0.75%, 1.00%and 1.25%. After 15 days, histological and enzymatic analyses were conducted. The 0.25% LSEO group exhibited lower glutathione peroxidase and catalase activity compared to the 1.00% group. Additionally, fish in the 0.25% LSEO group showed improved liver, kidneyand splenic integrity indices. These findings support the inclusion of 0.25% LSEO in the diet of D. rerio, suggesting potential benefits for fish physiology and encouraging further research on phytotherapeutics in fish diets.

Probing the Phytochemical Composition and Antioxidant Activity of Moringa oleifera under Ideal Germination Conditions.

Moringa oleifera is a rich source of polyphenols whose contents and profile may vary according to environmental conditions, harvest season, and plant tissue. The present study aimed to characterize the profile of phenolic compounds in different tissues of M. oleifera grown under different temperatures (25, 30, and 35 °C), using HPLC/MS, as well as their constituent phytochemicals and in vitro antioxidant activities. The in vitro antioxidant activity of the extracts was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylenebenzothiozoline-6-sulfonicacid (ABTS), and ferric-reducing antioxidant power (FRAP) methods. The polyphenolic compounds were mainly found in the leaves at 30 °C. UPLC/QTOF-MS allowed for the identification of 34 polyphenolic components in seedlings, primarily consisting of glucosides, phenols, flavonoids, and methoxy flavones. At 30 °C, the specific activities of antioxidative enzymes were the highest in leaves, followed by seedlings and then seeds. The leaf and seed extracts also exhibited a greater accumulation of proline, glycine betaine, and antioxidants, such as ascorbic acid, and carotenoids, as measured by the inhibition of ROS production. We found that changes in the expression levels of the validated candidate genes Cu/Zn-SOD, APX, GPP, and TPS lead to significant differences in the germination rate and biochemical changes. These findings demonstrate that M. oleifera plants have high concentrations of phytochemicals and antioxidants, making them an excellent choice for further research to determine their use as health-promoting dietary supplements.

Use of a Biostimulant to Mitigate the Effects of Excess Salinity in Soil and Irrigation Water in Tomato Plants.

Global warming is linked to progressive soil salinisation, which reduces crop yields, especially in irrigated farmland on arid and semiarid regions. Therefore, it is necessary to apply sustainable and effective solutions that contribute to enhanced crop salt tolerance. In the present study, we tested the effects of a commercial biostimulant (BALOX®) containing glycine betaine (GB) and polyphenols on the activation of salinity defense mechanisms in tomato. The evaluation of different biometric parameters and the quantification of biochemical markers related to particular stress responses (osmolytes, cations, anions, oxidative stress indicators, and antioxidant enzymes and compounds) was carried out at two phenological stages (vegetative growth and the beginning of reproductive development) and under different salinity conditions (saline and non-saline soil, and irrigation water), using two formulations (different GB concentrations) and two doses of the biostimulant. Once the experiments were completed, the statistical analysis revealed that both formulations and doses of the biostimulant produced very similar effects. The application of BALOX® improved plant growth and photosynthesis and assisted osmotic adjustment in root and leaf cells. The biostimulant effects are mediated by the control of ion transport, reducing the uptake of toxic Na+ and Cl- ions and favoring the accumulation of beneficial K+ and Ca2+ cations, and a significant increase in leaf sugar and GB contents. BALOX® significantly reduced salt-induced oxidative stress and its harmful effects, as evidenced by a decrease in the concentration of oxidative stress biomarkers, such as malondialdehyde and oxygen peroxide, which was accompanied by the reduction of proline and antioxidant compound contents and the specific activity of antioxidant enzymes with respect to the non-treated plants.

Stress response to trace elements mixture of different embryo-larval stages of Paracentrotus lividus.

This study investigated for the first time the oxidative biomarkers responses in all larval stages of sea urchin. The contamination effects were reproduced by using contaminated seawater to concentrations measured in the area adjacent to an old asbestos mine at factors of 5 and 10. The results suggested that the concentrations were not sufficiently high to induce a major oxidative stress. The biometric differences make this method a more sensitive approach for assessing the effects on sea urchin larvae. Measurements of specific activities of antioxidant enzymes at each stage suggested a high capacity of the larvae to respond to oxidative stress. This normal activity of the organism must be considered in future research. This work also highlighted the importance of spawners provenance in ecotoxicological studies. These data are essential to better understand the stress responses of sea urchin larvae and provide baseline information for later environmental assessment research.

Effects of pyridinium-based ionic liquids with different alkyl chain lengths on the growth of maize seedlings

The effects of four water-soluble pyridinium-based ionic liquids (ILs) differing in alkyl side chain length, namely, N-ethyl pyridinium bromide ([EPy]Br), N-butyl pyridinium bromide ([BPy]Br), N-hexyl pyridinium bromide ([HPy]Br), and N-octyl pyridinium bromide ([OPy]Br), on the growth of maize seedlings were investigated for the first time. The results revealed that the phytotoxicity of these ILs was significantly correlated with their concentration and alkyl side chain length. The 8-day 50% inhibition values indicated that the toxicity increased as the length of the alkyl chain increased: [EPy]Br < [BPy]Br < [HPy]Br < [OPy]Br. In addition, root growth was found to be more sensitive to ILs than stem growth. In response to exposure to ILs of increasing concentration, we observed different trends in the pigment contents and specific antioxidant enzyme activities in maize seedlings, whereas the contents of malondialdehyde were significantly increased. In addition, RNA sequencing analysis, performed to examine the gene expression profiles of maize leaves under [HPy]Br and [OPy]Br treatments, revealed that a larger number of genes were differentially expressed in response to [OPy]Br treatment. Furthermore, pathway enrichment analysis revealed that both [HPy]Br and [OPy]Br treatments, and particularly the latter, caused a down-regulation of genes involved in photosynthesis and carbohydrate and nitrogen metabolism. Our findings thus indicate that pyridinium-based IL toxicity might be associated with oxidative stress and changes in gene expression profiles.

Seed Treatment with Biostimulants Extracted from Weeping Willow (Salix babylonica) Enhances Early Maize Growth.

Biostimulants can be used as innovative and promising agents to address current needs of sustainable agriculture. Weeping willow tree (Salix babylonica) extracts are rich in many bioactive compounds, including, but not limited, to salicylates and phenolics. In this study, the potential of willow bark (WB) and willow leaf (WL) extracts is evaluated as plant-based biostimulants to improve the early growth of maize (Zea mays) under control and salinity stress conditions. In 3 days, seed treatment with salicylic acid and willow extract increased the shoot FW of maize seedlings 130% and 225%, respectively. The root area was, on average, enhanced by 43% with SA and 87% with willow extract applications. Moreover, these extracts increased the leaf protein concentration and reduced the negative effects of salinity during early growth. Reductions in lipid peroxidation and specific activities of antioxidative enzymes by seed treatments with willow extracts suggests a mitigation of salinity-induced oxidative stress. For most reported traits, WL applications were at least as effective as WB applications. Results indicate that aqueous extracts of weeping willow leaves, as well as bark, can be used as seed treatment agents with biostimulant activity to improve seedling growth and establishment under control and stress conditions.

The Negative Effect of Protein Phosphatase Z1 Deletion on the Oxidative Stress Tolerance of Candida albicans Is Synergistic with Betamethasone Exposure.

The glucocorticoid betamethasone (BM) has potent anti-inflammatory and immunosuppressive effects; however, it increases the susceptibility of patients to superficial Candida infections. Previously we found that this disadvantageous side effect can be counteracted by menadione sodium bisulfite (MSB) induced oxidative stress treatment. The fungus specific protein phosphatase Z1 (CaPpz1) has a pivotal role in oxidative stress response of Candida albicans and was proposed as a potential antifungal drug target. The aim of this study was to investigate the combined effects of CaPPZ1 gene deletion and MSB treatment in BM pre-treated C. albicans cultures. We found that the combined treatment increased redox imbalance, enhanced the specific activities of antioxidant enzymes, and reduced the growth in cappz1 mutant (KO) strain. RNASeq data demonstrated that the presence of BM markedly elevated the number of differentially expressed genes in the MSB treated KO cultures. Accumulation of reactive oxygen species, increased iron content and fatty acid oxidation, as well as the inhibiting ergosterol biosynthesis and RNA metabolic processes explain, at least in part, the fungistatic effect caused by the combined stress exposure. We suggest that the synergism between MSB treatment and CaPpz1 inhibition could be considered in developing of a novel combinatorial antifungal strategy accompanying steroid therapy.

Comparative Studies on the Physiological and Biochemical Responses to Salt Stress of Eggplant (Solanum melongena) and Its Rootstock S. torvum

This study investigated the physiological and biochemical responses to salinity stress of Solanum melongena and its wild relative, Solanum torvum, commonly used as eggplant rootstock. Young plants of both species were watered during 25 days with NaCl aqueous solutions at the following four final concentrations: 0 (for the controls), 100, 200, and 300 mM. Plant growth parameters, photosynthetic pigments content, monovalent ion concentrations in roots and leaves, leaf levels of osmolytes (proline and total soluble sugars), oxidative stress markers (MDA and H2O2), non-enzymatic antioxidants (total phenolic compounds and total flavonoids), and enzymatic antioxidant activities (superoxide dismutase, catalase, glutathione reductase) were determined after the stress treatments. Salt-induced growth reduction was more significant in S. melongena than in S. torvum, especially at high salt concentrations, indicating a (slightly) higher salt tolerance of the wild species. The mechanisms of tolerance of S. torvum were partly based on the active transport of toxic ions to the leaves at high external salinity and, presumably, a better capacity to store them in the vacuoles, as well as on the accumulation of proline to higher concentrations than in the cultivated eggplant. MDA and H2O2 contents did not vary in response to the salt treatments in S. torvum. However, in S. melongena, MDA content increased by 78% when 300 mM NaCl was applied. No activation of antioxidant mechanisms, accumulation of antioxidant compounds, or increase in the specific activity of antioxidant enzymes in any of the studied species was induced by salinity. The relatively high salt tolerance of S. torvum supports its use as rootstock for eggplant cultivation in salinized soils and as a possible source of salt-tolerance genes for the genetic improvement of cultivated eggplant.

Changes in Antioxidant Enzymes Activity and Metabolomic Profiles in the Guts of Honey Bee (Apis mellifera) Larvae Infected with Ascosphaera apis.

The fungus Ascosphaera apis, an obligate fungal pathogen of honey bee brood, causes chalkbrood disease in honey bee larvae worldwide. Biological characteristics of the fungal pathogen and the molecular interactions between A. apis and honey bees have been studied extensively. However, little is known about the effects of A. apis infection on antioxidant enzyme activities and metabolic profiles of the gut of honey bee larvae. In this study, sandwich enzyme-linked immunosorbent assay and LC-MS based untargeted metabolomic analysis were employed to determine the changes in the specific activities of antioxidant enzymes and the metabolomic profiles in gut tissues of A. apis-infected larvae (105 A. apis spores per larva) and controls. Results showed that specific activities of superoxide dismutase, catalase and glutathione S-transferase were significantly higher in the guts of the control larvae than in the guts of the A. apis-infected larvae. The metabolomic data revealed that levels of 28 and 52 metabolites were significantly higher and lower, respectively, in the guts of A. apis-infected larvae than in the guts of control larvae. The 5-oxo-ETE level in the infected larvae was two times higher than that in the control larvae. Elevated 5-oxo-ETE levels may act as a potential metabolic biomarker for chalkbrood disease diagnosis, suggesting that A. apis infection induced obvious oxidative stress in the honey bee larvae. The levels of metabolites such as taurine, docosahexaenoic acid, and L-carnitine involved in combating oxidative stress were significantly decreased in the gut of A. apis-infected larvae. Overall, our results suggest that A. apis infection may compromise the ability of infected larvae to cope with oxidative stress, providing new insight into changing patterns of physiological responses to A. apis infection in honey bee larvae by concurrent use of conventional biochemical assays and untargeted metabolomics.

Soil moisture deficit induced changes in antioxidative defense mechanism of sugarcane (Saccharum officinarum) varieties differing in maturity

A split plot experiment was conducted at Regional Research Station, CCS HAU, Uchani, Karnal during 2014–15 and 2015–16 to investigate the effect of different soil moisture regimes on antioxidative defense mechanism of sugarcane (Saccharum officinarum L.) varieties. The experiment consisted of three moisture regimes based on available soil moisture i.e. irrigation at 50% ASM, 40% ASM and 30% ASM in main plot and four commercial sugarcane varieties, i.e. CoS 767, CoH 128, CoJ 64 and Co 0238 in sub plot with three replications. The observations recorded on antioxidative defense system have suggested possible key characteristics of drought tolerance. Low ASM levels induced the antioxidative defense system by increasing ROS and the specific activities of antioxidative enzymes, viz. peroxidase, catalase and ascorbate peroxidase. Specific activity of these enzymes increased in varieties Co 0238 and CoS 767 at 60 and 90 DAP. Severe stress of 30% ASM levels also resulted in a sharp rise in total ascorbic acid content (9.36 to 13.14 mg/g), total soluble proteins (from 9.6 to 13.77 mg/g), and the increase was more in varieties Co 0238 and CoS 767. A gradual decrease was observed in all the parameters after stress revival (120 DAP). ASM levels 30% and 40% significantly reduced K+ content in leaves (2.93 to 1.83%) as compared to 50% ASM level. So, it might be concluded from this study that biochemical traits had a significant varietal variation, indicating that these parameters could be used as screening criteria for selecting the tolerant and sensitive cultivars exposed to water limiting stress.

Phosphine resistance and antioxidant enzyme activity in Trogoderma granarium Everts

In recent study, phosphine resistance was assessed in 14 populations of Trogoderma granarium collected from North India. These populations were resistant to phosphine as compared to susceptible laboratory population and the resistance ratios at LC50 ranged from 1.16 to 31.62-fold. In order to determine the trend and magnitude of evolution of phosphine resistance under laboratory conditions, phosphine resistant strain of T. granarium was developed in the laboratory by subjecting the parental strain to a selection pressure of 70% in each generation for ten successive generations. Resistant strain showed 12.74-fold resistance as compared to parental strain. Specific activity of antioxidant enzymes viz., catalase, peroxidase and superoxide dismutase was measured in both collected populations and successive generations, and correlated with phosphine resistance. Specific activity of peroxidase and superoxide dismutase was increased significantly with an increase in phosphine resistance (P < 0.05), whereas the specific activity of catalase was non-significantly increased. The results of our study have revealed that levels of peroxidase and superoxide dismutase increased significantly with increased phosphine resistance in T. granarium. Our study has demonstrated the possible role of antioxidant enzymes in scavenging reactive oxygen species (ROS) associated with tolerance to phosphine in T. granarium.

Effects of green synthesis of sulfur nanoparticles from Cinnamomum zeylanicum barks on physiological and biochemical factors of Lettuce (Lactuca sativa).

In this study, the effect of green synthesized sulfur nanoparticle (SNP) at different concentration (0, 0.01, 0.1, 1 and 10mg/ml) on some physiological, phytochemical and biochemical traits of lettuce plants was investigated. For the first time, SNP were green synthesized using Cinnamomum zeylanicum barks extract. Our results indicated that the treatment of lettuce plants with 1mg/ml of SNP improved the growth and photosynthetic parameters of lettuce plants than related control. Some other physiological parameters such as proline, glycine betaine and soluble sugars levels along with some phytochemical parameters like anthocyanin, total phenol, flavonoids and tannin contents were enhanced after treatment of the plants with same concentration of SNP. On the other hand, specific activity of antioxidant enzymes (catalase, ascorbate peroxidase and polyphenol oxidase) and stress markers level, MDA and H2O2 were reduced in the same treated lettuce plants. However, a concentration of 10mg/ml of SNP exhibited toxicity on lettuce plants with inducing oxidative stress markers (H2O2 and MDA) and consequently reducing plant growth and biomass. This oxidative stress tend to diminish some physiological, phytochemical and biochemical parameters in treated lettuce plants. Overall, it can be concluded that the green synthesis SNP at an optimal concentration of 1mg/ml improved physiological parameters in the lettuce plants making thempotent to tolerate stressful conditions. However, higher concentration of SNP (10mg/ml) indicated toxic effects on all of the physiological parameters.

Bioallethrin-induced generation of reactive species and oxidative damage in isolated human erythrocytes

Bioallethrin is an insecticide that is widely used to control mosquitoes, fleas and cockroaches. The widespread use of bioallethrin has resulted in both occupational and non-occupational human exposure. Bioallethrin enters blood, regardless of the route of exposure, where it can interact with erythrocytes. We have studied the effect of bioallethrin on isolated human erythrocytes under in vitro conditions. Erythrocytes were incubated with increasing concentrations of bioallethrin (10–200 μM) for 4 h at 37 °C. Several biochemical parameters were analyzed in bioallethrin treated and untreated (control) cells. Incubation of erythrocytes with bioallethrin increased protein oxidation, lipid peroxidation and depleted sulfhydryl group content. Membrane damage was evident from cell lysis, osmotic fragility, inhibition of bound enzymes and transmembrane electron transport system. Bioallethrin also increased hemoglobin oxidation, heme degradation and the release of free iron moiety. This will decrease the oxygen transporting ability of blood. Bioallethrin treatment altered the specific activities of antioxidant enzymes and diminished the antioxidant power of cells. Scanning electron microscopy showed that bioallethrin treatment also altered erythrocyte mophology. Almost all changes were in a bioallethrin concentration dependent manner. The cytotoxicity of bioallethrin is probably mediated by reactive oxygen and nitrogen species whose formation was significantly enhanced in treated erythrocytes. Thus bioallethrin enhances the generation of reactive species which cause oxidative damage of cell components in human erythrocytes.

Reactive Oxygen Species-Mediated Apoptosis and Cytotoxicity of Newly Synthesized Pyridazin-3-Ones In P815 (Murin Mastocytoma) Cell Line.

In cancer cells, the intracellular antioxidant capacity and the redox homeostasis are mainly maintained by the glutathione- and thioredoxin-dependent systems which are considered as promising targets for anticancer drugs. Pyridazinones constitute an interesting source of heterocyclic compounds for drug discovery. The present investigation focused on studying the in-vitro antitumor activity of newly synthesized Pyridazin-3(2h)-ones derivatives against P815 (Murin mastocytoma) cell line. The in-vitro cytotoxic activities were investigated toward the P815 cell line using tetrazolium-based MTT assay. Lipid peroxidation and the specific activities of antioxidant enzymes were also determined. The newly compounds had a selective dose-dependent cytotoxic effect without affecting normal cells (PBMCs). Apoptosis was further confirmed through the characteristic apoptotic morphological changes and DNA fragmentation. Two compounds (6F: and 7H: ) were highly cytotoxic and were submitted to extend biological testing to determine the likely mechanisms of their cytotoxicity. Results showed that these molecules may induce cytotoxicity via disturbing the redox homeostasis. Importantly, the anticancer activity of 6F: and 7H: could be due to the intracellular reactive oxygen species hypergeneration through significant loss of glutathione reductase and thioredoxin reductase activities. This eventually leads to oxidative stress-mediated P815 cell apoptosis. Furthermore, the co-administration of 6F: or 7H: with Methotrexate exhibited a synergistic cytotoxic effect. considering their significant anticancer activity and chemosensitivity, 6F: and 7H: may improve the therapeutic efficacy of the current treatment for cancer.

Cytotoxicity of new pyridazin-3(2H)-one derivatives orchestrating oxidative stress in human triple-negative breast cancer (MDA-MB-468).

Triple-negative breast cancer (TNBC) is a complex and aggressive subtype of breast cancer characterized by high morbidity and mortality. In the absence of targeted therapy, only chemotherapy is available in this case of cancer. The current study investigated the antitumor effect of new pyridazin-3(2H)-one derivatives on the human TNBC cell line, MD-MB-468. The in vitro cytotoxic activities were investigated using the tetrazolium-based MTT assay. Lipid peroxidation, H2 O2 content, and the specific activities of antioxidant enzymes were also determined. Two molecules, 6f and 7h, were found to be selectively highly active against tumor cells with IC50 values of 3.12 and 4.9 µM, respectively. Furthermore, cells exposed to 6f showed a significant increase in H2 O2 and lipid peroxidation levels, accompanied by a decrease in the enzyme activities of glutathione reductase (GR) and thioredoxin reductase (TrxR). The cytotoxicity of the compound 6f may improve the therapeutic efficacy of the current treatment for TNBC via the inhibition of GR and TrxR activities.

24-Epibrassinolide reduces stress in nematode-infected tomato (Solanum lycopersicum L.) plants cultured in vitro

24-Epibrassinolide (EBL) is considered the most probable brassinosteroid (BR) candidate that could be used for practical application in agriculture. EBL-induced stress-protective properties were evaluated in in vitro-grown tomato (Solanum lycopersicum L.) varieties Pusa Ruby (susceptible to nematodes) and PNR-7 (resistant to nematodes) during nematode pathogenesis. Sterilized tomato seeds treated with 10−11, 10−9, or 10−7 M EBL and germinated in vitro were inoculated with second-stage juveniles of Meloidogyne incognita [(Kofoid and White) Chitwood]. Whole plant analyses of morphological and biochemical parameters 7 d after inoculation showed significant improvements in plant growth and development for both varieties and a highly significant reduction in the number of galls in the susceptible variety. Increased specific activities of antioxidative enzymes (catalase, ascorbate peroxidase, glutathione reductase, glutathione peroxidase, guaiacol peroxidase, and superoxide dismutase) were observed in EBL-treated seedlings of both varieties, but increases were higher in the resistant variety. A highly significant increase in antioxidants (ascorbic acid content, total flavonoid content, total glutathione content, and total phenolic content) was observed in EBL-treated Pusa Ruby seedlings, whereas in PNR-7, significant increases were found except for total flavonoid content, which increased non-significantly. Confocal microscopic images showed amelioration of stress in roots of EBL-treated seedlings as indicated by the decrease in level of green fluorescence in them as compared to untreated and nematode-inoculated roots.

In Vivo Assessment of Cold Tolerance through Chlorophyll-a Fluorescence in Transgenic Zoysiagrass Expressing Mutant Phytochrome A.

Chlorophyll-a fluorescence analysis provides relevant information about the physiology of plants growing under abiotic stress. In this study, we evaluated the influence of cold stress on the photosynthetic machinery of transgenic turfgrass, Zoysia japonica, expressing oat phytochrome A (PhyA) or a hyperactive mutant phytochrome A (S599A) with post-translational phosphorylation blocked. Biochemical analysis of zoysiagrass subjected to cold stress revealed reduced levels of hydrogen peroxide, increased proline accumulation, and enhanced specific activities of antioxidant enzymes compared to those of control plants. Detailed analyses of the chlorophyll-a fluorescence data through the so-called OJIP test exhibited a marked difference in the physiological status among transgenic and control plants. Overall, these findings suggest an enhanced level of cold tolerance in S599A zoysiagrass cultivars as reflected in the biochemical and physiological analyses. Further, we propose that chlorophyll-a fluorescence analysis using OJIP test is an efficient tool in determining the physiological status of plants under cold stress conditions.

Lophirones B and C extenuate AFB1-mediated oxidative onslaught on cellular proteins, lipids, and DNA through Nrf-2 expression.

The capability of lophirones B and C to extenuate aflatoxin B1 (AFB1)-mediated onslaught on cellular proteins, lipids, and DNA was investigated for 6 weeks. Lophirones B and C significantly (P < 0.05) increase the expression and specific activity of cytoprotective enzymes (glutathione-S-trans-ferase, nioctinamide adenine dicludeotide:quinone oxidoreductase-1, epoxide hydrolase, and uridyl glucuronosyl transferase). There was significant (P < 0.05) reduction in the level of antioxidant system in AFB1-induced hepatocarcinogenesis. Furthermore, lophirones B and C significantly (P < 0.05) attenuated AFB1-mediated decrease in the specific activities of antioxidant enzymes. Oxidative stress biomarkers, malondialdehyde, lipid hydroperoxides, conjugated dienes, protein carbonyl, and fragmented DNA were significantly (P < 0.05) elevated in AFB1-treated rats. Although lophirones B and C did not significantly (P < 0.05) alter these biomarkers, an AFB1-mediated increase in these biomarkers was significantly attenuated. Results obtained showed that lophirones B and C extenuate AFB1-mediated onslaught on cellular proteins, lipids, and DNA by enhancing nuclear erythroid-related factor-2 expression.

Antioxidant enzymes activity and physiological response of tomato (Lycopersicon esculentum M.) genotypes under mild temperature stress

Tomato being sensitive to high temperature experiences mild to high temperature stresses under cli- mate change conditions. To understand the response of tomato genotypes to mild temperature stress, a study was conducted in temperature gradient tunnel facility. The results revealed that across the genotypes studied, specific activity of antioxidant enzymes viz., superoxide dismutase (SOD), peroxidase (POX) and glutathione reductase (GR) increased significantly. Among the genotypes, increase in SOD activity was highest in cv. Arka Vikas, followed by IIHR 2195 and least in Abhinava. The GR activity was highest in Abhinava, followed by IIHR 2195 and least in cv. Arka Vikas. The mild temperature stress caused reduction in catalase (CAT) activity. The decrease in CAT activity and concomitant increase in POX activity was observed in cv. Arka Vikas. Low leaf water potential (Wleaf) and higher electrolyte leakage indicated that the membrane integrity was affected across the tomato geno- types even under mild temperature stress. Among the genotypes studied, cv. Arka Vikas showed greater activity of SOD and POX, higher membrane stability and least reduction in water potential under mild temperature stress.