Metal Chelating Research Articles

A Telechelic Fluorescent Indicator Based on Polymer Conformational Change for Free Copper(II) Ions

A novel copper(II) ion indicator based on polymer conformational change is designed and its chemo-response to the target analyte is tested in this paper. The word ‘telechelic’ in the title means that a polymer has two different fluorophores on either end. If one of them is a fluorescent donor and the other is a fluorescent acceptor, then the extent of Foerster resonance energy transfer (FRET) will depend on polymer conformation. The sensitivity of these sensors is tunable based on the chain length and the amount of the receptor on the polymer. This is revealed by the fluorescence response of 30mer, 50mer, and 100mer of poly(N-isopropyl)acrylamide with different amounts of metal chelation monomers. We also address the change in fluorescence over time due to the untangling of poly(N-isopropylacrylamide) in water. The fluorescent signal can maintain stability after metal binding. The photoluminescence results agree with the length calculation of polyelectrolytes. A fluorescent standard curve is created for the measurement of different concentrations of copper ions. The sensing limit can reach 10−10 M analytes, which is suitable for the measurement of chemicals in trace amounts in the environment.

Phytochemical Analysis, In Vitro Free Radical Scavenging, and LDL Protective Effects of Different Solvent Fractions of Calotropis procera (R.) Br. Root Bark Extract

In the present study, the methanolic extract of Calotropis procera root bark was subjected to solvent-solvent partitioning using n-hexane fraction (HF), dichloromethane fraction (DMF), ethyl acetate fraction (EAF), and methanol fraction (MF). The resultant fractions were tested for antioxidant activity using in vitro radical scavenging assay. Preliminary phytochemical investigation revealed the presence of varying proportions of secondary metabolites in solvent fractions such as glycosides, flavonoids, triterpenoids, sterols, and polyphenolic compounds. The total phenolic content of EAF was 25.7 ± 3.12 mg TAE/g followed by 19.05 ± 3.29 mg TAE/g in DMF. The total flavonoid content was 13.69 ± 1.74 mg QUE/g in DMF and 11.4 ± 1.88 mg QUE/g in EAF. The EAF showed significant radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH, IC50 = 369.87 μg/mL), nitric oxide (IC50 = 317.46 μg/mL), hydrogen peroxide (H2O2 , IC50 = 396.85 μg/mL), and hydroxyl radicals (IC50 = 195.39 μg/mL). DMF was most effective in scavenging superoxide radicals (IC50 = 679.60 μg/mL), while greater metal chelating activity was exhibited by MF (IC50 = 614.73 μg/mL). Moreover, the total antioxidant activity for EAF was found to be 94.14 ± 9.114 mg AAE followed by DMF (68.10 ± 8.78 mg AAE). EAF also significantly reduced the formation of thiobarbituric acid reactive substances in a dose-dependent manner in CuSO4. The observed antioxidant effect might be attributed to the presence of secondary metabolites. Subsequent GC-MS analysis of EAF confirmed the presence of lupeol, α-amyrin, β-amyrin, and ursolic acid. The current investigation reveals that the high polyphenolic and antioxidant pentacyclic triterpenes in EAF of C. procera root bark methanol extract correlates with its good antioxidant activity and can provide protection against free radicals-induced damage in a variety of chronic health conditions.

Fluorescent 2′-Deoxyuridine (dU) Analogue: Tropolonyl triazolyl-dU (tt-dU) Exhibits Solvatochromism/HeLa Cell Internalization and Its Triphosphate (tt-dUTP) Is Incorporated into DNA Enzymatically

AbstractThis era has witnessed the development and extensive application of modified nucleosides, including fluorescent nucleosides that clinically served humankind. Most fluorescent nucleoside analogues are derived from benzenoid aromatic scaffolds. However, the non-benzenoid aromatic moiety, tropolone, which exhibits unique hydrogen bonding and metal chelating properties, also occurs in nature. Recently, we introduced the tropolone unit at deoxyuridine through an ethyne linker and prepared its DNA analogues, which are fluorescent. This report describes the synthesis of a new troponyl triazolyl-dU (tt-dU) analogue, possessing a triazolyl linker, through click chemistry. tt-dU exhibits fluorescence with solvatochromism and enters into Hela cells without any cytotoxicity. Its triphosphate (tt-dUTP) was also synthesized and incorporated enzymatically into DNA, as shown in primer extension experiments. The unique photophysical properties and metal-chelating ability of the tropolone group make tt-dU a promising modified nucleoside.

Effects of black seed oil combined with olive oil or honey on antioxidant activities, phenolic content, and identification and quantification of thymoquinone, a key bioactive compound

The plant Nigella sativa (NS) has a rich history in folk medicine, being utilized for various illnesses and as tonic drugs. Furthermore, thymoquinone (TQ), a major compound found in the seeds of NS, may exhibit antioxidant activity. In addition to black candles, traditional medicine employs olive oil and honey to nourish the body. Some folk medicine systems combine NS, honey, and olive oil for improved efficacy; however, knowledge regarding the antioxidant properties of black seed oil (BSO), BSO with olive oil (BSOO), and BSO with honey (BSOH) remains limited. Therefore, in this study, we investigated the antioxidant properties of BSO, BSOO, and BSOH. Gas chromatography-mass spectrometry analysis showed that BSO contained 73.48 ± 1.23 mg/kg TQ. BSO, BSOO, and BSOH exhibited remarkable antioxidant activity, with NO scavenging activities of 94.32, 76.53, and 50.37, respectively. The 2,2-diphenyl-1-picrylhydrazyl and metal chelating activity assays (with half-maximal inhibitory concentration values), oxygen radical antioxidant capacity, and total flavonoid compound content of BSO were 0.135 ± 0.003 mg/mL, 0.005 ± 0.003 mg/mL, 32 ± 0.4 μM Trolox/g extract, and 997 ± 20 mg catechin equivalent/g of extract, respectively. These results are potentially linked to the increased antioxidant activity, as suggested by Pearson's correlation coefficients. In the ferric-reducing antioxidant power assay, the highest antioxidant activity was demonstrated by BSOO and BSOH, with total phenolic content of 7288 ± 300 mM FeSO4/mg and 346 ± 17 mg of gallic acid equivalent/g E, respectively. This study affirms the potent antioxidant properties of BSO, BSOO, and BSOH, emphasizing the importance of further research on NS infusion as a promising antioxidant agent and its application as an anti-aging and tonic drug.

Evaluation of primary and secondary oxidation products in fish oil-in-water emulsions: Effect of metal-complexing peptides and protein hydrolysates

A novel approach consisting of preselection of peptides using bioinformatics tool followed by final selection using Surface Plasmon Resonance (SPR) - an efficient technique to investigate metal complexing properties of peptides/hydrolysates - was developed. Selected pea hydrolysates and synthetic metal chelating peptides potentially present in pea hydrolysates were investigated for their ability to inhibit the lipid oxidation in emulsions composed of 5 % w/w fish oil and stabilized with Tween® 20. Results indicated that addition of peptides/hydrolysates did not impact the physical stability of emulsions and led to lower level of lipid hydroperoxides. Moreover, peptide KGKSR inhibited the generation of 1-penten-3-ol and hexanal to the same level as ethylenediaminetetraacetic acid (EDTA) did and the formation of 2 ethyl-furan was lower than when EDTA was added. Peptide GRHRQKHS showed same concentration of hexanal as EDTA thus confirming efficacy of using SPR for selecting peptides/hydrolysates to use as antioxidants in emulsions.

Extract of Ginkgo biloba Leaves (EGb) Decrease Lipid Oxidation in Fish Feed and Meat and Enhance Growth and Antioxidant Capacity in Jian Carp (Cyprinus carpio var. Jian)

Firstly, a linoleic and linolenic acid emulsion were incubated with petroleum ether extract, ethyl acetate extract (EAE), ethanol extract and aqueous extract of Ginkgo biloba leaves. The flavonoids content, total antioxidant capacity (T-AOC) and metal-chelating ability (MCA) were determined in EGbs above. Results showed that the extracts of Ginkgo biloba leaves (EGbs) inhibited the lipid oxidation in material above. Of all of EGbs, EAE showed the strongest T-AOC, MCA and protective effects against the lipid oxidation. Next, fish feeds were incubated with graded levels of EAE. The results showed that EAE inhibited lipid oxidation in fish feeds. The optimal inclusion levels of EAE for minimizing lipid oxidation were 4.26 g kg−1 feeds. The effect of EGbs on the lipid oxidation may be closely associated with their flavonoid content. Finally, juvenile carp (14.8 ± 0.4 g) were fed with EAE at concentrations ranging from 0.0 to 6.0 g kg−1 for 60 days. Current data displayed that dietary EAE increased the growth performance of fish. This result of EAE may be ascribed to its enhancing effect on the activity of digestive and absorptive enzymes and antioxidant capacity in digestive organs of fish. Furthermore, dietary EAE decreased the hot-drying-induced lipid oxidation in fish meat through inhibiting the induction effect of hemoglobin in erythrocytes. Our study suggests that EGb can be considered as a potential natural antioxidant for fish and fish feed.

Oral Administration of Sargassum horneri Suppresses Particulate Matter-Induced Oxidative DNA Damage in Alveolar Macrophages of Allergic Airway Inflammation: Relevance to PM-Mediated M1/M2 AM Polarization.

Particulate matter (PM) can cause cellular oxidative damage and promote respiratory diseases.Ithas recently shown that Sargassum horneri ethanol extract (SHE) containing sterols and gallic acid reduces PM-induced oxidative stress in mice lung cells through ROS scavenging and metal chelating. In this study, the role of alveolar macrophages (AMs) is identified that are particularly susceptible to DNA damage due to PM-triggered oxidative stress in lungs of OVA-sensitized mice exposed to PM. The study scrutinizes if PM exposure causes oxidative DNA damage to AMs differentially depending on their type of polarization. Further,SHE's potential is investigated in reducing oxidative DNA damage in polarized AMs and restoring AM polarization in PM-induced allergic airway inflammation.The study discovers that PM triggers prolonged oxidative stress to AMs, leading to lipid peroxidation in them and alveolar epithelial cells. Particularly,AMs are polarized to M2 phenotype (F4/80+ CD206+ ) with enhanced oxidative DNA damage when subject to PM-induced oxidative stress. However, SHE repairs oxidative DNA damage in M1- and M2-polarized AMs and reduces AMs polarization imbalance due to PM exposure. These results suggest the possibility of SHE as beneficial foods against PM-induced allergic airway inflammation via suppression of AM dysfunction.

Phytosiderophore pathway response in barley exposed to iron, zinc or copper starvation

Efficient micronutrient acquisition is a critical factor in selecting micronutrient dense crops for human consumption. Enhanced exudation and re-uptake of metal chelators, so-called phytosiderophores, by roots of graminaceous plants has been implicated in efficient micronutrient acquisition. We compared PS biosynthesis and exudation as a response mechanism to either Fe, Zn or Cu starvation. Two barley (Hordeum vulgare L.) lines with contrasting micronutrient grain yields were grown hydroponically and PS exudation (LC-MS) and root gene expression (RNAseq) were determined after either Fe, Zn, or Cu starvation. The response strength of the PS pathway was micronutrient dependent and decreased in the order Fe > Zn > Cu deficiency. We observed a stronger expression of PS pathway genes and greater PS exudation in the barley line with large micronutrient grain yield suggesting that a highly expressed PS pathway might be an important trait involved in high micronutrient accumulation. In addition to several metal specific transporters, we also found that the expression of IRO2 and bHLH156 transcription factors was not only induced under Fe but also under Zn and Cu deficiency. Our study delivers important insights into the role of the PS pathway in the acquisition of different micronutrients.

Effects of pH-dependent speciation on the photolytic degradation mechanism of phosphonates

Phosphonates, commonly used as strong metal chelating agents in household and industrial products, partially persist through water treatment processes, releasing significant amounts into the environment and raise concerns about potential environmental impacts. This study investigated effects of pH-dependent speciation of phosphonates on their photolysis by a medium-pressure mercury lamp in aqueous solution under ambient air conditions. Different species of aminotrimethylphosphonic acid (ATMP), and its most important transformation products iminodimethylphosphonic acid(IDMP) and aminomethylphosphonic acid(AMPA) were analyzed by liquid chromatography in combination with isotope ratio (CSIA) and high resolution mass spectrometry. UV radiation (<320 nm) was required for the photolytic degradation of ATMP, IDMP, and AMPA, and their photolysis was influenced by pH-dependent speciation. Degradation rate constant of ATMP was affected by pH, but a direct correlation between kobs and pH was not found. In contrast, IDMP and AMPA exhibited a direct correlation between pH and kobs during photolysis. CSIA revealed an inverse carbon kinetic isotope effect (KIE) for ATMP, while a normal carbon KIE was observed for IDMP and AMPA. Quantum chemical calculations supported degradation pathway interpretation and KIE understanding. Energy barrier calculations distinguished N-C vs C-P bond cleavage, favoring N-C cleavage on average, consistent with observed transformation products. Further calculations, considering possible transition states, provide first promising hints for elucidation of present KIEs.

Radiometal Complexes as Pharmacokinetic Modifiers: A Potent 68Ga-Labeled Gastrin-Releasing Peptide Receptor Antagonist Based on the Macrocyclic Metal Chelator NODIA-Me.

The gastrin-releasing peptide receptor (GRPr) is overexpressed in various cancer types including prostate and breast carcinomas, making it an attractive target for molecular imaging and therapy. In this work, we designed a novel GRPr antagonistic probe comprising metal chelator NODIA-Me. This 1,4,7-triazacyclononane-based chelator forms positively charged metal complexes due to its neutral methylimidazole arms. Because a positive charge at the N-terminus of GRPr conjugates is responsible for high receptor affinity as exemplified by the current gold standard DOTA-RM2, we investigated if a positively charged radiometal complex can be used as a pharmacokinetic modifier to also produce high-affinity GRPr conjugates. In this respect, the bioconjugate NODIA-Me-Ahx-JMV594 was prepared by a combination of solid-phase peptide synthesis and solution-based reactions in a 94% yield. Radiolabeling provided the 68Ga-labeled conjugate in radiochemical yields of >95% and radiochemical purities of >98% with mean molar activities of Am ∼17 MBq nmol-1. The competitive GRPr affinity of the metal-free and 69/71Ga-labeled conjugate was determined to be IC50 = 0.41 ± 0.06 and 1.45 ± 0.06 nM, respectively. The metal-free GRPr antagonist DOTA-RM2 and its corresponding 69/71Ga complex had IC50 values of 1.42 ± 0.07 and 0.98 ± 0.19 nM, respectively. Small-animal PET imaging of mice bearing GRPr(+) PC-3 tumors revealed high radioactivity accumulation in the tumors and in the pancreas as an organ with high levels of GRPr expression. These findings were corroborated by the corresponding ex vivo biodistribution data, in which the tumors and the pancreas exhibited the highest radioactivity accumulation. By coinjection of an excess of NODIA-Me-Ahx-JMV594, uptake in the tumors and GRPr(+) organs was significantly reduced, confirming specific receptor-mediated uptake. The estrogen receptor-positive tumor of a female breast cancer patient was clearly visualized by PET imaging using 68Ga-labeled NODIA-Me-Ahx-JMV594. To summarize, the positive charge at the N-terminus of the conjugate induced by the Ga(NODIA-Me) complex resulted in high GRPr affinity comparable to that of the potent antagonist DOTA-RM2. The conjugate NODIA-Me-Ahx-JMV594 is a promising probe for imaging of GRPr tumors that warrants further evaluation in larger patient cohorts as well as in combination with other radiometals.

Synthesis, crystal structure and Hirshfeld analysis of trans-bis-(2-{1-[(6R,S)-3,5,5,6,8,8-hexa-methyl-5,6,7,8-tetra-hydronaphthalen-2-yl]ethyl-idene}-N-methyl-hydrazinecarbo-thio-amidato-κ2N2,S)palladium(II) ethanol monosolvate.

The reaction between the (R,S)-fixolide 4-methyl-thio-semicarbazone and PdII chloride yielded the title compound, [Pd(C20H30N3S)2]·C2H6O {common name: trans-bis-[(R,S)-fixolide 4-methyl-thio-semicarbazonato-κ2 N 2 S]palladium(II) ethanol monosolvate}. The asymmetric unit of the title compound consists of one bis-thio-semicarbazonato PdII complex and one ethanol solvent mol-ecule. The thio-semicarbazononato ligands act as metal chelators with a trans configuration in a distorted square-planar geometry. A C-H⋯S intra-molecular inter-action, with graph-set motif S(6), is observed and the coordination sphere resembles a hydrogen-bonded macrocyclic environment. Additionally, one C-H⋯Pd anagostic inter-action can be suggested. Each ligand is disordered over the aliphatic ring, which adopts a half-chair conformation, and two methyl groups [s.o.f. = 0.624 (2):0.376 (2)]. The disorder includes the chiral carbon atoms and, remarkably, one ligand has the (R)-isomer with the highest s.o.f. value atoms, while the other one shows the opposite, the atoms with the highest s.o.f. value are associated with the (S)-isomer. The N-N-C(=S)-N fragments of the ligands are approximately planar, with the maximum deviations from the mean plane through the selected atoms being 0.0567 (1) and -0.0307 (8) Å (r.m.s.d. = 0.0403 and 0.0269 Å) and the dihedral angle with the respective aromatic rings amount to 46.68 (5) and 50.66 (4)°. In the crystal, the complexes are linked via pairs of N-H⋯S inter-actions, with graph-set motif R 2 2(8), into centrosymmetric dimers. The dimers are further connected by centrosymmetric pairs of ethanol mol-ecules, building mono-periodic hydrogen-bonded ribbons along [011]. The Hirshfeld surface analysis indicates that the major contributions for the crystal cohesion are [atoms with highest/lowest s.o.f.s considered separately]: H⋯H (81.6/82.0%), H⋯C/C⋯H (6.5/6.4%), H⋯N/N⋯H (5.2/5.0%) and H⋯S/S⋯H (5.0/4.9%).

Multifunctional Nanocarriers for Alzheimer's Disease: Befriending the Barriers.

Neurodegenerative diseases (NDDs) have been increasing in incidence in recent years and are now widespread worldwide. Neuronal death is defined as the progressive loss of neuronal structure or function which is closely associated with NDDs and represents the intrinsic features of such disorders. Amyotrophic lateral sclerosis, frontotemporal dementia, Alzheimer's, Parkinson's, and Huntington's diseases (AD, PD, and HD, respectively) are considered neurodegenerative diseases that affect a large number of people worldwide. Despite the testing of various drugs, there is currently no available therapy that can remedy or effectively slow the progression of these diseases. Nanomedicine has the potential to revolutionize drug delivery for the management of NDDs. The use of nanoparticles (NPs) has recently been developed to improve drug delivery efficiency and is currently subjected to extensive studies. Nanoengineered particles, known as nanodrugs, can cross the blood-brain barrier while also being less invasive compared to the most treatment strategies in use. Polymeric, magnetic, carbonic, and inorganic NPs are examples of NPs that have been developed to improve drug delivery efficiency. Primary research studies using NPs to cure AD are promising, but thorough research is needed to introduce these approaches to clinical use. In the present review, we discussed the role of metal-based NPs, polymeric nanogels, nanocarrier systems such as liposomes, solid lipid NPs, polymeric NPs, exosomes, quantum dots, dendrimers, polymersomes, carbon nanotubes, and nanofibers and surfactant-based systems for the therapy of neurodegenerative diseases. In addition, we highlighted nanoformulations such as N-butyl cyanoacrylate, poly(butyl cyanoacrylate), D-penicillamine, citrate-coated peptide, magnetic iron oxide, chitosan (CS), lipoprotein, ceria, silica, metallic nanoparticles, cholinesterase inhibitors, an acetylcholinesterase inhibitors, metal chelators, anti-amyloid, protein, and peptide-loaded NPs for the treatment of AD.

Highly efficient dissolution and reinforcement mechanism of robust and transparent cellulose films for smart packaging

The packaging of fresh foods increasingly focuses on renewable and eco-friendly cellulose films, but their low dissolution efficiency and weak mechanical strength greatly limit their wide application, which also cannot be used for smart packaging. Here, a highly efficient synergistic chloride-salt dissolution method was proposed to fabricate robust, transparent, and smart cellulose films. Cellulose films with appropriate Ca2+ concentration exhibited robust mechanical strength, better thermal stability, high transparency and crystallinity. The metal chelation of Ca2+ with cellulose chains could induce cellulose chain arrangement during the cellulose regeneration process. Particularly, compared to pure cellulose films, the tensile strength and elongation at break of cellulose films with suitable Ca2+ were increased by 167 % and 200 %, respectively. Moreover, optimal cellulose films can be used to reflect the quality of the fruit by detecting changes in ethanol gas. Hence, a novel strategy is presented to fabricate robust and transparent cellulose films with great potential application for smart packaging.

Multifunctional agents against Alzheimer’s disease based on oxidative stress: Polysubstituted pyrazine derivatives synthesized by multicomponent reactions

As Alzheimer’s disease (AD) is a neurodegenerative disease with a complex pathogenesis, the exploration of multi-target drugs may be an effective strategy for AD treatment. Multifunctional small molecular agents can be obtained by connecting two or more active drugs or privileged pharmacophores by multicomponent reactions (MCRs). In this paper, two series of polysubstituted pyrazine derivatives with multifunctional moieties were designed as anti-AD agents and synthesized by Passerini-3CR and Ugi-4CR. Since the oxidative stress plays an important role in the pathological process of AD, the antioxidant activities of the newly synthesized compounds were first evaluated. Subsequently, selected active compounds were further screened in a series of AD-related bioassays, including Aβ1-42 self-aggregation and deaggregation, BACE-1 inhibition, metal chelation, and protection of SH-SY5Y cells from H2O2-induced oxidative damage. Compound A3B3C1 represented the best one with multifunctional potencies. Mechanism study showed that A3B3C1 acted on Nrf2/ARE signaling pathway, thus increasing the expression of related antioxidant proteins NQO1 and HO-1 to normal cell level. Furthermore, A3B3C1 showed good in vitro human plasma and liver microsome stability, indicating a potential for further development as multifunctional anti-AD agent.

The use of active compounds to shape the quality of active double-layer films based on furcellaran intended for packaging salad-dressing – Assessment of utilitarian and storage properties

In order to obtain innovative, high-quality biodegradable packaging, double-layer films based on furcellaran and gelatin, enriched with plant extracts were created. The films were assessed considering their potential utility, applications and environmental impact. The mechanical properties over a period of nine months were studied and it was noted that the passing of time had a beneficial effect on these parameters. The antioxidant properties was also examined, with the highest results obtained using the DPPH and metal chelating activity methods for GE (76.64 % and 9.85 % respectively), while this film showed the lowest FRAP value (5.99 %) compared to the highest obtained for DTE (52.62 %). For the first time, the possibility of using the double-layer active FUR/GEL film as packaging for salad-dressing was evaluated, but no improvement in parameters was observed regardless of the extract used. The environmental impact analysis showed the ability to completely decomposed in vermicompost within several days.

Spectroscopic and Computational pH Study of NiII and PdII Pyrrole-Imine Chelates with Human Serum Albumin.

Human serum albumin (HSA) efficiently transports drugs in vivo: most are organic. Therefore, it is important to delineate the binding of small molecules to HSA. Here, for the first time, we show that HSA binding depends not only on the identity of the d8 metal ion, NiII or PdII, of their complexes with bis(pyrrole-imine), H2PrPyrr, but on the pH level as well. Fluorescence quenching data for native and probe-bound HSA showed that sites close to Trp-214 (subdomain IIA) are targeted. The affinity constants, Ka, ranged from ~3.5 × 103 M-1 to ~1 × 106 M-1 at 37 °C, following the order Pd(PrPyrr) > Ni(PrPyrr) at pH levels of 4 and 7; but Ni(PrPyrr) > Pd(PrPyrr) at a pH level of 9. Ligand uptake is enthalpically driven, dependent mainly on London dispersion forces. The induced CD spectra for the protein-bound ligands could be simulated by hybrid QM:MM TD-DFT methods, allowing us to delineate the binding site of the ligands and to prove that the metal chelates neither decompose nor demetallate after uptake by HSA. The transport and delivery of the metal chelates by HSA in vivo is therefore feasible.

Pyrophosphate detection method using 5-Br-PAPS to detect nucleic acid amplification - Application to LAMP method

Genetic testing has been increasingly used in several fields. In many applications, nucleic acid amplification technology is required. However, current methods to detect nucleic acid amplification require expensive reagents and special equipment or exhibit limited sensitivity, which hinders their use. To address this issue, this study reports an assay method for detecting occurrence of acid amplification in post-amplification samples using pyrophosphate, a highly sensitive byproduct of nucleic acid amplification. The method proposed requires two reagents and an automated analyzer. First, hydrogen peroxide is derived from pyrophosphate, an indicator of nucleic acid amplification, and the oxidizing power of hydrogen peroxide is used to produce Fe (III) from Fe (II). The specific metal chelator 5-Br-PAPS forms a complex with the trivalent iron produced, resulting in a highly sensitive coloration. The within-run reproducibility of our method (n = 20) was less than 3.67% at each concentration tested, and the detection limit was 0.075 μmol/L, sufficient for quantitative analysis. The technique described could detect pyrophosphate in a sample that was amplified using the loop-mediated isothermal amplification method after only 10 min. Therefore, the proposed method has the potential to be a new, rapid, and simple detection technique for amplified nucleic acids.

Spectral, thermal, and biological activity studies of some nano divalent (E,Z)-methyl N {[(methylamino)carbonyl]oxy}ethanimidothioate metal chelates

A novel set of biologically active Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) chelates was prepared from (E,Z)-methylN-{[(methylamino)carbonyl]oxy}ethanimidothioate. The chemical structural of the reported chelates was identified by means of some physicochemical and spectral approaches. All chelates were found to be non-electrolytic except Cd(II) possessed electrolytic character. The elemental analysis declared that the designated complexes were formed with (1:1), (2:1) and (1:3) (M:L) stoichiometry. The infrared spectral data revealed the neutral ONS tridentate and NS bidentate behavior of ligand towards metal ions. The octahedral structure of the produced chelates was proposed from the electronic absorption spectral data alongside the magnetic susceptibility measurements. TG/DTG demonstrated the superior complexes' thermal stability in comparison to that of free ligand. Ligand and its synthesized chelates were screened in vitro towards E. vermiculata for their anti-molluscicidal characteristic. The findings showed that each tested compound had varying degrees of sensitivity to the tested land snail species, with significant anti-molluscicidal action. In addition, ligand and its chelates were examined for their antibacterial screening towards both gram-positive (B. subtilis, S. aureus and M. sp. RCMB 028 (1)) and gram-negative bacteria (E. coli, P. aeruginosa and P. vulgaris) as well as their antifungal activity against C. albicans and A. fumigatus. The results indicated that the coordinated constructions have extraordinary activity compared to the ligand, in which Ni(II) and Cd(II) chelates were more active than the reference itself. X-ray diffraction data reflected that Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) crystallized at nano-scale. Some theoretical studies were validated, and the experimental results were interpreted.

Hydroxamate Assays for High‐Throughput Screening of Transketolase Libraries Against Arylated Substrates

AbstractWe recently reported that the transketolase from Geobacillus stearothermophilus (TKgst) upon acyl transfer to nitrosoarenes generates N‐aryl hydroxamic acids (HA). The latter are metal chelating compounds that in the presence of Fe(III) ions form deep‐red complexes. Here, we applied this principle to the development of a colorimetric assay in both solid‐ and liquid‐phase formats for the high‐throughput screening of TKgst and its variants. Screening a set of positive hits from a L382X/D470X library validated the specificity and sensitivity of the assays. The solid surface assay allows a clear distinction between positive and negative colonies by the naked eye in qualitative mode, and further also to measure activity in semi‐quantitative fashion in the liquid‐phase format. The assay will be important for engineering the TKgst enzyme towards improved conversion of aromatic aldehydes by their close structural analogy to nitrosoarenes.

Antioxidant peptides from alternative sources reduce lipid oxidation in 5% fish oil-in-water emulsions (pH 4) and fish oil-enriched mayonnaise.

Bioinformatics tools were used to predict radical scavenging and metal chelating activities of peptides derived from abundant potato, seaweed, microbial, and spinach proteins. The antioxidant activity was evaluated in 5% oil-in-water emulsions (pH4) and best-performing peptides were tested in mayonnaise and compared with EDTA. Emulsion physical stability was intact. The peptide DDDNLVLPEVYDQD showed the highest protection against oxidation in both emulsions by retarding the formation of oxidation products and depletion of tocopherols during storage, but it was less efficient than EDTA when evaluated in mayonnaise. In low-fat emulsions, formation of hydroperoxides was reduced 4-folds after 5days compared to control. The concentration effect of the peptide was confirmed in mayonnaise at the EDTA equimolar concentration. The second-best performing peptides were NNKWVPCLEFETEHGFVYREHH in emulsion and AGDWLIGDR in mayonnaise. In general, the peptide efficacy was higher in low-fat emulsions. Results demonstrated that peptide negative net charge was important for chelating activity.