Search Results (922)

The physicochemical characteristics of hydrochars produced from tobacco stems through hydrothermal carbonization (HTC) at different temperatures were investigated, along with the variation in contents of nicotine, niacin, and chlorogenic acid in both the hydrochars and the liquid phase. The results indicated that dehydration was the predominant reaction during HTC of wet tobacco stems (WTS), leading to a decrease in the H/C and O/C atomic ratios of the hydrochars. As temperature increased, polycondensation and aromatization reactions became more pronounced, which corresponded with a reduction in the intensity of functional group vibrations such as C–N and N–O in FT-IR spectra. XPS analysis revealed a gradual increase in C=O content, whereas the proportions of C–OH and C–O bonds declined from 51.74% and 35.13% to 36.95% and 20.84%, respectively. Furthermore, the content of pyridine-N rose from 31.08% to 41.30%, while pyrrole-N and quaternary-N contents decreased to varying degrees. Both nicotine and niacin levels in the hydrochars and carbonization liquids exhibited an initial increase followed by a decline, whereas chlorogenic acid content consistently decreased. The underlying mechanisms for the observed changes in nicotine, niacin, and chlorogenic acid contents during HTC are discussed in detail. Full article

Reactivity of non-aromatic 2,5-dichloro-2H-pyrroles toward S-nucleophiles was investigated. It was found that these non-aromatic derivatives exhibit both oxidative and electrophilic properties. Their reaction with thiols and xanthates proceeds as redox process to form disulfides and 5-chlorinated pyrroles as a result of 2,5-dichloro-2H-pyrroles reduction. However, the reaction with ammonium thiocyanate afforded the corresponding 5-thiocyanated 1H-pyrroles. Based on these findings, a novel one-pot method for the thiocyanation of 2,3,4-trisubstituted pyrroles was developed. The protocol involves the in situ generation of highly reactive 2,5-dichloro-2H-pyrroles via dearomative chlorination of the corresponding pyrroles using trichloroisocyanuric acid (TCCA). Subsequent addition of ammonium thiocyanate leads to regioselective incorporation of a thiocyanate group at the C5 position and rearomatization of the pyrrole core. A broad scope of pyrrole-5-thiocyanates was obtained in yields up to 82%. Furthermore, these derivatives were efficiently transformed into 5-trifluoromethylthiolated pyrroles using Ruppert’s reagent in up to 94% yield. This reaction sequence provides a cost-effective way to obtain 5-trifluoromethylthiolated pyrroles, avoiding the need for high-cost electrophilic reagents. The synthetic utility of these novel sulfur-containing pyrrole derivatives was also demonstrated. Full article

Self-powered integrated electrochemical systems require electrode materials that can simultaneously provide energy storage and sensing functions. Boron-doped diamond (BDD) electrodes have good chemical stability and a wide potential window, but their small specific surface area and slow interfacial charge transfer limit their use in such bifunctional applications. In this work, we prepared a three-dimensional porous BDD scaffold on titanium foam by hot-filament chemical vapor deposition, and then grew polypyrrole (PPy) layers on the scaffold by in situ oxidative polymerization. The polymerization time was varied from 8 to 20 h. The BDD/PPy composite obtained after 12 h showed an areal capacitance of 398.6 ± 15.2 mF/cm² at 1 mA/cm², which is about 5.8 times that of the porous BDD alone (67.9 mF/cm²). Its charge transfer resistance (R_ct) was as low as 1.3 ± 0.1 Ω, among the lowest reported for BDD-based electrodes. The porous BDD framework provides ion diffusion pathways, while the PPy layer introduces pseudocapacitance. X-ray photoelectron spectroscopy reveals that the PPy layer contains pyrrolic –NH– groups, which are known to chelate various water pollutants (e.g., heavy metal ions and organic molecules). Based on these surface properties and the low R_ct, we suggest that this composite may have theoretical potential for preconcentrating and detecting multiple pollutants. This work demonstrates a way to improve the capacitance of BDD-based electrodes and may serve as a starting point for future exploration in integrated energy-sensing devices after experimental validation. Full article

Microwave-assisted polymerization is a transformative technique for synthesizing conductive polymers such as polypyrrole (PPy). Unlike conventional chemical or electrochemical methods that rely on external heating or electrode mediated oxidation, microwave irradiation induces volumetric and selective heating through dipole orientation and ionic conduction, which leads to faster reaction kinetics, improved uniformity and higher yields. This review highlights the fundamental mechanisms governing microwave polymer interactions, compares conventional and microwave-assisted polymerization routes and traces the evolution of pyrrole polymerization. Special emphasis is placed on the microwave-synthesized PPy composites and their superior electrochemical performance in energy storage, sensing and biomedical applications. Case studies of graphene/PPy, PPy–metal oxide (e.g., SnO₂@PPy nanotubes) and magnetic ferrite hybrids (e.g., BaFe₁₂O₁₉/PPy) nanocomposites demonstrate enhanced electrical conductivity, specific capacitance and more uniform nanostructures. Beyond energy storage, microwave polymerization techniques have led to the development of PPy composites that are used for sensing, antimicrobial activity and photothermal cancer therapy, highlighting the technique’s versatility across biomedical sciences. Reactor scale up, temperature and pressure control under sealed conditions, reproducibility and deeper mechanism understanding of how microwave radiation influences nucleation, chain growth, doping and charge transport were identified as the outstanding challenges that must be addressed to transform microwave-assisted synthesis from pilot to industrial scale. Overall, microwave-assisted polymerization is on its way to becoming a mainstream, energy efficient method for manufacturing high performance polymer composite materials. Full article

The yellow mealworm (Tenebrio molitor, Linnaeus) is a cosmopolitan pest of stored grains, causing losses up to 15%. Due to the environmental and health risks of synthetic fumigants, botanical alternatives are needed, but their ecotoxicological assessment is also required. Thus, the aim of this study was to assess the insecticidal, insectistatic, and ecotoxicological effects of Salvia connivens (Epling) dichloromethane extract and to identify its compounds. Insecticidal and insectistatic activities were assessed through the consumption of an artificial diet containing the extract over 30 days. Ecotoxicological activity was evaluated through acute toxicity assays on Danio rerio (Hamilton) adults and embryos. The extract showed insecticidal activity against T. molitor achieving 50% mortality at 10,000 ppm (LC₅₀ = 9367.19 ppm). Additionally, at 10,000 ppm larval weight gain was reduced by 53.37% at 30 days compared to the control. Ecotoxicological assays revealed slight toxicity toward D. rerio adults (LC₅₀ = 84.27 ppm) and embryos (LC₅₀ = 32.60 ppm). GC-MS analysis identified hexadecanoic acid (7.08%), 1-(2-methoxyphenyl)-2,5-dihydro-1H-pyrrole-2,5-dione (6.30%), cis-9-octadecenoic acid (3.91%), β-sitosterol (3.05%), and eicosane (3.00%) as the major constituents according to the chromatographic method used. These findings suggest that S. connivens dichloromethane extract is a potential botanical product for T. molitor management. Full article

Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder characterized by the accumulation of the toxic protein amyloid-β, formation of tau-containing neurofibrillary tangles, neuroinflammation, and synaptic dysfunction, highlighting the need for new therapeutic strategies capable of modulating multiple pathological pathways simultaneously. In this study, a structure-based in silico approach was applied to evaluate the multi-target potential of two previously reported pyrrole-based compounds (pyrrole 1 and pyrrole 2) with known monoamine oxidase-B (MAO-B) inhibitory activity and low neurotoxicity. Molecular docking studies were performed against a panel of key AD-related targets, including GSK-3β, APP, MAO-B, BACE1, AChE, BChE, COX-2, GABA-B receptor, NMDA receptor, and E3 ubiquitin ligase CHIP, using Glide XP docking. The results revealed that compound pyrrole 1 may have favorable predicted binding affinities across several targets, with relatively strong docking scores for GSK-3β and COX-2. The binding mode analysis indicated that pyrrole 1 adopts poses consistent with interaction patterns commonly observed for ATP-competitive GSK-3β inhibitors and COX-2 ligands. In silico ADMET profiling using the software SwissADME and ProTox 3.0 indicated distinct pharmacokinetic and safety profiles for the two compounds, with pyrrole 2 showing superior drug-likeness and predicted blood–brain barrier penetration, while pyrrole 1 displayed a more favorable overall toxicity profile. Collectively, these findings identify pyrrole 1 as a theoretically promising multi-target candidate for AD requiring experimental validation, while providing a strong structural basis for further optimizations and subsequent experimental confirmation. Full article

The chemical composition and sensory profile of coffee are influenced by brewing method, namely extraction pressure, temperature, contact time, and equipment. This study compared coffee prepared with a traditional moka pot, a conventional espresso machine, and a novel Italian device (Kamira). Volatile compounds were analyzed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS), leading to the determination of furan (34–42%), pyrrole (4–10%), and pyrazine (13–14%) derivatives. The most abundant fatty acids were palmitic (36–37%), linoleic (40%), and oleic (11%) acids. Physicochemical parameters (total solids, pH, and refractive index) were also measured. Caffeine and chlorogenic acids were quantified by liquid chromatography (HPLC). Differences in chlorogenic acids and volatile compounds were associated with variations in bitterness, acidity, astringency, and aroma intensity. Finally, a trained panel performed sensory evaluation to evaluate the olfactory and flavor attributes of the three types of coffee brews. Significant differences emerged among brewing systems. Espresso showed the highest caffeine content (55.3 ± 4.1 mg/100 g) and total solids (2.61 ± 0.11 g/100 g), together with a stable crema and intense sensory attributes. Moka coffee exhibited a rich aromatic profile but limited crema. The Kamira device produced an abundant crema and a chemical profile partially comparable to espresso. These findings confirm that brewing technology markedly affects coffee composition and sensory perception. Full article

Bacterial biofilms pose a major public health challenge by increasing the antimicrobial tolerance in pathogenic bacteria, thereby limiting the effect of medication-based treatment and promoting the development of antimicrobial resistance. Hence, there is a need to discover new molecules with the ability to prevent biofilm formation. We screened seven synthetic analogues of the breitfussin family of natural products for antimicrobial and antibiofilm activity using a broth microdilution and crystal violet method, respectively. Two compounds inhibited the growth of Gram-positive bacteria in their planktonic state at concentrations of 50 µM, of which one compound (2) demonstrated the ability to inhibit the biofilm formation of Staphylococcus epidermidis at sub-growth-inhibitory, low micromolar concentrations. Compound 2 did not inhibit biofilm growth in Staphylococcus aureus or Listeria monocytogenes, or the ability to eradicate pre-established biofilms. Initial Mode of Action (MoA) studies with compound 2 against S. epidermidis showed a modest impact on the cell surface hydrophobicity and early-stage adhesion to polystyrene. These findings highlight the breitfussin framework as a promising scaffold for the development of new antimicrobial and antibiofilm agents. Full article

Pyrrole-based hydrazide–hydrazones constitute a class of organic compounds that has attracted increasing attention in pharmaceutical research due to their potential application in the treatment of neurodegenerative diseases. In the present study, a series of ten novel pyrrole-containing hydrazide–hydrazones was synthesized. The structures of the newly obtained compounds were characterized by IR spectrophotometry, ¹H-NMR, and ¹³C-NMR spectroscopy, while their purity was confirmed by mass spectrometry and melting point determination. The antioxidant activity of the synthesized compounds was evaluated in vitro using ABTS, DPPH, FRAP, and a commercial Antioxidant Assay Kit (CS0790). Their neurotoxicity and neuroprotective effects were subsequently assessed in rat brain subcellular fractions. Two of the tested compounds, VV4 and VV6, exhibited the most pronounced antioxidant and neuroprotective effects, along with the lowest levels of neurotoxicity. The key pharmacokinetic parameters of the most active compounds were predicted in silico, and their stability and reactivity were subsequently evaluated using DFT analysis. Full article

Inspired by natural porphyrin-containing enzymatic active sites, metalloporphyrins have become important platforms for oxygen reduction reaction (ORR) catalysis because of their well-defined structures and tunable coordination environments. Recently, breaking the N₄-coordination environment of cobalt porphyrins by inverting one pyrrolic unit to generate N₃C₁-site, i.e., N-confused porphyrin, has emerged as an effective strategy to promote their electro-catalyzing ORR capability. Herein, we reviewed recent progress in N-confused cobalt porphyrin in catalyzing ORR, with special emphasis on the influence of the catalyst’s architecture. We first summarized the general ORR mechanism on metalloporphyrins and the computational methods commonly used for mechanistic studies. Then, for comparison, the more common modification strategies like meso- and β-position substitution, axial coordination, and dinuclear design were reviewed for cobalt porphyrin-based catalysts. The main part reviewed the N-confused cobalt porphyrins with three different architectures, i.e., molecular, framework, and supported heterogeneous molecular form, highlighting their synthesis, characterization, electrocatalytic ORR behavior, and mechanistic interpretation from both experimental and theoretical perspectives. It summarizes the current understanding of why CoN₃C₁ systems outperform the original CoN₄ porphyrin systems. The architecture of catalysts was found to affect the selectivity and mechanisms of ORR, along with the discussion of pH. The effects of N-confused strategy were compared to other modification strategies. Finally, we proposed possible directions for integrated catalyst design and mechanism studies. Full article

Reaction of 5-oxo-1-(4-(phenylamino)phenyl)pyrrolidine-3-carbohydrazide with selected aldehydes and ketone provided novel hydrazone derivatives bearing azole moieties: pyrazole, pyrrole, and indole. The drug likeness of the newly synthesized compounds and their physicochemical characteristics were examined to fit Lipinski’s Rule of Five. N-(2,5-dimethyl-1H-pyrrol-1-yl)-5-oxo-1-(4-(phenylamino)phenyl)pyrrolidine-3-carboxamide (5) exhibited the most favorable overall ADMET profile, combining compliance with key physicochemical requirements for antimicrobial activity with superior solubility and reduced predicted hepatotoxicity and nephrotoxicity. Despite generally elevated plasma protein binding across the series, this compound provided the most advantageous balance between permeability, systemic exposure, and safety. Full article

This study is dedicated to the development of novel boron-dipyrromethene (BODIPY)-based photosensitizers, focusing on investigating the regulatory mechanism of introducing different electron-donating groups at the α-position on the photosensitizing performance of thieno-bis-BODIPY derivatives, aiming to provide a theoretical basis for cancer photodynamic therapy (PDT). Five thieno-bis-BODIPY molecules (FD1-FD5) were constructed by connecting two BODIPY units via a thiophene π-bridge and introducing various substituents at the α-position of their phenyl groups. Systematic theoretical studies revealed that unilaterally substituted molecules exhibit superior photophysical properties compared to their bilaterally substituted counterparts. The key mechanisms involve structural planarization, increased electrostatic potential difference, and the formation of hybrid LE/CT characteristics in the excited state, all of which collectively promote the intersystem crossing (ISC) process. Specifically, the pyrrole-substituted FD4 exhibits the highest ISC efficiency due to its stronger electron-donating ability and greater molecular planarity, and it is predicted to possess a stronger singlet oxygen generation capability than the methoxy-substituted FD2 while maintaining fluorescence emission. In contrast, bilateral substitution leads to structural distortion, which favors fluorescence emission, as seen in FD5 which exhibits the longest absorption wavelength. This research elucidates the key mechanisms for enhancing ISC and photosensitizing performance from the perspectives of electronic structure and excited-state characteristics, providing theoretical guidance for overcoming limitations such as insufficient tissue penetration in traditional BODIPY photosensitizers and clarifying structure–activity relationships. Full article

The development of efficient catalysts for acetylene hydrochlorination is critical for replacing the industrially prevalent mercury chloride catalysts. Herein, a defective nitrogen-doped carbon material (NC-APT) is engineered via a facile co-polymerization of pyrrole, aniline, and thiophene, followed by a controlled calcination procedure. This co-polymerization strategy introduces abundant structural defects compared to mono-polymerization processes, primarily due to the lattice mismatch and steric hindrance between the distinct monomers, which disrupts the regularity of the polymer chain and prevents graphitic ordering. The resulting NC-APT catalyst features a high specific surface area of 375.7 m²·g⁻¹ and a substantial nitrogen dopant content of 14.4%, with 81% of the nitrogen existing as catalytically active edge structures (pyrrolic and pyridinic N). Consequently, the catalyst delivers exceptional performance, achieving 92% acetylene conversion at 220 °C with a C₂H₂ gas hourly space velocity (GHSV) of 80 h⁻¹. This performance significantly outperforms many reported metal-free counterparts and rivals that of traditional metal-based catalysts. This work offers new insights into the rational design of carbon-based, metal-free catalysts through monomer mismatch engineering. Full article

UVA exposure elicits immediate and persistent pigment darkening of the skin, which is thought to result from the oxidation and polymerization of existing melanin and/or precursors. Melanocytes produce eumelanin and pheomelanin. Eumelanin consists of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), while pheomelanin consists of benzothiazine and benzothiazole units. Melanins can be analyzed by quantifying specific degradation products using HPLC. Specifically, eumelanin can be analyzed as pyrrole-2,3,5-tricarboxylic acid (PTCA) and pyrrole-2,3-dicarboxylic acid (PDCA), specific degradation products of DHICA and DHI, respectively. Benzothiazole pheomelanin can be analyzed as thiazole-2,4,5-tricarboxylic acid (TTCA), whereas benzothiazine pheomelanin is analyzed as 4-amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (3-AHP). Upon UVA exposure, melanins undergo structural modifications. Eumelanin undergoes oxidative cleavage to free pyrrole-2,3,5-tricarboxylic acid (Free PTCA) and undergoes cross-linking to form pyrrole-2,3,4,5-tetracarboxylic acid (PTeCA). UVA exposure of pheomelanin induces oxidative conversion from the benzothiazine to the benzothiazole. Nevertheless, these structural modifications have never been previously characterized in human skin. In this study, we exposed ex vivo skin to increasing UVA1 doses (60, 90 and 120 J/cm²; n = 6 in triplicate) and characterized the induced pigment darkening before, immediately, and 2 h after exposure through colorimetry, HPLC and spectrophotometry. The results showed changes in the CIELAB colorimetric parameters, namely a decrease in Luminance L*, the yellow-blue component b* and the Individual Typology Angle (ITA) in UVA1-exposed samples, indicative of skin darkening. In parallel, UVA1 exposure induced significant modifications of the levels of absorbance at 500 nm (A500) and melanin markers PTCA, PTeCA, PDCA, TTCA, and 4-AHP, as well as in the ratios of various markers, such as PTeCA/PTCA, Free/Total PTCA, and TTCA/4-AHP, indicative of photooxidation/degradation of melanins. Our study provides the first evidence of UVA1-induced modifications of melanins associated with pigment darkening occurring in human skin. Full article

Pipecolic acid (PA) is an important biomarker associated with peroxisomal and neurological disorders, necessitating the development of rapid, selective, and cost-effective detection methods beyond conventional chromatographic techniques. In this study, a molecularly imprinted electrochemical sensor (PA-MIP/Au) was developed for the selective determination of PA. The sensor was fabricated by electropolymerizing pyrrole on a gold electrode in the presence of PA as a template, followed by template removal to create specific recognition cavities. The electrochemical behavior and analytical performance were evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) in a ferri/ferrocyanide redox system. The sensor exhibited a linear response over 5–100 µM, with a detection limit of 1.05 µM. This range covers the reported physiological plasma concentrations of pipecolic acid (0.7–2.6 µM) and extends to elevated levels observed in pathological conditions, thereby demonstrating its suitability for clinical and biochemical monitoring applications. The sensor also demonstrated high selectivity against structurally similar amino acids, good repeatability, reproducibility, and stability, retaining over 87% of its initial response after 28 days. Recovery studies in spiked artificial plasma samples yielded values between 97.2% and 98.4%, confirming its applicability in complex matrices. Overall, the proposed sensor offers a simple, rapid, and cost-effective alternative for PA determination with potential for clinical and point-of-care applications. Full article