Introduction Of New Functional Groups Research Articles

Aged polystyrene microplastics exposure affects apoptosis via inducing mitochondrial dysfunction and oxidative stress in early life of zebrafish

In recent years, the toxic effects of microplastics (MPs) on aquatic organisms have been increasingly recognized. However, the developmental toxicity and underlying mechanisms of photoaged MPs at environmental concentrations remain unclear. Therefore, the photodegradation of pristine polystyrene (P-PS) under UV irradiation was used to investigate, as well as the developmental toxicity and underlying mechanisms of zebrafish (Danio rerio) exposed to P-PS and aged polystyrene (A-PS) at environmentally relevant concentrations (0.1–100 μg/L). Mortality, heart rate, body length, and tail coiling frequency of zebrafish larvae were the developmental toxicity endpoints. A-PS had increased crystallinity, the introduction of new functional groups, and higher oxygen content after UV-photoaging. The toxicity results showed that exposure to A-PS resulted in more adverse developmental toxicity than exposure to P-PS. Exposure to A-PS induced oxidative damage, as evidenced by elevated production of reactive oxygen species (ROS) and DNA damage, and led to decreased mitochondrial membrane potential (MMP) and causes the release of cytochrome c (cyt c) from the mitochondria. The caspase-3/-9 activation signaling pathways may cause developmental toxicity via mitochondrial apoptosis. Significant changes in the expression of genes were further explored linking with oxidative stress, mitochondria dysfunctions and apoptosis pathways following A-PS exposure. These findings underscore the importance of addressing the environmental applications of aged MPs and call for further research to mitigate their potential risks on aquatic ecosystems and human health.

An Overview of Pyridazinone Analogs: Chemical and Pharmacological Potential

Abstract: Pyridazinones are classical molecules that occupy an important place in heterocyclic chemistry, and since their discovery, they have been widely developed. The introduction of new functional groups into pyridazinone structures has enabled the synthesis of a large diversity of compounds. The pharmacological and agrochemical importance of pyridazinone derivatives has aroused the interest of chemists and directed their research toward the synthesis of new compounds with the aim of improving their biological effectiveness. In this review, we have compiled and discussed the different synthetic routes, reactivity, and pharmacological and agrochemical applications of the pyridazinone ring.

In Silico Design of Potential Small-Molecule Antibiotic Adjuvants against Salmonella typhimurium Ortho Acetyl Sulphydrylase Synthase to Address Antimicrobial Resistance.

The inhibition of O-acetyl sulphydrylase synthase isoforms has been reported to represent a promising approach for the development of antibiotic adjuvants. This occurs via the organism developing an unpaired oxidative stress response, causing a reduction in antibiotic resistance in vegetative and swarm cell populations. This consequently increases the effectiveness of conventional antibiotics at lower doses. This study aimed to predict potential inhibitors of Salmonella typhimurium ortho acetyl sulphydrylase synthase (StOASS), which has lower binding energy than the cocrystalized ligand pyridoxal 5 phosphate (PLP), using a computer-aided drug design approach including pharmacophore modeling, virtual screening, and in silico ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) evaluation. The screening and molecular docking of 4254 compounds obtained from the PubChem database were carried out using AutoDock vina, while a post-screening analysis was carried out using Discovery Studio. The best three hits were compounds with the PubChem IDs 118614633, 135715279, and 155773276, possessing binding affinities of -9.1, -8.9, and -8.8 kcal/mol, respectively. The in silico ADMET prediction showed that the pharmacokinetic properties of the best hits were relatively good. The optimization of the best three hits via scaffold hopping gave rise to 187 compounds, and they were docked against StOASS; this revealed that lead compound 1 had the lowest binding energy (-9.3 kcal/mol) and performed better than its parent compound 155773276. Lead compound 1, with the best binding affinity, has a hydroxyl group in its structure and a change in the core heterocycle of its parent compound to benzimidazole, and pyrimidine introduces a synergistic effect and consequently increases the binding energy. The stability of the best hit and optimized compound at the StOASS active site was determined using RMSD, RMSF, radius of gyration, and SASA plots generated from a molecular dynamics simulation. The MD simulation results were also used to monitor how the introduction of new functional groups of optimized compounds contributes to the stability of ligands at the target active site. The improved binding affinity of these compounds compared to PLP and their toxicity profile, which is predicted to be mild, highlights them as good inhibitors of StOASS, and hence, possible antimicrobial adjuvants.

Lipoic Acid Ligase A‐Mediated Ligation: Mechanism, Applications, and Emerging Innovations in Bioconjugation

AbstractThis review outlines the latest findings on bioconjugation using lipoic acid ligase A (LplA), a key enzyme that allows the introduction of new functional groups into biomolecules. LplA functions via a characteristic mechanism of covalently binding orthologous lipoic acid derivatives in vivo to a specific 13 amino acid sequence called the LplA acceptor peptide (LAP). This unique functionality has enabled a wide range of applications, including cell‐surface modification, protein immobilization, fluorescent labeling of antibodies. Recently, the modification of proteins without LAP sequences has been demonstrated, suggesting their potential for future biopharmaceutical production. Although several review articles on enzyme ligation have been published, research on LplA remains limited. This review attempts to fill this gap by introducing LplA based on its mechanism, applications, and recent research reports.

SYNTHESIS OF POTENTIAL LIQUID CRYSTALS WITH CHOLESTEROL FRAGMENT BY WITTIG REACTION

Liquid crystals are substances that owing to the features of their structure and physical properties are of interest not only as objects for theoretical research, but also significantly important practically due to the possibilities of their effective application in various brunches of industry, medicine, in household etc. Among the known classes of liquid crystals, substances known as cholesterics are an important group.
 Cholesteric liquid crystals demonstrate very high optical activity, that significantly exceeds the optical activity of most other known classes of organic compounds. Their ability for appreciable change of color at change of the temperature and environment composition is also practically important.
 Among all compounds belonging to the class of cholesterics an important place possess cholesterol derivatives, especially cholesterol esters. Therefore, the elaboration of new methods of their synthesis and the introduction of new functional groups into their molecules are an urgent tasks indeed.
 This work is devoted to the investigation of the possibility of synthesis of new cholesterol derivatives, namely cholesteryl esters of unsaturated acids by the Wittig reaction - the interaction of various classes of aldehydes with phosphonium salts, with the intermediate formation of phosphorus ylides - alkylidene phosphoranes. We found that the Wittig reaction is a convenient method for the synthesis of cholesteryl esters of unsaturated carboxylic acids. We have developed methods for the synthesis of potential cholesteric liquid crystals by the Wittig reaction, which use a phosphonium salt containing a cholesterol fragment and corresponding aldehydes. The process proceed without the release of an intermediate compound – alkylidene phosphorane, which reduces the labor intensity of the method.
 The application of various aldehydes enables the easily obtaining of cholesteryl esters of unsaturated acids containing various aliphatic, aromatic and heterocyclic fragments in the acid radical. The reaction takes place in mild conditions, without using of high temperatures or aggressive environments. The resulting esters show signs of mesophase formation, which is a confirmation of their liquid crystalline properties.

Comparative studies of acetylated and carboxymethylated starches obtained from red cocoyam (Colocasia esculenta) and white cocoyam (Colocasia antiquorum)

Interest in biopolymer is on the rise due to the non-biodegradability of synthetic polymers. Starches obtained from red cocoyam and white cocoyam were subjected to chemical modifications through acetylation using acetic anhydride and carboxymethylation using monochloroacetic acid in the presence of sodium hydroxide followed by determination of their physicochemical and functional properties. The proximate analysis showed that moisture, protein and fat contents reduced following the modification. Moisture content falls within the permissible limit with white cocoyam starch (WCS) having the least in both native and modified starches. Carboxymethylated starches had higher fat and ash content than acetylated starches while acetylated starches had higher protein content. In addition, swelling power, solubility, oil and water absorption capacities increased following modification. Pasting temperature and peak time reduced following modifications, with carboxymethylation having slight reduction. There was a significant difference in the peak, rough, breakdown, final and setback viscosities of native and modified cocoyam starches. The viscosities increased following acetylation but decreased following carboxymethylation. Viscosities of the acetylated red cocoyam were higher than that of acetylated white cocoyam starches. FTIR studies revealed the introduction of new functional groups in the modified starches, with the bands of the - C=O shifting to a higher and -OH to a lower value. Chemical modification improved the physicochemical properties of the starches studied. The physicochemical properties of the native and modified red cocoyam starch make it a better binder than white cocoyam.

Recent Studies on the Preparation and Application of Ionic Amphiphilic Lignin: A Comprehensive Review.

As the second most abundant natural polymer after cellulose, lignin has received considerable attention recently due to its reproducibility, safety, and biodegradability. Studies are now focusing on the development of new lignin applications to replace petroleum-based chemicals. Unfortunately, lignin has several inherent problems, such as poor water solubility and a tendency to agglomerate. However, after chemical modification, lignin can gain new functions through the introduction of new functional groups. For example, amphiphilic lignin is a polymer that is soluble in both water and organic solvents. Amphiphilic lignin polymers can be divided into anionic, cationic, and anionic-cationic amphoteric lignin-based polymers, according to the ions contained in their molecular structure. Amphiphilic lignin polymers also have a wide range of applications in various industrial fields and can be used as wetting agents, detergents, controlled release fertilizers, adsorbents, and emulsifiers. Thus, this article reviews research progress on the synthesis and applications of amphiphilic lignin-derived polymers over the past 10 years, providing a theoretical reference for the utilization of high-added-value and high-performance lignin.

Adsorption of 1,2-Dichlorobenzene from the Aqueous Phase onto Activated Carbons and Modified Carbon Nanotubes.

This study aimed to describe the adsorption process of ortho-dichlorobenzene (o-DCB) onto activated carbons (ACs) and modified carbon nanotubes (CNTs) from the aqueous phase. The starting material NC_7000 carbon nanotubes were modified by chlorination (NC_C) and then by the introduction of hydroxyl groups (NC_C_B). The concentration of o-DCB in solutions was performed by UV-VIS spectrophotometry. After adsorption, the activated carbons were regenerated by extraction with organic solvents such as acetone, methanol, ethanol, and 1-propanol; the carbon nanotubes were regenerated by methanol. The degree of adsorbate recovery was determined by gas chromatography (GC) with flame ionization detection, using ethylbenzene as an internal standard. The equilibrium isotherm data of adsorption were satisfactorily fitted by the Langmuir equations. The results indicate that carbon adsorbents are effective porous materials for removing o-DCB from the aqueous phase. Additionally, activated carbons are more regenerative adsorbents than carbon nanotubes. The recoveries of o-DCB from ACs were in the range of 76–85%, whereas the recoveries from CNTs were in the range of 23–46%. Modifications of CNTs affect the improvement of their adsorption properties towards o-DCB compared to unmodified CNTs. However, the introduction of new functional groups on carbon nanotube surfaces makes the regeneration process less effective.

MODIFICATION OF HUMIC SUBSTANCES FOR DEVELOPMENT OF MATERIALS FOR ENVIRONMENTAL TECHNOLOGIES

Humic substances are high molecular weight refractory polycationites formed during decay of living organic matter and through biosynthesis of low molecular weight organic substances (metabolites or decay products of living organisms). Presence of many functional groups in the structure of humic substances determines their ability to interact with metal ions forming stable complexes and influencing metal ion speciation in the environment and mobility, behaviour and speciation forms in the environment. Presently humic substances are a product of industrial scale and quantities in amounts of hundreds of tons are produced. The aim of this study is to analyse derivatization possibilities of humic substances. To achieve this aim derivatization of humic substances using acylation (at first introduction of acetylgroups, but also changing length acyl chains are considered) are used. Also alkylation is used. Mild oxidation can help to obtain modified products with reduced molecular weight. Another approach includes introduction of new functional groups and structures. To achieve this aim, conjugates with short peptides, amines and sugar derivatives using coupling with water-soluble carbodiimides are obtained. As basic characteristics elemental analysis as well as functional analysis have been used, supported with Fourier transform infrared (FTIR), 13C nuclear magnetic resonance spectrometry and other methods. Derivatives of humic substances containing sulpho, amino, and hydroxylgroups and thiolgroups were synthesized and their properties were analyzed in respect to their their elemental composition; functional group content changes in spectral characteristics. The derivatives of humic substances showed significant differences in the number and in ability to interact with the metal ions, which were reflected in their complexation properties towards metal ions. FTIR spectra gave evidence of the presence of metal ions, strongly bound and protected in inner sphere complexes. The obtained derivatives of humic substances can be used for remediation of environment contaminated with heavy metal ions.

Temperature-regulated flexibility of polymer chains in rapidly self-healing hydrogels

Without the introduction of new functional groups, altering the properties of a substance, such as by changing from a non-self-healing to a rapidly self-healing material, is often difficult. In this work, we report that the properties of 2-hydroxyethyl methacrylate and acrylamide (HEMA/AAm) hydrogels can be easily altered from non-self-healing to rapidly self-healing by simply tuning the reaction temperature. Notably, the hydrogels that are prepared at room temperature do not exhibit self-healing behavior, while those treated at an elevated temperature show automatic self-healing performance within ~15 s. Interestingly, in contrast with the previous self-healing HEMA-based polymeric hydrogels, which function only above their glass transition temperatures (Tg), the hydrogels prepared herein exhibit rapid self-healing properties at room temperature, which is below their Tg. In addition, the stretching capabilities of the hydrogels can be greatly enhanced by up to 30-fold. The hydrogels also exhibit good adhesive performance and can adhere strongly onto various substrates, such as wood, glass, fabric, paper, leather, porcelain, and steel. For example, a 10 kg weight could be suspended from a wooden substrate with the aid of these hydrogels. These results may provide valuable insight regarding the design of self-healing hydrogels and their large-scale production.

Asymmetric Addition of Pyrazolones to Allenamides Catalyzed by a Chiral Phosphoric Acid

We describe a new asymmetric allylic alkylation of pyrazolones, in which an all‐carbon quaternary stereocenter with broad substrate scope and good enantioselectivity was generated. The asymmetric addition of pyrazolones to allenamides could be carried out under mild conditions in excellent yields with a relatively low catalyst loading. The allylic products with an enamide structure can be easily transformed to the pyrazolones with other functional groups, which provides a new approach for the asymmetric introduction of new functional groups into the pyrazolone skeleton.

Novel route for amine grafting to chitosan electrospun nanofibers membrane for the removal of copper and lead ions from aqueous medium

A novel step wise synthetic route was developed to prepare amine grafted nanofibers (AGNFs) affinity membrane. The chemical structure of the nanofibers (NFs) after grafting was studied by acquiring Fourier Transform Infrared (FT-IR) spectra and Carbon, Hydrogen and Nitrogen (CHN) data. The morphology of the NFs before and after grafting was studied by Field Emission Scanning Electron Microscope (FE-SEM). FT-IR and CHN data confirmed the introduction of new functional groups into the primary structure of chitosan (CH). FE-SEM showed denser membrane with no deterioration of the NFs morphology after grafting. The aqueous stability of the membranes was studied in distilled water. The AGNFs membranes showed good aqueous stabilities (with only ∼ 6% loss in weight until 24 h and remained stable thereafter) which was less than the weight loss by glutaraldehyde treated nanofibers (GNFs) (∼44% loss in weight until 24 h) and pristine NFs (100% loss in weight as soon as the NFs were immersed in distilled water). The maximum adsorption (qm) capacity of AGNFs for Cu (II) and Pb (II) was observed to be 166.67 mg.g−1 and 94.34 mg.g−1. The adsorption capacity of the present systems was much higher for Cu (II) when compared to the already existing conventional and chitosan adsorbents. This increased might be related not just to the size, but more potentially to the increase in the number of nitrogen binding sites (chelating sites). Nitrogen donates lone-pair of electrons for chelation. The combination of processing into nano size and amine grafting (AG) has significantly increased the adsorption capacity of CH NFs membrane.

Complementary Sample Preparation Strategies for Analysis of Cereal β-Glucan Oxidation Products by UPLC-MS/MS.

The oxidation of cereal (1→3,1→4)-β-D-glucan can influence the health promoting and technological properties of this linear, soluble homopolysaccharide by introduction of new functional groups or chain scission. Apart from deliberate oxidative modifications, oxidation of β-glucan can already occur during processing and storage, which is mediated by hydroxyl radicals (HO•) formed by the Fenton reaction. We present four complementary sample preparation strategies to investigate oat and barley β-glucan oxidation products by hydrophilic interaction ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), employing selective enzymatic digestion, graphitized carbon solid phase extraction (SPE), and functional group labeling techniques. The combination of these methods allows for detection of both lytic (C1, C3/4, C5) and non-lytic (C2, C4/3, C6) oxidation products resulting from HO•-attack at different glucose-carbons. By treating oxidized β-glucan with lichenase and β-glucosidase, only oxidized parts of the polymer remained in oligomeric form, which could be separated by SPE from the vast majority of non-oxidized glucose units. This allowed for the detection of oligomers with mid-chain glucuronic acids (C6) and carbonyls, as well as carbonyls at the non-reducing end from lytic C3/C4 oxidation. Neutral reducing ends were detected by reductive amination with anthranilic acid/amide as labeled glucose and cross-ring cleaved units (arabinose, erythrose) after enzyme treatment and SPE. New acidic chain termini were observed by carbodiimide-mediated amidation of carboxylic acids as anilides of gluconic, arabinonic, and erythronic acids. Hence, a full characterization of all types of oxidation products was possible by combining complementary sample preparation strategies. Differences in fine structure depending on source (oat vs. barley) translates to the ratio of observed oxidized oligomers, with in-depth analysis corroborating a random HO•-attack on glucose units irrespective of glycosidic linkage and neighborhood. The method was demonstrated to be (1) sufficiently sensitive to allow for the analysis of oxidation products also from a mild ascorbate-driven Fenton reaction, and (2) to be specific for cereal β-glucan even in the presence of other co-oxidized polysaccharides. This opens doors to applications in food processing to assess potential oxidations and provides the detailed structural basis to understand the effect oxidized functional groups have on β-glucan's health promoting and technological properties.

Quaternized cashew gum: An anti-staphylococcal and biocompatible cationic polymer for biotechnological applications

Chemical modifications to cashew gum (CG) structure have been previously reported to obtain new physicochemical characteristics, however until now there were no reports of modifications by introduction of new functional groups to add cationic character. This study presents a quaternization route for CG using a quaternary ammonium reagent. The chemical features of the quaternized cashew gum derivatives (QCG) were analyzed by: FTIR, elemental analysis, degree of substitution, Zeta potential, 1H NMR and 1H-13C correlation (HSQC). QCG were evaluated for their anti-staphylococcal activity by determining minimum inhibitory and bactericidal concentrations against pathogenic Staphylococcus spp. and by imaging using atomic force microscopy. Moreover, the mammalian cell biocompatibility were also assessed through hemolytic and cell toxicity assays. QCG presented promising antimicrobial activity against methicillin-resistant S. aureus and biocompatibility on tested cells. These results show that QCG could be a promising tool in the development of biomaterials with an anti-septic action.

Aromatization of (Z) and (E)-α-atlantones isolated from Cedrus atlantica essential oil followed by condensation with thiosemicarbazide: synthesis of new thiadiazolines derivatives

Aromatization, using Pd/C (10%) of (Z) and (E)-α-atlantones isolated from Cedrus atlantica essential oil, followed by condensation with thiosemicarbazide gave novel 1,3,4-thiadiazolic derivatives by the introduction of new functional groups on the terpenic skeletons. After aromatization and thiosemicarbazide condensation, all products were obtained in good yields to give thiadiazolic compounds bearing new spiro carbons.

Palladium-catalyzed R2(O)P-directed C(sp2)-H activation

In recent years, transition-metal-catalyzed inert C-H bond activation has developed rapidly and is a powerful protocol for the construction of new C-C or C-X bonds and the introduction of new functional groups. Our group has also developed a series of R2(O)P-directed Pd-catalyzed C-H functionalizations involving olefination, hydroxylation, acetoxylation, arylation, and acylation through an uncommon seven-membered cyclo-palladium pretransition state. Unlike previously used directing groups, the R2(O)P group acts as a directing group and is also involved in the construction of P,-hetero-ligands.

Surface chemistry of atmospheric plasma modified polycarbonate substrates

Surface of polycarbonate substrates were activated by atmospheric plasma torch using different gas pressure, distance from the substrates, velocity of the torch and number of treatments. The modifications were analyzed by contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV–vis spectrophotometry. Plasma treatment caused the surface characteristics to become more hydrophilic as measured by the water contact angle, which decreased from 88° to 18°. The decrease in contact angle was mainly due to oxidation of the surface groups, leading to formation of polar groups with hydrophilic property. XPS results showed an increase in the intensity of –(C–O)– groups and also introduction of new functional groups i.e. –(O–CO)– after the treatment process. AFM topographic images demonstrated an increase in the rms roughness of the surface from 2.0nm to 4.0nm caused by the treatment. Increase in rms roughness of the surface caused relevant decrease in transmission up to ∼2–5%.

Chemical and Biochemical Transformations of 5‐Ethoxycarbonyl‐5‐phenyl‐2‐isoxazolines.

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Chemical and biochemical transformations of 5-ethoxycarbonyl-5-phenyl-2-isoxazolines

The salts, 2-methyl-5,5-disubstituted 4,5-dihydroisoxazolium methylsulfates comprising various substituents at the C-3 carbon atom were subjected to transformations. The structure of applied compounds permitted to monitor the effect of this factor on the transformation course of the 2-isoxazoline ring. The nucleophilic addition of cyanide anion to the selected salts enabled the obtaining of a next heterocyclic system of changed physicochemical and biological properties in comparison to the starting 2-isoxazolines. The diastereoselective hydrolysis of the cyanide group in 2-isoxazolidines by the bacteria strain Rhodococcus rhodochrous PCM 909 leads to the obtaining of a racemic mixture of the trans-hydroxyacid. The introduction of new functional groups into the heterocyclic ring made these compounds attractive objects for further chemical and microbial transformations and to study their biological activity.

Upgrading of an industrial lignin by using laccase produced by Fusarium proliferatum and different laccase-mediator systems

An industrial lignin recovered from a paper factory effluent was characterized and treated in buffered media under three different conditions. The first system contained only partially purified laccase produced by Fusarium proliferatum. The other two were supplemented with 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) or 1-hydroxylbenzotriazole (1-HBT) as mediators. During incubation the lignin remained solubilized and its spectral and chromatographic characteristics depended on time and conditions. UV–vis spectrum of lignin recovered from the first system showed a strong increase at the outset of incubation, reflecting the introduction of new functional groups in the polymer. No changes in its molecular mass distribution pattern were detected. Longer incubation produced minor alterations in its UV–vis spectrum, together with a polymerization in the recovered substrate, appearing as a new peak around 200 kDa. Lignin recovered from the laccase-ABTS system showed an intensive depolymerization together with a minor polymerization also in the high molecular mass fraction (200 kDa). That lignin sample was soluble under acid conditions. These sharp modifications contrasted with those detected in the lignin incubated with 1-HBT as mediator. Treating industrial lignin by these simple procedures rapidly enhances the technological potential of this paper-mill byproduct.