Chelator EDTA Research Articles

Isolation and identification of a Cytobacillus oceanisediminis strain with ochratoxin A detoxification ability

Ochratoxin A (OTA) is a polyketide mycotoxin produced by several Aspergillus and Penicillium species that is of great concern as a contaminant in agricultural products. In this study, the bacterial strain CO29 with high OTA-detoxification ability was isolated from vineyards and was identified as Cytobacillus oceanisediminis based on morphological and physiological characteristics, combined with 16S rRNA gene sequencing and phylogenetic analysis. The removal of OTA by CO29 was partly attributed to physical absorption, but the main mechanism of OTA removal was degradation. The degradation activity was completely removed by boiling, and could be significantly reduced by proteinase K treatment, but was only partially inhibited by the metal chelator EDTA. Zn2+ significantly improved the degradation of OTA, while Ca2+ and Mg2+ significantly inhibited the degradation. In addition, organic solvents inhibited OTA degradation in a dose-dependent manner. Thus, the mechanism of degradation by CO29 cell lysates was deduced as being enzymatic. Two OTA degradation intermediates were observed, one of which was identified as OTα. The time-profiles of OTA degradation by cell lysates showed an increase of OTα corresponding to the decrease of OTA. To our best knowledge, this is the first report of a Cytobacillus oceanisediminis strain with the ability to detoxify OTA, with potential applications in the bioremediation of contaminated soils.

Retrospective Evaluation of Liver and Kidney Functions in Patients with Chronic Occupational Lead Intoxication Treated with EDTA Chelation Therapy

Objective: This study aimed to investigate hepatic and renal functions in patients who received calcium disodium edetate (CaNa2EDTA) chelation treatment for chronic occupational lead intoxication. Material and Methods: This single-center retrospective descriptive research was conducted in a secondary-level health facility. The study included patients treated with CaNa2EDTA chelation for chronic occupational lead intoxication between September 15, 2020, and May 31, 2021. Demographic and occupational characteristics, as well as and laboratory parameters obtained before and after the chelation therapy were evaluated. Results: All 75 patients were male, and 73.3% had an occupation in metal scrap recycling. Renal parameters were within normal range before and after the chelation. However, mild elevations were observed in liver parameters. After the adjustment for demographic and occupational variables, the odds of having an elevated liver parameter and an elevated alanine transaminase (ALT) result after the chelation therapy were 9.3 (95%CI 2.6–33.2, p<0.001) and 11.4 (95%CI 2.4–53.2, p<0.001) for patients with pre-chelation elevated any liver parameter and pre-chelation elevated ALT result, respectively. Conclusion: The current study documented mild elevations of the liver parameters in patients with chronic occupational lead poisoning after CaNa2EDTA chelation therapy, particularly those with elevated basal liver parameters, although their renal parameters stayed within reference ranges. The results serve as an example of the safe application of CaNa2EDTA chelation for chronic occupational lead poisoning, by monitoring kidney and liver parameters in a secondary-level health facility. Future prospective studies with structured treatment protocols may investigate the risk and determinants of hepatic and renal adverse effects.

Adsorptive removal of Cr(III)-EDTA chelate from an aqueous solution by magnetic mesoporous silica microspheres.

The 3-aminopropyltrimethoxysilane-modified magnetic mesoporous adsorbent (FNMs/APTES) was synthesized and applied to remove Cr(III)-EDTA chelates from water. The characterization of FNMs/APTES showed that the prepared adsorbent with a magnetic mesoporous structure was successfully grafted by APTES, which has good stability under acid conditions. The maximum capacities of FNMs/APTES for Cr(III)-EDTA adsorption at 15, 25 and 35 °C and pH 4.0 were 12.58, 13.13 and 14.00 mg·g-1, respectively. The adsorption isotherm of FNMs/APTES for Cr(III)-EDTA conforms to the Freundlich model, and the adsorption kinetic model accords with the pseudo-second-order kinetic model. Adsorption of Cr(III)-EDTA on the adsorbent was not affected in the presence of Na+, K+ and Ca2+ even at 100 mmol·L-1. Cr(III)-EDTA was anchored on FNMs/APTES through electrostatic interaction between protonated amino groups of adsorbents and Cr(III)-EDTA anions, and Cr(III)-EDTA chelates were adsorbed as a whole on the adsorbent. The Cr(III)-EDTA-saturated adsorbent can be readily regenerated in HCl solution and 83.03% of the initial Cr(III)-EDTA adsorption capacity remains after four adsorption-regeneration experiment cycles. The results highlighted that the FNMs/APTES as a potential adsorbent can be applied for the minimization of Cr(III)-EDTA chelates from water.

Facile Fabrication of SiO2/Zr Assisted with EDTA Complexed-Impregnation and Templated Methods for Crude Palm Oil to Biofuels Conversion via Catalytic Hydrocracking

Zr-containing SiO2 and their parent catalysts were fabricated with different methods using EDTA chelation and template-assist. The activity of the catalysts was explored in crude palm oil (CPO) hydrocracking, conducted under a continuous system micro-cylindrical reactor. The conversion features and the selectivity towards biofuel products were also examined. The physicochemical of catalysts, such as structure phase, functional groups, surface morphologies, acidity features, and particle size, were investigated. The study showed that the template method promoted the crystalline porous catalysts, whereas the chelate method initiated the non-porous structure. The catalysts’ acidity features of SiO2 and SiO2/Zr were affected by the preparation, which revealed that the EDTA chelate-assisted method provided higher acidity features compared with the template method. The CPO hydrocracking study showed that the SiO2/Zr-CEDTA provided the highest catalytic activity towards the hydrocracking process, with 87.37% of conversion attained with 66.29%.wt of liquid product. This catalyst exhibited selectivity towards bio-jet (36.88%), bio-diesel (31.43%), and bio-gasoline (26.80%). The reusability study revealed that the SiO2/Zr-CEDTA had better stability towards CPO conversion compared with SiO2/Zr-CEDTA, with a low decrease in catalyst performance at three consecutive runs.

Study on internal structure of casein micelles in reconstituted skim milk powder

In the current study, the internal structure of casein micelles (CMs), primary casein cluster, has been studied by size-exclusion chromatography (SEC) coupled with small-angle X-ray scattering (SAXS), isothermal titration calorimetry (ITC), transmission electron microscopy (TEM) and molecular dynamics (MD) simulations. The casein cluster featured a hierarchical structure predominately consisting of αs-CN and β-CN molecules and a trace of κ-CN. ITC profile showed a typical enthalpogram of CMs with a critical micelle concentration (CMC) of ~0.85 μg/mL. The casein cluster exhibited apparent characteristics of intrinsically disordered proteins (IDPs) with a secondary structure content of 24 % in α-helix, 35.4 % in antiparallel-parallel, 20.2 % in β-turn and 20.4 % in random coil. SAXS results revealed a slightly elongated and tortuous worm-like conformation for the casein cluster in solution with an aspect ratio of 1.36 and an estimated molecular weight of 162.7 kDa. Further scattering data analysis proposed three coexisted species (αs1-β-αs2-CN, αs1-CN and αs1-β-αs2-CN dimer) with a volume fraction of 57.4 %, 30.1 %, and 12.5 % respectively in the casein cluster. TEM observation was consistent with the results of spectra, SAXS and MD that calcium sequestration resulted in a more extended and loose structure, instead, EDTA chelation induced a more compact conformation of the casein cluster.

Phytoremediation of CdS/Te quantum dots by Ocimum basilicum in the presence of EDTA.

The use of nanomaterials like quantum dots (QDs) with optical properties has increased in the last decade because of their electronics, medicine, and environmental applications. The lack of recycling and appropriate disposal causes these materials to be considered new emerging contaminants. In this research, the extraction and translocation (phytoextraction) of cadmium as QDs by Ocimum basilicum "basil" in the presence of EDTA (chelating agent) was studied. For edible plants are essential to know where the contaminants are located to minimize human consumption. In this work, the phytoextraction, distribution, and translocation of cadmium (under ionic solution-CdIS and CdS/Te QDs) at 25 and 50mg/kg-soil and in the presence of 1,000mg/kg-soil EDTA was studied in O. basilicum (a commercialized culinary herb) for three and six weeks. Basil seedlings were grown in an environmentally controlled chamber at 24-28o C and 12/12 hours periods of light and darkness. The highest cadmium concentration was found in the roots from where it is translocated to stems and leaves. CdS/Te QDs at low concentration (25mg/kg and 3 weeks of exposure) had the highest translocation factor, indicating that cadmium's nanocrystal (QDs) forms can affect the phytoextraction mechanism. The highest bioconcentration of cadmium was reached at a high contaminant concentration. The bioconcentration factors confirm that O. basilicum phytoextracts cadmium from soils contaminated with CdS/Te QDs and CdIS. The bioconcentration factors of cadmium (under both species CdS/Te QDs and CdIS) increase in the presence of EDTA. The bioconcentration and translocation factors suggest that consuming "basil" from contaminated soils with CdS/Te QDs at low concentrations increases the exposition to this metal.

Naked-eye detection of Staphylococcus aureus in powdered milk and infant formula using gold nanoparticles

Nonspecific binding of proteins from complex food matrices is a significant challenge associated with a biosensor using gold nanoparticles (AuNPs). To overcome this, we developed an efficient EDTA chelating treatment to denature milk proteins and prevent their adsorption on AuNPs. The use of EDTA to solubilize proteins enabled a sensitive label-free apta-sensor platform for colorimetric detection of Staphylococcus aureus in milk and infant formula. In the assay, S. aureus depleted aptamers from the test solution, and the reduction of aptamers enabled aggregation of AuNPs upon salt addition, a process characterized by a color change from red to purple. Under optimized conditions, S. aureus could be visually detected within 30 min with the detection limit of 7.5 × 104 CFU/mL and 8.4 × 104 CFU/mL in milk and infant formula, respectively. The EDTA treatment provides new opportunities for monitoring milk contamination and may prove valuable for biosensor point-of-need applications.

Lattice-strain induced photophysical properties of NaYF4: Yb3+, Tm3+ upconverting phosphors

The present work describes the underlying mechanism associated with the synthesis of “NaYF4: Yb3+, Tm3+ upconverting phosphors (UCP)" having diverse morphology (spheres, cubes, hexagonal micro-prism, and micro-rod) as well as enhanced luminescence intensity. Indeed the reported hydrothermal method facilitates an easy and inexpensive strategy for obtaining upconverting phosphors with requisite characteristics through a synergistic combination of substrates and chelating agents, which is the first of its kind. Substrates like ITO, FTO, and plain silica glass (P.G.) are used in synergistic combination with various chelating agents, i.e., EDTA DTPA and EGTA, which ultimately develops nearly hexagonal upconverting phosphors. Overall it is observed that substrate along with chelating ligand coordinates the formation of upconverting phosphors having diverse morphology, while the degree of crystallinity and lattice strain have played crucial role in optimizing the upconversion luminescence.

Zinc Binding Inhibits Cellular Uptake and Antifungal Activity of Histatin-5 in Candida albicans.

Histatin-5 (Hist-5) is a polycationic, histidine-rich antimicrobial peptide with potent antifungal activity against the opportunistic fungal pathogen Candida albicans. Hist-5 can bind metals in vitro, and metals have been shown to alter the fungicidal activity of the peptide. Previous reports on the effect of Zn2+ on Hist-5 activity have been varied and seemingly contradictory. Here, we present data elucidating the dynamic role Zn2+ plays as an inhibitory switch to regulate Hist-5 fungicidal activity. A novel fluorescently labeled Hist-5 peptide (Hist-5*) was developed to visualize changes in internalization and localization of the peptide as a function of metal availability in the growth medium. Hist-5* was verified for use as a model peptide and retained antifungal activity and mode of action similar to native Hist-5. Cellular growth assays showed that Zn2+ had a concentration-dependent inhibitory effect on Hist-5 antifungal activity. Imaging by confocal microscopy revealed that equimolar concentrations of Zn2+ kept the peptide localized along the cell periphery rather than internalizing, thus preventing cytotoxicity and membrane disruption. However, the Zn-induced decrease in Hist-5 activity and uptake was rescued by decreasing the Zn2+ availability upon addition of a metal chelator EDTA or S100A12, a Zn-binding protein involved in the innate immune response. These results lead us to suggest a model wherein commensal C. albicans may exist in harmony with Hist-5 at concentrations of Zn2+ that inhibit peptide internalization and antifungal activity. Activation of host immune processes that initiate Zn-sequestering mechanisms of nutritional immunity could trigger Hist-5 internalization and cell killing.

Thermal decomposition characterization and kinetics of copper, iron, manganese and zinc chelates of ethylenediaminetetraacetic acid in air atmosphere

The analysis of the thermal stability of Cu, Fe, Mn, and Zn-EDTA (copper, iron manganese, and zinc chelates of ethylenediaminetetraacetic acid) chelates indicates a high complexity of occurring decomposition processes, ranging from two to three simplified stages of the decomposition process. Obtained results reports that the thermal stability decreased in the following order: Zn-EDTA > Mn-EDTA > Cu-EDTA > Fe-EDTA. The initial model-free kinetic analysis suggested that three out of four chelates had a multi-step first stage of the decomposition. Model-fitting methodology resulted in the best fit in the first stage of decomposition of the studied EDTA chelates that corresponded to An (nth-dimensional nucleation) or Cn (nth-order autocatalytic reaction) models with correlation coefficients within 0.9951 to 0.9991. The activation energy values were within the range 126.27–253.25 kJ·mol−1. The least stable chelates, Cu and Fe, were defined by using competitive An and Cn reaction types, while the most stable, Zn, has a single-step Cn first stage of the decomposition process. The study showed the initial possibility of using EDTA chelates of zinc, manganese, and possibly copper in fertilizer production.

Alpha-Lipoic Acid (ALA), fatty acid and promising chelating agent for neurological ailments

Alpha-lipoic acid, a sulphur-containing fatty acid, also known as thioctic acid, occurs as a coenzyme and component of the pyruvate dehydrogenase complex in the mitochondria of almost all living things with a cell nucleus. As a natural substance, it is considered a safe, well tolerated chelating agent. Unlike the hydrophilic chelating agents DMSA, DMPS or EDTA, which are prescription items, not easily available in some countries, the lipophilic α-lipoic acid (ALA) is a natural substance and as such not regulated as strictly. It has the ability to pass the blood brain barrier (BBB) and can thus penetrate all areas of the nervous system. Consequently, current research investigates whether and to what extent oral administration influences the development of metal-based multiple sclerosis (MS) and M. Alzheimer. With our clinical research we could confirm ALAs metal-binding ability and the extend of urinary excretion for the metals Arsenic, Barium, Manganese, Mercury and Nickel following oral application. We established a treatment protocol, suitable for people of all ages and confirmed the safety of ALA, if given in moderate doses.

The trial to assess chelation therapy 2 (TACT2): Rationale and design

BackgroundIntravenous edetate disodium-based infusions reduced cardiovascular events in a prior clinical trial. The Trial to Assess Chelation Therapy 2 (TACT2) will replicate the initial study design. MethodsTACT2 is an NIH-sponsored, randomized, 2x2 factorial, double masked, placebo-controlled, multicenter clinical trial testing 40 weekly infusions of a multi-component edetate disodium (disodium ethylenediamine tetra-acetic acid, or Na2EDTA)-based chelation solution and twice daily oral, high-dose multivitamin and mineral supplements in patients with diabetes and a prior myocardial infarction (MI). TACT2 completed enrollment of 1000 subjects in December 2020, and infusions in December 2021. Subjects are followed for 2.5 to 5 years. The primary endpoint is time to first occurrence of all-cause mortality, MI, stroke, coronary revascularization, or hospitalization for unstable angina. The trial has >;85% power to detect a 30% relative reduction in the primary endpoint. TACT2 also includes a Trace Metals and Biorepository Core Lab, to test whether benefits of treatment, if present, are due to chelation of lead and cadmium from patients. Design features of TACT2 were chosen to replicate selected features of the first TACT, which demonstrated a significant reduction in cardiovascular outcomes in the EDTA chelation arm compared with placebo among patients with a prior MI, with the largest effect in patients with diabetes. ResultsResults are expected in 2024. ConclusionTACT2 may provide definitive evidence of the benefit of edetate disodiumbased chelation on cardiovascular outcomes, as well as the clinical importance of longitudinal changes in toxic metal levels of participants.

A Schiff base luminescent chemosensor for selective detection of Zn2+ in aqueous medium

Luminescent chemosensors based on Schiff bases have drawn tremendous research interest owing to their easy synthesis, enriched photophysical properties, and potential applications in biology and materials science. A dinitrophenyl-based Schiff base molecular probe (L) was synthesized and characterized to estimate its selective detection of Zn2+. The probe L exhibits weak emission in the DMSO-H2O solvent mixture due to excited-state intramolecular proton transfer (ESIPT). Interestingly, fluorescence is enhanced with the addition of Zn2+ to the DMSO-H2O solution of L, whereas the emission remains unchanged with the addition of other ions. This specifies that probe L acts as a selective chemosensor for Zn2+. The binding stoichiometry for the L: Zn2+ complex is 1:1, which was calculated using the Benesi-Hildebrand plot from fluorescence data. Furthermore, the binding modes are also supported by density functional theory (DFT) calculation. The binding constant and detection limits are 6.35 × 107 M−1 and 1.1 × 10−8 M, respectively. The L-Zn2+ complex formation is reversible upon the addition of a strong chelating EDTA ligand. In addition, L is also used to detect Zn2+ in living Hela cells and selective sensing of Zn2+ in the solid phase.

An analytical method for the quantitative determination of iron ion chelating capacity: development and validation

Iron is a fundamental microelement for human life; however, deficiencies or excesses of these metal ions can cause severe complications and mortality. Chelators are compounds that bind and inhibit iron. Ultraviolet-visible (UV-vis) spectrophotometric methods are key analytical tools in the identification of chemical entities, with the benefits of having good precision and accuracy, and the equipment being easily available as well as quick and simple to implement. In this study, we aimed to provide an alternative, cheaper method for the quantification of iron ion chelation by substituting ferrozine for gallic acid and validating its use with UV-vis according to official ANVISA and ICH guidelines. The parameters assessed were specificity, linearity, precision, accuracy, robustness, and finally, the percentage of iron ions chelating was calculated. The results demonstrated that this method was accurate, simple, specific, selective, precise, and reproducible, and was successfully validated for the determination of iron ions chelating. The percentage of iron ions chelating, promoted by the standard chelator EDTA, was 45% and 47% for Fe2+ and Fe3+, respectively. It is concluded that this new method is beneficial in terms of its simplicity, rapidness, low cost, and the fact that it produces very low levels of dangerous residues.

Utilization of dairy beta stream to produce phospholipids products by salt precipitation and solvent fractionation

AbstractDairy phospholipids (PLs) have unique functional and nutraceutical properties over PLs obtained from other sources that typically lack phosphatidylserine (PS) and sphingomyelin (SM). In this study, an underutilized dairy by‐product, beta stream, was used for the production of enriched dairy PLs products and membrane proteins by solvent extractions. After calcium salt precipitation of the membrane components, various green (i.e., safer or bioderived) solvent systems were evaluated for their capabilities for PLs extraction from the PLs‐protein‐salt precipitate in comparison to the standard Folch extraction (chloroform: methanol, 2:1, v/v). Among the five solvent systems (Folch alternatives) evaluated, the combination of hexane and isopropanol (H:IP, 3:2, v/v) was identified as the best for total lipid and PLs extraction, resulting in a recovery of 74.4% and 65.7% (w/w), respectively. EDTA chelating of the calcium ions was applied to produce a salt‐free membrane protein product. A treatment with 0.2% EDTA was able to significantly reduce the calcium content to 0.20 mg/g protein compared to 58.81 mg/g in the initial calcium‐precipitated MFGM. EDTA chelating of cations also facilitated the extraction of lipids during H:IP (3:2) treatment, which increased the total recovery of total lipid and PLs to 90.7% and 82.5% (w/w), respectively. Overall, this study demonstrates a great potential for the utilization of beta stream and other low‐solids content aqueous dairy by‐products for PLs recovery and further fractionation. Value‐added dairy products (PLs and membrane proteins) can be obtained using green solvents identified in this study, and the process is industrially scalable.

Zng1 is a GTP-dependent zinc transferase needed for activation of methionine aminopeptidase.

The evolution of zinc (Zn) as a protein cofactor altered the functional landscape of biology, but dependency on Zn also created an Achilles' heel, necessitating adaptive mechanisms to ensure Zn availability to proteins. A debated strategy is whether metallochaperones exist to prioritize essential Zn-dependent proteins. Here, we present evidence for a conserved family of putative metal transferases in human and fungi, which interact with Zn-dependent methionine aminopeptidase type I (MetAP1/Map1p/Fma1). Deletion of the putative metal transferase in Saccharomyces cerevisiae (ZNG1; formerly YNR029c) leads to defective Map1p function and a Zn-deficiency growth defect. Invitro, Zng1p can transfer Zn2+ or Co2+ to apo-Map1p, but unlike characterized copper chaperones, transfer is dependent on GTP hydrolysis. Proteomics reveal mis-regulation of the Zap1p transcription factor regulon because of loss of ZNG1 and Map1p activity, suggesting that Zng1p is required to avoid a compounding effect of Map1p dysfunction on survival during Zn limitation.

Highly sensitive ascorbic acid sensors from EDTA chelation derived nickel hexacyanoferrate/ graphene nanocomposites

Significance of ascorbic acid (AA) determination has been increasing due to its importance in both human life and industrial applications. This work demonstrates the development of a highly sensitive non-enzymatic AA sensor by using Graphene/Nickel hexacyanoferrate nanocomposite (Gr/NiHCF). In this work, EDTA chelation strategy was used for the formation of homogeneously distributed NiHCF nanoparticles on graphene sheets. EDTA residue-supported pyramidal and spherical nanoparticles of NiHCF deposited on graphene sheets were used for the development of a highly sensitive AA sensor. The formation of EDTA residue supported NiHCF nanoparticles on graphene surface was confirmed by different characterization techniques (XRD, SEM, TEM, FTIR, XPS). Cyclic voltammetry (CV) of Gr/NiHCF nanocomposites confirmed the electrochemical sensing of AA by oxidation mechanism. The Sensitivity of the fabricated Gr/NiHCF based AA sensor as determined by amperometric characterization was found to be 7.029 µA µM−1 cm−2. The sensor fabricated in the present study shows much better sensitivity over other AA sensors reported in the literature. The LOD of the fabricated sensors was found as 0.25 µM. Repeatability, reproducibility, and interference studies of fabricated sensors reveal the high accuracy and selectivity of a fabricated sensor for AA measurement. Stability study of fabricated sensors showed excellent stability up to 30 days, indicating the potential usage of Gr/NiHCF for AA sensing. The real-time use of fabricated sensors in accurate determination of AA in samples like Vitamin C supplements and different fruit juices indicated their potential usage for AA measurement in real samples.

The stress sigma factor σS/RpoS counteracts Fur repression of genes involved in iron and manganese metabolism and modulates the ionome of Salmonella enterica serovar Typhimurium.

In many Gram-negative bacteria, the stress sigma factor of RNA polymerase, σS/RpoS, remodels global gene expression to reshape the physiology of quiescent cells and ensure their survival under non-optimal growth conditions. In the foodborne pathogen Salmonella enterica serovar Typhimurium, σS is also required for biofilm formation and virulence. We have previously identified sRNAs genes positively controlled by σS in Salmonella, including the two paralogous sRNA genes, ryhB1 and ryhB2/isrE. Expression of ryhB1 and ryhB2 is repressed by the ferric uptake regulator Fur when iron is available. In this study, we show that σS alleviates Fur-mediated repression of the ryhB genes and of additional Fur target genes. Moreover, σS induces transcription of the manganese transporter genes mntH and sitABCD and prevents their repression, not only by Fur, but also by the manganese-responsive regulator MntR. These findings prompted us to evaluate the impact of a ΔrpoS mutation on the Salmonella ionome. Inductively coupled plasma mass spectrometry analyses revealed a significant effect of the ΔrpoS mutation on the cellular concentration of manganese, magnesium, cobalt and potassium. In addition, transcriptional fusions in several genes involved in the transport of these ions were regulated by σS. This study suggests that σS controls fluxes of ions that might be important for the fitness of quiescent cells. Consistent with this hypothesis, the ΔrpoS mutation extended the lag phase of Salmonella grown in rich medium supplemented with the metal ion chelator EDTA, and this effect was abolished when magnesium, but not manganese or iron, was added back. These findings unravel the importance of σS and magnesium in the regrowth potential of quiescent cells.

Enhanced Degradation of Micropollutants in a Peracetic Acid-Fe(III) System with Picolinic Acid.

Activation of peracetic acid (PAA) with iron species is an emerging advanced oxidation process (AOP). This study investigates the use of the chelating agent picolinic acid (PICA) to extend the pH range and enhance the performance of the PAA-Fe(III) AOP. Compared to the PAA-Fe(III) system, the PAA-Fe(III)-PICA system degrades various micropollutants (MPs: methylene blue, naproxen, sulfamethoxazole, carbamazepine, trimethoprim, diclofenac, and bisphenol-A) much more rapidly at higher pH, achieving almost complete removal of parent compounds within 10 min. PAA significantly outperforms the coexistent H2O2 and is the key oxidant for rapid compound degradation. Other chelating agents, EDTA, NTA, citric acid, proline, and nicotinic acid, could not enhance MP degradation in the PAA-Fe(III) system, while 2,6-pyridinedicarboxylic acid with a structure similar to PICA moderately enhanced MP degradation. Experiments with scavengers (tert-butyl alcohol and methyl phenyl sulfoxide) and a probe compound (benzoic acid) confirmed that high-valent iron species [Fe(IV) and/or Fe(V)], rather than radicals, are the major reactive species contributing to MP degradation. The oxidation products of methylene blue, naproxen, and sulfamethoxazole by PAA-Fe(III)-PICA were characterized and supported the proposed mechanism. This work demonstrates that PICA is an effective complexing ligand to assist the Fenton reaction of PAA by extending the applicable pH range and accelerating the catalytic ability of Fe(III).

Chelation Therapy in Patients With Cardiovascular Disease: A Systematic Review.

BackgroundEDTA is an intravenous chelating agent with high affinity to divalent cations (lead, cadmium, and calcium) that may be beneficial in the treatment of cardiovascular disease (CVD). Although a large randomized clinical trial showed benefit, smaller studies were inconsistent. We conducted a systematic review of published studies to examine the effect of repeated EDTA on clinical outcomes in adults with CVD.Methods and ResultsWe searched 3 databases (MEDLINE, Embase, and Cochrane) from database inception to October 2021 to identify all studies involving EDTA treatment in patients with CVD. Predetermined outcomes included mortality, disease severity, plasma biomarkers of disease chronicity, and quality of life. Twenty‐four studies (4 randomized clinical trials, 15 prospective before/after studies, and 5 retrospective case series) assessed the use of repeated EDTA chelation treatment in patients with preexistent CVD. Of these, 17 studies (1 randomized clinical trial) found improvement in their respective outcomes following EDTA treatment. The largest improvements were observed in studies with high prevalence of participants with diabetes and/or severe occlusive arterial disease. A meta‐analysis conducted with 4 studies reporting ankle‐brachial index indicated an improvement of 0.08 (95% CI, 0.06–0.09) from baseline.ConclusionsOverall, 17 studies suggested improved outcomes, 5 reported no statistically significant effect of treatment, and 2 reported no qualitative benefit. Repeated EDTA for CVD treatment may provide more benefit to patients with diabetes and severe peripheral arterial disease. Differences across infusion regimens, including dosage, solution components, and number of infusions, limit comparisons across studies. Additional research is necessary to confirm these findings and to evaluate the potential mediating role of metals.RegistrationURL: https://www.crd.york.ac.uk/; Unique identifier: CRD42020166505.