Ferric Diethylenetriaminepentaacetic Acid Research Articles

Iron Sources Effects on Growth, Physiological Parameters and Nutrition of Cacao

Productivity and sustainability of cacao (Theobroma cacao L.) in tropical soils are affected by levels of iron. Information is lacking on the cacao response to various sources of iron (Fe). A greenhouse experiment was conducted to evaluate the effects of five iron sources iron sulfate heptahydrate, ferric ethylenediamine-N,N’-bis(2-hydroxyphenylacetic acid), ferric diethylenetriaminepentaacetic acid, ferric ethylenediaminetetraacetic acid, fiesta herbicide (FeSO4 · 7H2O, FeEDDHA, FeDTPA, FeEDTA,) at 10 mg Fe kg−1 soil on growth, photosynthesis, content of photosynthetic pigments and starch and macro- and micronutrient nutrition of cacao. The various iron sources had significant effects on shoot and root dry biomass accumulation, leaf chlorophyll a and b content, carotenoid levels, SPAD index and PN. These parameters were significantly correlated with concentration, uptake, influx, and transport and use efficiency of Fe. In cacao net photosynthesis, stomatal conductance, internal carbon dioxide (CO2), and transpiration in leaf level responded differently to the sources of Fe. Invariably, macro and micronutrient uptake, influx, transport, and use efficiency showed differential responses to sources of iron but significant effects were only observed for copper (Cu), Fe, manganese (Mn), and zinc (Zn). Overall, FeDTPA, FeEDTA and FeHEDTA could be the best sources of Fe in improving, growth, photosynthesis and macro and micro nutrition of cacao.

Iron chelates as low-cost and effective electrocatalyst for oxygen reduction reaction in microbial fuel cells

Iron-chelated electrocatalysts for the oxygen reduction reaction (ORR) in a microbial fuel cell (MFC) were prepared from sodium ferric ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) (FeE), sodium ferric diethylene triamine pentaacetic acid (FeD) supported on carbon Vulcan XC-72R carbon black and multi-walled carbon nanotubes (CNTs). Catalyst morphology was investigated by TEM; and the total surfaces areas as well as the pore volumes of catalysts were examined by nitrogen physisorption characterization. The catalytic activity of the iron based catalysts towards ORR was studied by cyclic voltammetry, showing the higher electrochemical activity of FeE in comparison with FeD and the superior performance of catalysts supported on CNT rather than on Vulcan XC-72R carbon black. FeE/CNT was used as cathodic catalyst in a microbial fuel cell (MFC) using domestic wastewater as fuel. The maximum current density and power density recorded are 110 (mA m−2) and 127 ± 0.9 (mW m−2), respectively. These values are comparable with those obtained using platinum on carbon Vulcan (0.13 mA m−2 and 226 ± 0.2 mW m−2), demonstrating that these catalysts can be used as substitutes for commercial Pt/C.

Effectiveness of Various Iron Sources for Correcting Iron Chlorosis in Dwarf Ixora

`Petite Yellow' dwarf ixoras (Ixora spp.) were grown in an alkaline substrate (3 limestone gravel: 2 coir dust) or a poorly aerated composted seaweed substrate to induce iron (Fe) chlorosis. Chlorotic plants were fertilized every 2 months with soil applications of 0.1 g (0.0035 oz) Fe per 2.4-L (0.63-gal) pot using ferrous sulfate, ferric diethylenetriaminepentaacetic acid (FeDTPA), ferric ethylenediaminedi-o-hydroxyphenylacetic acid (FeEDDHA), Hampshire Iron (FeHEDTA plus FeEDTA), ferric citrate, iron glucoheptonate, or DisperSul Iron (sulfur plus ferrous sulfate). Additional chlorotic ixoras growing in a substrate of 3 sedge peat: 2 cypress sawdust: 1 sand were treated every 2 months with foliar sprays of Fe at 0.8 g·L-1 (0.11 oz/gal) from ferrous sulfate, FeDTPA, FeEDDHA, ferric citrate, or iron glucoheptonate. Only chelated Fe sources significantly improved ixora chlorosis when applied to the soil, regardless of whether the chlorosis was induced by an alkaline substrate or a poorly aerated one. As a foliar spray, only FeDTPA was effective in improving chlorosis in dwarf ixora. Leaf Fe content either showed no relationship to plant color or was negatively correlated with plant chlorosis ratings.

Correcting Iron Deficiency in Calibrachoa Grown in a Container Medium at High pH

The objective was to evaluate and compare foliar spray and soil drench application methods of iron (Fe) for correcting Fe deficiency in hybrid calibrachoa (Calibrachoa × hybrida) grown in a container medium at pH 6.9 to 7.4. Untreated plants showed severe chlorosis and necrosis, stunting, and lack of flowering. An organosilicone surfactant applied at 1.25 mL·L-1 (0.160 fl oz/gal) increased uptake of Fe from foliar applications of both ferrous sulfate (FeSO4) and ferric ethylenediamine tetraacetic acid (Fe-EDTA). Foliar sprays at 60 mg·L-1 (ppm) Fe were more effective when Fe was applied as Fe-EDTA than FeSO4. Increasing Fe concentration of foliar sprays up to 240 mg·L-1 Fe from Fe-EDTA or 368 mg·L-1 Fe (the highest concentrations tested) from ferric diethylenetriamine pentaacetic acid (Fe-DTPA) increased chlorophyll content compared with lower spray concentrations, but leaf necrosis at the highest concentrations may have been caused by phytotoxicity. Drenches with ferric ethylenediaminedi(o-hydroxyphenylacetic) acid (Fe-EDDHA) at 20 to 80 mg·L-1 Fe were highly effective at correcting Fe-deficiency symptoms, and had superior effects on plant growth compared with drenches of Fe-DTPA at 80 mg·L-1 Fe or foliar sprays. Efficacy of Fe-DTPA drenches increased as concentration increased from 20 to 80 mg·L-1 Fe. An Fe-EDDHA drench at 20 to 80 mg·L-1 Fe was a cost-effective option for correcting severe Fe deficiency at high medium pH.

Photodegradation of FeDTPA in Nutrient Solutions. II. Effects on Root Physiology and Foliar Fe and Mn Levels in Marigold

Marigold (Tagetes erecta L.) grown hydroponically in an irradiated nutrient solution containing FeDTPA had root ferric reductase activity 120% greater, foliar Fe level 33% less, and foliar Mn level 90% greater than did plants grown in an identical, nonirradiated solution, indicating that the plants growing in the irradiated solution were responding to Fe-deficiency stress with physiological reactions associated with Fe efficiency. The youngest leaves of plants grown in the irradiated solution had symptoms of Mn toxicity (interveinal chlorosis, shiny-bronze necrotic spots, and leaf deformation). Plants grown in irradiated solution in which the precipitated Fe was replaced with fresh Fechelate were, in general, no different from those grown in the nonirradiated solution. Chemical name used: ferric diethylenetriaminepentaacetic acid (FeDTPA).

Photodegradation of FeDTPA in Nutrient Solutions. I. Effects of Irradiance, Wavelength, and Temperature

Irradiation of FeDTPA-containing nutrient solutions by a fluorescent plus incandescent light source resulted in the loss of both Fe-chelate and soluble Fe, the formation of a precipitate that was composed mostly of Fe, and a rise in pH. The rate of Fe-chelate photodegradation in solution increased with irradiance intensity and with solution temperature under irradiation, but irradiance had the greater effect. Fe-chelates absorb in the blue and UV regions of the spectrum. Removal of these wavelengths with a spectral filter eliminated photodegradation. Chemical name used: ferric diethylenetriaminepentaacetic acid (FeDTPA).

Marigold Cultivars Vary in Susceptibility to Iron Toxicity

The susceptibility of seven African marigold (Tagetes erecta L.) cultivars to iron toxicity was assessed. Plants were grown in a greenhouse in a soilless medium and Fe-DTPA was incorporated into the nutrient solution at either 0.018 mmol·L-1 (low) or 0.36 mmol·L-1 (high). Symptoms of Fe toxicity (bronze speckle disorder in marigold characterized by chlorotic and necrotic speckling and downward leaf cupping and curling) developed only in the high-Fe treatment. The concentration of Fe in leaves in the high-Fe treatment was 5.6 and 1.7 times as great as in the low-Fe treatment for `Orange Jubilee' and `Discovery Orange', respectively. Based upon the percentage of plants affected and leaf symptom severity, relative cultivar susceptibility to Fe toxicity was Orange Jubilee > First Lady > Orange Lady > Yellow Galore > Gold Lady > Marvel Gold > Discovery Orange. Chemical names used: ferric diethylenetriaminepentaacetic acid, disodium salt dihydrate (Fe-DTPA).

Iron Toxicity Stress Causes Bronze Speckle, a Specific Physiological Disorder of Marigold (Tagetes erecta L.)

A specific physiological disorder, bronze speckle (J.P.A.'s nomenclature), was consistently induced in `First Lady' and `Voyager' marigold with Fe-DTPA concentrations greater than 0.018 mm Fe-DTPA (1 ppm) applied to a soilless medium. The disorder was characterized by specific symptomology distinguished visually by speckled patterns of chlorosis and necrosis, and downward curling and cupping of leaves. The percentage of total leaf dry weight affected with symptoms generally increased with increasing Fe-DTPA treatments. Symptomatic leaf tissue had a greater Fe concentration than corresponding asymptomatic leaf tissue. Leaf Mn concentrations in symptomatic and asymptomatic tissue were similar. In `First Lady', older leaf tissue accumulated more total Fe and was associated with more severe symptoms than younger tissue. Media leachate Fe concentrations increased over 6 weeks and were larger at greater Fe-DTPA treatments. Adjustment of nutrient solution pH to 4.0, 5.25, or 6.5 did not alter media pH, nor did it prevent disorder symptoms. Application of Fe-DTPA containing nutrient solution to a soilless medium resulted in leachate Fe levels 3 times greater than for FeSO4 treatments. Chemical names used: ferric diethylenetriaminepentaacetic acid, monosodium salt (Fe-DTPA).

Iron Deficiency Stress Influences Physiology of Iron Acquisition in Marigold (Tagetes erecta L.)

Excised roots of `First Lady' marigold (Tagetes erecta L.) grown in an aerated 0 Fe nutrient solution had Fe(III)-DTPA reductase activity 14-fold greater, and an enhanced ability to acidify the rhizosphere than plants grown in a solution containing 0.018 mm (1 ppm) Fe-DTPA. Reductase activity and rhizosphere acidification of plants grown in 0.018 and 0.09 mm Fe-DTPA were similar. Manganese concentration in leaves of plants grown in the 0 Fe treatment was 2-fold greater than in leaves of plants grown in the 0.018 mm Fe-DTPA treatment. These results indicated that `First Lady' marigold is an Fe-efficient plant that possesses both an inducible or adaptive reductase system and the ability to acidify the rhizosphere, and that these Fe-efficiency reactions do not occur when Fe is sufficient. Chemical name used: ferric diethylenetriaminepentaacetic acid, monosodium salt (Fe-DTPA).

Oxygen Radical Generation by Isolated Microsomes from Soybean Seedlings

The generation of active oxygen species by microsomes isolated from soybean seedlings was studied. NADPH-dependent superoxide anion production was 5.0 +/- 0.4 nmol . min(-1) mg(-1) of microsomal protein. Hydrogen peroxide generation by microsomes was 1.40 +/- 0.05 nmol . min(-1) mg(-1) of protein. Hydroxyl radical production, in the presence of ferric EDTA, evaluated through the generation of formaldehyde from dimethyl sulfoxide or tert-butyl alcohol was 0.50 +/- 0.04 and 0.44 +/- 0.03 nmol . min(-1) mg(-1), respectively. NADH proved to be suitable as cofactor for oxygen radical generation by microsomes from soybean seedlings. Because transition metals are implicated in radical generation by biological systems, the ability of microsomal membranes to reduce iron complexes was studied. Ferric ATP, ferric citrate, ferric ADP, ferric diethylenetriamine pentaacetic acid, and ferric EDTA were efficiently reduced in the presence of either NADPH or NADH as cofactor. The pattern of effectiveness of the different ferric complexes, on superoxide anion, hydrogen peroxide, and hydroxyl radical production, was similar to that found with animal microsomes. The data presented here indicate that microsomal ability to catalyze oxygen radical generation must be considered as an important contribution to cellular radical steady-state concentrations in cells from soybean seedlings.

Detailed method to screen dicot cultivars for resistance to Fe‐chlorosis using FeDTPA and bicarbonate in nutrient solutions

Abstract The use of bicarbonate additions to nutrient solutions containing low levels of available Fe have allowed screening for susceptibility to Fe‐deficiency chlorosis in many dicots (soybean, bean, chickpea, citrus, etc.). Research has shown that relative susceptibility among cultivars in this nutrient solution has a high correlation with the relative susceptibility observed in wet calcareous soils which induce chlorosis. This paper provided the specific details needed by plant breeders to adapt the research reports to their own laboratory situation. We provide full details on the present recommended method using FeDTPA (ferric diethylenetriaminepentaacetic acid) in place of FeEDDHA (ferric ethylene‐di‐o‐Chydroxyphenylacetic acid) used in earlier screens, including preparation of nutrient solutions, inducing varied severity of Fe‐stress or potential chlorosis severity, use of indicator cultivare, and measuring plant response. The method described has been developed in cooperation with industrial and a...

Reduction of paraquat and related bipyridylium compounds to free radical metabolites by rat hepatocytes

The toxicity of paraquat is due to the oxygen-derived radicals formed by the reaction of oxygen with bipyridylium radical cations. Although paraquat is known to cause lung toxicity, the related bipyridylium compounds such as diquat and morfamquat do not affect the lung as seriously, but rather cause liver toxicity. Paraquat, diquat, morfamquat, and benzyl viologen are reduced by rat hepatocytes to their respective radical cations. An intracellular component of the signal was detected from diquat and benzyl viologen radical cations. These radical cations generated inside the cell can cross the plasma membrane. Generation of the diquat radical cation by hepatocytes is not affected by the inhibition of cytochrome P-450 by carbon monoxide or metyrapone, suggesting that this enzyme is probably not involved in the reduction of diquat as had been proposed previously. The reduction of paraquat is generally attributed to NADPH-cytochrome P-450 reductase, and presumably diquat is also reduced by this flavoprotein. Some transition metal chelates such as ferric diethylenetriaminepentaacetic acid delay the detection of the diquat radical cation. This may be due to the reduction of the ferric chelate by the diquat radical cation resulting in the formation of the ferrous chelate and the parent bipyridylium dication. When all the ferric chelate has been reduced to the ferrous chelate, then the bipyridylium radical can be detected. Alternatively, if the ferric chelate enters the cell, it can compete with the parent bipyridylium dication for the reductase, which would also lead to delayed detection.

NADH-dependent microsomal interaction with ferric complexes and production of reactive oxygen intermediates

The interaction of NADPH with ferric complexes to catalyze microsomal generation of reactive oxygen intermediates has been well studied. Experiments were carried out to characterize the ability of NADH to interact with various ferric chelates to promote microsomal lipid peroxidation and generation of .OH-like species. In the presence of NADH and iron, microsomes produced .OH as assessed by the oxidation of a variety of .OH scavenging agents. Rates of NADH-dependent .OH production were 50 to 80% those of the NADPH-catalyzed reaction. The oxidation of dimethyl sulfoxide or t-butyl alcohol was inhibited by catalase and competitive .OH scavengers but not by superoxide dismutase or carbon monoxide. NADH-dependent .OH production was effectively catalyzed by ferric-EDTA and ferric-diethylenetriaminepentaacetic acid (DTPA), whereas ferric-ATP and ferric-citrate were poor catalysts. All these ferric chelates were reduced by microsomes in the presence of NADH (and NADPH). H 2O 2 was produced in the presence of NADH in a reaction stimulated by the addition of ferric-EDTA, consistent with the increase in .OH production. The latter appeared to be limited by the rate of H 2O 2 generation rather than the rate of reduction of the ferric chelate. NADH-dependent lipid peroxidation was much lower than the NADPH-catalyzed reaction and showed an opposite response to catalysis by ferric complexes compared to .OH generation as production of thiobarbituric acid-reactive material was increased with ferric-ATP and -citrate, but not with ferric-EDTA or -DTPA, and was not affected by catalase, SOD, or .OH scavengers. These results indicate that NADH can support microsomal reduction of ferric chelates, with the subsequent production of .OH-like species and peroxidation of lipids. The pattern of response of the NADH-dependent reactions with respect to catalytic effectiveness of ferric chelates and sensitivity to radical scavengers is similar to that found with NADPH. Many of the metabolic actions of ethanol have been ascribed to production of NADH as a consequence of oxidation by alcohol dehydrogenase. Since the cytosol normally maintains a highly oxidized NAD +/NADH redox ratio, it is interesting to speculate that increased availability of NADH from the oxidation of ethanol may support microsomal reduction of iron complexes, with the subsequent generation of reactive oxygen intermediates.

Interactions between paraquat and ferric complexes in the microsomal generation of oxygen radicals

Transition metals may play a central role in the toxicity associated with paraquat. Studies were carried out to evaluate the interaction of paraquat with several ferric complexes in the promotion of oxygen radical generation by rat liver microsomes. In the absence of added iron, paraquat produced some increase in low level chemiluminescence by microsomes; there was a synergistic increase in light emission in the presence of paraquat plus ferric-ATP or ferric-citrate, but not paraquat plus either ferric-EDTA or ferric-diethylenetriamine pentaacetic acid (ferric-DETAPAC). Synergistic interactions could be observed at a paraquat concentration of 100 μM and a ferric-ATP concentration of 3 μM. In the absence or presence of paraquat, microsomal light emission was not affected by catalase or dimethyl sulfoxide (DMSO), indicating no significant role for hydroxyl radicals. Superoxide dismutase (SOD) did not affect chemiluminescence in the absence of paraquat but produced some inhibition in the presence of paraquat; this inhibition by SOD was most prominent in the absence of added iron and less pronounced in the presence of ferric-ATP or ferric-citrate. Although microsomal chemiluminescence is closely associated with lipid peroxidation, paraquat did not increase malondialdehyde production as reflected by production of thiobarbituric acid-reactive components. However, lipid peroxidation was sensitive to inhibition by SOD in the presence, but not in the absence, of paraquat, analogous to results with chemiluminescence. Paraquat synergistically increased microsomal hydroxyl radical production as measured by the production of ethylene from 2-keto-4-thiomethylbutyrate in the presence of ferric-EDTA or ferric-citrate. The interaction of paraquat with microsomes and ferric complexes resulted in an increase in oxygen radical generation. Various ferric complexes can increase the catalytic effectiveness of paraquat in promoting microsomal generation of oxygen radicals, although, depending on the reaction being investigated, the nature of the ferric complex is important.

Synergistic interactions between nadph-cytochrome P-450 reductase, paraquat, and iron in the generation of active oxygen radicals

The toxicity associated with paraquat is believed to involve the generation of active oxygen radicals and the production of oxidative stress. Paraquat can be reduced by NADPH-cytochrome P-450 reductase to the paraquat radical; this results in consumption of NADPH. A variety of ferric complexes, including ferric-ATP, -citrate, -EDTA, ferric diethylenetriamine pentaacetic acid and ferric ammonium sulfate, produced a synergistic increase in the paraquat-mediated oxidation of NADPH. This synergism could be observed with very low concentrations of iron, e.g. 0.25 μM ferric-ATP. Very low rates of hydroxyl radical were generated by the reductase with paraquat alone, or with ferric-citrate or -ATP or ferric ammonium sulfate in the absence of paraquat; however, synergistic increases in the rate of hydroxyl radical generation occurred when these ferric complexes were added together with paraquat. Ferric-EDTA and -DTPA catalyzed some production of hydroxyl radicals, which was also synergistically elevated in the presence of paraquat. Ferric desferrioxamine was essentially inert in the absence or presence of paraquat. This enhancement of hydroxyl radical generation was sensitive to catalase and competitive scavengers but not to superoxide dismutase. The interaction of paraquat with NADPH-cytochrome P-450 reductase and ferric complexes resulted in an increase in oxygen radical generation, and various ferric complexes increased the catalytic effectiveness and potentiated significantly the toxicity of paraquat via this synergistic increase in oxygen radical generation by the reductase.

Chemiluminescence studies on the generation of oxygen radicals from the interaction of NADPH—Cytochrome P-450 reductase with iron

The ability of NADPH—cytochrome P-450 reductase to interact with iron and generate oxygen radicals was evaluated by assaying for low level chemiluminescence. The basic reaction system which contained the reductase, an NADPH-generating system, ferric-EDTA as an electron acceptor, and t-butyl hydroperoxide as the oxidant acceptor, resulted in the production of chemiluminescence. Omission of any of these components resulted in a complete loss of chemiluminescence. The light emission was completely sensitive to inhibition by glutathione and butylated hydroxytoluene, partially sensitive (about 60% decrease) to catalase and hydroxyl radical scavengers, and relatively insensitive (about 20% decrease) to superoxide dismutase. The ability of other ferric chelates to replace ferric-EDTA in catalyzing the reductase-dependent chemiluminescence was evaluated. Ferric-citrate, -ADP, -ATP, and ferric-ammonium sulfate were ineffective in promoting chemiluminescence, whereas ferric-diethylenetriaminepentaacetic acid was even more effective than ferric-EDTA. Thus, the ferric chelates, which catalyze reductase-dependent chemiluminescence, are those which are efficient electron acceptors from the reductase and were previously shown to be those capable of catalyzing hydroxyl radical production by microsomes and the reductase. It is suggested that chemiluminescence results from (a) the direct interaction of the reduced iron chelate with the hydroperoxide (Fenton-type of reaction) to generate alkoxyl and peroxyl radicals, and (b) the generation of hydroxyl radicals, which subsequently react with the hydroperoxide to generate secondary radicals. The latter, but not the former, would be sensitive to inhibition by catalase and competitive hydroxyl radical scavengers, whereas both would be sensitive to antioxidants such as butylated hydroxytoluene. Chemiluminescence appears to be a versatile tool for studying the reductase-dependent generation of oxygen radicals and for the interaction of reductase with iron.

The role of iron chelates in hydroxyl radical production by rat liver microsomes, NADPH-cytochrome P-450 reductase and xanthine oxidase

Uninduced rat liver microsomes and NADPH-Cytochrome P-450 reductase, purified from phenobarbital-treated rats, catalyzed an NADPH-dependent oxidation of hydroxyl radical scavenging agents. This oxidation was not stimulated by the addition of ferric ammonium sulfate, ferric citrate, or ferric-adenine nucleotide (AMP, ADP, ATP) chelates. Striking stimulation was observed when ferric-EDTA or ferric-diethylenetriamine pentaacetic acid (DTPA) was added. The iron-EDTA and iron-DTPA chelates, but not unchelated iron, iron-citrate or iron-nucleotide chelates, stimulated the oxidation of NADPH by the reductase in the absence as well as in the presence of phenobarbital-inducible cytochrome P-450. Thus, the iron chelates which promoted NADPH oxidation by the reductase were the only chelates which stimulated oxidation of hydroxyl radical scavengers by reductase and microsomes. The oxidation of aminopyrine, a typical drug substrate, was slightly stimulated by the addition of iron-EDTA or iron-DTPA to the microsomes. Catalase inhibited potently the oxidation of scavengers under all conditions, suggesting that H 2O 2 was the precursor of the hydroxyl radical in these systems. Very high amounts of superoxide dismutase had little effect on the iron-EDTA-stimulated rate of scavenger oxidation, whereas the iron-DTPA-stimulated rate was inhibited by 30 or 50% in microsomes or reductase, respectively. This suggests that the iron-EDTA and iron-DTPA chelates can be reduced directly by the reductase to the ferrous chelates, which subsequently interact with H 2O 2 in a Fenton-type reaction. Results with the reductase and microsomal systems should be contrasted with results found when the oxidation of hypoxanthine by xanthine oxidase was utilized to catalyze the production of hydroxyl radicals. In the xanthine oxidase system, ferric-ATP and -DTPA stimulated oxidation of scavengers by six- to eightfold, while ferric-EDTA stimulated 25-fold. Ferric-desferrioxamine consistently was inhibitory. Superoxide dismutase produced 79 to 86% inhibition in the absence or presence of iron, indicating an iron-catalyzed Haber-Weiss-type of reaction was responsible for oxidation of scavengers by the xanthine oxidase system. These results indicate that the ability of iron to promote hydroxyl radical production and the role that superoxide plays as a reductant of iron depends on the nature of the system as well as the chelating agent employed.