Multifaceted activities of plant gum synthesised platinum nanoparticles: catalytic, peroxidase, PCR enhancing and antioxidant activities.

A single pot, green method for platinum nanoparticles (Pt NP) production was devised with gum ghatti (Anogeissus latifolia). Analytical tools: ultraviolet-visible (UV-vis), dynamic light scattering, zeta potential, transmission electron microscope, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy were employed. Wide continuous UV-vis absorption and black solution colouration proved Pt NP formation. Face-centred cubic crystalline structure of NP was evidenced from XRD. NPs formed were nearly spherical with a mean particle size of 3 nm. NP demonstrated a myriad of properties including catalytic, peroxidase, polymerase chain reaction (PCR) enhancing and antioxidant activities. Catalytic action of NP was probed via NaBH4 reduction of arsenazo-III dye. NP displayed considerable peroxidase activity via catalysis of 3, 3', 5, 5'-tetramethylbenzidine oxidation by H2O2. NP showed exceptional stability towards varying pH (3-11), temperature (25-100°C), salt concentration (0-100 mM) and storage time duration (0-12 months). In comparison with horse radish peroxidase, its applicability as an artificial peroxidase is advantageous. NP caused a two-fold enhancement in PCR yield at 0.4 nM. Also showed significant 1', 1' diphenyl picryl-hydrazyle scavenging (80.1%) at 15 µg/mL. Author envisages that the biogenic Pt NP can be used in a range of biological and environmental applications.

Pectin Demethylesterification Generates Platforms that Anchor Peroxidases to Remodel Plant Cell Wall Domains.

Plant cell walls are made of polysaccharidic-proteinaceous complex matrices. Molecular interactions governing their organization remain understudied. We take advantage of the highly dynamic cell walls of Arabidopsis seed mucilage secretory cells to propose a hierarchical multi-molecular interaction model within a cell wall domain. We show that the PECTINMETHYLESTERASE INHIBITOR6 activity creates a partially demethylesterified pectin pattern acting as a platform allowing positioning of PEROXIDASE36 in a remote primary cell wall domain during early development. This allows triggering the loosening of this domain during later development, in turn leading to proper physiological function upon mature seed imbibition and germination. We anticipate that this pioneer example of molecular scaffold within a cell wall domain is more widespread through other combinations of the individual molecular players all belonging to large multigenic families. These results highlight the role of cell wall polysaccharide-protein interactions in the organization of cell wall domains.

VPO1 Modulates Vascular Smooth Muscle Cell Phenotypic Switch by Activating Extracellular Signal-regulated Kinase 1/2 (ERK 1/2) in Abdominal Aortic Aneurysms.

Background Hydrogen peroxide (H2O2) is a critical molecular signal in the development of abdominal aortic aneurysm ( AAA ) formation. Vascular peroxidase 1 ( VPO 1) catalyzes the production of hypochlorous acid ( HOC l) from H2O2 and significantly enhances oxidative stress. The switch from a contractile phenotype to a synthetic one in vascular smooth muscle cells ( VSMC s) is driven by reactive oxygen species and is recognized as an early and important event in AAA formation. This study aims to determine if VPO 1 plays a critical role in the development of AAA by regulating VSMC phenotypic switch. Methods and Results VPO 1 is upregulated in human and elastase-induced mouse aneurysmal tissues compared with healthy control tissues. Additionally, KLF 4, a nuclear transcriptional factor, is upregulated in aneurysmatic tissues along with a concomitant downregulation of differentiated smooth muscle cell markers and an increase of synthetic phenotypic markers, indicating VSMC phenotypic switch in these diseased tissues. In cultured VSMC s from rat abdominal aorta, H2O2 treatment significantly increases VPO 1 expression and HOC l levels as well as VSMC phenotypic switch. In support of these findings, depletion of VPO 1 significantly attenuates the effects of H2O2 and HOC l treatment. Furthermore, HOC l treatment promotes VSMC phenotypic switch and ERK 1/2 phosphorylation. Pretreatment with U0126 (a specific inhibitor of ERK 1/2) significantly attenuates HOC l-induced VSMC phenotypic switch. Conclusions Our results demonstrate that VPO 1 modulates VSMC phenotypic switch through the H2O2/ VPO 1/ HOC l/ ERK 1/2 signaling pathway and plays a key role in the development of AAA . Our findings also implicate VPO 1 as a novel signaling node that mediates VSMC phenotypic switch and plays a key role in the development of AAA . Clinical Trial Registration URL : www.chictr.org.cn . Unique identifier: Chi CTR 1800016922.

Effects of molecular weight of hyaluronic acid on its viscosity and enzymatic activities of lysozyme and peroxidase.

OBJECTIVES: To investigate the effects of the molecular weight of hyaluronic acid on its viscosity and enzymatic activities of lysozyme and peroxidase in solution and on the hydroxyapatite surface. DESIGN: Hyaluronic acids of four different molecular weights (10 kDa, 100 kDa, 1 MDa, and 2 MDa), hen egg-white lysozyme, bovine lactoperoxidase, and human whole saliva were used. Viscosity values of hyaluronic acids were measured using a cone-and-plate viscometer at six different concentrations (0.1-5.0 mg/mL). Enzymatic activities of lysozyme and peroxidase were examined by hydrolysis of fluorescein-labeled Micrococcus lysodeikticus and oxidation of fluorogenic 2',7'-dichlorofluorescein to fluorescing 2',7'-dichlorofluorescein, respectively. RESULTS: In solution assays, only 2 MDa-hyaluronic acid significantly inhibited lysozyme activities in saliva. In surface assays, hyaluronic acids inhibited lysozyme and peroxidase activities; the inhibitory activities were more apparent with high-molecular-weight ones in saliva than in purified enzymes. The 100 kDa-hyaluronic acid at 5.0 mg/mL, 1 MDa-one at 0.5 mg/mL, and 2 MDa-one at 0.2 mg/mL showed viscosity values similar to those of human whole saliva at a shear rate range required for normal oral functions. The differences among the influences of the three conditions on the enzymatic activities were not statistically significant. CONCLUSIONS: High-molecular-weight hyaluronic acids at low concentration and low-molecular-weight ones at high concentration showed viscosity values similar to those of human whole saliva. Inhibitory effects of hyaluronic acids on lysozyme and peroxidase activities were more significant with high-molecular-weight ones on the surface and in saliva compared with in solution and on purified enzymes.

Early habituation of maize (Zea mays) suspension-cultured cells to 2,6-dichlorobenzonitrile is associated with the enhancement of antioxidant status.

The cellulose biosynthesis inhibitor 2,6-dichlorobenzonitrile (DCB) has been widely used to gain insights into cell wall composition and architecture. Studies of changes during early habituation to DCB can provide information on mechanisms that allow tolerance/habituation to DCB. In this context, maize-cultured cells with a reduced amount of cellulose (∼20%) were obtained by stepwise habituation to low DCB concentrations. The results reported here attempt to elucidate the putative role of an antioxidant strategy during incipient habituation. The short-term exposure to DCB of non-habituated maize-cultured cells induced a substantial increase in oxidative damage. Concomitantly, short-term treated cells presented an increase in class III peroxidase and glutathione S-transferase activities and total glutathione content. Maize cells habituated to 0.3-1 µM DCB (incipient habituation) were characterized by a reduction in the relative cell growth rate, an enhancement of ascorbate peroxidase and class III peroxidase activities, and a net increment in total glutathione content. Moreover, these cell lines showed increased levels of glutathione S-transferase activity. Changes in antioxidant/conjugation status enabled 0.3 and 0.5 µM DCB-habituated cells to control lipid peroxidation levels, but this was not the case of maize cells habituated to 1 µM DCB, which despite showing an increased antioxidant capacity were not capable of reducing the oxidative damage to control levels. The results reported here confirm that exposure and incipient habituation of maize cells to DCB are associated with an enhancement in antioxidant/conjugation activities which could play a role in incipient DCB habituation of maize-cultured cells.

In vitro antioxidant properties, free radicals scavenging activities of extracts and polyphenol composition of a non-timber forest product used as spice: Monodora myristica.

BACKGROUND: Excessive production of free radicals causes direct damage to biological molecules such as DNA, proteins, lipids, carbohydrates leading to tumor development and progression. Natural antioxidant molecules from phytochemicals of plant origin may directly inhibit either their production or limit their propagation or destroy them to protect the system. In the present study, Monodora myristica a non-timber forest product consumed in Cameroon as spice was screened for its free radical scavenging properties, antioxidant and enzymes protective activities. Its phenolic compound profile was also realized by HPLC. RESULTS: This study demonstrated that M. myristica has scavenging properties against DPPH(•), OH(•), NO(•), and ABTS(•) radicals which vary in a dose depending manner. It also showed an antioxidant potential that was comparable with that of Butylated Hydroxytoluene (BHT) and vitamin C used as standard. The aqueous ethanol extract of M. myristica barks (AEH); showed a significantly higher content in polyphenolic compounds (21.44 ± 0.24 mg caffeic acid/g dried extract) and flavonoid (5.69 ± 0.07 quercetin equivalent mg/g of dried weight) as compared to the other studied extracts. The HPLC analysis of the barks and leaves revealed the presence of several polyphenols. The acids (3,4-OH-benzoic, caffeic, gallic, O- and P- coumaric, syringic, vanillic), alcohols (tyrosol and OH-tyrosol), theobromine, quercetin, rutin, catechine and apigenin were the identified and quantified polyphenols. All the tested extracts demonstrated a high protective potential on the superoxide dismutase (SOD), catalase and peroxidase activities. CONCLUSION: Finally, the different extracts from M. myristica and specifically the aqueous ethanol extract reveal several properties such as higher free radical scavenging properties, significant antioxidant capacities and protective potential effects on liver enzymes.

The effects of xylitol and sorbitol on lysozyme- and peroxidase-related enzymatic and candidacidal activities.

OBJECTIVE: To investigate whether xylitol and sorbitol affect enzymatic and candidacidal activities of lysozyme, the peroxidase system, and the glucose oxidase-mediated peroxidase system. DESIGN: Xylitol and sorbitol were added to hen egg-white lysozyme, bovine lactoperoxidase, glucose oxidase-mediated peroxidase, and whole saliva in solution and on hydroxyapatite surfaces. The enzymatic activities of lysozyme, peroxidase, and glucose oxidase-mediated peroxidase were determined by the turbidimetric method, the NbsSCN assay, and production of oxidized o-dianisidine, respectively. Candidacidal activities were determined by comparing colony forming units using Candida albicans ATCC strains 10231, 11006, and 18804. RESULTS: While xylitol and sorbitol did not affect the enzymatic activity of hen egg-white lysozyme both in solution and on hydroxyapatite surfaces, they did inhibit the enzymatic activity of salivary lysozyme significantly in solution, but not on the surfaces. Xylitol and sorbitol enhanced the enzymatic activities of both bovine lactoperoxidase and salivary peroxidase significantly in a dose-dependent manner in solution, but not on the surfaces. Sorbitol, but not xylitol, inhibited the enzymatic activity of glucose oxidase-mediated peroxidase significantly. Both xylitol and sorbitol did not affect candidacidal activities of hen egg-white lysozyme, the bovine lactoperoxidase system, or the glucose oxidase-mediated bovine lactoperoxidase system. CONCLUSIONS: Xylitol and sorbitol inhibited salivary lysozyme activity, but enhanced both bovine lactoperoxidase and salivary peroxidase activities significantly in solution. Xylitol and sorbitol did not augment lysozyme- and peroxidase-related candidacidal activities.

In vitro antioxidant properties, free radicals scavenging activities of extracts and polyphenol composition of a non-timber forest product used as spice: Monodora myristica

BACKGROUND: Excessive production of free radicals causes direct damage to biological molecules such as DNA, proteins, lipids, carbohydrates leading to tumor development and progression. Natural antioxidant molecules from phytochemicals of plant origin may directly inhibit either their production or limit their propagation or destroy them to protect the system. In the present study, Monodora myristica a non-timber forest product consumed in Cameroon as spice was screened for its free radical scavenging properties, antioxidant and enzymes protective activities. Its phenolic compound profile was also realized by HPLC. RESULTS: This study demonstrated that M. myristica has scavenging properties against DPPH',OH',NO', and ABTS'radicals which vary in a dose depending manner. It also showed an antioxidant potential that was comparable with that of Butylated Hydroxytoluene (BHT) and vitamin C used as standard. The aqueous ethanol extract of M. myristica barks (AEH); showed a significantly higher content in polyphenolic compounds (21.44 ± 0.24 mg caffeic acid/g dried extract) and flavonoid (5.69 ± 0.07 quercetin equivalent mg/g of dried weight) as compared to the other studied extracts. The HPLC analysis of the barks and leaves revealed the presence of several polyphenols. The acids (3,4-OH-benzoic, caffeic, gallic, O- and P- coumaric, syringic, vanillic), alcohols (tyrosol and OH-tyrosol), theobromine, quercetin, rutin, catechine and apigenin were the identified and quantified polyphenols. All the tested extracts demonstrated a high protective potential on the superoxide dismutase (SOD), catalase and peroxidase activities. CONCLUSION: Finally, the different extracts from M. myristica and specifically the aqueous ethanol extract reveal several properties such as higher free radical scavenging properties, significant antioxidant capacities and protective potential effects on liver enzymes.

Benzothiadiazole effect in the compatible tomato-Meloidogyne incognita interaction: changes in giant cell development and priming of two root anionic peroxidases.

MAIN CONCLUSION: BTH application is effective in root-knot nematode-tomato interaction in a way that involves a delay in the formation of nematode feeding site and triggers molecular responses at several levels. The compatible interaction between root-knot nematodes and their hosts requires the nematode to overcome plant defense systems so that a sophisticated permanent feeding site (giant cells) can be produced within the host roots. It has been suggested that activators of plant defenses may provide a novel management strategy for controlling root-knot nematodes but little is known about the molecular basis by which these elicitors operate. The role of pre-treatment with Benzothiadiazole (BTH), a salicylic acid analog, in inducing resistance against Meloidogyne incognita infection was investigated in tomato roots. A decrease in galling in roots and feeding site numbers was observed following BTH treatment. Histological investigations showed a delay in formation of feeding sites in treated plants. BTH-treated galls had higher H2O2 production, lignin accumulation, and increased peroxidase activity than untreated galls. The expression of two tomato genes, Tap1 and Tap2, coding for anionic peroxidases, was examined by qRT-PCR and in situ hybridization in response to BTH. Tap1 was induced at all infection points, reaching the highest level at 15 dpi. Tap2 expression, although slightly delayed in untreated galls, increased during infection in both treated and untreated galls. The expression of Tap1 and Tap2 was observed in giant cells of untreated roots, whereas the transcripts were localized in both giant cells and in parenchyma cells surrounding the developing feeding sites in treated plants. These results show that BTH applied to tomato plants makes them more resistant to infection by nematodes, which become less effective in overcoming root defense pathway.

Quantitative proteomics identifies the membrane-associated peroxidase GPx8 as a cellular substrate of the hepatitis C virus NS3-4A protease.

UNLABELLED: The hepatitis C virus (HCV) NS3-4A protease is not only an essential component of the viral replication complex and a prime target for antiviral intervention but also a key player in the persistence and pathogenesis of HCV. It cleaves and thereby inactivates two crucial adaptor proteins in viral RNA sensing and innate immunity, mitochondrial antiviral signaling protein (MAVS) and TRIF, a phosphatase involved in growth factor signaling, T-cell protein tyrosine phosphatase (TC-PTP), and the E3 ubiquitin ligase component UV-damaged DNA-binding protein 1 (DDB1). Here we explored quantitative proteomics to identify novel cellular substrates of the NS3-4A protease. Cell lines inducibly expressing the NS3-4A protease were analyzed by stable isotopic labeling using amino acids in cell culture (SILAC) coupled with protein separation and mass spectrometry. This approach identified the membrane-associated peroxidase GPx8 as a bona fide cellular substrate of the HCV NS3-4A protease. Cleavage by NS3-4A occurs at Cys 11, removing the cytosolic tip of GPx8, and was observed in different experimental systems as well as in liver biopsies from patients with chronic HCV. Overexpression and RNA silencing studies revealed that GPx8 is involved in viral particle production but not in HCV entry or RNA replication. CONCLUSION: We provide proof-of-concept for the use of quantitative proteomics to identify cellular substrates of a viral protease and describe GPx8 as a novel proviral host factor targeted by the HCV NS3-4A protease.

A study on the antioxidant effect of Coriolus versicolor polysaccharide in rat brain tissues.

The objective of the study was to investigate the antioxidant effect of Chinese medicine Coriolus versicolor polysaccharide on brain tissue and its mechanism in rats. SOD, MDA and GSH-Px levels in rat brain tissues were determined with SD rats as the animal model. The results showed that Coriolus versicolor polysaccharide can reduce the lipid peroxidation level in brain tissues during exhaustive exercise in rats, and can accelerate the removal of free radicals. The study concluded that its antioxidant effect is relatively apparent.

Potential of the aquatic fern Azolla filiculoides in biodegradation of an azo dye: modeling of experimental results by artificial neural networks.

The potential of an aquatic fern, Azolla filiculoides, in phytoremediation of a mono azo dye solution, C.I. Acid Blue 92 (AB92), was studied. The effects of operational parameters such as reaction time, initial dye concentration, fern fresh weight, pH, temperature and reusability of the fern on biodegradation efficiency were investigated. The intermediate compounds produced by biodegradation process were analyzed using GC-MS analysis. An artificial neural network (ANN) model was developed to predict the biodegradation efficiency. The findings indicated that ANN provides reasonable predictive performance (R2 = 0.961). The effects of AB92 solutions (10 and 20 mg L(-1)) on growth, chlorophylls and carotenoids content, activity of antioxidant enzymes such as superoxide dismutase, peroxidase and catalase and formation of malondialdehyde were analyzed. AB92 generally showed inhibitory effects on the growth. Moreover, photosynthetic pigments in the fronds significantly decreased in the treatments. An increase was detected for lipid peroxidation and antioxidant enzymes activity, suggesting that AB92 caused reactive oxygen species production in Azolla fronds, which were scavenged by induced activities of antioxidant enzymes.

[Function of nitric oxide in initiating production of lignin degrading peroxidases by Phanerochaete chrysosporium].

OBJECTIVE: By analyzing the function and mechanism of nitric oxide in initiating producing lignin peroxidases by phanerochaete chrysosporium, we studied the regulation mechanism triggering the secondary metabolism of white-rot fungi. METHODS: Mutant (pcR5305) and wild-type (pc530) strains of phanerochaete chrysosporium were respectively cultured under both the conditions of nitrogen limitation and nitrogen sufficiency. To compare their lignin peroxidases (LiP)-production and nitric oxide(NO)-production kinetics and their different influences on producing LiP after the NO donor Sodium Nitroprusside (SNP) and scavenger cPTIO were respectively added to the nitrogen limitation or sufficiency culture medium to show the function and mechanism of nitric oxide in initiating production of lignin peroxidases by white-rot fungi. RESULTS: Both strains produced nitric oxide (NO) under the two opposite nutritional conditions, but the levels of NO produced were related with the type of strain and the nutritional conditions. Strain pc530 produced NO requiring nutrition depletion and producing of NO was strongly delayed and reduced when it was cultured under nitrogen sufficiency condition. On the contrary, pcR5305 did not require nitrogen depletion to trigger and the levels of NO were higher than that of pc530. The results indicate that LiP content had positive correlation with NO value except the occurrence time of LiP peak value was later than that of NO. The ability of producing LiP was promoted after the NO donor SNP added, but SNP affected more on pc530 than pcR5305 in promoting producing LiP. 15mM cPTIO would greatly repress producing LiP, but could not completely restrain the synthesis of LiP for both strains. CONCLUSION: By producing NO, Phanerochaete chrysosporium triggers LiP synthesis. However, the evidences do not indicate that NO participates or effect directly in LiP synthesis. It is more likely that NO is reacting as an upstream signal molecule. Besides NO, there are other signal molecules that have a positive effect on NO levels also involving in the regulation producing LiP. The mechanism of the resistance to nutritional repression of pcR5305 in synthesizing lignin degrading peroxidases may be the answer to the different NO production mechanism of pcR5305 from pc530.

Effect of soil salinity on physiological characteristics of functional leaves of cotton plants.

This study analyzes the effects of soil salinity on fatty acid composition, antioxidative enzyme activity, lipid peroxidation, and photosynthesis in functional leaves during the flowering and boll-forming stages of two cotton cultivars, namely, CCRI-44 (salt-tolerant) and Sumian 12 (salt-sensitive), grown under different soil salinity conditions. Saturated (C16:0 and C18:0) and unsaturated fatty acid (FA) contents (C18:1), as well as superoxide dismutase activity increased, whereas high-unsaturated FA (C18:2 and C18:3) decreased, with the increase in soil salinity. The production of malondialdehyde increased with increasing lipoxygenase (LOX) activity, indicating that LOX catalyzed FA peroxidation under salt stress. Soil salinity had no significant effect on catalase (CAT) and peroxidases (POD) activity in the salt-sensitive cultivar Sumian 12, but significantly increased CAT and POD activities in the salt-tolerant cultivar CCRI-44. Net photosynthesis and stomatal conductance of the cotton cultivars decreased in response to salt stress; however, CCRI-44 showed a smaller reduction in photosynthesis than Sumian 12. The results indicated that stomatal apparatus limited leaf photosynthetic capacity in the salinity-treated plants of both cultivars. The net photosynthetic rate, maximum photochemical efficiency, and photochemical quantum yield of the cotton functional leaves showed positive correlation with double-bond index (DBI). These results suggested that salt stress caused DBI reduction and decreased the photochemical conversion efficiency of solar radiation and, thereby resulting in lower net photosynthetic rates.

[Silibinin and its hepatoprotective action from the perspective of a toxicologist]. / Sylibinina i jej dzialanie hepatoprotekcyjne z punktu widzenia toksykologa.

Silibinin is the most active component of a complex of flavonoids -silymarin contained in fruit milk thistle (Sylibum marianum). Its mechanism of action is complex and highly beneficial in protecting hepatocytes. On the one hand this compound blocks the penetration of various toxins (for example amanitin) into the hepatocytes not allowing in this way for the cell death and on the other hand, it prevents apoptosis through intracellular. It protects the liver from oxidative intracellular free radicals by increasing the activity of enzyme superoxide dismutase and peroxidase, as well as by increasing the concentration of glutathione and the activity of the peroxidase. Silibinin strengthens and stabilizes the cell membranes, inhibits the synthesis of prostaglandins associated with the lipid peroxidation and promotes regeneration of liver through the stimulation of protein synthesis and effect on the production of new hepatocytes. A particularly interesting topic from the perspective of a toxicologist is the application of silibinin in Amanita phalloides poisoning. Clinical trials conducted in this respect are very encouraging. The other beneficial application of silibinin is in therapy of the alcoholic liver cirrhosis. The evidence shows that the use of silymarin leads to a significant reduction in liver-related mortality and even reduction in the number of patients with encephalopathy in the course of the disease. Application of silibinin goes beyond liver disease and expands in the direction of cancer and even diabetes. What is interesting is the fact, that the substance of herbal origin occurring in the environment is so strong, favorable, beneficial and multidirectional. Science has contributed to improving the bioavailability of silibinin thus making it more effective.

Biphasic dose-response of antioxidants in hypericin-induced photohemolysis.

In the present paper the photodynamic effect of hypericin on superoxide dismutase activity and the possibility of reduction of hypericin phototoxicity by antioxidants were studied. It was shown an almost twice decrease in superoxide dismutase activity of red blood cells under the photosensitization by hypericin. The influence of antioxidants (ascorbic acid and quercetin) on hypericin photodynamic action has revealed that these antioxidants suppress or stimulate photohemolysis caused by hypericin. The photosensitization reaction realized by hypericin could be shifted from type II to type I or vice versa by manipulating the antioxidant concentration. Strengthening of photohemolysis by antioxidants in some concentrations indicates the switching of alternative mechanisms of hypericin photodynamic action and its complicated manner. Thus the selection of antioxidant concentrations is of extreme importance for changing the efficacy of photodynamic therapy with hypericin.

Hexaconazole induces antioxidant protection and apigenin-7-glucoside accumulation in Matricaria chamomilla plants subjected to drought stress.

In this experiment, the possibility of enhancing the water deficit stress tolerance of chamomile (Matricaria chamomilla L.) during two growth stages by the exogenous application of hexaconazole (HEX) was investigated. To improve water deficit tolerance, HEX was applied in three concentrations during two different stages (50 and 80 days after sowing). After HEX applications, the plants were subjected to water deficit stress. Although all HEX concentrations improved the water deficit stress tolerance in chamomile plants, the application of 15 mg L(-1) provided better protection when compared to the other concentration. The exogenous application of HEX provided significant protection against water deficit stress compared to non-HEX-treated plants, significantly affecting the morphological characteristics and aspects of productivity, the relative water, protein and proline contents; non-enzymatic and enzymatic antioxidants; and the flower's apigenin-7-glucoside content. These results suggest that the HEX-induced tolerance to water deficit stress in chamomile was related to the changes in growth variables, antioxidants and the apigenin-7-glucoside content.

Heme oxygenase-1 is involved in the cytokinin-induced alleviation of senescence in detached wheat leaves during dark incubation.

This study tested whether an inducible isoform of heme oxygenase (HO, EC 1.14.99.3), HO-1, is involved in the cytokinin (CTK)-induced alleviation of senescence in detached wheat (Triticum aestivum L.) leaves during dark incubation. We discovered that exogenous supplement of 6-benzylaminopurine (6-BA) at 10 µM for 48 h not only delayed the dark-induced loss of chlorophyll and protein contents in detached wheat leaves, but also significantly increased HO activity in a time-dependent manner. This induction reached a maximum within 3h of 6-BA supply, which was further confirmed by using semi-quantitative RT-PCR and protein gel blot analysis. Furthermore, the decreases in intracellular thiobarbituric acid reactive substances (TBARS) content, and the increases in the transcript level, total and isozymatic activities of some important antioxidant enzymes, such as catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), superoxide dismutase (SOD, EC 1.15.1.1), and ascorbate peroxidase (APX, EC 1.11.1.11), were observed. Reversed responses of chlorophyll, protein and TBARS contents, HO activity, and the expression of above antioxidant enzymes were observed when zinc protoporphyrin-IX (ZnPPIX), a potent HO-1 inhibitor, was added together with 6-BA. In contrast, HO-1 inducer hemin could partially mimic the effects of 6-BA. Together, the results suggest that HO-1 might be involved in the CTK-induced alleviation of senescence and lipid peroxidation in detached wheat leaves.

Ecotoxicological effects of aluminum and zinc on growth and antioxidants in Lemna minor L.

The present study aimed at investigating effects of zinc and aluminum (0.15 and 0.3mM) in duckweed (Lemna minor L.) over a 15-day period. High bioaccumulation of both metals was accompanied by an increase in dry weight under higher metal treatments. Antioxidant response was observed under both metal stresses, with large increases in superoxide dismutase and peroxidases. Catalase activity declined only in duckweed exposed to Zn while lipid peroxidation as well as H(2)O(2), proline and ascorbate levels increased. The results suggest induction of oxidative stress under both aluminum and zinc toxicity, and also demonstrate duckweed's capacity to upregulate its antioxidative defense. Additionally, Zn was found to be more toxic than Al to duckweed for the concentrations applied. Due to its high bioaccumulation potential and tolerance via increased antioxidant capacity, duckweed has a potential for phytoremediation of water bodies polluted by low levels of zinc and aluminum.

Differential response of antioxidant enzymes to cadmium stress in tolerant and sensitive cell line of cucumber (Cucumis sativus L.).

Previously, a stable cell suspension of cucumber tolerant to 100 microM CdCl(2) was obtained (Gzyl & Gwózdz, 2005, Plant Cell Tissue Organ Cult 80: 59-67). In this study, the relationship between the activity of antioxidant enzymes and cadmium tolerance of cucumber cells was analyzed. A cadmium-sensitive and the cadmium-tolerant cell lines were exposed to 100 microM and 200 microM CdCl(2) and the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APOX) and guaiacol peroxidase (POX) were determined. In the sensitive cell line, a decrease of total activity of SOD and POX was observed, whereas the activity of CAT and APOX significantly increased in metal-supplemented medium. By contrast, in the tolerant cells, the total activity of antioxidant enzymes decreased (SOD, CAT) or was maintained at approximately the same level (APOX, POX). Moreover, a different pattern of isoenzyme activity was observed in the tolerant and sensitive cells. These results suggest that an enhanced activity of antioxidant enzymes is not directly involved in the increased tolerance to cadmium of the selected cucumber cell line.