Chelate Complexes Research Articles

Preparation and Antifungal Properties of Cyclopropyl Derivatives of 3-Aminoquinazolin-4(3H)-one and Salicylal Schiff Base Nickel(II) Chelate Complex

N-substituted 2-cyclopropyl-3-R-quinazoline-4()-ones [R: NH2 (1), N=CH(2-hydroxyphenyl) (2)] and Ni(II) chelate compound of 2-cyclopropyl-3-[(Z)-(2-hydroxybenzylidene)amino]quinazoline-4(3H)-one (3) were synthesized and their structures and properties were characterized using X-ray diffraction data, computational optimization, 1H and 13C NMR, IR spectroscopy, and diffuse reflectance spectra. Compounds 1 and 2 are monoclinic (space group P21/n). Unit cell parameters (a, b, c) are 9.2529; 4.7246; 22.3460 Å and 10.2811; 4.6959; 30.972 Å for 1 and 2, respectively. Nickel(II) chelate compound crystallizes in an orthorhombic crystal system (space group Pbca). Unit cell parameters (a, b, c) for 3 are 26.5010; 14.8791; 8.904975 Å, respectively. Schiff base 2 in the crystalline state exhibits two rotary isomers in a molar ratio of 1:3, among which only a minor component as a bidentate ligand can form compound 3 with Ni(II) ion. Nickel(II) ion in 3 is coordinated by N donor atoms and deprotonated O atoms of Schiff base ligands to form square-planar chelate node NiN2O2. All synthesized compounds revealed high antifungal activity against bread mold (Mucor mucedo).

Fluoride Ingestion Induces Formation of Unusual Macromolecular Complexes in Gut Lumen Which Retard Absorption of Essential Minerals and Trace Elements by Chelation.

This study investigates the impact of chronic fluoride exposure on the absorption of essential minerals in the gut and explores the mechanisms underlying mineral deficiencies due to fluoride ingestion. Male Wistar rats were randomly assigned to three groups: group 1 (G-1) served as the control (non-fluoride exposed), while group 2 (G-2) and group 3 (G-3) received human equivalent doses (HED) of fluoride (50 and 100ppm ad libitum, corresponding to 5 and 10ppm in humans, respectively) for 75days. Serum fluoride concentrations were measured, and the levels of essential minerals and trace elements in blood and stool were analyzed using ICP-MS. X-ray diffraction (XRD) analysis was performed on stool samples to identify chemical compounds. The chemical compounds and macromolecular complexes containing fluoride and essential minerals were identified and quantified using Match3 software. Results indicated that the blood concentrations of essential minerals were significantly lower (p ≤ 0.05) in the fluoride-exposed groups compared to the control, while excretion of essential elements in stool was significantly higher (p ≤ 0.05) in the fluoride-administered groups. XRD analysis revealed the formation of unusual macromolecular chemical complexes in the stool of fluoride-treated groups, with the types and concentrations of these compounds increasing with higher fluoride doses. The study concludes that fluoride in the stomach chelates minerals, reducing their absorption, and induces the formation of unusual high molecular weight macromolecular chelation complexes, which alter the chemical species in the gut and further impair the absorption of essential minerals.

Colloidal Stabilizer‐Mediated Crystal Growth Regulation and Defect Healing for High‐Quality Perovskite Solar Cells

AbstractHigh‐quality perovskite (PVK) films is essential for the fabrication of efficient and stable perovskite solar cells (PSCs). However, unstable colloidal particles in PVK suspensions often hinder the formation of crystalline films with low defect densities. Herein, ethylenediaminetetraacetic acid (EDTA) as a colloidal stabilizer into lead iodide (PbI2) is introduced colloidal solutions. EDTA forms chelated complexes with Pb2+, enhancing the electrostatic repulsion and steric hindrance between colloidal particles. This stabilizes the particles and inhibits disordered motion (Brownian motion) and excessive aggregation. As a result, PbI2 films with a uniform hole distribution are formed, providing ample pathways for subsequent PVK film growth and sufficient space. During the film formation process, the replacement of molecules by formamidinium iodide (FAI) and EDTA slows down crystallization, ultimately leading to PVK films with large grain sizes and low defect density. By using this approach, champion power conversion efficiencies (PCEs) of 24.05% for FA0.97Cs0.03PbI3 PSC, 11.08% for CsPbBr3 PSC, and 25.19% for FA0.945MA0.025Cs0.03Pb(I0.975Br0.025)3 PSC are achieved. Moreover, the EDTA‐based FA0.97Cs0.03PbI3 device retains over 90% of its initial PCE after 1000 h at the maximum power point (MPP) under continuous illumination.

The phytosiderophore analogue proline-2′-deoxymugineic acid is more efficient than conventional chelators for improving iron nutrition in maize

ABSTRACT Iron (Fe) is an essential nutrient but has poor bioavailability because of its low solubility under conditions of high pH, such as calcareous soils. Previously, we synthesized an analogue of the natural Fe(III) chelator 2′-deoxymugineic acid secreted by graminaceous plants for efficient Fe uptake, designated as proline-2′-deoxymugineic acid (PDMA). Soil application of Fe(III)-PDMA ameliorated symptoms of Fe deficiency in rice. In the present study, we explored the potential of PDMA as Fe nutrition supplement in maize, a major graminaceous crop, and rice for comparison. In calcareous soil pots, Fe deficiency chlorosis of maize was efficiently recovered by a single application of Fe(III)-PDMA. In contrast, maize plants treated with conventional Fe(III)-chelator complexes, such as Fe(III)-ethylenediaminetetraacetic acid (EDTA) or Fe(III)-N,N′-di(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid monohydrochloride (HBED), showed little or no recovery. Similarly, rice Fe chlorosis in calcareous soil pots was efficiently recovered by a single application of Fe(III)-PDMA, but not by other conventional Fe(III)-chelator complexes. Application of Fe(III)-PDMA was also effective in ameliorating Fe deficiency chlorosis in hydroponically grown maize seedlings; other Fe(III)-chelator complexes showed minimal or no efficacy. Addition of low concentrations of metal-free PDMA recovered Fe chlorosis of maize or rice in the presence of Fe(III)-EDTA, suggesting possible ligand exchange from EDTA to PDMA for subsequent Fe(III)-PDMA uptake by ZmYS1 and OsYSL15 transporters. Similar effects were observed with Fe(III)-HBED, which has a higher stability constant, but to a lesser extent than Fe(III)-EDTA, suggesting that ligand exchange from HBED to PDMA might be less prone to occur than for chelators with moderate stability constants, such as EDTA. Ferric-chelate reductase assays of maize roots showed substantial reduction of Fe(III)-PDMA, but this reduction activity was not increased under Fe-deficient condition. These results suggested that PDMA is an efficient reagent for improvement of Fe nutrition in graminaceous crops, including maize, because of suitability of Fe(III)-PDMA as a substrate for chelation-based Fe uptake systems.

Modified nanomagnetite silica core shell with new Cu (II) N,N‐ chelating complex as an efficient and reusable catalyst in the C‐N bond formation

In this article, initially, the TCTCl (DiPrAEA)2 ligand was synthesized and characterized by Fourier transform infrared (FT‐IR), X‐ray crystallography, 1H‐ and 13C‐NMR spectroscopy, and elemental analysis. The crystallographic structure data for the ligand has been deposited at the Cambridge Crystallographic Data Centre (CCDC No. 2282732). Then, using of this novel multidentate ligand, a novel and stable copper (II) nanocatalyst complex was synthesized by anchoring copper (II) acetate onto the core‐shell surface (Fe3O4@SiO2) via the novel multidentate ligand TCTCl (DiPrAEA)2. The successful synthesis of the Fe3O4@SiO2‐NH‐TCT (DiPrAEA)2‐Cu (II) nanocatalyst was confirmed by employing physicochemical techniques such as FT‐IR, X‐ray diffraction, ultraviolet‐visible, thermogravimetric analysis, X‐ray photoelectron spectroscopy, Brunauer–Emmett–Teller, energy‐dispersive X‐ray, dynamic light scattering, inductively coupled plasma, transmission electron microscopy, field emission scanning electron microscopy, and vibrating sample magnetometer. Subsequently, this novel copper (II) nanomagnetic complex was evaluated as an efficient, reusable, and novel catalyst for the formation of C‐N bonds via the Ullmann coupling reaction of aryl halides and nitrogen‐containing compounds. The influence of this novel TCTCl (DiPrAEA)2 ligand on the reactivity and stability of the nanomagnetic copper complex was visible in the Ullmann reaction, which resulted in rapid reaction times and excellent yields, and seven times reusability.

Harnessing the Power of a Novel Triple Chelate Complex in Fermented Probiotic Dairy Products: A Promising Solution for Combating Iron Deficiency Anemia.

This study discovered and examined novel triple chelate complexes involving iron, ascorbic acid, and essential amino acids (AsA-Fe-AmA triple chelate complexes) for the first time. The mechanism of complex formation was studied using FTIR spectroscopy and quantum chemical modeling. The produced complexes were shown to be suitable for fortifying food items with a pH of 3-7 that have not been exposed to heat treatment at temperatures over 75 °C for more than 15 min. Thus, it can be said that the concentration for milk fortification should be 0.005 mol/L or less. In vivo experiments in rats models revealed that the synthesized complexes increased serum iron levels after a single application to reference values within 24 h of oral administration. The iron level increased by 14.0 mmol/L at 2 mL dose of the complex. This fact makes it possible to consider the use of developed complexes and developed fermented dairy products for the prevention of iron deficiency and iron deficiency anemia. Research on the effect of discovered compounds on the physicochemical and organoleptic qualities of milk was conducted. Furthermore, iron ascorbate threoninate, iron ascorbate methioninate, iron ascorbate lysinate, and iron ascorbate tryptophanate all had a beneficial effect on Lacticaseibacillus rhamnosus at concentrations as low as 0.0005 mol/L, which is significant for milk fermentation. A study of fermented milk products revealed that the most effective AsA-Fe-AmA triple chelate complex is iron ascorbate lysinate, which might be further investigated as a viable molecule for dietary fortification in iron deficiency anemia. It was found that fortified fermented milk products had a titratable acidity of 67 ± 1°T, pH of 4.38 ± 0.05, and a viscosity of 2018 ± 142 Pa·s.

Exploring enzyme inhibition and comprehensive mechanisms of antioxidant/prooxidative activity of natural furanocoumarin derivatives: A comparative kinetic DFT study

This study aimed to explore the antioxidant and prooxidative activity of two natural furanocoumarin derivatives, Bergaptol (4-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, BER) and Xanthotoxol (9-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, XAN). The collected thermodynamic and kinetic data demonstrate that both compounds possess substantial antiradical activity against HO• and CCl3OO• radicals in physiological conditions. BER exhibited better antiradical activity in comparison to XAN, which can be attributed to the enhanced deprotonation caused by the positioning of the –OH group on the psoralen ring. In contrast to highly reactive radical species, newly formed radical species BER• and XAN• exhibited negligible reactivity towards the chosen constitutive elements of macromolecules (fatty acids, amino acids, nucleobases). Furthermore, in the presence of O2•─, the ability to regenerate newly formed radicals BER• and XAN• was observed. Conversely, in physiological conditions in the presence of Cu(II) ions, both compounds exhibit prooxidative activity. Nevertheless, the prooxidative activity of both compounds is less prominent than their antioxidant activity. Furthermore, it has been demonstrated that anionic species can engage in the creation of a chelate complex, which restricts the reduction of metal ions when reducing agents are present (O2•─ and Asc─). Moreover, studies have demonstrated that these chelating complexes can be coupled with other radical species, hence enhancing their ability to inactivate radicals. Both compounds exhibited substantial inhibitory effects against enzymes involved in the direct or indirect generation of ROS: Xanthine Oxidase (XOD), Lipoxygenase (LOX), Myeloperoxidase (MPO), NADPH oxidase (NOX).

Unravelling the role of precursors phosphine`s features in governing the reactivity of [MCl2(P-P)] (M = Pd, Pt) towards formation of thiolate complexes via S−S and S−C bond cleavage

Group 10 thiolate complexes have been in the quest zone of research due to pertinent catalytic potential. The present work unravels the role of precursor phosphine`s feature in their reactivity towards 4,6-dimethylpyrimidine-2-thiol and subsequent thiolate complex. Synthesized thiolate complexes were thoroughly characterized using elemental analyses, NMR (1H, 13C{1H}, 31P{1H}), UV–Vis spectroscopy and Single Crystal X-ray diffraction analyses. Treatment of [MCl2(PPh3)2] (M = Pd, Pt) with two equivalents of NaSC4H(4,6-Me)N2 resulted in chelated [Pd{κ-S, κ-N: SC4H(4,6-Me)2N2}{SC4H(4,6-Me)2N2}(PPh3)] (1a) as well as an expected trans compound [Pt{SC4H(4,6-Me)2N2}2(PPh3)2] (1b). A similar reaction with the chelating phosphine ‘dppm’ (dppm = 1,1-bis(diphenylphosphino)methane) as an ancillary ligand resulted in the serendipitous product of composition [Pd2(µ2-S){SC4H(4,6-Me)2N2}2(µ2-dppm)2] (2a) depending upon competitive cleavage of S-S and S-C bond. The reaction of [PdCl2(dppe)] afforded a cis configured compound [Pd{2-SC4H(4,6-Me)2N2}2(dppe)] (2b). Contrary, the similar reaction of [PdCl2(dppp)] results in removal of ‘dppp’ (1,3-bis(diphenylphosphino)propane) yielding the chelated complex [Pd{κ-S, κ-N: SC4H(4,6-Me)2N2}2] (2c). Above all, the reactivity of 4,6-dimethylpyrimidine-2-thiol significantly differs compared to unsubstituted pyrimidyl, pyridyl analogue which has been attributed to the additional richness of electrons/activation in the ring which in turn facilitates competitive reactivity pattern of S-S and S-C bond. The virtue of such activation can easily be understood by the isolation of complex [Pd2(µ2-S){SC4H(4,6-Me)2N2}2(µ2-dppm)2] (2a). Rationalization of results via DFT calculation reveals that projection angle P-M-P (ranging from ∼75 to 92°) driven structural change in the chelating phosphine and associated degree of softness in ligand molecule played a crucial role in governing the resulting product of substitution reaction as dimeric, monomeric and chelated complexes. Thus, projection angle- driven geometrical and electronic structure and variation provide opportunity and direction to efficiently derive biologically as well as academically important complexes.

Catalytically Active SiO2 Aerogels Comprising Chelate Complexes of Palladium.

A series of silica-based aerogels comprising novel bifunctional chelating ligands was prepared. To produce target aerogels, two aminosilanes, namely (3-aminopropyl)trimethoxysilane (APTMS) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPTMS), were acylated by natural amino acids ((S)-(+)-2-phenylglycine or L-phenylalanine), followed by gelation and supercritical drying (SCD). Lithium tetrachloropalladate was used as the metal ion source to prepare strong complexes of Pd2+ with amino acids covalently bonded to a silica matrix. Aerogels bearing chelate complexes retain the Pd2+ oxidation state after supercritical drying in CO2, but the Pd ion is reduced to Pd metal after SCD in isopropanol. Depending on the structure of amino complexes, Pd-containing aerogels showed catalytic activity and selectivity in the hydrogenation reactions of C=C, C≡C and C=O bonds.

A simple naked eye detection of Pb2+ on a gold nanocluster decorated disposable paper spot arrays

Among all the heavy metal ions, Lead (Pb2+) has become a serious threat to human health and the environment. It is vital to develop an accurate system to monitor the Pb2+ level. Fluorescent and colorimetric sensors are one such system to detect Pb2+ with high accuracy. Herein, we used thiolated gold nanoclusters (GNC) decorated paper spot arrays for the detection of Pb2+ through a simple colorimetric method. The prepared GNC and the developed complex were well-studied using various characterizations. The addition of Pb2+ to GNC results in a slight shift in the absorption spectra from 485 nm to 534 nm. Further, GNC showed a broad emission peak centered around 650 nm, and the addition of Pb2+ resulted in an enhancement in the peak intensity, due to cation-induced-aggregation-induced emission enhancement (AIEE). The HR-TEM analysis confirms the spherical shape of the prepared GNCs with an average size of 2.60 nm. Whereas, the addition of Pb2+ onto GNC leads to the formation of an aggregated structure of size 6.17 nm due to the formation of a chelation complex. The GNC showed a particle size of 2 nm with a zeta potential of −16.45 mV, whereas the Pb2+@GNC complex exhibited an increment in an average size to 96 nm having a zeta potential of −19.67 mV, substantially demonstrating the capturing of Pb2+ by GNC. Overall, spectroscopic and surface morphology studies indicated aggregated induced emission (AIE) phenomena between GNC and Pb2+. The selective detection of Pb2+ by GNC was observed by the appearance of salmon pink to mauves colour and was captured using a smartphone. The developed paper spot array can detect up to 10 ppm of Pb2+. Further, the developed probe showed a distinguishable color change for Pb2+ along with other cations of interest such as Hg2+, Mg2+, K+, Mn2+, and Fe2+. Therefore, the present paper spot array could detect Pb2+ even in the presence of other metal ions due to its evident distinguishability. The fabricated GNC-embedded paper spot array obeys the new REASSURED criteria proposed by the World Health Organization (WHO) and could be used for on-spot detection of Pb2+.

An Adenine‐Based Chromone‐Coupled ‘Off‐On‐Off’ Fluorogenic Dyad for Cascade Detection of Zn2+ and HSO₄− Ions or Zn2+ Ions and Picric Acid

AbstractA chromone‐coupled adenine‐based fluorogenic chemosensor (BD1) has been introduced for cascade detection of Zn2+ and HSO4−ions or Zn2+ and picric acid (PA) based on the fluorescence ‘OFF‐ON‐OFF’ mechanism. A momentous fluorescence improvement has been observed due to the accumulation of Zn2+ ions in the BD1 solution because of the formation of the Zn2+ chelated BD1 complex. A cyan color fluorescence enhancement is visible under the exposure of a 365 nm UV lamp, which is also manifested in the CIE diagram. The detection limit of our developed sensor BD1 and Zn2+−BD1 complex towards the identification of Zn2+ and HSO4− ions are in the nM and μM range, respectively, in the solution phase. Among the several explosive nitroaromatic compounds (NACs), only PA quenches the fluorescence of the Zn2+ chelated BD1 complex, and the nature of quenching is both static and dynamic. A paper strips‐based test kit experiment is performed for on‐spot identification of Zn2+ ions and PA. Based on these chemically encoded inputs and the fluorescence intensity as optical output, we have constructed an INHIBIT molecular logic circuit. The present report evokes a new approach for the development of new chemosensors from bioinspired materials such as adenine, a purine nucleobase.

Adsorption behavior of self-loading bayberry tannin resin for UO22+ with surface phenolic hydroxyl groups

In this study, self-polymerization of bayberry tannin and formaldehyde condensation were used to prepare a self-loading tannin resin (STR). The environmental conditions for UO22+ capture by STR were thoroughly investigated; the experimental results indicated that the UO22+ adsorption capacity of STR could reach 691.9 mg/g under optimal adsorption conditions. The mechanism of UO22+ capture by STR was studied using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results showed that STR possessed a significant number of phenolic hydroxyl groups, which enabled the reduction of U(VI) in water to U(IV). Subsequently, stable chelation complexes were formed by filling vacant orbitals of uranium through the lone electron pair of oxygen, resulting in the formation of O = U = O structural motifs, which facilitated the effective capture of UO22+ in water. Moreover, the evaluation of the performance of STR in low-concentration UO22+ extraction from seawater revealed its favorable UO22+ removal capacity, even in simulated seawater conditions. These findings highlight the substantial potential of STR for practical applications in uranium remediation.

Stepwise and selective synthesis of chelating, multimetallic and mixed-metal π-diborene complexes.

The reaction of a pyridyl-substituted, doubly Lewis base-stabilised diborene with different amounts of copper(I) precursors led to the formation of the first chelating π-diborene complexes, the first π-diborene complexes in which metals are bound to both faces of the BB bond, and the first mixed-metal π-diborene species.

Discovery of a New Siderophore Cephalosporin, Cefiderocol

Cefiderocol is a novel siderophore-conjugated cephalosporin with a catechol residue acting as an iron chelator. Cefiderocol forms a chelating complex with ferric iron and is transported rapidly into bacterial cells through iron-uptake systems. As a result, cefiderocol shows good activity against Gram-negative bacteria, including carbapenem-resistant isolates that are causing significant global health issues. Cefiderocol has been approved for clinical use in the United States and Europe, where it is being used to treat infection caused by carbapenem-resistant Gram-negative pathogens.

Manganese 2-phosphinophosphinine precatalysts for methanol/ethanol upgrading to isobutanol.

Two Mn-phosphinophosphinine complexes were synthesised from reaction of the proligand with [MnBr(CO)5] at 80 °C for 2 h; 2-diphenylphosphino-3-methyl-6-trimethylsilylphosphinine manganese tricarbonyl bromide (2TMS) and 2-diphenylphosphino-3-methyl-phosphinine manganese tricarbonyl bromide (2H). 31P{1H} NMR spectroscopy revealed characteristic chemical shifts for the phosphinine and phosphine donors bound to Mn (255.4 and 23.7 ppm for 2TMS; 234.2 and 24.8 ppm for 2H), and single crystal X-ray diffraction established the structure of the chelating complex 2TMS. Rapid reaction of both complexes with water was observed with 2TMS reacting to eventually yield a single product, syn-3TMS, from the syn-1,2-addition of water across the PC multiple bond on the bromide face, confirmed by X-ray diffraction for both an unsolvated and solvated structure, where MeOH was found to be H-bonding to the P-OH functionality. The reaction of 2R with dry methanol gave multiple products that were not in equilibrium with each other, and the molecular structure of one isomer was definitively established by X-ray diffraction as an unusual 1,4-addition product (1,4-4TMS). However, reaction of 2R with methanol in the presence of trace water showed that hydrolysis products 3R were formed preferentially. Both phosphinine complexes acted as pre-catalysts for the Guerbet upgrading of methanol/ethanol to isobutanol at 180 °C over 90 h, giving yields of isobutanol (based on moles of ethanol) of 22% for 2TMS and 27% for 2H. This is superior to known Mn dppm complexes [dppm = bis(diphenylphosphino)methane], including the 21% yield recorded for the best derivative [MnBr(κ2-PPh2C(H)PhPPh2)(CO)3] shown to date.

Adsorption properties of the surface of Silochrome S-80 modified with aluminium alizarinate

Silica-based materials are widely used in the processes of concentration and separation of various organic substances. Successful use of SiO2 is due to its chemical resistance, thermal stability, the nature and distribution of functional groups on the surface, as well as the possibility of creating materials based on it with certain textural characteristics, which are regulated by synthesis conditions and surface modification. For the solution of specific problems of chromatography, it is necessary to obtain new adsorbents with fixed functional groups, layers or elements, by varying which the number and types of adsorption centres of the original surface change. Chelate complexes of transition metals, including those deposited in the form of adsorption layers, are used as promising modifying additives of particular interest. In this work, SiO2 based on Silochrome S-80, modified with aluminium alizarinate was studied by physicochemical method. Using thermogravimetry it was established that aluminium alizarinate is stable up to 270 °C. Using adsorption porosimetry, it was shown that modification of silica leads to a decrease in the average diameters and total volumes of pores, and specific surface areas from 84 to 79 m²/g. Using IR and Raman spectroscopy, the fixation of chelates on the surface of Silochrome was proven. The gas chromatographic method was used to study the adsorption processes of organic compounds (n-alkanes, nitromethane, heptene-1, aromatic hydrocarbons, ketones and alcohols) capable of various types of intermolecular interactions. The modification of silica with an alizarin-containing complex contributes to a change in the Henry adsorption constants and the contributions of specific interactions to the heat of adsorption. In this case, the highest values of ∆ q̅dif,1(special) are characteristic of organic compounds prone to donor-acceptor and π-complex formation. According to the analysis of compensation thermodynamic dependencies q̅dif,1 - ∆S̅S1,c it was shown that entropy is the determining thermodynamic parameter during the adsorption of test compounds on the surface of the studied chromatographic materials.

Study of Anticorrosive Action of Alkylphosphonic Acid Solutions in Monoethanolamine Based on the Formation of Chelate Complexes With Iron Ions

Study of Anticorrosive Action of Alkylphosphonic Acid Solutions in Monoethanolamine Based on the Formation of Chelate Complexes With Iron Ions

Establishment of the mechanism of purification and levigation of green chemistry-assisted biocomposites of red ochre (Gairika): synthesis, characterization, and antibacterial, prebiotic, antioxidant, and antacid activities of the traditional Ayurvedic medicine Laghu Sutashekhara Rasa

Gairika (red ochre) has a long history of influencing human civilization. Gairika is a rich source of nutrients used for reproductive and brain health. Gairika is mentioned as an antacid drug in Indian Ayurvedic medicine under Laghu Sutashekhara Rasa (LSR). However, a detailed study on LSR has not been reported to date. In the present study, LSR was prepared, and a pharmaceutical SOP (standardization procedure) was reported to obtain batch-to-batch reproducibility. LSR was characterized using FTIR, XRD, SEM-EDX, and TGA analyses. LSR was tested in vitro for its antacid activity. Advanced instrumentation revealed that LSR formation produced symmetrical particles (5–8 µm) with kaolin, kaolinite, quartz, goethite, and hematite, along with the phytoconstituents of Goghrita (clarified cow’s butter), Shunthi, and Nagawalli, as confirmed by GC-MS/MS analysis. The FTIR study revealed the formation of a chelating complex of goethite and hematite along with their phytoconstituents. XRD analysis confirmed the presence of kaolin, kaolinite, quartz, goethite, and hematite. Using in vitro antacid experiments, LSR and Shunthi demonstrated significant antacid activity as compared to antacid drugs and standards in the market, such as CaCO3. The DPPH assay revealed IC50 values of 12.16 ± 1.23 mg/mL, which is 0.0029 of Trolox-equivalent antioxidant activity. The inhibition (18 ± 4 mm) against pathogens (S. aureus, E. coli, P. aeruginosa, and B. subtilis) and the prominent growth of gut microbiota-supported strains (S. boulardii, L. paracasei, and L. plantarum) observed on LSR formulation were indicative of LSR application as a prebiotic. Here, the mechanism of purification and levigation mentioned in the classical literature of LSR was established. Overall, purification of Gairika with cow ghee and levigation with Nagawalli may enhance the solubility, bioavailability, and shelf-life of LSR through hydration and co-crystallization mechanisms. This is the first comprehensive report on the pharmaceutical validation of LSR and its characterization. The results of the present study could contribute to the development and reliable reproduction of LSR and the utility of environmental red ochre as a medicine in combination with Shunthi (Zingiber officinale Roxb.), as prescribed under Indian Ayurvedic medicine.

Synthesis, spectroscopic characterization studies of chelating complexes and their applications as antimicrobial agents, DNA binding, molecular docking, and electrochemical studies

N,N′‐bis(2,4‐dihydroxy benzaldehyde‐1,2‐diaminobenzene) (H4L) formed from the reaction of 2,4‐dihydroxybenzaldehyde and 1,2‐diaminobenzene was complexed with Cu (II), Co (II), Ni (II), Mn (II), and UO2(II) ions. The formed complexes have been characterized by their physical data, spectral studies such as FT‐IR, Uv–Vis., 1H & 13C NMR, Mass, elemental microanalysis (C.H.N.), thermal analysis, X‐ray diffraction, and magnetic susceptibility measurements. The molecular docking between the protein receptors of the H4L ligand and its complexes was studied as theoretical method. The ligand and its metal complexes (1–5) were tested for their ability to inhibit the growth of various pathogenic microbial strains. The biological significance of the Schiff base compound and complexes as antifungal, antibacterial, and anticandidal agents as well as cytotoxicity was studied. The tested microorganisms respond better to the metal complexes than the Schiff base ligand. In comparison to the ligand, complexes, and penicillin, the UO2(II) complex (5) demonstrated the strongest antibacterial activity. In comparison to ligand, complexes, and miconazole, the UO2(II) complex (5) has antifungal activity against Aspergillus niger and Candida albicans. Complexes (1) and (5) have higher activity of antibacterial than other complexes against Pseudomonas sp. and the highest antifungal and anticandidal activity in comparison with miconazole. The ligand and its complexes showed a dose‐dependent antibacterial action according to the minimum inhibition concentration test. Using Tafel polarization and electrochemical impedance spectroscopy experiments, the protective impact of the bis‐Schiff base ligand (H4L) ligand versus Q235 Steel and its adsorption performance were investigated. The interaction between H4L Schiff base and complexes (1)–(5) and calf thymus DNA shows hypochromism effect coupled with obvious bathochromic shift.

Comparative study of hydroxyapatite synthesized using Schiff base and wet chemical precipitation methods

Hydroxyapatite (HAp) exists as an inorganic and crystalline composition present in bones and dental enamel, and hence can be utilized as a direct element or as part of the composition of biomaterials and implants for dental and orthopaedic applications. Listed below are a few synthesis techniques for HAp that are listed in the literature: solid-state and mechano-chemical methods (dry methods), wet chemical precipitation and sol-gel methods (wet methods), and combustion and pyrolysis methods (high-temperature processes). Nevertheless, there are new and more productive techniques that result in HAp with a regulated morphology, such as the Schiff base method, which, on reaction with calcium and phosphate precursors, forms chelating complexes to produce HAp nuclei. This research paper presents the comparison in characteristics between HAp synthesized using Schiff base (HAp-SB), wet chemical precipitation (HAp-WC) methods, and commercial HAp (HAp-CM) in their powdered and pelleted form. The average size of HAp-WC particles in the spherical form was found to be 603 nm ± 176, HAp-SB were found to have rod-like morphology, which is very similar to human bone-like HAp, with an average length and width of 1522 nm ± 759 and 400 nm ± 112, respectively, and HAp-CM were found to have spherical morphology with dimensions of 52 nm ± 25. Biological studies show that cell viability of HAp-SB pellet (202.01% ± 8.16) seemed to have higher cell proliferation properties than HAp-WC pellet (145.7% ± 5.11) and HAp-CM pellet (71.53% ± 3.61) due to its higher aspect ratio, and hence higher surface area for the cells to adhere. In a detailed study, it is observed that both techniques had their advantages, and there were no significant disadvantages observed.