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At least 19 recordsLinked to original sources
PubMed2002

Final report on the safety assessment of EDTA, calcium disodium EDTA, diammonium EDTA, dipotassium EDTA, disodium EDTA, TEA-EDTA, tetrasodium EDTA, tripotassium EDTA, trisodium EDTA, HEDTA, and trisodium HEDTA.

EDTA (ethylenediamine tetraacetic acid) and its salts are substituted diamines. HEDTA (hydroxyethyl ethylenediamine triacetic acid) and its trisodium salt are substituted amines. These ingredients function as chelating agents in cosmetic formulations. The typical concentration of use of EDTA is less than 2%, with the other salts in current use at even lower concentrations. The lowest dose reported to cause a toxic effect in animals was 750 mg/kg/day. These chelating agents are cytotoxic and weakly genotoxic, but not carcinogenic. Oral exposures to EDTA produced adverse reproductive and developmental effects in animals. Clinical tests reported no absorption of an EDTA salt through the skin. These ingredients are likely, however, to affect the passage of other chemicals into the skin because they will chelate calcium. Exposure to EDTA in most cosmetic formulations, therefore, would produce systemic exposure levels well below those seen to be toxic in oral dosing studies. Exposure to EDTA in cosmetic formulations that may be inhaled, however, was a concern. An exposure assessment done using conservative assumptions predicted that the maximum EDTA dose via inhalation of an aerosolized cosmetic formulation is below that shown to produce reproductive or developmental toxicity. Because of the potential to increase the penetration of other chemicals, formulators should continue to be aware of this when combining these ingredients with ingredients that previously have been determined to be safe, primarily because they were not significantly absorbed. Based on the available data, the Cosmetic Ingredient Review Expert Panel found that these ingredients are safe as used in cosmetic formulations.

Abnormalities, Drug-Induced↗
PubMed2002

Effects of EDTA saturated with Ca2+ (Ca-EDTA) on pig, bovine and mouse oocytes at the germinal vesicle stage during maturation culture and the involvement of chelation of Zn2+ in pronuclear formation induction by Ca-EDTA.

EDTA saturated with Ca(2+), Fe(3+) or Cu(2+) can induce parthenogenetic activation of pig oocytes at the germinal vesicle stage, whereas EDTA saturated with Zn(2+), which is unable to chelate Zn(2+), does not, indicating that chelation of Zn(2+) with EDTA saturated with Ca(2+) (Ca-EDTA) in maturing pig oocytes plays a pivotal role in the induction of parthenogenetic activation of oocytes. In the present study, the involvement of Zn(2+) chelation in the induction of parthenogenetic activation of pig oocytes at the germinal vesicle stage was confirmed first by examining the effects of concomitant addition of Zn(2+), Cu(2+) or Ni(2+) at various concentrations together with 1 mmol Ca-EDTA l(-1) to the maturation medium. The titration experiments revealed that the pronuclear formation induced by 1 mmol Ca-EDTA l(-1) was completely inhibited by the addition of > 30 micromol Zn(2+) l(-1) to the medium, but not by the addition of Cu(2+) and Ni(2+) at any concentration examined. Second, bovine and mouse oocytes at the germinal vesicle stage were cultured in medium with or without 1 mmol Ca-EDTA l(-1) for 48 h to examine the effects of Ca-EDTA treatment on these oocytes during maturation culture. Most (70-86%) of the bovine oocytes that underwent germinal vesicle breakdown matured to the MII stage via the MI phase, regardless of whether Ca-EDTA was present for the first 24 h of culture. However, 61% of oocytes that had been cultured with Ca-EDTA for 48 h formed a pronucleus without a second polar body, whereas oocytes cultured in the absence of Ca-EDTA were not observed to form a pronucleus at any time during culture. However, even when mouse oocytes at the germinal vesicle stage were cultured for up to 48 h in maturation medium containing Ca-EDTA, pronuclear formation was not observed. Finally, when bovine oocytes that had been cultured with 1 mmol Ca-EDTA l(-1) for 48 h from the germinal vesicle stage were cultured further in medium without Ca-EDTA that was supplemented with 5% fetal calf serum, only 26% of the oocytes developed to the cleaved stage, and none could develop further.

Animals↗
PubMed1999

Competitive Adsorption of Cu(II)-EDTA and Cd(II)-EDTA onto TiO2.

Cu(II), EDTA, Cu(II)-EDTA, Cd(II)-EDTA, and Cu(II)/Cd(II) and Cu(II)-EDTA/Cd(II)-EDTA competitive adsorption onto TiO2 has been studied with variation of pH and concentration. For Cu(II) and EDTA, typical cationic and anionic types of adsorption are noted, respectively. Ligand-type adsorption is found for Cu(II)-EDTA and Cd(II)-EDTA under both single and competitive conditions. Surface complexation modeling considered inner-sphere complexation and the diffuse layer model employing MINTEQA2; surface complexes used include Ti-(OH2)O-Cu+, Ti-(OH)EDTAH-22, Ti-(OH)EDTA-Cu-2, and Ti-(OH)EDTA-Cd-2. Experimental and model predictions suggest no competitive adsorption between Cu(II) and Cd(II) at 5 x 10(-5) M. On the other hand, adsorption data and model predictions indicate that Cd(II)-EDTA adsorption is favored over that of Cu(II)-EDTA with some competition for adsorption sites. Cd(II)-EDTA adsorption was only slightly affected by the presence of Cu(II)-EDTA; however, Cu(II)-EDTA adsorption was strongly influenced by the presence of Cd(II)-EDTA, especially as the molar ratio of Cd(II)-EDTA/Cu(II)-EDTA increased. A modified surface complexation constant for Cd(II)-EDTA is required to explain the competitive data, suggesting surface site heterogeneity. Copyright 1999 Academic Press.

Journal Article↗
PubMedDate not supplied

N-(iodoacetyl)-p-phenylenediamine-EDTA: a reagent for high-efficiency incorporation of an EDTA-metal complex at a rationally selected site within a protein.

We have developed a highly efficient procedure to incorporate an EDTA:metal complex at a rationally selected site within a full-length protein. Our procedure has two steps: In step one, we use site-directed mutagenesis to introduce a unique solvent-accessible cysteine residue at the site of interest. In step two, we derivatized the resulting protein with N-(iodoacetyl)-p-phenylenediamine-EDTA:metal, a novel haloacetyl derivative of EDTA:metal. We have used this procedure to incorporate each of three EDTA:metal complexes at amino acid 2 of the helix-turn-helix motif of the sequence-specific DNA binding protein Cro: a radioactive and nucleolytic EDTA:metal complex (EDTA:55Fe), a radioactive EDTA:metal complex (EDTA:63Ni), and a fluorescent and heavy-atom EDTA:metal complex (EDTA:Eu). Incorporation of EDTA:metal was highly efficient (> 80% for EDTA:55Fe and EDTA:63Ni; 60% for EDTA:Eu) and highly site-specific (> 99%). We have analyzed DNA affinity cleaving by the Cro derivative having EDTA:55Fe at amino acid 2 of the helix-turn-helix motif. The Cro derivative cleaves DNA at base pairs -4 to 6 of the DNA half site in the protein-DNA complex, indicating that amino acid 2 of the helix-turn-helix motif of Cro is close to base pairs -4 to 6 of the DNA half site in the Cro-DNA complex in solution.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage lambda↗
PubMed1998

Purification and characterization of EDTA monooxygenase from the EDTA-degrading bacterium BNC1.

The synthetic chelating agent EDTA can mobilize radionuclides and heavy metals in the environment. Biodegradation of EDTA should reduce this mobilization. Although several bacteria have been reported to mineralize EDTA, little is known about the biochemistry of EDTA degradation. Understanding the biochemistry will facilitate the removal of EDTA from the environment. EDTA-degrading activities were detected in cell extracts of bacterium BNC1 when flavin mononucleotide (FMN), NADH, and O2 were present. The degradative enzyme system was separated into two different enzymes, EDTA monooxygenase and an FMN reductase. EDTA monooxygenase oxidized EDTA to glyoxylate and ethylenediaminetriacetate (ED3A), with the coconsumption of FMNH2 and O2. The FMN reductase provided EDTA monooxygenase with FMNH2 by reducing FMN with NADH. The FMN reductase was successfully substituted in the assay mixture by other FMN reductases. EDTA monooxygenase was purified to greater than 95% homogeneity and had a single polypeptide with a molecular weight of 45,000. The enzyme oxidized both EDTA complexed with various metal ions and uncomplexed EDTA. The optimal conditions for activity were pH 7.8 and 35 degreesC. Kms were 34.1 microM for uncomplexed EDTA and 8.5 microM for MgEDTA2-; this difference in Km indicates that the enzyme has greater affinity for MgEDTA2-. The enzyme also catalyzed the release of glyoxylate from nitrilotriacetate and diethylenetriaminepentaacetate. EDTA monooxygenase belongs to a small group of FMNH2-utilizing monooxygenases that attack carbon-nitrogen, carbon-sulfur, and carbon-carbon double bonds.

Cations↗
PubMed1999

Transport of EDTA into cells of the EDTA-degrading bacterial strain DSM 9103.

In the bacterial strain DSM 9103, which is able to grow with the complexing agent EDTA as the sole source of carbon, nitrogen and energy, the transport of EDTA into whole cells was investigated. EDTA uptake was found to be dependent on speciation: free EDTA and metal-EDTA complexes with low stability constants were readily taken up, whereas those with stability constants higher than 1016 were not transported. In EDTA-grown cells, initial transport rates of CaEDTA showed substrate-saturation kinetics with a high apparent affinity for CaEDTA (affinity constant Kt= 0.39 microM). Several uncouplers had an inhibitory effect on CaEDTA transport. CaEDTA uptake was also significantly reduced in the presence of an inhibitor of ATPase and the ionophore nigericin, which dissipates the proton gradient. Valinomycin, however, which affects the electrical potential, had little effect on uptake, indicating that EDTA transport is probably driven by the proton gradient. Of various structurally related compounds tested only Ca2+-complexed diethylenetriaminepentaacetate (CaDTPA) competitively inhibited CaEDTA transport. Uptake in fumarate-grown cells was low compared to that measured in EDTA-grown bacteria. These results strongly suggest that the first step in EDTA degradation by strain DSM 9103 consists of transport by an inducible energy-dependent carrier. Uptake experiments with 45Ca2+ in the presence and absence of EDTA indicated that Ca2+ is transported together with EDTA into the cells. In addition, these transport studies and electron-dispersive X-ray analysis of electron-dense intracellular bodies present in EDTA-grown cells suggest that two mechanisms acting simultaneously allow the cells to cope with the large amounts of metal ions taken up together with EDTA. In one mechanism the metal ions are excreted, in the other they are inactivated intracellularly in polyphosphate granules.

Biodegradation, Environmental↗
PubMed1995

Concurrent reduction of iodine and oxidation of EDTA at the active site of horseradish peroxidase: probing the iodine binding site by optical difference spectroscopy and steady state kinetic analysis for the formation of active enzyme-I(+)-EDTA ternary complex for iodine reductase activity.

Horseradish peroxidase (HRP) catalyzes the reduction of iodine to iodide by EDTA with pseudocatalatic degradation of H2O2 to O2 (Banerjee et al., (1986) J. Biol. Chem. 261, 10592-10597; and Banerjee (1989) J. Biol. Chem. 264, 9188-9194). The reduction of iodine (I+) is dependent on EDTA concentration and is blocked by spin trap, DMPO, indicating the involvement of free radical species in the reduction process. Incubation of EDTA with both HRP and H2O2 results in the appearance of triplet ESR signal of spin-trapped EDTA radical (aN = 15 G), indicating its one-electron oxidation to a nitrogen-centered monocation radical (N-N+). The latter oxidizes H2O2 to evolve O2 and regenerate EDTA. In the presence of I+, a ternary complex of compound I-I(+)-EDTA is formed, which generates compound II-I. complex and both nitrogen-centered dication radical (N(+)-N+) through intermolecular electron transfer from EDTA nitrogens. Compound II-I. complex is further reduced similarly by another molecule of EDTA to form ferric enzyme, I-, and (N(+)-N+).(N(+)-N+) the oxidation product of EDTA, which may be released from the active site and, being more reactive, oxidizes H2O2 to O2 at a faster rate to regenerate EDTA. The existence of (N(+)-N+) is suggested from the similarity of its ESR signal with that of single nitrogen-centered monocation radical (N-N+). EDTA degradation by oxidative decarboxylation due to two-electron oxidation from the same or both nitrogen, atoms is not evident, and EDTA concentration remains the same throughout the reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1987

Identification of carbohydrate moieties involved in EDTA-stable or EDTA-sensitive cell contact of Dictyostelium discoideum.

Antisera against purified contact site A glycoprotein, with an apparent molecular weight of 80 X 10(3) (80 kDa), from Dictyostelium discoideum were raised by using Freund's adjuvant (antiserum-A) and by using Alu-Gel-S (antiserum-B) as immunoadjuvants. They were converted into Fab fragments for the cell agglutination assay. Fab fragments of antiserum-B inhibited only EDTA-stable cell contact, whereas Fab fragments of antiserum-A (Fab-A) inhibited EDTA-sensitive cell contact as well as EDTA-stable cell contact. We prepared several cell types in order to identify target antigens for the adhesion-blocking Fab-A in EDTA-sensitive cell contact or EDTA-stable cell contact. One of these cell types produced contact site A without N-glycosidically-linked carbohydrate chains. It is known that contact site A contains two kinds of N-glycosidically-linked carbohydrate chains (carbohydrates I and II, Yoshida, M., Stadler, J., Bertholdt, G., and Gerisch, G. (1984) EMBO J. 3, 2653-2670). When growth-phase cells were treated with tunicamycin (TM) at a final concentration of 2 micrograms/ml in nutrient medium (TM-pretreated cells), the cells produced contact site A without N-glycosidically-linked carbohydrate chains (53 kDa) at the normal developmental stage. These cells lacked EDTA-sensitive cell contact as well as EDTA-stable cell contact. The neutralization of the adhesion-blocking Fab-A was done by using particulate fractions from each cell type. The blocking activity in EDTA-stable cell contact was neutralized by the cell type with carbohydrate II. Taking these results into consideration, EDTA-stable cell contact may be formed by the interaction between protein moieties of contact site A and carbohydrate II. Concerning EDTA-sensitive cell contact, the blocking activity was neutralized by each cell type irrespective of TM treatment. This suggests that O-glycosidically-linked carbohydrate chains play a role in EDTA-sensitive cell contact. Moreover, the biological activity in EDTA-sensitive cell contact of TM-pretreated cells suggests that N-glycosidically-linked carbohydrate chains may also be involved in this contact.

Antibodies, Monoclonal↗
PubMed1992

Oxidative damage to bovine serum albumin induced by hydroxyl radical generating systems of xanthine oxidase + EDTA-Fe3+ and ascorbate + EDTA-Fe3+.

Oxidative damage to bovine serum albumin (BSA) was induced by hydroxyl radical (HO.) generating systems of xanthine oxidase (XO) + EDTA-Fe3+ and ascorbate + EDTA-Fe3+. Formation of bityrosine and loss of tryptophan were observed in the ascorbate + EDTA-Fe3+ system and carbonyl formation was induced by both systems. Mannitol and ethanol very strongly inhibited the carbonyl and/or bityrosine formation, indicating that the oxidative damage to BSA was due to HO(.). The sulfhydryl (SH) groups of BSA were very sensitive to the XO + EDTA-Fe3+ but not to the ascorbate + EDTA-Fe3+ system. Catalase but not hydroxyl radical scavengers or superoxide dismutase strongly inhibited the loss of SH groups, indicating that H2O2 is involved in their oxidation. Fragmentation of BSA was observed during exposure to the XO + EDTA-Fe3+ and ascorbate + EDTA-Fe3+ systems and the products presented a broad band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Little formation of amine groups was observed in these systems, indicating that little peptide bond cleavage occurred. BSA exposed to the ascorbate + EDTA-Fe3+ system was more readily degraded by trypsin than that exposed to the XO + EDTA-Fe3+ system. Elastase degraded BSA exposed to the ascorbate + EDTA-Fe3+ system but not to the XO + EDTA-Fe3+ system.

Amines↗
PubMed1993

Iodide modulation of the EDTA-induced iodine reductase activity of horseradish peroxidase by interaction at or near the EDTA-binding site.

Horseradish peroxidase (HRP) catalyses the reduction of iodinium ion (I+) to iodide by H2O2 in the presence of EDTA. I+ reduction occurs optimally at pH 6 whereas the enzyme catalyses iodide oxidation optimally at pH 3.5. Thus the two activities reside on the same enzyme with two characteristic pH optima. Iodide modulates the expression of the reductase activity by EDTA. Higher concentrations of iodide inhibit the reductase activity by EDTA. Nitrite, an electron donor, acts similarly to iodide. Both EDTA and nitrite competitively inhibit iodide oxidation, indicating that they compete with iodide for the same binding site for electron flow to the haem iron group. However, unlike iodide, EDTA converts compound I, not into the native enzyme, but into a compound absorbing at 416 nm which reduces I+ and then returns to the native form. The apparent equilibrium dissociation constant, KD, for the formation of the EDTA-HRP complex (15 mM) is doubled in the presence of iodide, indicating interference with EDTA binding by iodide. EDTA binds away from the haem iron centre and not through intramolecular Ca2+. The pH-dependence of EDTA binding indicates that an ionizable group of the enzyme with pKa 5.8, presumably a distal histidine, controls the binding. The data suggest that iodide competes with EDTA for compound I and modulates the iodine reductase activity by limiting the formation of the 416 nm-absorbing active compound.

Anions↗
PubMed2003

Decalcifying effect of EDTA-T, 10% citric acid, and 17% EDTA on root canal dentin.

OBJECTIVE: An in vitro study was conducted to determine the efficacy of 17% EDTA plus 1.25% sodium lauryl ether sulfate (EDTA-T), 10% citric acid, and 17% EDTA with respect to Ca(++) extraction. STUDY DESIGN: The root canals of 90 extracted human canines were instrumented by using the step-back technique. The teeth were randomly divided into 9 groups of 10 teeth each according to the solution and time intervals involved (ie, 3, 10, and 15 minutes). The Ca(++) concentration of the solution was determined by using atomic absorption spectroscopy. RESULTS: At 3 minutes, there was no significant difference between Ca(++) extraction by 10% citric acid and 17% EDTA (P >.05). EDTA-T had the least efficacy for Ca(++) extraction (P <.05). At 10 minutes and 15 minutes, there were no significant differences between 10% citric acid and 17% EDTA or between EDTA-T and 17% EDTA (P >.05). However, 10% citric acid was significantly better than EDTA-T in terms of Ca(++) extraction (P <.05). CONCLUSION: Both 10% citric acid and 17% EDTA are good decalcifying agents when the step-back technique is used.

Chelating Agents↗
PubMed1994

Platelet release reaction during EDTA-induced platelet agglutinations and inhibition of EDTA-induced platelet agglutination by anti-glycoprotein II b/III a complex monoclonal antibody.

To characterize the nature of EDTA-induced platelet agglutination, the spontaneous release of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) was examined during EDTA-induced platelet agglutinations. A slight release of beta-TG and PF4 was observed when EDTA-anticoagulated whole blood from cases with EDTA-induced platelet agglutination was kept for 60 minutes, whereas a high spontaneous release of these proteins was found from normal blood anticoagulated with EDTA. These findings imply that EDTA-dependent platelet agglutinin may stabilize the platelet membrane surfaces. Secondly, we found that pretreatment of fresh blood with anti-glycoprotein (GP) II b/III a complex monoclonal antibody dramatically reduced EDTA-induced platelet agglutinations. This study indicated that the binding sites of EDTA-dependent antibody might be GP II b/III a complex. The use of an anti-GP II b/III a complex monoclonal antibody may be useful in avoiding analytical errors in some cases with EDTA-induced pseudothrombocytopenia.

Adenosine Diphosphate↗
PubMed2003

Slow complexation kinetics for ferric iron and EDTA complexes make EDTA non-biodegradable.

Published experimental data on ethylenediaminetetraacetic acid (EDTA) biodegradation in the presence of ferric iron (Fe(III)) showed that rapid biodegradation of EDTA suddenly stopped, leaving a residual of unbiodegraded EDTA that was equal to the concentration of dissolved Fe(III). We hypothesize that slow kinetics for the dissociation of two iron-EDTA complexes--FeEDTA(-) and FeOHEDTA(2-)--sequestered the EDTA in a form that is biologically unavailable. To evaluate this hypothesis, we added to the biogeochemical model CCBATCH a new submodel for kinetically controlled complexation. CCBATCH simulations with kinetically controlled complexation for FeEDTA(-) and FeOHEDTA(2-) and the observed concentration of total dissolved Fe(III) accurately predicted the sudden cessation of EDTA biodegradation at the exact time shown experimentally. Our simulations also correctly predicted the observed residual EDTA concentration and the amounts of biomass and NH4+. Alternate explanations for the experimental results--strong equilibrium complexation of ferric iron and EDTA and precipitation of calcium and magnesium solids--could not capture the observed trends. This analysis using CCBATCH's new sub-model for kinetically controlled complexation shows that EDTA, once it becomes complexed with Fe(III), becomes biologically unavailable.

Algorithms↗
PubMed2004

Effectiveness of EDTA and EDTA-T brushing on the removal of root surface smear layer.

The purpose of this study was to compare the removal of root surface smear layer following active application of EDTA gel and EDTA-T (texapon) gel in different concentrations (5%, 10%, 15%, 20% and 24%), using scanning electron microscopy. A total of 220 dentin blocks obtained from the root surfaces of extracted teeth were divided into 3 groups: Group I - (control) application of saline solution (n = 20); Group II - EDTA gel (pH 7.0) was applied in the following concentrations: 5%, 10%, 15%, 20% and 24% (n = 100); Group III - EDTA-T gel (pH 7.0) applied in the same concentrations described above (n = 100). The photomicrographs were evaluated by one calibrated examiner using a smear layer removal index and following statistical analysis (Kruskal-Wallis test). The results demonstrated that the specimens treated with EDTA and EDTA-T gel presented a better smear layer removal than the control group (p < 0.01); no statistically significant differences were observed between the EDTA and EDTA-T groups and between the concentrations tested (Mann-Whitney, p > 0.05). Within the limits of this study, it can be concluded that all treatment modalities effectively removed the smear layer from the root surface. The addition of texapon into the EDTA gel formulation did not increase its effectiveness.

Bicuspid↗
PubMed1993

Toxicological profile, current use, and regulatory issues on EDTA compounds for assessing use of sodium iron EDTA for food fortification.

The U.S. Food and Drug Administration (FDA) has approved the use of disodium and calcium disodium ethylenediaminetetraacetate (EDTA) for direct addition to food. The international nutrition community is interested in obtaining approval for the use of sodium iron(III) EDTA (NaFeEDTA) for dietary iron fortification because of its high iron bioavailability, its enhancement of intrinsic food iron uptake, and its stability under storage and food preparation conditions. A major concern in the United States has been the presumed extensive use of EDTA in the American food supply. Recently, an update of the estimated exposure to EDTA suggests that the exposure is much lower than previously assumed. This reduction may allow new uses of NaFeEDTA in food. The following issues are discussed in relation to the possible use of NaFeEDTA: toxicological profile of EDTA compounds, acceptable daily intake of EDTA, and estimated daily intake of EDTA in the United States.

Edetic Acid↗
PubMed2001

Competitive photocatalytic oxidation of Cu(II)--EDTA and Cd(II)--EDTA with illuminated TiO2.

Competitive photocatalytic oxidation (PCO) of mixtures of Cu(II)-EDTA and Cd(II)-EDTA was studied with variation of molar ratio of these two complexes (1 x 10(-4):0, 8 x 10(-5): 2 x 10(-5), 5 x 10-5:5 x 10(-5), 2 x 10-5:8 x 10(-5), 0:1 x 10(-4) M) and in the pH range of 4-8. PCO rates for each compound can be described using a combined aqueous + adsorbed pathway: -dC/dt = k1Caq(1+ k2Caq)+ kadsCads. This expression is valid under both noncompetitive and competitive conditions. Differences in rates under competition result from differences in the partitioning of the two species between the TiO2 surface and the aqueous phase. Total initial complex degradation rates (rTT), obtained by summation of the total destruction rates for Cu(II)-EDTA and Cd(II)-EDTA, were relatively constant at pH 4 and 5 for all ratios. At these pH values, contribution of adsorbed pathways to rTT was important, and rates were similar to those of the aqueous phase pathways. From pH 6 to 8, the degree of adsorption, and thus the adsorbed pathway rate, diminished. Through the adsorbed pathway, no difference in rate constants was found between Cu(II)-EDTA and Cd(II)-EDTA; Cd(II)-EDTA is somewhat more reactive through the aqueous phase pathway.

Adsorption↗
PubMed2002

Effects of Pb-EDTA and EDTA on oxidative stress reactions and mineral uptake in Phaseolus vulgaris.

Sequestration of Pb by synthetic chelates has been reported to increase bioavailability, uptake, and translocation of this metal in plants. In this work the potential phytotoxic effects of Pb-EDTA were investigated in Phaseolus vulgaris L. cv. Limburgse vroege plants grown on hydroponics. Addition of 50 microM Pb-EDTA to the nutrient solution caused a significant induction of syringaldazine peroxidase (SPOD; EC 1.11.1.7) in roots and primary leaves and guaiacol peroxidase (GPOD; EC 1.11.1.7) in leaves. Addition of 100 microM Pb-EDTA further exacerbated ascorbate peroxidase (APOD; EC 1.11.1.11), GPOD, dehydroascorbate reductase (DHAR; EC 1.8.5.1), glutathione reductase (GR; EC 1.6.4.2) and malic enzyme (ME; EC 1.1.1.40) in roots and APOD and ME in primary leaves. Addition of 200 microM Pb-EDTA also induced DHAR in leaves. This induction of peroxidases (SPOD, GPOD, APOD), enzymes of the ascorbate-glutathione cycle (DHAR, GR in roots) and of an NADP+ reducing enzyme in roots and primary leaves indicates that oxidative stress has been initiated. At 200 microM Pb-EDTA, chlorophyll a and b content in leaves was significantly reduced while visible effects on root morphology and shoot length were observed, while no significant morphological effects were found in the leaves, confirming the sensitive character of the measured enzymes as plant stress indicators. Elevation of the Pb-EDTA concentration in the growth medium significantly reduced the content of Ca, Fe, Mn and Zn taken up by plants, probably due to ion leakage as a result of observed toxicity. Addition of up to 200 microM EDTA increased chelation of divalent cations in nutrient solution resulting in reduced plant uptake of Zn, Cu, Fe and Mn. This did not result in phytotoxicity.

Journal Article↗