Search Results (1,208)

The synergistic effects of glucose (Glu) concentration and clay mineral type (kaolinite [Kao], montmorillonite [Mon]) on abiotic humification via the polyphenol-Maillard reaction remain poorly understood. To address these scientific challenges, a series of controlled, sterile batch experiments was conducted. Specifically, a glucose concentration gradient (0, 0.03, 0.06, 0.12, and 0.24 mol/L) was established; Kao and Mon were separately introduced as mineral catalysts; and the Maillard reaction was facilitated in the presence of catechol and glycine under strictly abiotic conditions to preclude any potential biological interference. Comprehensive analyses were performed on the reaction products—namely, the supernatant and the dark-brown residue generated during the reaction process. These analyses included: the E₄/E₆ ratio and total organic carbon (TOC) content of the supernatant; the carbon-based ratio of humic-like acid to fulvic-like acid (C_HLA/C_FLA); and the structural characteristics of humic-like acid (HLA) isolated from the dark-brown residue. Results showed dynamic E₄/E₆ ratio and TOC changes in the supernatant were accurately described by the Logistic function. Kao favored soluble organic C accumulation and enhanced retention of early-stage, low-molecular-weight intermediates in the dark-brown residue, while Mon promoted humic-like substances (HLS) polymerization and aromatic condensation. FTIR spectroscopy analysis identified optimal Glu thresholds for maximal HLS formation—0.03 mol/L for Kao and 0.06 mol/L for Mon—indicating non-linear, rather than monotonic, dependence on Glu dosage. Comparative pre- and post-reaction Fourier-transform infrared (FTIR) spectroscopy further demonstrated that Mon, owing to Mg–OH octahedral sites arising from isomorphic substitution, formed more stable Cat chelates than Kao. These chelates effectively stabilized surface-bound hydroxyl-associated water molecules and modulated the electron cloud distribution around Si–O bonds. Collectively, this study clarified the dual regulatory role of Glu concentration and clay mineral identity in abiotic humification pathways, advanced mechanistic understanding of clay mineral-mediated polyphenol-Maillard reactions, and established a scientific foundation for optimizing humification efficiency in both engineered and natural systems. Full article

The self-assembly of a novel synthesized chiral dipeptide, Boc-p-nitro-L-phenylalanyl-tyrosine, into supramolecular structures is investigated by optical absorption and photoluminescence spectroscopy as well as single crystal X-ray diffraction. The compound is a diphenylalanine derivative belonging to a family of aromatic dipeptides that spontaneously self-organize into nanostructures through molecular recognition. The dipeptide exhibits several step-like peaks in its absorption band, indicative of self-assembly into quantum-confined nanostructures. In contrast, the parent Boc-p-nitro-L-phenylalanine amino acid lacks these features, indicating that the tyrosine residue favors quantum-confined self-assembly. Crystal structure determination reveals distinct packing styles: Boc-p-nitro-L-phenylalanine forms two-dimensional hydrogen-bonded layers, while the related p-nitro-free Boc-L-phenylalanyl-tyrosine dipeptide organizes into a 3D helical columnar architecture, driven by the additional hydrogen-bonding capacity of the peptide bond and tyrosine hydroxyl group, which favors the formation of a channel-type tetragonal architecture network over the planar sheets of the monomer. Furthermore, the introduction of a tyrosine residue into the Boc-p-nitro-L-phenylalanine molecule alters its supramolecular assembly, as the dipeptide Boc-p-nitro-L-phenylalanyl-tyrosine crystallizes as a monohydrate. The water molecule present in the structure acts as a bridge, participating in a hydrogen-bonding network between the tyrosine hydroxyl groups of neighboring columns through intermolecular interactions. Full article

Charge transport underpins essential biological processes, including cellular respiration, photosynthesis, and enzymatic catalysis. Advances in molecular electronics have enabled single-molecule measurements that unequivocally establish redox-active proteins as efficient electron conductors, with their metal cofactors serving as intrinsic redox relays. By contrast, ubiquitous non-redox proteins lacking such redox centers have long been considered poor conductors. However, recent research has challenged this view, demonstrating that efficient charge transport in non-redox proteins can be mediated through polypeptide backbones, aromatic side-chain arrays, and hydrogen bond networks. This review surveys progress in understanding the single-molecule conductance of non-redox proteins. Firstly, we elucidate the fundamental transport mechanisms, highlighting the interplay between coherent tunneling and thermally activated hopping. We then provide an overview of state-of-the-art experimental techniques for single-molecule characterization. Through analysis of diverse systems spanning short peptides to large enzymes, we illustrate how aromatic amino acid networks and dynamic conformational fluctuations govern conductance, enabling emerging applications in label-free biosensing and single-molecule protein/DNA sequencing. Finally, we discuss persistent challenges and outline future opportunities for integrating protein-based conductors into bioelectronic devices. This review aims to stimulate further research and pave the way for novel applications harnessing protein conductance. Full article

Bee pollen is an extraordinary nutritional product of honeybees. Its valuable profile depends on the concentration of bioactive compounds, influenced by multiple factors, such as geographical origin and botanical species. Pollen samples produced by a single farm and collected during four different seasonal periods were first subjected to palynological analysis and then evaluated for their volatile profile and the content of selected nutraceutical compounds. The June sample, characterized by a high percentage of Castanea pollen, exhibited the higher concentration of soluble sugars, proteins, antioxidant molecules and minerals. The heatmap and hierarchical clustering confirmed a pronounced seasonal variability in bee pollen volatile composition, strongly linked to changes in floral availability. The greatest dissimilar volatilomic fingerprints are represented by samples collected in November (monofloral pollen of Hedera helix) and April (polyfloral pollen). The seasonal variability on the bioactive compounds, as well as in aromatic composition, seem to be linked to the different compositions of plant pollen, related to its botanical origin. This study expands current knowledge on the chemical characterization of bee pollen and supports the use of volatilome analysis as a complementary tool to palynological investigation for assessing botanical origin, quality, and the ecological and sensory value of this bee product. Full article

We present a modular building block strategy for synthesizing phosphonated polyaromatic systems as an alternative to the conventional late-stage phosphonation of prefabricated aromatic scaffolds, which often requires harsh conditions and has limited tolerance for functional groups. A monophosphonated biphenyl building block was obtained via nickel-catalyzed phosphonation of dibromobiphenyl at 170 °C for three hours. This synthesis is more economical and milder than typical high-temperature palladium systems. In parallel, a borated pyrene derivative was prepared by Suzuki–Miyaura borylation. The final palladium-catalyzed Suzuki cross-coupling reaction produced the target compound, octaethyl(pyrene-tetrakis(biphenyl))tetrakis(phosphonate), Et₈-PyTPPE. Single-crystal X-ray diffraction reveals a centrosymmetric molecule that crystallizes in the triclinic space group P–1, with the inversion center located at the central C–C bond of the pyrene core. The pyrene unit is essentially planar, while the biphenylphosphonate arms are highly twisted relative to the core and to each other. The crystal packing is dominated by weak intermolecular interactions, and no significant π–π stacking is observed. Hirshfeld surface analysis shows that H···H (60.5%) and C···H (22.5%) contacts predominate, while O···H interactions (14.4%) with phosphoryl oxygen atoms represent the most relevant directed contacts. From photophysical investigations, Et₈-PyTPPE exhibits blue fluorescence (λ_em. = 452 nm) in solution and aggregation-induced red-shifted emission with nanosecond lifetimes in the solid state, confirming purely fluorescent behavior. Full article

Biologically controlling Microcystis aeruginosa blooms in saline–alkaline environments remains a major challenge in aquatic ecosystem management. Here, the algicidal performance of an indigenous algicidal bacterium, Bacillus cereus strain PT1 isolated from a sulfate-type saline–alkaline pond, against M. aeruginosa was evaluated, and the underlying metabolic mechanisms were elucidated using non-targeted metabolomics. PT1 exhibited pronounced, stable algicidal activity under saline–alkaline conditions, decreasing the algal cell density from 2 × 10⁶ to 1.25 ± 0.5 × 10⁵ cells mL⁻¹ within 4 days at a rate of 93.75 ± 2.5% (p < 0.05). The above results demonstrate that strain PT1 has a significant lytic effect on M. aeruginosa. Non-targeted liquid chromatography–mass spectrometry analysis identified 298 PT1-induced accumulated metabolic features, and the top 30 candidates comprised organic acids and aromatic compounds, including benzoic acid, coumarin, malonic acid, and signaling-related molecules, including indoleacetaldehyde and nitroprusside. These differential metabolites were associated with algicidal-related pathways, including quorum sensing, two-component systems, ABC transporters, and tryptophan metabolism, outlining a coordinated “regulation–transport–metabolic remodeling” framework. Our findings demonstrate the potential of the indigenous algicidal strain PT1 from saline–alkali ponds to control M. aeruginosa blooms. They also provide an important theoretical basis and data foundation for further elucidating the molecular characteristics of algae solubilizing activity under saline–alkali conditions and developing microbial agents for preventing and controlling Microcystis blooms in saline–alkali ponds. Full article

To elucidate the mechanisms by which the hydrophobic hydrocarbon chain length of emulsifiers and the surface properties of aggregates influence the adhesive performance at the emulsified asphalt–aggregate interface, this study employed molecular dynamics simulations to construct interface models. Key parameters, including relative concentration, diffusion coefficients, and interfacial adhesion work, were systematically analysed to reveal the intrinsic effects of imidazoline-type emulsifier chain length and aggregate type on interfacial behaviour. The results indicate that increasing the hydrophobic chain length of the emulsifier suppresses the adsorption of emulsified asphalt at the aggregate interface. The diffusion coefficients of both emulsifier and asphalt molecules initially increase and subsequently decrease with chain length, with the non-polar asphalt components (aromatics and saturates) exhibiting greater sensitivity to chain length variations. Moderate extension of the hydrophobic chain enhances interfacial adhesion work, whereas exceeding the optimal chain length reverses this trend, weakening adhesion. Aggregate surface properties exert a significant influence on interfacial behaviour. Compared with the acidic SiO₂ (0 0 1) surface, the basic CaCO₃ (1 0 4) surface exhibits lower peak relative concentrations of emulsified asphalt, reduced sensitivity to variations in emulsifier chain length, lower molecular diffusion coefficients, and stronger interactions with asphalt molecules, resulting in superior interfacial adhesion. This study provides a molecular-level theoretical basis for the targeted design of emulsifier structures and the efficient adaptation of emulsified asphalt to different aggregate systems. Full article

Phenothiazine is a heteroaromatic molecule capable of various noncovalent interactions, including halogen bonding and π-stacked association. Despite its broad use in functional materials and pharmaceutical ingredients, a systematic comparison of these interaction modes has been lacking. Here, we report a combined experimental and computational study of intermolecular interactions of phenothiazine with a prototypical halogen-bond (HaB) donor (tetrabromomethane), planar π-electron acceptors (tetracyanopyrazine and tetrafluoro-p-benzoquinone), and multifunctional species capable of both interaction types (iodo- and bromo-3,5-dinitrobenzenes). X-ray structural analysis revealed that CBr₄ forms exclusively C–Br···π halogen bonds with the aromatic rings of phenothiazine, whereas all π-acceptors yield alternating donor–acceptor stacks characterized by multiple short contacts indicative of multicenter interactions. Notably, co-crystals of iodo- and bromodinitrobenzenes with phenothiazine display only π-stacked architectures. Density-functional calculations showed that isolated HaB complexes involving N, S, or π sites of phenothiazine possess comparable binding energies (≈−3 kcal mol⁻¹), whereas π-stacked complexes are substantially stronger (≈−9–12 kcal mol⁻¹). QTAIM, NCI, NBO, and energy-decomposition analyses indicated that while amounts of charge transfer in halogen-bonded and π-stacked complexes are comparable, the enhanced stability of the latter originates primarily from a large dispersion contribution. These results rationalize the solid-state preference for π-stacking over halogen bonding in systems where both motifs are accessible and clarify the hierarchy and physical origin of noncovalent interactions involving phenothiazine, providing guidance for the design of supramolecular assemblies and functional materials based on this versatile electron donor. Full article

CD38 is a multifunctional enzyme that plays a pivotal role in NAD⁺ metabolism and calcium signaling, and its abnormal activity is closely associated with multiple myeloma, age-related metabolic decline, neurodegenerative diseases, and other disorders. Although monoclonal antibodies such as daratumumab have been approved for clinical application, their inherent limitations necessitate the development of novel small-molecule CD38 inhibitors. In this study, we employed DNA-encoded library (DEL) technology for the high-throughput screening of CD38 inhibitors, using a DEL library containing more than 100,000 unique compounds to screen against recombinant human CD38. A total of 1043 enriched compounds were initially identified, and after rigorous validation and screening to exclude non-specific binding and previously reported active compounds, eight hit compounds with diverse chemical scaffolds were obtained, among which Fenbendazole—a clinically approved antiparasitic drug—was included. Surface plasmon resonance (SPR) assays confirmed the direct binding of these hit compounds to CD38, with dissociation constants (KD) ranging from 7.74 × 10⁻⁵ M to 2.15 × 10⁻⁴ M. Fluorescence-based enzymatic activity assays demonstrated that these compounds exert dose-dependent inhibitory effects on both the hydrolase (with ε-NAD as substrate) and cyclase (with NGD as substrate) activities of CD38. Further structure–activity relationship (SAR) analysis of Fenbendazole analogues revealed the critical structural features that regulate CD38 inhibitory potency, and Flubendazole was found to exhibit excellent inhibitory activity, with an IC₅₀ of 14.78 ± 4.21 μM against CD38 hydrolase and 26.31 ± 3.40 μM against cyclase. Molecular docking and 100 ns molecular dynamics (MD) simulations further elucidated the molecular mechanism of CD38 inhibition by lead compounds, confirming that van der Waals interactions are the main driving force for the binding of small-molecule ligands to CD38, with conserved aromatic residues in the active site mediating ligand recognition. This study validates DEL technology as an efficient and reliable platform for the discovery of CD38 inhibitors, and the identified lead compounds—especially Fenbendazole and its analog Flubendazole—provide valuable molecular scaffolds for the further structural optimization of CD38 inhibitors. These findings lay a solid foundation for the development of novel therapeutic agents for the treatment of CD38-associated diseases. Full article

Proliferating cell nuclear antigen (PCNA) is a critical regulator of DNA replication and repair, and its cancer-associated isoforms represent promising therapeutic targets. The small molecule AOH1996 has been previously reported as a PCNA inhibitor with potent antiproliferative activity. Here, a series of novel AOH1996-based structural analogs were synthesized using structure–activity relationship (SAR) and scaffold-hopping strategies, including 1,2,3-triazole, glycine, and amide derivatives with diverse aromatic and polar substituents. The antiproliferative activity of these compounds was evaluated in MCF-7 (breast cancer) and U87 (glioblastoma) cell lines using the MTT assay. The parent compound AOH1996 exhibited the strongest cytotoxicity, reducing cell viability below 30% at 10 μM. Among the analogs, compounds 1f, 2b, 3b, 3c, and 3d demonstrated significant activity, reducing MCF-7 viability by 60–70% and U87 viability to 30–40% at 10 μM. SAR analysis revealed that electron-withdrawing or moderately lipophilic substituents on the amide side chain and aromatic extensions on the triazole ring enhanced potency, while bulky or strongly electron-donating groups diminished activity. ADMET predictions indicated that most derivatives possessed favorable drug likeness and absorption potential, but high plasma protein binding, short predicted half-lives, and potential cardiotoxicity represent limitations that will require further optimization. Several active compounds were predicted to inhibit P-glycoprotein, suggesting their potential to overcome multidrug resistance. Overall, compounds 2b and 3b showed relatively favorable predicted profiles and can serve as useful lead scaffolds for further optimization and experimental validation. Full article

A comprehensive MD + QC methodology was developed and applied to evaluate various aspects of Arbidol interactions with functional amino acids of surface proteins of influenza virus and SARS-CoV-2. The spatial structure, solvation features, conformational behavior of Arb AA (AA–Trp, Tyr, Phe, and Val) complexes were established, and the statistics of intermolecular interactions in the complex were described. It was found that Arb can participate in strong and long-lived π-π stacking interactions with aromatic amino acids. The binding energy (BE) of Arbidol and amino acids in aqueous solution was estimated using an explicit solvation model, QTAIM analysis and correlation of BE vs. total electron density at the bond critical points of the complex. Theoretical calculations were validated by experimental studies of fluorescence (FL) quenching of aromatic AA by Arbidol. Spectral-fluorescent properties of Arbidol hydrochloride in aqueous solutions were studied, and the luminescence quantum yield for the electronically excited state of Arb was determined. Full article

The ultraviolet (UV) copolymers of two monomers, one methacrylic and the other vinyl monomer (styrene, S) were prepared. As methacrylic monomers, citronellyl methacrylate (CM) or geranyl methacrylate (GM) were used. The preparation was proven to contain high solvent- and chemical-resistant copolymers due to their cross-linked structure with the conversion degree of the double bonds above 0.92 for poly(citronellyl methacrylate)/polystyrene (PCM/PS) and above 0.85 for poly(geranyl methacrylate)/polystyrene (PGM/PS) copolymers. The obtained copolymers showed only one glass transition temperature (T_g). Depending on the structure and amount of the used methacrylic monomer, the T_g values were from 0.4 °C to −15.2 °C for PCM/PS copolymers and from −23.2 °C to −50.5 °C for PGM/PS copolymers. The thermogravimetric analysis (TG/DTG) showed a higher thermal stability for PCM/PS (148–187 °C) than for PGM/PS copolymers (119–159 °C) in inert and oxidative atmospheres. The simultaneous thermogravimetric analysis coupled with Fourier Transform Infrared spectroscopy (TG/FTIR) showed that the pyrolysis and oxidative decomposition of the tested copolymers took place according to the radical mechanism. This led to receiving a mixture of low molecular mass organic molecules containing saturated and unsaturated fragments, carbonyl groups, aromatic fragments as well as to CO, CO₂ and H₂O. This indicated the depolymerization process (inert) and further oxidation processes of the initially formed volatiles and/or residues in oxidative conditions. Full article

The increasing energy demand and global dependence on conventional fuels have resulted in severe greenhouse gas (GHG) emissions, necessitating the development of sustainable bioenergy alternatives. Algal is recognized as a promising feedstock for the production of fourth-generation biofuels. This study optimizes catalytic pyrolysis of Arthrospira platensis for bio-oil production via a dual-bed catalyst system of iron-impregnated dolomite (Fe/DM) and a copper-impregnated spent fluid catalytic cracking catalyst (Cu/sFCC). A face-central composite design (FCCD) and response surface methodology (RSM) were used for the delineation of optimal conditions, ensuring that all experimental tests remained within feasible operating conditions of 500–600 °C, a reaction time of 45–75 min, a N₂ flow rate of 50–200 mL/min, and a catalyst loading of 5–20 wt%. The bio-oil yield was maximized at 39.73 ± 2.86 wt% at 500 °C for 45 min, a N₂ flow of 50 mL/min, and 5 wt% catalyst loading to feedstock with a 0.4:0.6 mass ratio of Fe/DM: Cu/sFCC. The dual-catalysts combined Brønsted and Lewis acid sites enhanced the catalytic activity, which promotes the cleavage of carbon–carbon and carbon–hydrogen bonds, including the mechanism of catalytic pathways such as dehydration, decarboxylation, oligomerization, aromatization, and further cracking reactions, and was successful in converting high-molecular-weight molecules into lighter hydrocarbons and significantly improving product selectivity, demonstrating a highly effective pathway for producing high-quality sustainable biofuel. Full article

Background: The growing interest in developing new bioactive agents from natural sources led to medicinal and aromatic plants. These plants provide valuable phytochemicals that can serve as natural preservatives, food additives, and flavorings, with various applications. The aim of this study is to evaluate the potential of Juniperus oxycedrus berries’ supercritical extract through preliminary screenings related to in vitro antibacterial activity, as well as bioinformatics assessments of absorption and toxicity. Methods: Supercritical carbon dioxide (CO₂) was used to extract the bioactive phytochemical compounds from the berries. The extract was characterized using spectrophotometric methods and reverse-phase high-performance liquid chromatography (RP-HPLC). The antibacterial potential was tested against Staphylococcus aureus ATCC 25923, where the Minimal Inhibitory Concentration and the Minimal Bactericidal Concentration were determined. Additionally, the influence of the extract on the growth curve kinetics of S. aureus was assessed. For the bioinformatics analyses, SwissADME and ProTox-3.0 prediction software were utilized, focusing on the identified phenolic compounds as fingerprint molecules. Results: The results demonstrated that exposure to the juniper extract inhibited bacterial growth, resulting in a prolonged lag phase of 6 to 8 h, depending on the concentration of the extract. The software predictions revealed that the investigated phenolic compounds might exhibit high gastrointestinal absorption, along with potential interactions with metabolic mediators and pathways. Conclusions: The in vitro and in silico findings support the application of J. oxycedrus berries extract as an alternative or complementary strategy for pharmacological treatment and food applications aimed at targeting S. aureus. Full article

Advanced oxidation processes using porphyrin-based heterogeneous catalysts hold promise for removing hazardous pollutants from wastewater. Their high visible-light absorption coefficients enable absorption of light from the solar spectrum. Moreover, their conjugated aromatic skeletons and intrinsic electronic properties facilitate the delocalization of photogenerated electrons during photodegradation. Delaying the recombination of photogenerated electron–hole pairs by introducing specific materials increases efficiency, as separated charges have more time to participate in redox reactions, boosting photocatalytic activities. However, applying these photocatalysts for wastewater treatment is challenging owing to facile agglomeration, deactivation, and recovery of the photocatalyst for reuse, which can significantly increase the overall cost. Therefore, new photocatalytic systems comprising porphyrin molecules must be developed. For this purpose, porphyrins can be conjugated to nanomaterials to create hybrid materials with photocatalytic efficiencies superior to those of free-standing starting porphyrins. Various transition metal oxides (TiO₂, ZnO, and Fe₃O₄) nanoparticles, main-group-element oxides (Al₂O₃ and SiO₂) nanoparticles, metal plasmons (silver nanoparticles), carbon-based platforms (graphene, graphene oxide, and g-C₃N₄), and polymer matrices have been used as nanostructured solid supports for the successful fabrication of porphyrin-conjugated hybrid materials. The conjugation of porphyrin molecules to solid supports improves the photocatalytic degradation activity in terms of visible-light conversion ability, recyclability, active porous sites, substrate mobility, separation of photogenerated charge species, recovery for reuse, and chemical stability, along with preventing the generation of secondary pollution. This review discusses the ongoing development of porphyrin-conjugated hybrid nanomaterials for the heterogeneous photocatalytic degradation of organic dyes, pharmaceutical pollutants, heavy metals, pesticides, and human care in water. Several important results and advancements in the field allow for a more efficient wastewater remediation process. Full article