Guiacol Peroxidase Research Articles

Colonization potential of endophytes from halophytic plants growing in the "Runn of Kutch" salt marshes and their contribution to mitigating salt stress in tomato cultivation.

Increasing soil salinity depreciates the quantity of the crop produce. Looking at the tremendous potential of plant-associated microorganisms in salinity stress mitigation, it would be very useful in exploring and deciphering salt-tolerant microorganisms from halophytic plants and their utilization in cultivated plants. With this aim, in the present study, four halophytic plants were taken from Rann of Kutch, and bacterial endophytes were isolated from different plant organs. These endophytes were characterized by plant growth and health promotion features. The molecular identification was done based on 16 s rRNA sequence similarity. It was found that the endophytic bacteria isolated from 4 different halophytes found sharing phylogenetic relatedness. Four potential endophytes Alkalihalobacillus gibsonii 2H2, Achromobacter insuavis 2H18, Terribacillus halophilus 2H20, and Bacillus siamensis 4H1 were tested in tomato for salinity stress alleviation. Changes in the levels of antioxidants were analyzed. Total chlorophyll, total phenolics, malondialdehyde, and proline content indicated reduced damage in the plant system due to salinity by the application of endophytes. All the treatments exhibited low levels of electrolyte leakage. The accumulation of enzymatic reactive oxygen species scavengers was assessed from the levels of peroxidase, catalase, superoxide dismutase, phenylalanine ammonia-lyase, ascorbate peroxidase, and guiacol peroxidase. The NBT and DAB staining confirmed the findings. The reduction in the accumulation of Na+ ions in tomato leaves was visualized using Sodium Green probes under CSLM and found to be lowest in Terribacillus halophilus 2H20 and Bacillus siamensis 4H1 inoculated plants. The endophyte Terribacillus halophilus 2H20 was the most promising isolate. The colonization in tomato roots was confirmed using a cell tracker system. Results showed that the endophytes were found to have salinity stress mitigation traits. The efficiency could be further improved with the combination of other endophytes tested earlier.

Acclimation of Photosynthesis to Changes in the Environment Results in Decreases of Oxidative Stress in Arabidopsis thaliana.

The dynamic acclimation of photosynthesis plays an important role in increasing the fitness of a plant under variable light environments. Since acclimation is partially mediated by a glucose-6-phosphate/phosphate translocator 2 (GPT2), this study examined whether plants lacking GPT2, which consequently have defective acclimation to increases in light, are more susceptible to oxidative stress. To understand this mechanism, we used the model plant Arabidopsis thaliana [accession Wassilewskija-4 (Ws-4)] and compared it with mutants lacking GPT2. The plants were then grown at low light (LL) at 100 μmol m−2 s−1 for 7 weeks. For the acclimation experiments, a set of plants from LL was transferred to 400 μmol m−2 s−1 conditions for 7 days. Biochemical and physiological analyses showed that the gpt2 mutant plants had significantly greater activity for ascorbate peroxidase (APX), guiacol peroxidase (GPOX), and superoxide dismutase (SOD). Furthermore, the mutant plants had significantly lower maximum quantum yields of photosynthesis (Fv/Fm). A microarray analysis also showed that gpt2 plants exhibited a greater induction of stress-related genes relative to wild-type (WT) plants. We then concluded that photosynthetic acclimation to a higher intensity of light protects plants against oxidative stress.

Stigmasterol Relieves the Negative Impact of Drought on Flax through Modulation of Redox Homeostasis

DROUGHT impacts on flax growth are aimed to be alleviated by soaking seeds in stigmasterol then sowing in pots. On the 24th day after sowing, water regime was applied and samples were harvested up to the 56th day after sowing for measuring growth parameters, free radicals, antioxidants and Ru-1,5-P carboxylase/oxygenase (Rubisco). At seed maturity, yield analysis measurements (capsules, seeds, oil yield and fatty acid composition) were performed. Drought provoked significant decreases in growth parameters, ascorbic acid and glutathione but elevated lipid peroxidation and H2O2 concurrently with significant inhibition in the activities of catalase, guiacol peroxidase, ascorbate peroxidase, glutathione reductase, glutathione peroxidase and Rubisco. Yield analysis demonstrated declines in capsule and seed numbers, the oil as well as both contents and composition of fatty acids. Nevertheless, stigmasterol diminished drought impacts on growth parameters, antioxidants and Rubisco and rendered the contents of lipid peroxides and H2O2 comparable to control. In the meantime, oil yield and fatty acid composition were improved in synchronization with the efficiency of antioxidants and reactive oxygen species (ROS) homeostasis. These findings conclude that stigmasterol alleviated these drastic impacts and improved oil yield and fatty acid composition via modulating efficient antioxidant capacity and ROS homeostasis.

PHYTOCHEMICAL SCREENING AND EVALUATION OF THE ENZYMATIC ANTIOXIDANT ACTIVITIES OF SELECTED Mangifera spp. LEAVES (ANACARDIACEAE)

A study was conducted on the chemical and biological properties of three different species of Mangifera i.e. Mangifera pajang, M. indica L., and M. kemanga leaves obtained from Pitas, Sabah. The aims of this study were to determine the presence of secondary metabolites as well as the antioxidative activities especially the catalase (CAT) and guiacol peroxidase specific activities (gPOD) in the leaves part of these three species. The extraction of these samples was carried out using three different polarities of solvents: hexane, ethyl acetate, and methanol. The total percentage of the crude extract of is 7.30% for M. pajang, 12.87% for M. indica and 7.98% for M. kemanga. Phytochemical screening was performed with various tests for each of the crude extracts. The results showed that these three species gave positive results for alkaloids, saponins, flavonoids, phenols, carbohydrates, phytosterols, and tannins metabolites. Based on the tests, CAT specific activities were significantly higher in the leaves of M. pajang with 4.35 ± 1.18 units/mg protein compared to M. indica L. and M. kemanga. The guaiacol peroxidase (gPOD) specific activities showed that M. indica L. has the highest activity with the value of 0.0047 ± 0.0004 units/mg protein.

Effect of 2,4-Dichlorophenoxy Acetic Acid on Antioxidant Systems in a Non-Target Plant (Zea mays L.)

This work aimed to study the impact of various concentrations of the herbicide 2,4-D dichlorophenoxyacetic acid (2, 5, 10 mg L-1) on fresh and dry biomasses, photosynthetic pigments, quantum yield of PSII (Fv/Fm) and oxidative stress parameters on 28-day old Zea mays leaves. Foliar application of a low dose of 2,4-D significantly promoted the growth biomarkers, whereas, the high doses induced severe disturbances and reduced the growth attributes. This situation produced over-accumulation of hydrogen peroxide (H2O2) and lipid peroxidation (MDA) and that was accompany with a significant increase in activity of superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G6PDH). Otherwise there was a significant decline in ascorbate peroxidase (APx), guiacol peroxidase (GPX), glutathione peroxidase (GSHPx) and glutathione reductase (GR). Moreover, a significant decline of glutathione (reduced form; GSH) and ascorbic acid (AsA) contents, glutathione redox potential (GSH/GSSG), NADPH and NADPH/NADP+ ratios were recorded. These observations might indicate that high doses of 2,4-D caused a menace to non-target plants through the disruption of antioxidant systems.

Effect of 2,4-Dichlorophenoxy Acetic Acid on Antioxidant Systems in a Non-Target Plant (Zea mays L.)

This work aimed to study the impact of various concentrations of the herbicide 2,4-D dichlorophenoxyacetic acid (2, 5, 10 mg L-1) on fresh and dry biomasses, photosynthetic pigments, quantum yield of PSII (Fv/Fm) and oxidative stress parameters on 28-day old Zea mays leaves. Foliar application of a low dose of 2,4-D significantly promoted the growth biomarkers, whereas, the high doses induced severe disturbances and reduced the growth attributes. This situation produced over-accumulation of hydrogen peroxide (H2O2) and lipid peroxidation (MDA) and that was accompany with a significant increase in activity of superoxide dismutase (SOD), catalase (CAT) and glucose-6-phosphate dehydrogenase (G6PDH). Otherwise there was a significant decline in ascorbate peroxidase (APx), guiacol peroxidase (GPX), glutathione peroxidase (GSHPx) and glutathione reductase (GR). Moreover, a significant decline of glutathione (reduced form; GSH) and ascorbic acid (AsA) contents, glutathione redox potential (GSH/GSSG), NADPH and NADPH/NADP+ ratios were recorded. These observations might indicate that high doses of 2,4-D caused a menace to non-target plants through the disruption of antioxidant systems.

Metabolic modifications to Ni excess in L. minor: Role of organic-, amino- and fatty acid profiles

In this study, the effects of excess nickel (Ni) (100 μM and 200 μM) on growth, antioxidant production, fatty acid, organic and amino acids profiles were examined in Lemna minor L. After 7 days of Ni treatment, chlorosis, growth inhibition and ROS overproduction were observed, accompanied by Ni accumulation. Interestingly, decreased malondialdehyde (MDA) levels were recorded in fronds upon Ni exposure. Fatty acid profiles in Ni-treated L. minor were characterized by increases in saturated- and decreases in unsaturated fatty acids. Ni excess increased the activities of antioxidant enzymes such as superoxide dismutase (SOD), guiacol peroxidase (GPX), and glutathione reductase (GR), and non-enzymatic antioxidants such as glutathione (GSH) and ascorbic acid (AsA); however, deactivation of ascorbate peroxidase (APX) and catalase (CAT) activities were also observed. Disruption of amino acid metabolism in Ni-exposed fronds was evidenced by the accumulation of cysteine, arginine, threonine, valine, isoleucine, leucine, lysine and phenylalanine, as well as reduced levels of tyrosine, alanine, aspartate and proline. Approximately 299%–396%, 139%–254% and 56%–97% concentration increments in citric, malic and oxalic acids, respectively, were concomitantly observed with significant decreases in tartaric, acetic, and fumaric acids in fronds subjected to Ni stress. Taken together, these results indicated that Ni stress induced negative effects on plant physiological, biochemical and morphological processes; however, it is likely that the coordination of metabolites and antioxidants may ameliorate the damaging effects of Ni accumulation.

Ameliorative roles of melatonin and/or zeolite on chromium-induced leaf senescence in marjoram plants by activating antioxidant defense, osmolyte accumulation, and ultrastructural modification

Growing medicinal herbs on chromium-rich soils can pose severe threats to humans, animals, plants, and ecosystems. Leaf senescence is a typical sign of chromium contamination and may be regulated by foliar application (melatonin) or soil amendment (zeolite) treatments. The favorable roles of melatonin and/or zeolite in the alleviation of chromium-induced senescence processes related to growth, some biochemical and ultrastructural attributes, and essential oil yield in marjoram (Origanum marjorana L.) plants were studied.Marjoram biomass, photosynthetic pigment concentration, nutrient percentage, water status, ascorbic acid level, essential oil yield, and catalase activity declined significantly under chromium-pollution. On the other hand, organic and antioxidant solute levels, superoxide dismutase and guiacol peroxidase activity, oxidized biomolecule levels, as well as chromium concentrations were increased in the herb under chromium contamination. Melatonin and/or zeolite application under normal or chromium-polluted conditions may compensate to some extent growth retardation, essential oil yield, and metabolic disturbance processes. The greatest herbal essential oil yield was obtained in the case of the application of melatonin plus zeolite under normal conditions. Under chromium pollution, cell organelles exhibited a noticeable malformation and lysis, but, melatonin plus zeolite application counteracts the malformation observed with chromium-pollution.The current investigation postulated that either soil amendment with 5 g zeolite kg−1 soil and/or foliar application with 100 μM melatonin have found a useful role to mitigate chromium-induced senescence processes in marjoram herb. Their ameliorating effects may be connected with the regulation of reactive oxygen species scavenging systems, stimulation of osmotic adjustment and preservation of plant cell ultrastructure. Melatonin and/or zeolite can make chromium-rich soils appropriate for the cultivation and production of high-quality herbs by minimizing chromium bioavailability and toxicity to plants.

Evaluation of cobalt hyperaccumulation and tolerance potential of the duckweed (Lemna minor L.)

Lemna minor could tolerate and accumulate more than 5,000 μg g-1 DW of cobalt (Co) without foliar symptoms, indicating it is a Co hyperaccumulator. However, the physiological and metabolomics mechanisms that are responsible for Co accumulation and tolerance are largely unknown. In the present study, Fourier transform infrared spectroscopy suggested that CO, CH, and OH groups are involved in Co biosorption. The activation of antioxidant enzymes, such as superoxide dismutase, guiacol peroxidase, catalase, and glutathione reductase, as well as ascorbic acid and glutathione might be involved in capturing reactive oxygen species as evidenced by decreased malondialdehyde in fronds treated with Co. Metabolomics analysis revealed that Co stress significantly increased the production of several amino acids (except aspartic acid and cysteine at 200 μM) and organic acids (with the exception of succinic acid). In particular, an approximate 15-fold increase was noted in the citric acid concentration. Upon exposure to Co, increases were observed in citrate synthase, malate dehydrogenase, and phosphoenolpyruvate carboxylase activities, and a decrease was observed in isocitrate dehydrogenase related to the metabolism of organic acids. Overall, the increase in concentration of organic and amino acids and antioxidants support their effective involvement in improving Co tolerance and accumulation in L. minor.

Lead (Pb2+) causes chlorophyll related changes and oxidative damage in Chlorella ellipsoides (Chlorophyceae)

The increasing production of anthropological wastes containing heavy metals has resulted to their discharge and contamination into freshwater ecosystems. Hence, the effects of heavy metals are of health concern for aquatic biodiversity. This study investigated the short term effects of Pb2+ (0.0, 10, 20, 40, 60, 80 and 100 µg.L-1) on the biomass (cell density, chlorophyll a, b) and antioxidant (catalase (CAT), superoxide dismutase (SOD), guiacol peroxidase (GPx), glutathione reductase (GRx), and malondialdehyde (MDA)). Chlorella ellipsoides (Chlorophyceae) was sensitive to Pb2+, a significant decrease (p < 0.05) of chlorophyll a and b was observed with increasing concentrations of Pb2+. Antioxidant Catalase, SOD, GPx and GRx relatively decreased significantly (p < 0.05) after exposure of microalga to Pb2+. However, MDA increased significantly (p < 0.05) after microalgae was exposed to Pb2+. The finding of this study indicates that exogenous concentrations are harmful for the welfare of C. ellipsoides. This study is important as it demonstrates the potential impact of Pb2+ on microalgae. Field studies in African freshwater biodiversity and monitoring of aquatic ecosystems are recommended to assess the level and impact of Pb2+ in aquatic ecosystems.

Foliar Application of Signal Molecules can Augment Quality in Andrographis paniculata under Prolonged Water Deficit Stress

The quality of a medicinal plant is decided by the content of specific secondary metabolite respective to the plant species. Therefore, an attempt was made to assess the effect of water deficit (WD) stress and signal molecules on physiological and biochemical responses of Andrographis paniculata under polyhouse condition. To keep the soil at field capacity (FC) in control (well-watered) treatment, a pre-measured quantity of water was applied to the pots once in a week. The signal molecules (i) ascorbic acid @200 mg l−1, (ii) glutamic acid @150 mg l−1 and salicylic acid @200 mg l−1 applied foliar at 10, 25, 40 and 55 days after WD treatment. Total chlorophyll, total carotenoid and proline content increased due to WD stress at 50 days after treatment (DAT) whereas, total chlorophyll and total carotenoid content decreased but, proline content increased at 80 DAT. Ascorbic acid enhanced the ascorbate peroxidase activity and glutamic acid enhanced guiacol peroxidase activity of leaves under WD stress. WD stress reduced actual efficiency of photosynthesis (Fv’/Fm’) and energy utilized for photochemistry (¦PSII) at 80 DAT. WD stress during 20–50 DAT did not improve the andrographolide content in leaves of A. paniculata. However, a prolonged WD stress till 80 DAT hastened andrographolide content in leaves. Foliar application of salicylic acid under polyhouse condition indicated its scope to augment the quality of Andrographis paniculata under prolonged WD stress.

Engineered Nickel Oxide Nanoparticle Causes Substantial Physicochemical Perturbation in Plants.

Concentration of engineered nickel oxide nanoparticle (NiO-NP) in nature is on the rise, owing to large scale industrial uses, which have accreted the scope of its exposure to plants, the primary producers of the ecosystem. Though an essential micronutrient for the animal system, supported by numerous studies confirming its toxicity at higher dosages, nickel oxide is graded as a human carcinogen by WHO. A few studies do depict toxicity and bioaccumulation of nickel in plants; however, interaction of NiO-NP with plants is not well-elucidated. It is known that exposure to NiO-NP can incite stress response, leading to cytotoxicity and growth retardation in some plants, but a defined work on the intricate physicochemical cellular responses and genotoxic challenges is wanting. The present study was planned to explore cytotoxicity of NiO-NP in the model plant, Allium cepa L., its internalization in the tissue and concomitant furore created in the antioxidant enzyme system of the plant. The prospect of the NiO-NP causing genotoxicity was also investigated. Detailed assessments biochemical profiles and genotoxicity potential of NiO-NP on A. cepa L. was performed and extended to four of its closest economically important relatives, Allium sativum L., Allium schoenoprasum L., Allium porrum L., and Allium fistulosum L. Growing root tips were treated with seven different concentrations of NiO-NP suspension (10–500 mg L−1), with deionised distilled water as negative control and 0.4 mM EMS solution as positive control. Study of genotoxic endpoints, like, mitotic indices (MI), chromosomal aberrations (CAs), and chromosome breaks confirmed NiO-NP induced genotoxicity in plants, even at a very low dose (10 mg L−1). That NiO-NP also perturbs biochemical homeostasis, disrupting normal physiology of the cell, was confirmed through changes in state of lipid peroxidation malonaldehyde (MDA), as well as, in oxidation marker enzymes, like catalase (CAT), super oxide dismutase (SOD), and guiacol peroxidase (POD) activities. It was evident that increase in NiO-NP concentration led to decrease in MIs in all the study materials, concomitant with a spike of stress-alleviating, antioxidant enzymes-CAT, POD, SOD, and significant increase in MDA formation. Hence, it can be confirmed that NiO-NP should be treated as an environmental hazard.

Nickel accumulation and its effect on growth, physiological and biochemical parameters in millets and oats.

With the boom in industrialization, there is an increase in the level of heavy metals in the soil which drastically affect the growth and development of plants. Nickel is an essential micronutrient for plant growth and development, but elevated level of Ni causes stunted growth, chlorosis, nutrient imbalance, and alterations in the defense mechanism of plants in terms of accumulation of osmolytes or change in enzyme activities like guiacol peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD). Ni-induced toxic response was studied in seedlings of finger millet, pearl millet, and oats in terms of seedling growth, lipid peroxidation, total chlorophyll, proline content, and enzymatic activities. On the basis of germination and growth parameters of the seedling, finger millet was found to be the most tolerant. Nickel accumulation was markedly lower in the shoots as compared to the roots, which was the highest in finger millet and the lowest in shoots of oats. Plants treated with a high concentration of Ni showed significant reduction in chlorophyll and increase in proline content. Considerable difference in level of malondialdehyde (MDA) content and activity of antioxidative enzymes indicates generation of redox imbalance in plants due to Ni-induced stress. Elevated activities of POD and SOD were observed with high concentrations of Ni while CAT activity was found to be reduced. It was observed that finger millet has higher capability to maintain homeostasis by keeping the balance between accumulation and ROS scavenging system than pearl millet and oats. The data provide insight into the physiological and biochemical changes in plants adapted to survive in Ni-rich environment. This study will help in selecting the more suitable crop species to be grown on Ni-rich soils.

Biochemical response of hybrid black poplar tissue culture (Populus×canadensis) on water stress.

In this study, poplar tissue culture (hybrid black poplar, M1 genotype) was subjected to water stress influenced by polyethyleneglycol 6000 (100 and 200mOsm PEG 6000). The aim of the research was to investigate the biochemical response of poplar tissue culture on water deficit regime. Antioxidant status was analyzed including antioxidant enzymes, superoxide-dismutase (SOD), catalase (CAT), guiacol-peroxidase (GPx), glutathione-peroxidase (GSH-Px), glutathione-reductase, reduced glutathione, total phenol content, Ferric reducing antioxidant power and DPPH radical antioxidant power. Polyphenol oxidase and phenylalanine-ammonium-lyase were determined as enzymatic markers of polyphenol metabolism. Among oxidative stress parameters lipid peroxidation, carbonyl-proteins, hydrogen-peroxide, reactive oxygen species, nitric-oxide and peroxynitrite were determined. Proline, proline-dehydrogenase and glycinebetaine were measured also as parameters of water stress. Cell viability is finally determined as a biological indicator of osmotic stress. It was found that water stress induced reactive oxygen and nitrogen species and lipid peroxidation in leaves of hybrid black poplar and reduced cell viability. Antioxidant enzymes including SOD, GPx, CAT and GSH-Px were induced but total phenol content and antioxidant capacity were reduced by PEG 6000 mediated osmotic stress. The highest biochemical response and adaptive reaction was the increase of proline and GB especially by 200mOsm PEG. While long term molecular analysis will be necessary to fully address the poplar potentials for water stress adaptation, our results on hybrid black poplar suggest that glycine-betaine, proline and PDH enzyme might be the most important markers of poplar on water stress and that future efforts should be focused on these markers and strategies to enhance their concentration in poplar.

Evaluation of genotoxicity and oxidative stress of aluminium oxide nanoparticles and its bulk form in Allium cepa

In the present study, we examined the effects of aluminium oxide nanoparticles (Al2O3 NPs) and bulk aluminium oxide (Al2O3) on Allium cepa in terms of genotoxicity and oxidative stress responses under in planta conditions. The concentrations ranged from 1.25 to 5 µM for NP and its bulk form. Results from this investigation indicated steady rise in chromosome aberrations, micronuclei and DNA strand breaks with increase in concentration of the NPs, effects of Al2O3 NPs being significantly higher than those treated with bulk Al2O3. The divisional frequency was affected by the NP treatment. Oxidative damage such as lipid peroxidation and cell death to Allium under Al2O3 NPs treatments was greater than that observed in bulk Al2O3. A significant increase in activity of guiacol peroxidase was observed in accordance with the depletion in catalase activity in both Al2O3 NPs and bulk Al2O3 treated plants as compared to control. In conclusion, the present study indicated that Al2O3 NPs treatment exerted higher genotoxicity and oxidative stress responses on A. cepa than bulk Al2O3 under in planta conditions.

Salinity Stress Tolerance Of Camelina Investigated In Vitro

Abstract The ability of Camelina sativa to withstand salinity stress in vitro by adding NaCl (0, 25, 50, 75, 100, 125, 150, 175, 200mM) in Murashige and Skoog basal medium was studied. Performance of the plants was measured in terms of various growth parameters and physiological and biochemical tests performed on fully grown plants. The germination capacity, cotyledon unfolding and first true leaf emergence was reduced by 30.6, 17.3, and 28.8%, respectively in 200mM salt treatment with respect to control. The plant height, relative water content, and plant water content were decreased by 85.4, 10.8, and 9.8%, respectively, in stressed plants with respect to control. A decrease in chlorophyll a and b and total chlorophyll contents (by 81.3%), as well as of protein content was registered. Electrical conductivity increased by 52.8% in stressed plants over control, as expected. Other stress indicators like guiacol peroxidase activity and malondialdehyde also increased with respect to control. At salt concentrations lower than 200mM, no clear cut retardation effects were seen. Thus, the present study opens up the scope of further assessment of survivability of camelina in salt contaminated soils.

Effect of salt stress on ion concentration, proline content, antioxidant enzyme activities and gene expression in tomato cultivars.

Salinity is a constraint limiting plant growth and productivity of crops throughout the world. Understanding the mechanism underlying plant response to salinity provides new insights into the improvement of salt tolerance-crops of importance. In the present study, we report on the responses of twenty cultivars of tomato. We have clustered genotypes into scale classes according to their response to increased NaCl levels. Three local tomato genotypes, representative of different saline scale classes, were selected for further investigation. During early (0 h, 6 h and 12 h) and later (7 days) stages of the response to salt treatment, ion concentrations (Na+, K+ and Ca2+), proline content, enzyme activities (catalase, ascorbate peroxidase and guiacol peroxidase) were recorded. qPCR analysis of candidate genes WRKY (8, 31and 39), ERF (9, 16 and 80), LeNHX (1, 3 and 4) and HKT (class I) were performed. A high K+, Ca2 +and proline accumulation as well as a decrease of Na+ concentration-mediated salt tolerance. Concomitant with a pattern of high-antioxidant enzyme activities, tolerant genotypes also displayed differential patterns of gene expression during the response to salt stress.

Diminution of hepatic response to 7, 12-dimethylbenz(α)anthracene by ethyl acetate fraction of Acacia catechu willd. through modulation of xenobiotic and anti-oxidative enzymes in rats.

BackgroundLiver is the primary metabolizing site of body and is prone to damage by exogenous as well as endogenous intoxicants. Polycyclic aromatic hydrocarbons such as 7, 12- dimethylbenz(α)anthracene (DMBA) is an exogenous hepatotoxin, which is well known for modulating phase I, II and anti-oxidative enzymes of liver. Plants contain plethora of polyphenolic compounds which can reverse the damaging effect of various xenobiotics. The present study investigated protective role of the ethyl acetate fraction of Acacia catechu Willd. (EAF) against DMBA induced alteration in hepatic metabolizing and anti-oxidative enzymes in rats.Methodology and Principal FindingsThe rats were subjected to hepatic damage by treating with DMBA for 7 weeks on alternative days and treatment schedule was terminated at the end of 14 weeks. The rats were euthanized at the end of protocol and livers were homogenized. The liver homogenates were used to analyse phase I (NADPH-cytochrome P450 reducatse, NADH-cytochrome b5 reductase, cytochrome P420, cytochrome b5), phase II (glutathione-S-transferase, DT diaphorase and γ-Glutamyl transpeptidase) and antioxidative enzymes (catalase, superoxide dismutase, ascorbate peroxidase, glutathione reductase, guiacol peroxidase and lactate dehydrogenase). Furthermore, other oxidative stress parameters (thiobarbituric acid reactive substances, lipid hydroperoxides and conjugated dienes and reduced glutathione) and liver marker enzymes (serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase and alkaline phosphatase) were also studied. The DMBA induced significant changes in activity of hepatic enzymes that was reversed by treatment with three dose levels of EAF.ConclusionIt is concluded that EAF affords hepato-protection against DMBA in rats through modulation of phase I, II and anti-oxidative enzymes.

Responses of Castor Bean (Ricinus communis L.) to Lead Stress

Castor bean (Ricinus communis L.) plantlets were exposed to lead to study the detoxification mechanism. The results showed that castor bean could survive in soils spiked with 800 mg/kg dry weight Pb for 30 days and grew normally without suffering phytotoxicity. Lead is accumulated mostly in the roots while a small quantity is translocated to the leaves. Changes were detected in both pattern and intensity of Ascorbate peroxidase isoenzyme, while, in case of Guiacol peroxidase, Superoxide dismutase and Glutathione reductase isoenzyme changes were detected only in the intensity. The band intensity of all the isoenzymes increased with the increase of extraneous lead. Increased amount of Malondialdehyde was indicative of lipid peroxidation and free radical generation under lead stress while increased level of proline pointed to the occurrence of mechanism of scavenging free radicals. A decline in chlorophyll content was observed under lead stress. In contrast, carotenoid content was increased in the treated plants. Semi-quantitative reverse transcriptase-PCR was performed to study the expression of an ATP binding casette transporter under lead stress. The expression of the ATP binding casette transporter was recorded only in roots and not in the leaves. The expression was maximum in 800 mg/kg dry weight lead treated plants. These results show that R. communis has a high tolerance and low avoidance to lead.

Potential Antioxidant Activities Improve Salt Tolerance in Ten Varieties of Wheat (<i>Triticum aestivum</i> L.)

The activity of antioxidative enzymes system is affected by salt stress, chlorophyll content (CHL), leaf relative water content (RWC), Na+ and K+ contents, their ratio and some oxidative stress indices were studied in leaves of ten bread wheat cultivarsSehar-06, Lu-26, NARC-09, BARC-09 and Pirsbak-09’(salt-tolerant) and Kaghan-94, Rohtas-90, Soughat-90, Shaheen-94 and Zardana-89’(salt-sensitive), grown under salinity treatments carried out in five levels (1 dS·m-1 as control, 2, 4, 8, 16 dS·m-1) via sodium chloride. Under high salt potency significant increase for activities of antioxidant enzymes such as ascorbate peroxidase (APX) and guiacol peroxidase (GPX), occured in salt tolerant varieties. Meanwhile, under salinity condition the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and (GPX) in sensitive cultivar were lower than control. Regarding (APX) activity there was no significant difference between salinity and control situation. Under salt stress membrane stability index (MSI) of both cultivars were negatively influenced. Hydrogen peroxide (H2O2) content of salinity sensitive cultivars was higher than control. Salt tolerant varieties had more amounts of K+ content, K+ and Na+ ratio, relative water content, yield and chlorophyll under salt conditions, and sensitive ones recorded higher Na+ content at tillering stage. The mechanism of salt stress might be achieved due to low lipid peroxidation, assumingly lower changes in membrane stability index and evasion of Na+ combination and amplified activity of antioxidant enzymes.