Search Results (477)

High-temperature cooking processes like frying, baking, smoking, or drying can induce chemical transformations in conventional food ingredients, causing deteriorative modifications. These reactions, including hydrolytic, oxidative, and thermal changes, are common and can alter the food’s chemical composition. This study transformed a combination of sucrose and histidine (Su-Hi) through charring or pyrolysis. The GC-MS profiling study showed that when sucrose and histidine (Su-Hi) were exposed to high temperatures (≈240 °C), they produced carbonyl and aromatic compounds including beta-D-Glucopyranose, 1,6-anhydro (10.11%), 2-Butanone, 4,4-dimethoxy- (12.89%), 2(1H)-Quinolinone-hydrazine (5.73%), Benzenamine (6.35%), 2,5-Pyrrolidinedione, 1-[(3,4-dimethylbenzoyl)oxy]- (5.82%), Benzene-(1-ethyl-1-propenyl) (5.62%), and 4-Pyridinamine-2,6-dimethyl (5.52%). The compounds mentioned can permeate the cell membrane and contribute to the development of cell death by necrosis in human immune cells. The evidence suggests that a specific set of pyrolytic compounds may pose a risk to immune cells. This investigation reveals the complex relationship between high-temperature cooking-induced transformations, compound permeation inside the cells, and downstream cellular responses, emphasizing the significance of considering the broader health implications of food chemical contaminants. Full article

Iron is a heavy metal that often contaminates water. High iron concentrations are toxic to human health, so monitoring its presence in water is necessary. Iron in water can be detected using an optical sensor (optode). This research aims to fabricate an optode based on a cellulose triacetate membrane with a selective reagent against Fe(III). The optode was fabricated by mixing cellulose triacetate polymer, a plasticiser (a mixture of oleic acid and acetophenone), aliquot-336, and thiocyanate as a selective reagent. Membrane performance was tested based on working range, linearity, limit of detection and quantitation, precision, and accuracy. The performance of the membrane showed a linear response in the concentration range of 0.1–4 mg/L with a coefficient of determination (R²) of 0.9937, limit of detection of 0.0250 mg/L, limit of quantitation of 0.0757 mg/L, repeatability precision with a relative standard deviation of 3.31%, and an accuracy of 100.49%. Optode selectivity was good for interfering ions Cr(VI) and Pb(II). The colour complex of the optode was stable until the 10th day. The application of iron detection in water samples shows an average concentration of 0.2541 mg/L with good precision and accuracy. Full article

The thioether-functionalized 2-azabutadiene (ⁱPrS)₂C=C(H)-N=CPh₂ L ligates to CdI₂ and HgI₂ to form the chelate compounds [CdI₂{(ⁱPrS)₂C=C(H)-N=CPh₂] (1) and [HgI₂(ⁱPrS)₂C=C(H)-N=CPh₂] (2). Their crystal structures were solved via X-ray diffraction. Both crystallize in the non-centrosymmetric space groups: monoclinic P2₁ (1) and orthorhombic P2₁2₁2₁ (2), respectively. The closed-shell d¹⁰ metal centers are four-coordinated (two iodides and S and N coordinating atoms from the ligand L) in both complexes. The geometrical indexes τ indicate that a highly distorted trigonal pyramidal is adopted for 1 and a seesaw geometry for 2. The comparative nature of metal–ligand bonds is discussed on the basis of metric parameters and of QT-AIM (quantum theory of atoms in molecules) calculations. L was also treated with CuI to obtain the dinuclear species [LCu(μ₂-I₂)CuL] (3), in which the two Cu(I) centers are linked by a short metal–metal bond. The geometric and electronic properties of 3 are compared with those of 1 and 2. Full article

A new polymorph of anhydrous β-cyclodextrin (polymorph III) was obtained and characterized for the first time using powder X-ray diffraction, infrared spectroscopy, and thermal analysis. The solution enthalpy and time of dissolution in water were determined using solution calorimetry for this polymorph and compared with those of the dried commercial form of β-cyclodextrin (polymorph I), its amorphous form, and 2-hydroxypropyl-β-cyclodextrin. The specific heat capacities of polymorphs I and III were determined using differential scanning calorimetry across a wide range of temperatures, providing enthalpy and Gibbs energy values for the polymorphic transition at 298 K. The affinities of polymorph III and 2-hydroxypropyl-β-cyclodextrin for water were characterized by determining their hydration isotherms, which provided values of hydration Gibbs energy. Being energy-rich, the new-found polymorph of β-cyclodextrin has a significantly higher dissolution rate and an increased affinity for water compared with the dried commercial form of β-cyclodextrin. These properties render the new polymorph promising in industrial applications for guest inclusion in aqueous solutions and pastes, and may be a desirable alternative for water-soluble β-cyclodextrin derivatives. Full article

Polyamides (PAs) undergo local environmental degradation, leading to a decline in their mechanical properties over time. PAs can experience various forms of degradation, such as thermal degradation, oxidation, hydrothermal oxidation, UV oxidation, and hydrolysis. In order to better comprehend the degradation process of PAs, it is crucial to understand each of these degradation mechanisms individually. While this review focuses on hydrolysis, the data from degrading similar PAs under pure thermal oxidation and/or hydrothermal oxidation are also collected to grasp more perspective. This review analyzes the available characterization data and evaluates the changes in molecular weight, crystallinity, chemical structure, and mechanical properties of PAs that have aged in oxygen-free water at high temperatures. The molecular weight and mechanical strength decrease as the crystallinity ratio rises over aging time. This development is occurring at a slower rate than degradation in pure thermal oxidation. By combining the data for the changes in mechanical properties with the ones for molecular weight and crystallinity, the point of embrittlement can be not only predicted, but also modeled. This prediction is also shown to be dependent on the fibers, additives, types of PA, pH, and more. Full article

A new method for the synthesis of azido-propargyloxy derivatives of 1,3,5-triazine has been developed utilizing the nitrosation of hydrazyno-1,3,5-triazines. New hydrazines (2-hydrazino-4,6-bis(propargyloxy)-1,3,5-triazine and 2,4-dihydrazino-6-propargyloxy-1,3,5-triazine) were synthesized and characterized via FTIR, NMR spectroscopy and elemental analysis. The hyperbranched polymers with azide (diazide monomer) and propargyloxy terminal groups were obtained via the azide-alkyne polycycloaddition reaction of diazide and monoazide AB₂-type monomers. The antibacterial activity against Escherichia coli bacteria of 2,4,6-trispropargyloxy-1,3,5-triazine, 2-azido-4,6-bispropargyloxy-1,3,5-triazine, and 2,4-diazido-6-propargyloxy-1,3,5-triazine and their hyperbranched polymers was studied. Only 2,4-diazido-6-propargyloxy-1,3,5-triazine has weak antibacterial activity in comparison with ampicillin. The cytotoxicity of these compounds against M-HeLa, FetMSC, and Vero cell lines was also studied. 2,4,6-trispropargyloxy-1,3,5-triazine does not show any cytotoxic effect (IC₅₀ ≥ 280 µM). It was shown that the presence of an azide group in the compound directly affects the cytotoxic effect. Hyperbranched polymers have a less cytotoxic effect against M-HeLa (IC₅₀ > 100) in comparison with monomers (IC₅₀ = 90–99 µM). This makes it possible to use these polymers as the basis for biocompatible materials in biomedical applications. Full article

The first total synthesis of the proposed structure of unprecedented indolyl derivative bearing 1,2-propanediol moiety is described. Isomerization of 3-alkoxyindolines through indolenium intermediates was the key step in the total synthesis. ¹H, ¹³C-NMR, IR, and HRMS spectra of the synthetic compound drastically differed to those of the originally reported structure, which suggests the natural product requires revision. Full article

Brown algae possess a diverse array of acidic polysaccharides, including fucoidan. The present research intends to investigate the extraction and characterization of algal polysaccharides to explore their antiviral activity. A light brown sulfated polysaccharide was extracted (with a yield of 18% of dry weight) from Sargassum asperifolium algal powder. The results of fractionation of sulfated polysaccharide revealed the occurrence of two primary fractions: low-sulfated polysaccharides (SPF1) and high-sulfated polysaccharides (SPF2). The bioassays conducted on SPF2 demonstrated a greater level of antioxidant activity compared to SPF1, with respective IC₅₀ values of 17 ± 1.3 µg/mL and 31 ± 1.1 μg/mL after a duration of 120 min. The cytotoxicity of SPF2 on Vero cells was determined, and the calculated half-maximal cytotoxic concentration (CC₅₀) was found to be 178 ± 1.05 µg/mL. Based on these results, an antiviral activity assay was conducted on SPF2. The results demonstrated that SPF2 had greater efficacy against Hepatitis A Virus (HAV) compared to Herpes Simplex Virus Type 1 (HSV-1), with corresponding half-maximal inhibitory concentrations (IC₅₀) of 48 ± 1.8 µg/mL and 123 ± 2.6 µg/mL, respectively. The active SPF2 was characterized by FT-IR, ¹H, and ¹³C NMR spectroscopy. The extracted fucoidan can be used as a natural therapeutic agent in combating various viral infections. Full article

In recent years, transition metal-catalyzed C–H activation and site-selective functionalization have been considered to be valuable synthetic tactics to functionalize organic compounds containing multiple C–H bonds. Pyrene is one of the privileged and notorious polycyclic aromatic hydrocarbons. Pyrene and its derivatives have found applications in various branches of chemical sciences, including organic chemistry, chemical biology, supramolecular sciences, and material sciences. Given the importance of pyrene derivatives, several classical methods, including the C–H functionalization method, have been developed for synthesizing modified pyrene scaffolds. This review attempts to cover the recent developments in the area pertaining to the modification of the pyrene motif through the C–H activation process and the functionalization of C–H bonds present in the pyrene motif, leading to functionalized pyrenes. Full article

Chiral hydroxamic acid (HA) and bis-hydroxamic acid (BHA) ligands have made significant contributions to the field of asymmetric synthesis, particularly in the synthesis of natural products. These ligands possess unique molecular structures that allow for exceptional stereochemical control, leading to their widespread use in catalytic systems. This review highlights the advancements made in asymmetric synthesis using chiral hydroxamic acid and bis-hydroxamic acid ligands and their impact on the synthesis of complex natural products. This discussion encompasses their role in enantioselective C–C bond formation, the functionalization of C–H bonds, the asymmetric transformations involving heteroatoms, and their application in the total synthesis of natural products. The versatility and efficiency of chiral hydroxamic acid ligands and bis-hydroxamic acid ligands make them invaluable tools for synthetic chemists working towards the efficient and selective synthesis of natural products. This review provides a comprehensive overview of their contributions, showcasing their potential to expand the boundaries of chemical synthesis and access the diverse array of natural product scaffolds. Full article

The iron-promoted 1,5-substitution reaction of endocyclic oxiranes with MeMgBr yields exocyclic 2,4,5-trienols with high diastereomeric ratios of up to 100:0. However, for the method’s success, the oxirane ring must have a trans-configuration. The reactions exhibit strong stereoselectivity concerning the methylation mode and the configuration of the resulting exocyclic double bond. Enantiomerically pure enyne oxiranes can be synthesized through Sharpless asymmetric dihydroxylation and subsequent manipulations. With these reagents, it has been possible to produce exocyclic 2,4,5-trienols in enantiopure forms. Importantly, this process maintains chirality without degradation during the center-to-axis transfer of chirality. Full article

It is my pleasure to welcome you to Chemistry (ISSN: 2624-8549), an open access peer-reviewed journal that publishes both primary reports and reviews highlighting important advances in fundamental areas of chemistry and/or illustrating the central role of chemistry in bridging the physical and life sciences [...] Full article

A series of 2,4-disubstituted pyrrolo[2,1-f][1,2,4]triazines containing both aryl and thienyl substituents were synthesized by exploiting the 1,3-cycloaddition reaction of N(1)-ethyl-1,2,4-triazinium tetrafluoroborates with dimethyl acetylenedicarboxylate. The antiviral activity of the synthesized compounds against influenza virus strain A/Puerto Rico/8/34 (H1N1) was studied in experiments on Madin-Darby canine kidney (MDCK) cell culture. Among the pyrrolo[2,1-f][1,2,4]triazine derivatives, compounds with low toxicity and high antiviral activity were identified. Dimethyl 4-(4-methoxyphenyl)-7-methyl-2-p-tolylpyrrolo[2,1-f][1,2,4]triazine-5,6-dicarboxylate was found to demonstrate the best antiviral activity (IC₅₀ 4 µg/mL and selectivity index 188). Based on the results of in vitro tests and molecular docking studies performed, a plausible mechanism of action for these compounds was suggested to involve inhibition of neuraminidase. Full article