Search Results (1,080)

Although Zn (II)-(−)-Epigallocatechin gallate (EGCg) complex (Zn-EGCg) is known for its promising bioactivities, little attention has been paid to its incorporation into daily green tea consumption. In this study, we aimed to incorporate Zn (II) into green tea extract to promote the formation of Zn-EGCg complex within the tea matrix. We then investigated how the formation of Zn-complexed green tea extract (Zn-GTE) influences the gut microbiota in a Western diet (WD)-fed mouse model. Structural analyses using ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (¹H NMR), and powder X-ray diffraction (PXRD) suggested that Zn (II) interacted with hydroxyl groups of polyphenols within the extract, consistent with Zn-EGCg formation, although the complex could not be unequivocally identified. Under intake levels equivalent to daily consumption, Zn-GTE administration restored WD-induced reductions in alpha-diversity and resulted in a distinct microbial composition compared to treatment with green tea extract (GTE) or Zn alone, as shown by beta-diversity analysis. Linear discriminant analysis Effect Size (LEfSe) analysis revealed increased abundances of bacterial taxa belonging to o_Clostridiales, o_Bacteroidales, and f_Rikenellaceae, and decreased abundances of g_Akkermansia in the Zn-GTE group compared to the GTE group. These findings highlight that Zn-GTE, prepared via Zn (II) supplementation to green tea, may exert distinct microbiota-modulating effects compared to its individual components. This study provides new insights into the role of dietary metal–polyphenol complexes, offering a food-based platform for studying metal–polyphenol interactions under physiologically relevant conditions. Full article

Streptomyces sp. AWH31-250, isolated from a tidal mudflat in the Nakdong River estuary in Busan, Republic of Korea, was found to produce two novel p-aminoacetophenone derivatives, mohangic acid H (1) and mohangiol (2). Their planar structures were established by comprehensive 1D and 2D NMR spectroscopy, mass spectrometry, and UV analysis, possessing a shorter carbon-chain with a diene moiety, whereas known mohangic acids A–F bear a longer carbon-chain with a triene moiety. The absolute configurations of the key stereogenic centers were determined via computational DP4+ calculations and bioinformatic analysis of the ketoreductase domain sequence from the biosynthetic gene cluster. Based on the careful gene analysis along with whole-genome sequencing, the first plausible biosynthetic pathway of mohangic acids A–G and mohangiol was proposed. Mohangic acid H (1) and mohangiol (2) displayed moderate inhibitory activity against Candida albicans isocitrate lyase with IC₅₀ values of 21.37 and 21.12 µg/mL, respectively. Full article

Two pyrene derivatives, substituted at position 1 with isoxazole or NH-pyrazole, were synthesized in 85–87% yield starting from 1-acetylpyrene and via the cyclocondensation reaction of a β-enaminone intermediate with hydroxylamine or hydrazine. The photophysics of the two 5-(1-pyrenyl)-1,2-azoles were explored, revealing that only the isoxazole derivative exhibits good emission properties (ϕ_F ≥ 74%) but without solvatofluorochromism behavior. However, both probes exhibited noticeable photophysics in the aggregated state (in the presence of H₂O and/or in the solid state) and through acid–base interactions (using TFA and TBACN), leveraging the basic and acidic character of the analyzed 1,2-azoles, which was also investigated by ¹H NMR spectroscopy. Therefore, the selective incorporation of N-heteroaromatic units into the pyrene scaffold effectively modulates the photophysics and environmental sensitivity of the corresponding probes. Full article

Background: Transition metal complexes incorporating fluorinated counter anions represent a significant class of compounds with broad applications in industry, pharmaceuticals, and biomedicine. These fluorinated anions are known to enhance the solubility, stability, and reactivity of the complexes, thereby expanding their functional utility in various chemical and biological contexts. Methods: A set of metal(II) complexes of the general formula [MPy₆][B(C₆F₅)₄]₂ where (Py = pyridine, M = Mn (1), Fe (2), Co (3), Ni (4), Cu (5), Zn (6)) have been synthesized by direct reaction of metal halides and pyridine in the presence of Ag[B(C₆F₅)₄]. The complexes were characterized using different techniques to assure their purity, such as elemental analysis (EA), electron paramagnetic resonance (EPR) spectroscopy, thermogravimetric analysis (TGA), ultraviolet–visible (UV–Vis) spectroscopy, ¹¹B-NMR, ¹H-NMR, and FT-IR spectroscopy. The antimicrobial and antifungal properties against different types of bacteria and fungi were studied for all prepared complexes. Results: The synthesized complexes exhibited broad-spectrum antimicrobial activity, demonstrating variable efficacy compared to the reference antibiotic, oxytetracycline (positive control). Notably, complex 6 displayed exceptional antibacterial activity against Streptococcus pyogenes, with a minimum inhibitory concentration (MIC) of 4 µg/mL, outperforming the control (MIC = 8 µg/mL). Complexes 1, 2, and 4 showed promising activity against Shigella flexneri, Klebsiella pneumoniae, and Streptococcus pyogenes, each with MIC values of 8 µg/mL. Conversely, the lowest activity (MIC = 512 µg/mL) was observed for complexes 3, 5, and 6 against Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae, respectively. Regarding antifungal properties, complexes 5 and 6 demonstrated the highest activity against Candida albicans, with MIC values of 8 µg/mL, equivalent to that of the positive control, fluconazole. Density functional theory (DFT) calculations confirmed an overall octahedral coordination geometry for all complexes, with tetragonal distortions identified in complexes 3, 4, and 5. Full article

This work proposes a systematic study of different computational schemes for fluorine Nuclear Magnetic Resonance (¹⁹F NMR) chemical shifts, with special emphasis placed on the basis set issue. This study encompasses two stages of calculation, namely, the development of the computational schemes for the geometry optimization of fluorine compounds and the NMR chemical shift calculations. In both stages, the performance of different density functional theory functionals is considered against the method of coupled-cluster singles and doubles (CCSD), with the latter representing a theoretical reference in this work. This exchange-correlation functional study is accompanied with a basis set study in both stages of calculation. Basis sets of different families, sizes, and valence-splitting levels are considered. Various locally dense basis sets (LDBSs) are proposed for the calculation of ¹⁹F NMR chemical shifts, and their performance is assessed by comparison of the calculated chemical shifts with both theoretical and experimental reference data. Overall, the pcS-3/pcS-2 LDBS scheme is recommended as the most balanced locally dense basis set scheme for fluorine chemical shift calculations. Full article

After reviewing the state of the art of the fluorination of inorganic solid electrolytes, an application of gas/solid fluorination is given and how it can be processed. Garnet-type oxide has been chosen. These oxides with an ideal structure of chemical formula A₃B₂(XO₄)₃ are mainly known for their magnetic and dielectric properties. Certain garnets may have a high enough Li⁺ ionic conductivity to be used as solid electrolyte of lithium ion battery. The surface of LLZO may be changed in contact with the moisture and CO₂ present in the atmosphere that results in a change of the conductivity at the interface of the solid. LiOH and/or lithium carbonate are formed at the surface of the garnet particles. In order to allow for handling and storage under normal conditions of this solid electrolyte, surface fluorination was performed using elemental fluorine. When controlled using mild conditions (temperature lower or equal to 200 °C, either in static or dynamic mode), the addition of fluorine atoms to LLZO with Li_6,4Al_0,2La₃Zr₂O₁₂ composition is limited to the surface, forming a covering layer of lithium fluoride LiF. The effect of the fluorination was evidenced by IR, Raman, and NMR spectroscopies. If present in the pristine LLZO powder, then the carbonate groups disappear. More interestingly, contrary to the pristine LLZO, the contents of these groups are drastically reduced even after storage in air up to 45 days when the powder is covered with the LiF layer. Surface fluorination could be applied to other solid electrolytes that are air sensitive. Full article

Glass curators often question how their treatments affect the long-term stability of historical glass. While damp cotton swabs are commonly used to remove surface salts and dust, the use of water remains controversial, particularly for heavily altered glass, due to concerns about worsening hydration. This study investigates the effect of water rinsing on an unstable soda-lime glass altered for six months (monoliths) and fifteen months (powders) at 35 °C and 85% relative humidity. Samples were then rinsed with Milli-Q water at 20 °C or 50 °C, and the monolithic glass was subsequently subjected to an additional 15 months of alteration under the same conditions. The glass surface was characterized by optical and scanning electron microscopy (SEM) as well as Raman spectroscopy to identify the nature of the salts. The evolution of the hydrated layer was assessed using transmission FTIR, Raman and solid-state NMR spectroscopies, ToF-SIMS, and thermogravimetric analysis (TGA). The results show that rinsing effectively removes surface salts—primarily sodium carbonate—and induces structural changes in the hydrated layer, promoting silicate network polymerization. Upon resuming alteration, rinsed monolithic samples exhibit no further degradation after the additional 15 months of alteration. These findings offer promising insights for conservation practices and may help curators refining their treatment strategies for altered glass. Full article

Background: Natural products play a crucial role in cancer treatment due to their ability to selectively target cancer cells. Andrographolide, a major constituent of Andrographis paniculata, exhibits potential anticancer properties. Considering the pharmacological importance of nitrogen-based heteroaromatic scaffolds, particularly pyrazole motifs, this study aimed to integrate the pyrazole pharmacophore with the andrographolide scaffold to develop novel therapeutic candidates. Methods: Twenty novel 3,19-(N-phenyl-3-aryl-pyrazole) acetals of andrographolide and isoandrographolide were synthesized and characterized using UV-Vis, FT-IR, NMR, and HRMS. Initial anticancer screening was conducted by the National Cancer Institute (NCI), USA, against 60 human cancer cell lines. The most promising compound, 1f (R = 4-F), was selected for further biological evaluation in the MDA-MB-231 breast cancer cell line. Results: The MTT assay results demonstrated that compound 1f exhibited strong, dose-dependent anti-proliferative effects. The apoptosis analysis of 1f revealed a time-dependent increase in apoptotic cells, and cell cycle studies indicated S phase arrest in MDA-MB-231 cells. Antioxidant activity via the DPPH assay identified compounds 1b (R = 3-NO₂) and 2b (R = 3-NO₂) as the most effective radical scavengers. The most active compounds were also evaluated for drug-likeness using in silico Lipinski’s rule assessments. Conclusions: The synthesized 3,19-(N-phenyl-3-aryl-pyrazole) acetals of andrographolide and isoandrographolide exhibited promising anticancer and antioxidant properties. Among them, compound 1f showed the most significant activity, supporting its potential as a lead candidate for further anticancer drug development. Full article

Fluorescent chemosensors are increasingly becoming relevant in recognition chemistry due to their sensitivity, selectivity, fast response time, real-time detection capability, and low cost. Boronic acids have been reported for the recognition of mycolactone, the cytotoxin responsible for tissue damage in Buruli ulcer disease. A library of fluorescent arylboronic acid chemosensors with various signaling moieties with certain beneficial photophysical characteristics (i.e., aminoacridine, aminoquinoline, azo, BODIPY, coumarin, fluorescein, and rhodamine variants) and a recognition moiety (i.e., boronic acid unit) were rationally designed and synthesised using combinatorial approaches, purified, and fully characterised using a set of complementary spectrometric and spectroscopic techniques such as NMR, LC-MS, FT-IR, and X-ray crystallography. In addition, a complete set of basic photophysical quantities such as absorption maxima (λ_abs^max), emission maxima (λ_em^max), Stokes shift (∆λ), molar extinction coefficient (ε), fluorescence quantum yield (Φ_F), and brightness were determined using UV-vis absorption and fluorescence emission spectroscopy techniques. The synthesised arylboronic acid chemosensors were investigated as chemosensors for mycolactone detection using the fluorescent-thin layer chromatography (f-TLC) method. Compound 7 (with a coumarin core) emerged the best (λ_abs^max = 456 nm, λ_em^max = 590 nm, ∆λ = 134 nm, ε = 52816 M⁻¹cm⁻¹, Φ_F = 0.78, and brightness = 41,197 M⁻¹cm⁻¹). Full article

Main-chain conjugated and non-conjugated polyelectrolytes are an important class of materials that have many technological applications ranging from fire-retardant materials to carbon-nanotube composites, nonlinear optical materials, electrochromic materials for smart windows, and optical sensors for biomolecules. Here, we describe a series of poly(pyridinium salt)s-fluorene containing 9,9-bis(4-aminophenyl)fluorene moieties with various organic counterions that were synthesized using ring-transmutation polymerization and metathesis reactions, which are non-conjugated polyelectrolytes. Their chemical structures were characterized by Fourier transform infrared (FTIR), proton (¹H) and fluorine 19 (¹⁹F) nuclear magnetic resonance (NMR) spectrometers, and elemental analysis. They exhibited polyelectrolytic behavior in dimethyl sulfoxide. Their lyotropic liquid-crystalline phases were examined by polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS) studies. Their emission spectra exhibited a positive solvatochromism on changing the polarity of solvents. They emitted greenish-yellow lights in polar organic solvents. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), whose λ_em peaks were blue shifted. Full article

Honeydew honey represents a bee-derived product with different organoleptic characteristics and distinct properties with respect to floral honey. The market interest in honeydew honey has been growing in recent years due to its higher bioactive characteristics with respect to floral honey. The need for a deeper chemical characterization aimed to evaluate a possible botanical differentiation attracted the use of different analytical approaches. The present work aims to distinguish the botanical honeydew origin by using Nuclear Magnetic Resonance (NMR) spectroscopy and a multivariate approach. Two different data pretreatments have been considered to obtain the best sample discrimination. The saccharide content significantly affects the differentiation of the botanical variety consisting of fir, oak, citrus fruits, eucalyptus, and forest mainly by using a classification approach taking advantage of the Orthogonal Signal Correction filters. Notwithstanding the botanical diversity of the honeydew honey (HDH) samples, fir honeydew (F-HDH), oak honeydew (O-HDH), and eucalyptus honeydew (E-HDH) resulted always well discriminated among all the botanical varieties investigated, while citrus fruits honeydew (CF-HD) and forest honeydew (FO-HDH) did not. In particular, F-HDH resulted characterized by sucrose, erlose, maltose, maltotriose, maltotetraose, and melezitose, E-HDH resulted enriched in α, β-glucose and β-fructose in furanosidic form, and O-HDH enriched in β-fructose in furanosidic form, isomaltose. Full article

A series of para-trifluoromethoxy-substituted and fluorobenzhydryl-functionalized 1,2-bis(imine)acenaphthene ligands: 1-[2,6-{(4-F-C₆H₄)₂CH}₂-4-F₃COC₆H₂N]-2-(ArN)C₂C₁₀H₆ (Ar = 2,6-Me₂C₆H₃ L1, 2,6-Et₂C₆H₃ L2, 2,6-iPr₂C₆H₃ L3, 2,4,6-Me₃C₆H₂ L4, 2,6-Et₂-4-MeC₆H₂ L5), were synthesized and used to generate their corresponding nickel(II) bromide complexes (Ni1–Ni5). Elemental analysis, ¹⁹F NMR, and FT-IR spectroscopy were employed to characterize these five nickel complexes. Single-crystal X-ray diffraction of Ni2 and Ni4 confirmed distorted tetrahedral geometries. Upon activation with either EtAlCl₂ (ethylaluminum dichloride) or EASC (ethyl aluminum sesquichloride), these complexes showed exceptional high activities (up to 22.0 × 10⁶ g PE mol⁻¹ (Ni) h⁻¹) and remarkable thermal stability (4.82 × 10⁶ g PE mol⁻¹(Ni) h⁻¹ at 80 °C) towards ethylene polymerization. The resulting polyethylenes are highly branched, with the type and extent of branches tunable by temperature, solvent, and co-catalyst choice. Moreover, these polymers demonstrated excellent tensile strength (σ_b up to 20.7 MPa) and elastic recovery (up to 58%), characteristic of thermoplastic elastomers (TPEs). These results highlight the dual role of trifluoromethoxy and fluorobenzhydryl groups in enhancing catalytic performance and polymer properties. Full article

The synthesis of a series of six chloro[N-alkyl-N-cinnamyl-benzimidazol-2-yliden]silver(I) complexes was successfully achieved, wherein allyl (3a), methoxymethyl (3b), benzyl (3c), 3-fluorobenzyl (3d), 4-fluorobenzyl (3e) and 4-methyl-benzyl (3f) substituents were grafted on the benzimidazole ring. The isolated silver N-heterocyclic carbene (NHC) complexes were identified by microanalyses and mass spectrometry and characterized by FT-IR and NMR spectroscopic techniques. Conclusive evidence for the structures of complexes 3c and 3d was provided by single-crystal X-ray crystallography. The in vitro inhibitory activity of the six Ag-NHC complexes was tested against trophozoites and cysts of the pathogenic Acanthamoeba castellanii strain and the efficacy sequence is as follows: 3d > 3c > 3f > 3a > 3b > 3e. At a concentration of 100 µM in complexes 3c, 3d and 3f and after 72 h of incubation, 5.3, 3.2 and 6.3% A. castellanii trophozoite viabilities were observed, respectively. The utilization of elevated silver(I) drug concentrations, 1000 µM, resulted in the near-total eradication of pathogenic protozoa. Full article

Biflavonoids are a unique subclass of dietary polyphenolic compounds known for their diverse bioactivities. Despite these benefits, these biflavonoids remain largely underexplored due to their limited natural availability and harsh conditions required for their synthesis, which restricts broader research and application in functional foods and nutraceuticals. To address this gap, we synthesized a library of rare biflavonoids using a radical–nucleophile coupling reaction previously reported by our group. The food grade coupling reaction under weakly alkaline water at room temperature led to isolation of 28 heterocoupled biflavones from 11 monomers, namely 3′,4′-dihydroxyflavone, 5,3′,4′-trihydroxyflavone, 6,3′,4′-trihydroxyflavone, 7,3′,4′-trihydroxyflavone, diosmetin, chrysin, acacetin, genistein, biochanin A, and wogonin. The structures of the dimers are characterized by nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectroscopy (HRMS). In addition, we evaluated the antioxidant potential of these biflavones using a DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay and the DPPH value ranges between 0.75 to 1.82 mM of Trolox/mM of sample across the 28 synthesized dimers. Additionally, a three-dimensional quantitative structure–activity relationship (3D-QSAR) analysis was conducted to identify structural features associated with enhanced antioxidant activity. The partial least squares (PLS) regression QSAR model showed acceptable r² = 0.936 and q² = 0.869. Additionally, the average local ionization energy (ALIE), electrostatic potential (ESP), Fukui index (F-), and electron density (ED) were determined to identify the key structural moiety that was capable of donating electrons to neutralize reactive oxygen species. Full article

Two new racemic mixtures, including a polyketide, (±)-penilactone F (1), and a butenolide, (±) phenylbutyrolactone IIa (2), were isolated from the mangrove sediment-derived strain Aspergillus spelaeus SCSIO 41433. Additionally, 20 known compounds were isolated, including four penicillin-like compounds (11–14), three alkaloids (15–17), one sesquiterpene (18), and four phenolic acids (19–22). Their structures were elucidated through NMR spectroscopy, HRESIMS, X-ray diffraction, and ECD calculations. In the PDE4 inhibitory activity and anticancer cell activity assays, compounds 2, 3, 5, 8, 9, 11–14, and 16 exhibited weak PDE4 inhibitory activity at a concentration of 10 µM, Compound 11 demonstrated potent inhibitory effects against six cancer cell lines (MDA-MB-231, MDA-MB-435, HCT116, SNB-19, PC3, and A549), with IC₅₀ values ranging from 3.4 to 23.7 µM. Full article