Compendium of the most significant studies with reference to properties, intake, effects.

Pinto IS, Neto IF, Soares HM. Biodegradable chelating agents for industrial, domestic, and agricultural applications--a review. Environ Sci Pollut Res Int. 2014 Oct;21(20):11893-906. doi: 10.1007/s11356-014-2592-6. 

Abstract. Aminopolycarboxylates, like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), are chelating agents widely used in several industrial, agricultural, and domestic applications. However, the fact that they are not biodegradable leads to the presence of considerable amounts in aquatic systems, with serious environmental consequences. The replacement of these compounds by biodegradable alternatives has been the object of study in the last three decades. This paper reviews the most relevant studies towards the use of environmentally friendly chelating agents in a large number of applications: oxidative bleaching, detergents and cleaning compositions, scale prevention and reduction, remediation of soils, agriculture, electroplating, waste treatment, and biocides. Nitrilotriacetic acid (NTA), ethylenediaminedisuccinic acid (EDDS), and iminodisuccinic acid (IDS) are the most commonly suggested to replace the nonbiodegradable chelating agents. Depending on the application, the requirements for metal complexation might differ. Metal chelation ability of the most promising compounds [NTA, EDDS, IDS, methylglycinediacetic acid (MGDA), L-glutamic acid N,N-diacetic acid (GLDA), ethylenediamine-N,N'-diglutaric acid (EDDG), ethylenediamine-N,N'-dimalonic acid (EDDM), 3-hydroxy-2,2-iminodisuccinic acid (HIDS), 2-hydroxyethyliminodiacetic acid (HEIDA), pyridine-2,6-dicarboxylic acid (PDA)] with Fe, Mn, Cu, Pb, Cd, Zn, Ca, and Mg was simulated by computer calculations. The advantages or disadvantages of each compound for the most important applications were discussed.

Wu Q, Duan G, Cui Y, Sun J. Removal of heavy metal species from industrial sludge with the aid of biodegradable iminodisuccinic acid as the chelating ligand. Environ Sci Pollut Res Int. 2015 Jan;22(2):1144-50. doi: 10.1007/s11356-014-3365-y. 

Abstract. High level of heavy metals in industrial sludge was the obstacle of sludge disposal and resource recycling. In this study, iminodisuccinic acid (IDS), a biodegradable chelating ligand, was used to remove heavy metals from industrial sludge generated from battery industry. The extraction of cadmium, copper, nickel, and zinc from battery sludge with aqueous solution of IDS was studied under various conditions. It was found that removal efficiency greatly depends on pH, chelating agent's concentration, as well as species distribution of metals. The results showed that mildly acidic and neutral systems were not beneficial to remove cadmium. About 68 % of cadmium in the sample was extracted at the molar ratio of IDS to heavy metals 7:1 without pH adjustment (pH 11.5). Copper of 91.3 % and nickel of 90.7 % could be removed by IDS (molar ratio, IDS: metals = 1:1) with 1.2 % phosphoric acid effectively. Removal efficiency of zinc was very low throughout the experiment. Based on the experimental results, IDS could be a potentially useful chelant for heavy metal removal from battery industry sludge.

Hodes J, Sielaff P, Metz H, Kessler-Becker D, Gassenmeier T, Neubert RHH. The role of chelating agents and amino acids in preventing free radical formation in bleaching systems. Free Radic Biol Med. 2018 Dec;129:194-201. doi: 10.1016/j.freeradbiomed.2018.09.023.

Abstract. The control of bleaching reaction is important in hair bleaching and laundry detergents to ensure quality of the final product. A better understanding of the reaction mechanisms is needed to minimize product failures. 31P NMR-spectroscopy-based spin trap technique was employed to detect and quantify the free radical species that were generated in different bleaching solutions. These solutions contained the key actives in an alkaline hair colorant/bleaching product, an ammonium salt and hydrogen peroxide at pH = 10. Generally, the main radical species detected in hair oxidative coloring or bleaching processes, were hydroperoxyl/superoxide radicals HO2·/O2.-, amino radicals ·NH2 and hydroxyl radicals ·OH. Their amounts showed a variation based on the chemical composition of the bleaching systems and the metal ion content. The generation of free radicals from reactions between transition metal ions, such as copper, and hydrogen peroxide at pH = 10 was evaluated. In the absence of chelating agents, the copper ions generated a significant level of hydroxyl radicals in a Fenton-like reaction with hydrogen peroxide at pH = 10. Besides that, an increase in copper ion content led to an increase of amino radical ·NH2, whereas the concentration of superoxide radical O2·- decreased which was not yet well reported in the previous literature. The effect of chelating agents like ethylenediaminetetraacetic acid (EDTA), tetrasodium-iminodisuccinate (IDS), a mixture of basic amino acids and dicarboxylic acid on free radical formation was investigated in the presence of binary Cu2+-Ca2+ bleaching systems. As expected, in the binary Cu2+-Ca2+ ion system EDTA did not suppress hydroxyl radical formation effectively, but the mixture containing sodium succinate, lysine and arginine reduced hydroxyl radical formation, whereas IDS (nearly) completely inhibited hydroxyl radical formation. The results indicated that each bleaching solution has its characteristic performance and damage profile. Whereas the reactivity can be controlled by the usage of chelating agents. Copyright © 2018 Elsevier Inc.

Thotakura N, Sharma S, Khurana RK, Babu PV, Chitkara D, Kumar V, Singh B, Raza K. Aspartic acid tagged carbon nanotubols as a tool to deliver docetaxel to breast cancer cells: Reduced hemotoxicity with improved cytotoxicity. Toxicol In Vitro. 2019 Sep;59:126-134. doi: 10.1016/j.tiv.2019.04.012. 

Abstract. The present study aimed to explore the potential of hydroxylated carbon nanotubes (CNTnols) conjugated with aspartic acid for the delivery of docetaxel (DTX) to breast cancer cells. The conjugate was well-characterized by FT-IR, NMR, XRD and FE-SEM. The nanoconjugate offered a hydrodynamic diameter of 86.31 ± 1.02 nm, with a PDI of 0.113 and zeta potential of -41.6 ± 0.17 mV. The designed nanosystem offered a controlled & pH dependent release vouching release of drug in the cancerous cytosol, not in blood, assuring delivery of the pay-load to the site of action. The carriers offered substantial hemocompatibility and lower plasma protein binding, ensuring more drug available at the site of action. The in-vitro cell viability studies in MDA MB-231 cells inferred approx. 2.8 times enhancement in the cytotoxicity potential of the conjugate vis-à-vis plain drug. Pharmacokinetic studies also corroborated the superiority of the designed nanoconjugate in terms of enhanced bioavailable fractions, reduced clearance and longer bioresidence to that of plain docetaxel. The present studies, successfully provide a workable nanomedicine, loaded with a BCS class-IV drug, for improved efficacy and safety in breast cancer. Copyright © 2019 Elsevier 

Kagra D, Preethi SP, Sharma P. Interaction of aspartic acid and asparagine with RNA nucleobases: a quantum chemical view. J Biomol Struct Dyn. 2020 Feb;38(3):943-955. doi: 10.1080/07391102.2019.1592025.

Yang X, Liu X, Wu Q, Lv X, Li B, Sun H, Xu W, Liao X. Dopamine-assisted immobilization of peptide arginine-glycine-aspartic acid to enhance the cellular performances of MC3T3-E1 cells of carbon-carbon composites. J Biomater Appl. 2019 Aug;34(2):284-296. doi: 10.1177/0885328219845962.