Search Results (139)

The organic compounds 2-aminopyrimidine (AP) and 4-aminobenzoic acid (PABA) were selected for the synthesis of a compound by establishing the phase diagram and adopting the solid-state synthesis method. The phase diagram analysis suggested the formation of a novel intermolecular compound (IMC) at a 1:1 stoichiometric ratio of AP and PABA, along with two eutectics at 0.25 and 0.90 mole fractions of AP. FTIR and NMR spectroscopy were used for the structure elucidation of the intermolecular compound. The powder X-ray diffraction analysis revealed the novel nature of IMC (APPABA) and the mechanical mixture nature of eutectics. The sharp and single peak of the DSC curve suggested the melting and pure nature of the synthesized IMC. Various thermodynamic parameters of IMC and eutectics were studied. A single crystal of the IMC was grown from solution and its single-crystal X-ray diffraction analysis revealed that it crystallized in a monoclinic system with the P21/n space group. Hirshfeld surface analysis further validated the weak non-covalent interactions summarized through the single-crystal X-ray analysis. Studies on the IMC were thoroughly conducted to evaluate its antibacterial activity with reference to antibiotics, and it showed significant positive responses against various pathogenic microbial isolates (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella aerogenes, and Shigella boydii) and non-pathogenic microbial isolates (Enterobacter cloacae, Pseudomonas azotoformans, and Burkholderia paludis). It was also found effective against methicillin-resistant bacterial strains viz. Staphylococcus aureus MRSA. Full article

The performance of electrochemical (bio)sensors is fundamentally determined by the precise engineering of interfacial layers that govern (bio)analyte–surface interactions. However, elucidating structure–function relationships remains challenging due to the complex architecture of modern sensors and the irregular nanoscale morphology of many high-performance materials. In this study, we present a strategy for designing custom functional interfaces as well-defined platforms for probing interfacial processes. Focusing on epinephrine (EP) detection as an important representative of catecholamines, we compare the interfacial behavior of two carboxy-functionalized electrodes—grafted with either para-aminobenzoic acid (PAB) or 3,4,5-tricarboxybenzenediazonium (ATA)—against atomically flat highly oriented pyrolytic graphite (HOPG) as a control. While both modifiers introduce carboxyl groups, PAB forms disordered multilayers that inhibit surface responsiveness, whereas ATA yields an ultrathin monolayer with accessible COOH groups. Electrochemical analysis reveals that ATA-HOPG significantly enhances EP detection at sub-micromolar levels, facilitated by electrostatic interactions between surface-bound COO⁻ and protonated EP and its redox products. These results demonstrate that nanoscale control of diazonium grafting is crucial for optimizing bioanalyte recognition. More broadly, this work highlights how molecular-level surface engineering on high-quality carbon substrates can serve as a test-bed platform for the rational design of advanced electrochemical sensing interfaces. Full article

The development of drug carriers with efficient absorption and controlled delivery properties is crucial for advancing medical treatments. Metal–organic frameworks (MOFs) with tunable porosity and a large surface area represent a promising class of materials for this application. Among them, NUIG4 stands out as a biocompatible MOF that exhibits exceptionally high doxorubicin (Dox) absorption (1995 mg dox/g NUIG4) and pH-controlled release properties. In this study, we report the synthesis and characterisation of multivariate MOFs (MV-NUIG4), which are analogues of NUIG4 that maintain the same topology while incorporating different functional groups within their framework. Eight new MV-NUIG4 MOFs have been synthesised through in situ reactions of the corresponding 4-aminobenzoic acid derivative with 4-formylbenzoic acid. The compounds were thoroughly characterised using a range of techniques, including powder X-ray diffraction, infrared spectroscopy, ¹H-NMR, and single-crystal X-ray crystallography. The experimental ratio of the reagents and ligand precursors for the synthesis of MV-NUIG4 MOFs matched the ratio of the linkers in the final products. These structures incorporate additional functional groups, such as methyl and hydroxyl, in varying ratios. Computational modelling was used to provide further insight into the crystal structure of the MOFs, revealing a random distribution of the functional groups in the framework. The Dox absorption and release capacity of all analogues were studied, and the results revealed that all analogues displayed high drug absorption in the range of 1234–1995 mg Dox/g MOF. Furthermore, the absorption and release rates of the drug are modulated by the ratio of functional groups, providing a promising approach for controlling drug delivery properties in MOFs. Full article

Ocular fungal infections are slow-progressing conditions that primarily affect the cornea but can also involve the entire eyeball. Candida albicans is one of the most involved species. Both diagnosing and treating these infections require prompt and effective action. However, the currently available treatment options mainly rely on azoles and polyenes, which are known for their poor penetration into ocular tissue and associated toxicity. Moreover, conventional antifungals are usually ineffective when tested against biofilm-associated infections, mainly due to the metabolically inactive state of dormant cells embedded in the extracellular biofilm matrix. Here, analysis of the in vitro antifungal activity of four 2-aminobenzoic acid derivatives synthesized using a green method and their combination with Fluconazole (FLC) showed efficacy against the FLC-resistant clinical isolate of C. albicans under both planktonic and biofilm formation conditions. Results showed that compounds 1 and 2 exhibited the best antifungal activity in the checkerboard association test, presenting a synergistic effect towards antifungal action. The downregulation of HWP, ERG11, and ASL3 genes during biofilm inhibition suggested a reduced capacity of the four compounds for hyphal growth and adhesion, as well as a decrease in pathogenicity due to the downregulation of some SAP genes. In vitro and in vivo toxicity profiles indicated that these compounds exhibited low toxicity, as well as the absence of genotoxic effects. Therefore, green-synthetized 2-aminobenzoic acid derivatives may have potential as antifungal agents for the inhibition of C. albicans growth and biofilm formation. Full article

This study explores the development of a non-enzymatic electrochemical glucose sensor based on poly(3-aminobenzoic acid) (P3ABA) combined with silver nanoparticles (AgNPs). Incorporating AgNPs into the P3ABA matrix enhances the sensor’s electrocatalytic properties, leading to a system with greater stability. Cyclic voltammetry and chronoamperometry were employed to evaluate the sensor’s performance, demonstrating a sensitivity of 50.71 µA mM⁻¹ cm⁻² and a limit of detection (LOD) of 0.2 µM. The sensor exhibited a linear response over a broad concentration range (1 to 16 mM), with a coefficient of determination (R²) of 0.998, indicating good reproducibility and precision. These results highlight the potential of the P3ABA/AgNP composite for glucose sensing applications, offering an extended linear range, allowing for the quantification of glucose concentrations from very low to significantly high levels, covering both physiological and pathological conditions. Full article

Corrosion protection in reinforced concrete structures exposed to aggressive environments remains a critical challenge in civil and architectural engineering. One promising approach involves the application of corrosion-inhibiting monolayers on the reinforcement, such as those formed using 4-aminobenzoic acid. Two methods have previously been employed to generate these monolayers: one relying on the adhesion of an organic compound and the other utilising an externally modified approach via electrolysis. This study assesses the influence of this treatment on the steel–concrete bond strength and durability, both critical properties for the structural performance of reinforced concrete under service conditions. For this purpose, pull-out tests were performed on specimens subjected to load–unload cycles to analyse bond behaviour and monolayer integrity. The results indicate that these treatments do not adversely affect the bond strength between reinforcement and concrete. Furthermore, the rebars treated with the inhibitor exhibit less corrosion damage than the untreated rebars. This fact is particularly significant in the rebars treated using the natural adhesion method, with the steel section loss being 32–37% lower than in the untreated rebars. These findings support the feasibility of applying this treatment without compromising structural functionality. Full article

Graphene quantum dots (GQDs) represent a class of promising nanomaterials characterized by adjustable optical properties, making them well suited for applications in biosensing and chemical detection. However, challenges persist in achieving scalable, cost-effective synthesis and enhancing detection sensitivity. In this study, we have developed a simple and environmentally friendly method to prepare blue graphene quantum dots, c-GQDs, using nitronaphthalene as a precursor, and yellow graphene quantum dots, y-GQDs, using nitronaphthalene doped acid. The quantum yield is 29.75%, and the average thickness is 2.08 nm and 3.95 nm, respectively. The synthesized c-GQDs exhibit a prominent cyan fluorescence at a wavelength of 490 nm under excitation at 380 nm, while the y-GQDs show a distinct yellow fluorescence at a wavelength of 540 nm under excitation at 494 nm. The introduction of p-aminobenzoic acid (PABA) introduced a marked red shift in fluorescence, attributed to the electron-withdrawing effect of the carboxyl groups on PABA. This key finding significantly enhanced the sensitivity of GQDs for detecting trace copper(II) ions (Cu²⁺), a heavy metal contaminant posing serious environmental risks. The fluorescence of the GQDs was selectively quenched in the presence of Cu²⁺, facilitating accurate and sensitive detection even in complex ion matrices. Mechanistic studies revealed that the quenching effect is driven by strong static quenching interactions, which inhibit non-radiative transitions. This work not only introduces a scalable method for producing high-performance GQDs but also highlights their potential as effective fluorescent probes for environmental monitoring and heavy metal ion detection. Full article

Cereals are among the foods rich in myo-inositol hexakisphosphate (phytic acid, IP6), lower myo-inositol phosphates (IPx), a wide range of phenolic compounds, as well as vitamins, minerals, oligosaccharides, phytosterols and para-aminobenzoic acid, and are attributed with multiple bioactivities, particularly associated with the prevention of metabolic syndrome and colon cancer. The bran fraction of wheat, maize, brown rice and other cereals contains high levels of phytate, free and total phenolics, and endogenous enzymes such as amylases, phytase, xylanase, β-glucanase and feruloyl esterase, whose activities can be increased by germination. The preliminary steps of digestion begin in the oral cavity where substrates for the action of endogenous cereal and salivary enzymes start to be released from the food matrix. IP6 released from phytate complexes with arabinoxylans, starch and protein bodies would eventually enhance the absorption of nutrients, including phenolics, by regulating tight junctions and, together with ferulic acid (FA), would maintain cell barrier integrity and epithelial antibacterial immunity. In addition, both IP6 and FA exert potent and complementary antioxidant effects, while FA together with IPx generated through advanced hydrolysis of IP6 by endogenous and microbial phytases may affect digestive enzyme activity and incretin secretion, resulting in modulated insulin and glucagon release and prevention of various diabetic complications. Contrary to widespread negative attitudes towards phytate, in this review, we present the strategy of selecting cereals with high phytate and phenolic content, as well as high endogenous phytase, feruloyl esterase and endoxylanase activities, to produce value-added health-promoting foods. The advanced hydrolysis of phytate and phenolic compounds by cereal and/or microbial enzymes would generate substantial amounts of “enzymatically generated inositol” (EGI), including IP6, IPx and myo-inositol, the compounds that, together with free FA, provide enhanced bioavailability of cereal nutrients through multiple synergistic effects not previously realised. Full article

Polymer films with combined properties of good thermoplasticity, good electrical properties, and good thermal endurance are highly required for two-layer flexible copper clad laminate (FCCL) applications. Meanwhile, the black appearance is also required for specific FCCL applications. Therefore, in the present work, a series of ester-linked polyimide (PEsI) films were designed and developed via the copolymerization chemistry of an ester-containing dianhydride of biphenyl dibenzoate-3,3′,4,4′-tetracarboxylic acid dianhydride (BPTME), a rigid-rod dianhydride of 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA), an ester-bridged diamine of 2-(4-aminobenzoate)-5-aminobiphenyl (ABABP), and a functional diamine of 4,4′-iminodianiline (NDA). The molar proportion of the BPTME/BPDA was fixed to be 20:80 and that of ABABP/NDA increased from 50:50 for PEsI-1 to 0:100 for PEsI-VI. The afforded PEsI films showed obviously enhanced blackness with the increasing molar ratio of NDA in the polymers. The PEsI-VI film exhibited the optical transmittance values of 0 and 27.4% at the wavelength of 500 nm (T₅₀₀) and 760 nm (T₇₆₀), respectively. The values were apparently lower than those of the standard PI-ref produced from common pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA) (T₅₀₀ = 63.2%; T₇₆₀ = 86.3%). Meanwhile, the PEsI-V film showed good blackness with the CIE Lab optical parameters of 1.83 for L*, 11.46 for a*, 3.13 for b*, and 0 for haze. The PEsI samples exhibited good thermoplasticity and the storage and loss modulus of the films rapidly decreased around the glass transition temperatures (T_g) in the dynamic mechanical analysis (DMA) tests. The PEsI samples revealed the T_g values from 247.2 °C to 286.1 °C in the differential scanning calorimetry (DSC) measurements. The PEsI samples exhibited the linear coefficients of thermal expansion (CTE) of (27.1~33.4) × 10⁻⁶/K from 50 to 250 °C, which was comparable to that of the PI-ref sample (CTE = 29.5 × 10⁻⁶/K), however, a bit higher than that of the copper foil (CTE = 17.0 × 10⁻⁶/K). Full article

This study focused on the synthesis, properties, and antibiological activity of NiO nanoparticles derived from polyvinyl alcohol (PVA) and aminobenzoic acid (P-ABA) derivatives by calcination method. The nanoparticles were synthesized using a simple, cost-effective method that involved the thermal decomposition of PVA and the incorporation of aminobenzoic acid. Characterization techniques such as X-ray diffraction (XRD), Kinetic analysis, and the thermal properties of nickel(II) metal complex in dynamic air were analyzed via TG and DTG. The kinetic analyses and thermodynamic parameters (∆H*, ∆G*, and ∆S*) for this compound were calculated by the Coats–Redfern and Horowitz–Metzger methods. The obtained kinetic parameters displayed the kinetic compensation effect. Electron microscopy (SEM and TEM) and (FT-IR) were employed to confirm the formation, morphology, and structural properties of the nanoparticles. The results indicated the successful synthesis of NiO nanoparticles with distinct crystalline phases and difference distributions. XRD confirmed that the resulting oxide was pure single-crystalline NiO nanoparticles. Scanning electron microscopy indicated that the crystallite size of nickel oxide nano-crystals was in the range of 26–36 nm. The magnetic moment was 2.59 B.M for Ni(II) complex. The antibiological activity of the synthesized nanoparticles was evaluated against bacterial strains, both Gram-positive and Gram-negative bacteria. The findings revealed significant antimicrobial properties, with the NiO nanoparticles demonstrating higher inhibitory effects against bacterial and fungal strains. This study highlights the potential of PVA and aminobenzoic acid derivatives as effective precursors for producing metal oxide nanoparticles with promising applications in antimicrobial treatments and materials science. Full article

Background/Objectives: Alzheimer’s disease (AD), a complex neurogenerative disorder, manifests as dementia and concomitant neuropsychiatric symptoms, including apathy, depression, and circadian disruption. The pathology involves a profound degeneration of the hippocampus and cerebral cortex, leading to the impairment of both short-term and long-term memory. The cholinergic hypothesis is among the various theories proposed, that assume the loss of the cholinergic tract contributes to the onset of AD and proves clinically effective in managing mild to moderate stages of the disease. This study explores the potential therapeutic efficacy of sulfonamide-based butyrylcholinesterase inhibitors in mitigating scopolamine-induced amnesia in rats. Methods: Behavioral assessments utilizing Y-maze, Barnes maze, and neurochemical assays were conducted to evaluate the effectiveness of the test compounds. Results: Results demonstrated a significant reduction in the impact of scopolamine administration on behavioral tasks at a dose of 20 mg/kg for both compounds. Correspondingly, neurochemical assays corroborated these findings. In silico docking analysis on rat butyrylcholinesterase (BChE) was performed to elucidate the binding mode of the compounds. Subsequent molecular dynamics studies unveiled the formation of stable complexes between the test compounds and rat BChE. Conclusions: These findings contribute valuable insights into the potential therapeutic role of sulfonamide-based butyrylcholinesterase inhibitors in addressing memory deficits associated with AD, emphasizing their in silico molecular interactions and stability. Full article

Selenium (Se) has garnered increasing attention in the field of nutrition, as it is essential for both humans and animals. Certain microorganisms can enrich inorganic selenium and convert it into organic selenium. The growth and metabolomic profiles of six lactobacilli strains exposed to 50 μg/mL of sodium selenite were performed using gas chromatography tandem time-off light mass spectrometry (GC-TOF-MS) analysis. The addition of selenium significantly increased both the population and weight of the Lacticaseibacillus rhamnosus PS5, Lbs. rhamnosus RT-B, Limosilactobacillus reuteri 3630, and Lmb. reuteri 1663 strains, while those of the other two strains decreased. A total of 271 metabolites were determined, with their concentrations ranked from highest to lowest as follows: organic acids and derivatives, oxygen compounds, lipids and lipid-like molecules, and benzenoids. In certain groups, the concentrations of serine, aspartic acid, trehalose, palmitic acid, methylthreonine, and melibiose increased significantly, whereas glucuronic acid, ribose, ornithine, and methionine were downregulated. The metabolic pathways were significantly associated with ABC transporters, glycine, serine, threonine metabolism, and aminobenzoate degradation and other pathways. Based on these findings, we concluded that the transport, absorption, assimilation, and stress response to selenium by lactobacilli in metabolomic changed. Furthermore, the metabolomic alterations among different types of lactobacilli varied primarily due to their distinct properties. Full article

Folic acid (FA) is an essential vitamin involved in crucial metabolic processes, while copper(II) ions play significant roles in various biological functions. This study aims to investigate the interaction between FA and Cu²⁺ using ¹H and ¹³C NMR spectroscopy under different pH levels and concentrations. The research employed detailed NMR analysis to explore how Cu²⁺ binds to FA, focusing on changes in chemical shifts, diffusion coefficients, and copper-induced paramagnetic effects. The key findings reveal that Cu²⁺ predominantly coordinates with the pteridine ring (PTE) of FA, with minimal involvement from the glutamic acid (Glu) moiety. The interaction is strongly concentration-dependent: at lower FA concentrations, Cu²⁺ binds effectively to the PTE ring, while at higher concentrations, intermolecular interactions among FA molecules hinder copper binding. The study also observed pronounced paramagnetic effects on the PTE and p-aminobenzoic acid protons, with negligible effects on Glu signals. These results provide new insights into the structural characteristics of FA-Cu²⁺ complexes, contributing to a better understanding of their biochemical interactions and implications for folate metabolism. Full article

The aim of this work was to obtain and evaluate, as antiprotozoals, new derivatives of benzoate imidazo-1,3,4-thiadiazole 18–23 based on the concepts of molecular repositioning and hybridization. In the design of these compounds, two important pharmacophoric subunits of the fexnidazole prototype were used: metronidazole was used as a repositioning molecule, p-aminobenzoic acid was incorporated as a bridge group, and 1,3,4-thiadiazole group was incorporated as a second pharmacophore, which at position 5 has an aromatic group with different substituents incorporated. The final six compounds were obtained through a five-step linear route with moderate to good yields. The biological results demonstrated the potential of this new class of compounds, since three of them 19–21 showed inhibitory activity on proliferation, in the order of 50%, in the in vitro assay against epimastigotes of T. cruzi (Strain Y sensitive to nifurtimox and benznidazole) and promastigotes of L. donovani, at a single concentration of 50 μM. Full article

Human exposure to PM2.5 and PM10 has been linked to respiratory and cardiovascular diseases through inflammation activation. The kynurenine pathway is associated with inflammation, and it is necessary to investigate the effects of long-term PM2.5 and PM10 exposure on this pathway. This study aimed to conduct a cross-sectional analysis of long-term PM2.5 and PM10 exposure’s impact on the kynurenine pathway using proton NMR spectroscopy (¹H-NMR). The participants were divided into a low-PM-exposure group (LG; n = 98), and a high-PM-exposure group (HG; n = 92). The metabolites of tryptophan were determined in blood by ¹H-NMR. Serotonin, cinnabarinic acid, xanthurenic acid, 5-hydroxytryptophan, indoleacetic acid, tryptamine, melatonin, L-tryptophan, 5-hydroxy-L-tryptophol, indoxyl, 2-aminobenzoic acid, 5-HTOL, hydroxykynurenine, L-3-hydroxykynurenine, N-formyl kynurenine, 3-hydroxy anthranilic acid, kynurenic acid, and picolinic acid significantly increased (p < 0.05) in the HG group. Conversely, NAD and quinolinic acid significantly decreased in the HG group compared to the LG group. The enzyme activities of indoleamine 2,3-dioxygenase and formamidase significantly decreased, while kynureninase and kynurenine monooxygenase significantly increased. The kynurenine pathway is linked to inflammation and non-communicable diseases. Disruption of the kynurenine pathway from particulate matter might promote diseases. Reducing exposure to the particulate matter is crucial for preventing adverse health effects. Full article