BMC Chemistry最新文献

In this study, we report the first synthesis and comprehensive characterization of two positional isomers of iodo-substituted imino Schiff bases, Im1 was synthesized using 2-iodoaniline, whereas Im2 was obtained from 4-iodoaniline. Compound Im1 represents a new derivative, while Im2 is fully characterized crystallographically for the first time. The structures were confirmed by FT-IR, UV-Vis, ¹H and ¹³C NMR spectroscopy, and single-crystal X-ray diffraction, which revealed that Im2 crystallizes in the monoclinic space group P2₁/c. Hirshfeld surface and fingerprint analyses provided insights into key intermolecular interactions governing crystal stability. Among the two compounds, Im2 exhibited the highest antibacterial activity, forming an 11.00 ± 0.00 mm inhibition zone against Klebsiella pneumonia, whereas Im1 demonstrated the strongest inhibition (11.67 ± 0.47 mm) against Escherichia coli. DFT calculations (B3LYP/LANL2DZ) and molecular docking with the FimH receptor (PDB ID: 8BVD) revealed electronic and structural features influencing binding affinity (-3.737 to -4.266 kcal/mol). ADME-T predictions indicated favorable drug-likeness, suggesting these Schiff bases as promising scaffolds for further optimization toward antibacterial development. This novel comparative analysis of the two imines revealed the pronounced influence of ortho and para-iodine substitution on biological activity and inhibitory potency, demonstrating a clear structure-activity relationship (SAR) governing their antibacterial performance. In the future, Im1 and Im2, when combined with other bioactive scaffolds, may serve as promising candidates for enhanced therapeutic and biological applications.

Analysis of critical biomarkers like L-lactate is extremely important in clinical practice. Herein, a non-invasive and sensitive colorimetric biosensor for accurate L-lactate determination has been developed. The proposed method demonstrates the ability of Fe³⁺ ions of iron(III) chloride to substitute the traditional horseradish peroxidase enzyme in the colorimetric determination of L-Lactate. The biosensor is based on the release of H₂O₂ by lactate oxidase enzyme (LOx) after 30 min incubation in a 37 °C water bath. Subsequently, H₂O₂ reacts with 3,3',5,5'-tetramethylbenzidine substrate (TMB) catalyzed by Fe³⁺ ion utilizing its peroxidase-mimetic activity. Fe³⁺ ion has peroxidase-like activity which could rapidly catalyze the oxidation reaction of TMB by H₂O_2, producing a characteristic blue colored product at 30 °C water bath for 15 min. Based on the catalytic mechanism of fast electron transfer between TMB and H₂O₂ with the assistance of the intrinsic peroxidase-like activity of Fe³⁺ ion, a colorimetric biosensor for determination of L-lactate was developed. The obtained colored product of oxidized TMB could be measured spectrophotometrically at λmax 652 nm. The biosensor yielded a reproducible response over a linear range of 5 µM-20 µM of L-lactate with a limit of detection of 1.278 µM. Furthermore, satisfactory results were obtained upon application of the method to artificial saliva samples.

In recent years, high-performance thin-layer chromatography (HPTLC) has gained prominence as a cost-effective, straightforward, and dependable analytical technique, particularly in forensic and pharmaceutical laboratories. With the rapid evolution of smartphone technologies, a novel dimension in analytical detection has emerged. Advent of smartphones with superior imaging modalities combined with simplicity of use and easy transition into the healthcare ecosystem has made the existing benchtop-based techniques much sleeker, cost-effective and rapid screening approaches. The developed and validated HPTLC method employing smartphone camera detection for simultaneous determination of Diazepam (DZP), its metabolite Oxazepam (OXP) and its degradation product 2-methylamino-5-chlorobenzophenone (ACB) was intended to meet this requirement and provide a useful replacement for the usual densitometric analysis. The chromatographic separation was performed on silica gel HPTLC plates with green mobile phase of heptane: ethyl acetate (7.0:3.0, v/v). After chromatographic development, the Dragendorff's reagent was applied for visualization, and the plates were photographed with smartphone camera. Spot intensities were quantitatively analyzed using ImageJ software in the concentration range 3.0-35.0 µg/spot for both DZP and ACB, and 5.0-35.0 µg/spot for OXP. The data developed by the proposed method were compared with benchtop densitometric method. Linearity was established from 0.2 to 1.0 µg/spot for the three analytes detected at 230.0 nm using HPTLC/densitometry while the HPTLC/smartphone method exhibited linearity from 3.0 to 35.0 µg/spot for both DZP and ACB, and 5.0-35.0 µg/spot for OXP. The developed HPTLC/smartphone method showed that it could successfully be employed to quantify DZP in pharmaceutically marketed formulations in terms of speed, eco-friendly and simplicity. Additionally, the enhanced sensitivity of the densitometric technique enabled successful determination of DZP and OXP in spiked human plasma samples using ACB as an internal standard. To assess the environmental and practical merit of the methods, greenness and sustainability were evaluated using the Green Analytical Procedure Index (GAPI), Analytical Greenness Metric (AGREE), White Analytical Chemistry (WAC), and Blue Applicability Grade Index (BAGI). Results confirmed the developed methods' analytical efficiency, environmental compatibility, and alignment with the principles of green and white analytical chemistry.

Covalent Organic Frameworks (COFs) have emerged as a promising class of crystalline porous materials with potential applications in various fields, including catalysis, gas storage, and energy conversion. A novel COF was prepared from the reaction of terephthalaldehyde and tris(2-aminoethyl)amine and characterized using various techniques including Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) surface area measurement, and thermal analysis. BET analysis revealed a surface area of 507.56 m²/g and an average pore diameter of 8.34 nm. Chromium modification applied to increase its electrocatalytic activity to be used in fuel cells applications. The electrochemical evaluation demonstrated superior catalytic activity of Cr-COF-coated Pt and Au electrodes toward methanol oxidation in alkaline media with current densities of 4.89 mA cm^- 2 and 1.79 mA cm^- 2 for Pt and Au electrodes, respectively. Also, the Tafel slpoe for Cr-COF/Pt (149 mV dec^- 1) and Cr-COF/Au (198 mV dec^- 1) were described. Specifically, the Cr-COF/Pt electrode exhibited a current density 2.2 times higher than bare Pt, while Cr-COF/Au achieved a 2.75-fold enhancement compared to bare Au. Moreover, chronoamperometry and electrochemical impedance spectroscopy revealed high stability, low resistance, and efficient charge transfer dynamics. These findings highlighted the potential of Cr-COF as a promising electrocatalyst for direct methanol fuel cells (DMFCs), offering improved activity, stability, and reduced reliance on noble metals.

In the field of drug analysis, there is a growing emphasis on developing techniques that are environmentally friendly, cost-effective, and efficient. To align with the principles of green analytical chemistry and to support the advancement of portable and handheld devices, an innovative microfabricated ion selective electrode (ISE) has been developed for the detection of Vonoprazan fumarate (VON). The development of this electrode involved a two-step optimization process. Initially, a range of ionophores were screened to determine the one with the highest selectivity for VON. Through molecular docking studies, gamma-cyclodextrin (γ-cyclodextrin) was identified as demonstrating maximal activity towards VON. The second optimization step involved incorporating a graphene nanocomposite as an ion to electron transducer layer between the γ-cyclodextrin polymeric membrane and the microfabricated copper (Cu) solid contact ISE. This nanocomposite layer contributed to enhanced stability, reduced potential drift, and rapid response times (approximately 30 s), likely due to its hydrophobic properties that prevent water layer formation at the interface between the Cu electrode and the polymeric membrane. The VON sensor was characterized according to IUPAC guidelines, revealing a linear dynamic range of 2.00 × 10⁻⁵ to 1.00 × 10⁻² M (equivalent to 9.23 to 4615.00 µg/mL) and a limit of detection (LOD) of 1.00 × 10⁻⁵ M. This sensor was successfully utilized for the selective determination of VON in bulk powder and pharmaceutical formulations. Statistical analysis showed no significant difference when comparing the results with those obtained using the reported method. The environmental impact of the method was assessed using Complex-GAPI and BAGI tools.

Tyrosinase is a critical rate-limiting enzyme in the melanogenesis pathway. Consequently, its inhibition represents a rational therapeutic strategy for treating skin disorders associated with excessive melanin production. In the present study, a series of novel 3-hydroxypyridine-4-one derivatives (6a-i) were synthesized, and their chemical structures were confirmed using spectroscopic techniques. The inhibitory potency of these compounds against tyrosinase was predicted using quantitative structure-activity relationship (QSAR) analysis. QSAR modeling was conducted on twenty-four previously synthesized 3-hydroxypyridin-4-one derivatives with established anti-tyrosinase activity. The best-performing model was subsequently employed to predict the IC₅₀ values of the newly synthesized compounds. Among the evaluated statistical methods, the Multiple Linear Regression (MLR) model demonstrated the highest accuracy and precision, exhibiting the lowest data dispersion. Furthermore, its predictive performance for pIC₅₀ values was superior, with R² = 0.93 and Q² = 0.81. The MLR results indicated hyperchem descriptors, 2-D functional descriptors, and GETAWAY descriptors as the most influential parameters contributing to model performance. Finally, molecular docking simulations revealed favorable interactions between the new synthesized compounds and the active site of tyrosinase, supporting their potential as effective tyrosinase inhibitors.

Over the recent years, there has been a notable surge in consumer demand for rapid and effective weight-loss pharmaceuticals that are also capable of managing type 2 diabetes. Owing to their exceptional efficacy, GLP-1 receptor agonists, including Tirzepatide (TIR) and Semaglutide (SEM), have had phenomenal outcomes and confidence among consumers. A rapid, straightforward, and thorough approach for quantifying SEM and TIR is essential for quality control purposes given the rising use of these drugs in the pharmaceutical industry. This work presents the first stability-indicating HPLC method for quantifying TIR and SEM under various stress conditions (acidic and basic hydrolysis, oxidative, and photolytic degradation) without interference from degradants. In addition, the proposed methods are capable of accurately quantifying each drug in bulk, pharmaceutical dosage forms, and spiked plasma. The analysis of TIR and SEM was performed using an Inertsil ODS-3 (4.6 × 250 mm, 5 μm particle size) C18 column and the elution of the drugs was achieved isocratically using 0.1% formic acid (pH 2.5) and ACN in the ratio 30:70 with a flow rate 1 mL/min using DAD detector at 220 nm with SEM and TIR eluting at 1.42 and 1.68 min respectively. The proposed method was validated in line with the International Conference of Harmonization (ICH) guidelines and has demonstrated excellent accuracy, linearity, and superior sensitivity with LOD values of 10 and 16 ng/mL for TIR and for SEM, respectively. The obtained linearity range for both TIR and SEM was 1-500 µg/mL with correlation coefficients > 0.9999. An in-depth six- edged sustainability assessment of the proposed method was conducted using greenness, whiteness, blueness and violet innovation metrics was performed using Analytical Greenness Metric (AGREE), Modified Green Analytical Procedure Index (MoGAPI), Analytical Eco-scale, Analytical Green Star Area (AGSA), Carbon Footprint Reduction Index (CaFRI), Whiteness using RGB algorithm, Blue Applicability Grade Index (BAGI), Click Analytical Chemistry Index (CACI), Violet Innovation Grade Index (VIGI) tools and Stability Toolkit for the Appraisal of Bio/Pharmaceuticals' Level of Endurance (STABLE).

The effective separation of radioactive strontium-90 (⁹⁰Sr) from high-level liquid waste (HLLW) produced by the PUREX process is essential for enhancing nuclear waste disposal safety and minimizing related expenses. This research work revealed that 4A zeolite showed excellent separation efficiency and selectivity for Sr²⁺ in very acidic and alkaline environments that mimic actual HLLW. 4A zeolite displayed superior performance, with an adsorption efficiency of 88.2%, a distribution coefficient (Kd) of 1298.47 mL/g, and a maximum sorption capacity of 18.734 mg/g in comparison to numerous standard sorbents reported for the removal of Sr²⁺. It demonstrated prompt adsorption kinetics (~ 2 h), extensive pH tolerance (pH 4-9), and outstanding resistance to radiation-induced degradation. In comparison to alternative adsorbents, 4A zeolite presents a distinctive amalgamation of superior efficacy, economical costs, simple synthesis, and environmental compatibility, making it a highly promising option for the remediation of ⁹⁰Sr in complex nuclear waste streams.

Bisphenol A (BPA) is a hazardous endocrine-disrupting compound which is frequently detected in water sources due to its extensive application in plastic manufacturing. This study introduces an environmentally sustainable liquid-liquid microextraction (LLME) approach, coupled with high-performance liquid chromatography with diode-array detection (HPLC/DAD), for the determination of BPA in drinking water bottles and pharmaceutical eye-drop solutions. 1-Decanol was employed as a green extraction solvent, and critical experimental parameters were systematically optimized to achieve maximum extraction efficiency. Furthermore, the mobile phase consisted of ethanol and water (40:60 v/v), both recognized as green solvents, further enhancing the method's eco-friendly profile. The developed method demonstrated accepted linearity (r = 0.9989) within the concentration range of 25-20,000 ng mL^- 1. The high recovery rates (98.23%-101.73%) and the low relative standard deviations (RSD ≤ 3.0%) confirmed the method's accuracy and precision. The method's environmental sustainability was confirmed through comprehensive greenness and performance evaluations using the Analytical Eco-Scale, Modified Green Analytical Procedure Index (MoGAPI), Analytical GREEnness Metric Approach (AGREE), Click Analytical Chemistry Index (CACI) and the Environmental, Performance, and Practicality Index (EPPI)metrics. In addition, the carbon footprint reduction index (CaFRI) score of 78 demonstrated a substantial decrease in environmental burden, while the red analytical performance index (RAPI) score of 75 reflected strong analytical performance suitable for routine laboratory application. The developed method achieved a greenness of 78% (MoGAPI), blueness of 78%, and redness of 75%, collectively indicating full compliance with the white analytical chemistry (WAC) framework. Together, this trio-colored assessment system effectively integrates environmental sustainability with analytical performance, offering a holistic paradigm for method evaluation. These findings position the proposed method as a viable and reliable alternative for BPA analysis in water samples and pharmaceutical solutions packed in plastic containers.

Two novel aspirin-chitosan conjugates were successfully designed and synthesized: A phenyl acetate derivative (PAD)/chitosan conjugate and an acetoxybenzoate derivative (ABD)/chitosan conjugate. The conjugates were prepared via freeze-drying methodology, where chitosan was reacted with the phenyl acetate derivative (PAD) 3a and the acetoxybenzoate derivative (ABD) 3b through nucleophilic attack of chitosan's amino groups on the carbonyl carbons of the aspirin-containing derivatives, forming stable amide linkages. The resulting conjugates were comprehensively characterized using infrared spectroscopy (IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) to confirm successful conjugation and evaluate structural properties. Antibacterial activity was assessed against methicillin-resistant Staphylococcus aureus (MRSA) using colony-forming unit (CFU) assays. Results demonstrated that the Cs/3a conjugate exhibited superior antibacterial efficacy, achieving a significant reduction in S. aureus growth compared to other formulations. These findings suggest that aspirin-chitosan conjugation represents a promising strategy for developing antimicrobial biomaterials with enhanced therapeutic potential against drug-resistant bacterial pathogens.