Molecules

13 pages, 1190 KB

Open AccessArticle

Thiofunctionalization of Silyl Enol Ether: An Efficient Approach for the Synthesis of β-Keto Sulfides

by Xinyao Zhao, Hexia Ye, Yajie Fu, Haibo Liu and Xiaojing Bi

Molecules 2025, 30(19), 4032; https://doi.org/10.3390/molecules30194032 - 9 Oct 2025

Viewed by 683

β-Keto sulfides are a class of compounds containing both carbonyl (C=O) and thioether (C–S–C) functionalities, exhibiting significant potential in the field of medicinal chemistry. This study employs the silyl enol ether as the substrate, enabling the formation of C–S bonds under catalyst- [...] Read more.

β-Keto sulfides are a class of compounds containing both carbonyl (C=O) and thioether (C–S–C) functionalities, exhibiting significant potential in the field of medicinal chemistry. This study employs the silyl enol ether as the substrate, enabling the formation of C–S bonds under catalyst- and additive-free conditions, thereby facilitating the efficient synthesis of β-keto sulfides. The reaction proceeds rapidly and efficiently, exhibiting a broad substrate scope, and a total of 31 target compounds were synthesized with up to 95% yields. Full article

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16 pages, 1083 KB

Open AccessArticle

Simultaneous Development and Validation of an HPLC Method for the Determination of Furosemide and Its Degraded Compound in Pediatric Extemporaneous Furosemide Oral Solution

by Katsanee Srejomthong, Thanawat Pattananandecha, Sutasinee Apichai, Suporn Charumanee, Busaban Sirithunyalug, Fumihiko Ogata, Naohito Kawasaki and Chalermpong Saenjum

Molecules 2025, 30(19), 4031; https://doi.org/10.3390/molecules30194031 - 9 Oct 2025

Viewed by 1559

Abstract

Furosemide (FUR) is a loop diuretic widely used in pediatric care. However, no standardized oral liquid formulation exists due to degradation concerns, particularly the formation of furosemide-related compound B (FUR-B). This study aimed to develop and validate the HPLC method for the simultaneous [...] Read more.

Furosemide (FUR) is a loop diuretic widely used in pediatric care. However, no standardized oral liquid formulation exists due to degradation concerns, particularly the formation of furosemide-related compound B (FUR-B). This study aimed to develop and validate the HPLC method for the simultaneous quantification of FUR, FUR-B, methylparaben (MP), and propylparaben (PP) in pediatric extemporaneous oral solutions. Chromatographic separation was achieved using a Symmetry^® C18 column (4.6 × 250 mm, 5 µm) with a mobile phase of 0.1% acetic acid in water and acetonitrile (60:40, v/v) at 1.0 mL/min of flow with injection volume at 10 µL. Detection at 272 nm provided optimal sensitivity, especially for low concentrations of FUR-B. Forced degradation confirmed baseline separation of FUR from its degradation products. The condition showed high linearity (R² > 0.995), accuracy (recoveries 98.2–101.0%), and precision (RSD ≤ 2%). Robustness and ruggedness tests under varied conditions, analysts, and intra-day yielded consistent performance. Application to extemporaneous formulations showed that refrigeration (2–8 °C) retained initial composition, while elevated temperatures (30 °C and 40 °C) promoted FUR degradation, with FUR-B increasing to 6.84% after 90 days and greater MP and PP degradation. This validated method offers a reliable analytical tool for monitoring chemical changes and supporting quality control of pediatric FUR extemporaneous formulations. Full article

(This article belongs to the Special Issue Recent Advances in Chromatography for Pharmaceutical Analysis)

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17 pages, 4728 KB

Open AccessArticle

Construction of Hierarchical Fe-MFI Nanosheets with Enhanced Fenton-like Degradation Performance

by Haibo Jiang, Lin Xu, Qingrun Meng, Xu Feng, Junxuan Wang, Yankai Li and Junjie Li

Molecules 2025, 30(19), 4030; https://doi.org/10.3390/molecules30194030 - 9 Oct 2025

Viewed by 446

Abstract

Introducing hierarchical structure into zeolites or synthesizing two-dimensional (2D) zeolite nanosheets have drawn much attention in catalysis and separation process due to the improvement in zeolites’ diffusion properties. In this study, Fe incorporated on the MFI zeolite framework (Fe-MFI) with the nanosheet morphology [...] Read more.

Introducing hierarchical structure into zeolites or synthesizing two-dimensional (2D) zeolite nanosheets have drawn much attention in catalysis and separation process due to the improvement in zeolites’ diffusion properties. In this study, Fe incorporated on the MFI zeolite framework (Fe-MFI) with the nanosheet morphology and unique hierarchical pore structure was successfully synthesized and applied for the adsorption and degradation of Rhodamine B (RhB) in a Fenton-like reaction in the presence of H₂O₂. The synthesis involved a seed-directed hydrothermal method in the presence of NH₄F and a subsequent NaOH treatment made the synthesized hierarchical Fe-MFI nanosheets (Fe-20-10) characterized by abundant highly dispersed framework Fe³⁺ species. As a result of these features, the Fe-20-10 showed excellent ability of adsorption and degradation efficiency of RhB, and enhanced durability due to negligible leaching of framework Fe³⁺ species. Moreover, the hydroxyl radicals were determined as the main the reactive oxygen species of RhB degradation, and a possible adsorption–degradation pathway was proposed. This work offers guidance for developing high-performance Fenton-like degradation catalysts. Full article

(This article belongs to the Special Issue Design, Synthesis, and Application of Zeolite Materials)

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14 pages, 1929 KB

Open AccessArticle

Targeted Enrichment and Characterization of Diester Diterpenoid Alkaloids in Aconitum Herbs Using Gas–Liquid Microextraction Coupled with High-Resolution Mass Spectrometry

by Yijun Wang, Ceyu Miao, Junxian Wu, Yutong Hua, Xiang Li, Liping Kang and Zidong Qiu

Molecules 2025, 30(19), 4029; https://doi.org/10.3390/molecules30194029 - 9 Oct 2025

Viewed by 574

Abstract

Diterpenoid diester alkaloids (DDAs) are the primary toxic constituents in aconite herbs, while also being the key pharmacologically active components. Consequently, establishing rapid enrichment and highly sensitive analytical methods for DDAs is of critical importance. Herein, we developed and constructed a gas–liquid microextraction [...] Read more.

Diterpenoid diester alkaloids (DDAs) are the primary toxic constituents in aconite herbs, while also being the key pharmacologically active components. Consequently, establishing rapid enrichment and highly sensitive analytical methods for DDAs is of critical importance. Herein, we developed and constructed a gas–liquid microextraction (GLME) device, which enables the rapid and selective enrichment of DDAs from complex matrices. The enriched extract can be directly analyzed by high-resolution Orbitrap mass spectrometry without requiring any further pretreatment. A comparative analysis of six commonly used Aconitum herbs medicines and their processed derivatives was conducted. Notably, GLME enhanced the mass spectrometric signals of DDAs by 3–4 orders of magnitude, facilitating the identification of 27 alkaloids, including 3 potential new compounds (15-Ethyl-13-deoxyanhydroaconitine, 13-Hydroxy-15-ethylanhydroaconitine and 8-eicosapentaenoic-benzoylmesaconine). It was found that among the tested samples, the DDAs response intensity of raw Caowu was the highest, and the DDA signals decreased significantly after processing. This result chemically validates the detoxification efficacy of traditional methods. The proposed GLME-MS strategy has the advantages of being green, economical, easy to operate, and highly selective (>1000-fold), which provides a technical reference for the rapid detection, safety assessment, and quality control of Aconitum herbs. Full article

(This article belongs to the Section Analytical Chemistry)

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29 pages, 943 KB

Open AccessReview

Volatile Organic Compounds (VOCs) in Neurodegenerative Diseases (NDDs): Diagnostic Potential and Analytical Approaches

by Jolanda Palmisani, Antonella Maria Aresta, Viviana Vergaro, Giovanna Mancini, Miriana Cosma Mazzola, Marirosa Rosaria Nisi, Lucia Pastore, Valentina Pizzillo, Nicoletta De Vietro, Chiara Boncristiani, Giuseppe Ciccarella, Carlo Zambonin, Gianluigi de Gennaro and Alessia Di Gilio

Molecules 2025, 30(19), 4028; https://doi.org/10.3390/molecules30194028 - 9 Oct 2025

Cited by 2 | Viewed by 1225

Abstract

Neurodegenerative diseases (NDDs) are a group of progressive diseases affecting neuronal cells in specific areas of the brain, causing cognitive decline and movement impairment. Nowadays, NDDs play a significant role in the global burden of disease, and their incidence is increasing, particularly due [...] Read more.

Neurodegenerative diseases (NDDs) are a group of progressive diseases affecting neuronal cells in specific areas of the brain, causing cognitive decline and movement impairment. Nowadays, NDDs play a significant role in the global burden of disease, and their incidence is increasing, particularly due to population aging. NDD onset is multi-factorial; based on the current knowledge, genetic, environmental, and cellular factors are believed to contribute to their occurrence and progression. Taking into account that at an early stage, the symptoms are not clearly defined, and diagnosis may be delayed, the development of innovative and non-invasive methodological approaches for early diagnosis of NDDs is strategic for timely and tailored disease management, as well as for the overall improvement of patients’ quality of life. The present review aims to provide, in the first part, an overview based on the current level of knowledge on the environmental risk factors that can explicate a role in the onset of the most common NDDs and on the main pathogenic mechanisms involved in disease initiation and progression. The second part aims to define the current state of the art regarding the significance of Volatile Organic Compounds (VOCs) in the volatome of different human biological matrices (exhaled breath, feces, and skin sebum) as candidate biomarkers of specific NDDs, with the aim of developing non-invasive diagnostic approaches for the early diagnosis and personalized management of the patients. A critical synthesis and discussion on the applied methodological approaches and on the relevant outcomes obtained across the studies is reported. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Analytical Chemistry)

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13 pages, 2885 KB

Open AccessArticle

Isopropanol Electro-Oxidation on PtCu Alloys for Aqueous Organic Redox Chemistry Toward Energy Storage

by Jinyao Tang, Xiaochen Shen, Laura Newsom, Rongxuan Xie, Parsa Pishva, Yanlin Zhu, Bin Liu and Zhenmeng Peng

Molecules 2025, 30(19), 4027; https://doi.org/10.3390/molecules30194027 - 9 Oct 2025

Viewed by 556

Abstract

Integration of renewable energy into modern power grids remains limited by intermittency and the need for reliable energy storage. Redox flow batteries (RFBs) are promising for large-scale energy storage, yet their widespread adoption is hindered by the high cost. In this study, we [...] Read more.

Integration of renewable energy into modern power grids remains limited by intermittency and the need for reliable energy storage. Redox flow batteries (RFBs) are promising for large-scale energy storage, yet their widespread adoption is hindered by the high cost. In this study, we investigate isopropanol as a redox-active species with Pt-Cu alloy electrocatalysts for aqueous-organic RFBs. A series of Pt_xCu catalysts with varying Pt:Cu ratios were synthesized and studied for isopropanol electro-oxidation reaction (IPAOR) performance. Among them, PtCu demonstrated the best performance, achieving a low activation energy of 14.4 kJ/mol at 0.45 V vs. RHE and excellent stability at 1 M isopropanol (IPA) concentration. Kinetic analysis and in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed significantly reduced acetone accumulation on PtCu compared to pure Pt, indicating enhanced resistance to catalyst poisoning. Density functional theory (DFT) calculations further identified the first proton-coupled electron transfer (PCET) as the rate-determining step (RDS) with C-H bond scission as the preferred pathway on PtCu. A proof-of-concept PtCu-catalyzed H-cell demonstrated stable cycling over 200 cycles, validating the feasibility of IPA as a low-cost, regenerable redox couple. These findings highlight PtCu-catalyzed IPA/acetone(ACE) chemistry as a promising platform for next-generation aqueous-organic RFBs. Full article

(This article belongs to the Section Electrochemistry)

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28 pages, 4553 KB

Open AccessArticle

Insights of Nanostructured Ferberite as Photocatalyst, Growth Mechanism and Photodegradation Under H₂O₂-Assisted Sunlight

by Andarair Gomes dos Santos, Yassine Elaadssi, Virginie Chevallier, Christine Leroux, Andre Luis Lopes-Moriyama and Madjid Arab

Molecules 2025, 30(19), 4026; https://doi.org/10.3390/molecules30194026 - 9 Oct 2025

Viewed by 532

Abstract

In this study, nanostructured ferberites (FeWO₄) were synthesized via hydrothermal routes in an acidic medium. It was then investigated as an efficient photocatalyst for degrading organic dye molecules, with methylene blue (MB) as a model pollutant. The formation mechanism of ferberite [...] Read more.

In this study, nanostructured ferberites (FeWO₄) were synthesized via hydrothermal routes in an acidic medium. It was then investigated as an efficient photocatalyst for degrading organic dye molecules, with methylene blue (MB) as a model pollutant. The formation mechanism of ferberite revealed that the physical form of the precursor, FeSO₄·7H₂O, acts as a decisive factor in morphological evolution. Depending on whether it is in a solid or dilute solution form, two distinct nanostructures are produced: nanoplatelets and self-organized microspheres. Both structures are composed of stoichiometric FeWO₄ (Fe: 49%, W: 51%) in a single monoclinic phase (space group P2/c:1) with high purity and crystallinity. The p-type semiconductor behavior was confirmed using Mott–Schottky model and the optical analysis, resulting in small band gap energies (≈1.7 eV) favoring visible absorption light. Photocatalytic tests under simulated solar irradiation revealed rapid and efficient degradation in less than 10 min under near-industrial conditions (pH 5). This was achieved using only a ferberite catalyst and a low concentration of H₂O₂ (4 mM) without additives, dopants, or artificial light sources. Advanced studies based on photocurrent measurements, trapping and stability tests were carried out to identify the main reactive species involved in the photocatalytic process and better understanding of photodegradation mechanisms. These results demonstrate the potential of nanostructured FeWO₄ as a sustainable and effective photocatalyst for water purification applications. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis—2nd Edition)

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14 pages, 2149 KB

Open AccessArticle

Interface Catalysts of In Situ-Grown TiO₂/MXenes for High-Faraday-Efficiency CO₂ Reduction

by Shaun Debow, Zichen Shen, Arjun Sathyan Kulathuvayal, Fuzhan Song, Tong Zhang, Haley Fisher, Jesse B. Brown, Yuqin Qian, Zhi-Chao Huang-Fu, Hui Wang, Zachary Zander, Mark S. Mirotznik, Robert L. Opila, Yanqing Su and Yi Rao

Molecules 2025, 30(19), 4025; https://doi.org/10.3390/molecules30194025 - 9 Oct 2025

Viewed by 695

Abstract

Climate change and the global energy crisis have led to an increasing need for greenhouse gas remediation and clean energy sources. The electrochemical CO₂ reduction reaction (CO₂RR) is a promising solution for both issues as it harvests waste CO₂ [...] Read more.

Climate change and the global energy crisis have led to an increasing need for greenhouse gas remediation and clean energy sources. The electrochemical CO₂ reduction reaction (CO₂RR) is a promising solution for both issues as it harvests waste CO₂ and chemically reduces it to more useful forms. However, the high overpotential required for the reaction makes it electrochemically unfavorable. Here, we fabricate a novel electrode composed of TiO₂ nanoparticles grown in situ on MXene charge acceptor 2D sheets with excellent CO₂RR characteristics. A straightforward solvothermal method was used to grow the nanoparticles on the Ti₃C₂T_x MXene flakes. The electrochemical performance of the TiO₂/MXene electrodes was analyzed. The Faradaic efficiencies of the TiO₂/MXene electrodes were determined, with a value of 99.41% at −1.9 V (vs. Ag/AgCl). Density functional theory mechanistic analysis was used to reveal the most likely mechanism resulting in the production of one CO molecule along with a carbonate anion through ∗CO, ∗O, and activated CO₂²⁻ intermediates. Bader charge analysis corroborated this pathway, showing that CO₂ gains a greater negative charge when TiO₂/MXene serves as a catalyst compared to MXene or TiO₂ alone. These results show that TiO₂/MXene nanocomposite electrodes may be very useful in the conversion of CO₂ while still being efficient in both time and cost. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Physical Chemistry, 3rd Edition)

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14 pages, 3698 KB

Open AccessArticle

Natural Tyrosinase Inhibitors from Lycopodium japonicum

by Zeng-Yue Ge, Ya-Qing Wang, Qi-Bin Yang, Xian-Yun Yan, Lei Wu, Min Zhang and Lin-Fu Liang

Molecules 2025, 30(19), 4024; https://doi.org/10.3390/molecules30194024 - 9 Oct 2025

Viewed by 514

Abstract

Natural tyrosinase inhibitors are an important group of compounds with cosmetical and medicinal applications. With the aim of finding new types of natural tyrosinase inhibitors from ornamental and medicinal plants, Lycopodium japonicum was selected and studied. As a result, fifteen structurally diverse secondary [...] Read more.

Natural tyrosinase inhibitors are an important group of compounds with cosmetical and medicinal applications. With the aim of finding new types of natural tyrosinase inhibitors from ornamental and medicinal plants, Lycopodium japonicum was selected and studied. As a result, fifteen structurally diverse secondary metabolites 1–15 were isolated and identified. Their chemical structures were identified by analysis of their spectral data and compared with those reported in the literature. In the tyrosinase inhibitory bioassay, five phytochemicals, 4, 12, 13, 14, and 15, exhibited significant inhibitory effects, with half-maximal inhibitory concentration (IC₅₀) values ranging from 1.46 to 6.82 mM. Additionally, molecular docking studies disclosed that Lys376, Lys379, Gln307, and other amino acid residues played key roles in the potential binding interactions between the active compounds and the tyrosinase. These findings suggest that the species L. japonicum is a warehouse of natural tyrosinase inhibitors. Full article

(This article belongs to the Special Issue Terpenes and Their Derivatives: From Nature to Medical Applications)

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12 pages, 1530 KB

Open AccessArticle

Optimizing Metal Sites in Hierarchical USY for Selective Hydrocracking of Naphthalene to BTX

by Kunyi Zheng, Mingjia Liu, Haidong Li, Xiu Chen and Xilong Wang

Molecules 2025, 30(19), 4023; https://doi.org/10.3390/molecules30194023 - 9 Oct 2025

Viewed by 485

Abstract

Metal components (CoMo, NiMo, NiW) supported on hierarchical porous USY zeolite (HPY) were systematically optimized for selective naphthalene hydrocracking to BTX (benzene, toluene, xylene). The hierarchical porosity enhanced mass transport and accessibility to active metal sites, improving reaction selectivity and efficiency. Supported metal [...] Read more.

Metal components (CoMo, NiMo, NiW) supported on hierarchical porous USY zeolite (HPY) were systematically optimized for selective naphthalene hydrocracking to BTX (benzene, toluene, xylene). The hierarchical porosity enhanced mass transport and accessibility to active metal sites, improving reaction selectivity and efficiency. Supported metal sulfides served as hydrogenation sites, crucial for aromatic ring activation and coke suppression. By optimizing the synergy between hydrogenation and cracking functions, the optimized Ni₁W/HPY catalyst achieved complete naphthalene conversion with a BTX yield of 92.5%. The spatial distribution of WO₃ crystallites facilitated functional separation, promoting selective conversion. These findings underscore the importance of metal–acid balance and pore architecture in designing efficient hydrocracking catalysts. Full article

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11 pages, 3631 KB

Open AccessArticle

A Facile Fluorescent Visualization Method Based on Copper Clusters for Formaldehyde Detection

by Jie Zou, Qing Chen, Guimin Mu, Miao Ma, Fang Yang, Mengtian Li, Fujian Xu and Hui Xia

Molecules 2025, 30(19), 4022; https://doi.org/10.3390/molecules30194022 - 8 Oct 2025

Viewed by 562

Abstract

Establishing a simple and effective method for the visual detection of formaldehyde plays an important role in environmental emergency monitoring. In this work, L-cysteine-stabilized copper clusters were synthesized via a green, mild, and facile one-step preparation method. Through the optimization of reaction conditions, [...] Read more.

Establishing a simple and effective method for the visual detection of formaldehyde plays an important role in environmental emergency monitoring. In this work, L-cysteine-stabilized copper clusters were synthesized via a green, mild, and facile one-step preparation method. Through the optimization of reaction conditions, including reactant concentration and pH, the clusters exhibited stable red fluorescence. Upon exposure to formaldehyde, the fluorescence intensity of copper clusters gradually quenched with increasing formaldehyde concentration, enabling the development of a visual detection method that was successfully applied to analyze formaldehyde samples in air. Furthermore, by immobilizing the copper clusters into hydrogels, the visual detection performance and portability of the material were significantly enhanced. This method offers the advantages of simple preparation and rapid and accurate determination, demonstrating potential for semi-quantitative field detection of formaldehyde in emergency scenarios. Full article

(This article belongs to the Section Analytical Chemistry)

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17 pages, 2692 KB

Open AccessArticle

Chemical Composition and Biological Activities of the Essential Oils from Different Parts of Rosa bracteata J.C.Wendl

by Shiyu Song, Yifang Chen, Hongrui Chen, Qinglei Han and Pengxiang Lai

Molecules 2025, 30(19), 4021; https://doi.org/10.3390/molecules30194021 - 8 Oct 2025

Cited by 1 | Viewed by 976

Abstract

Rosa bracteata J.C.Wendl. is a thorny, clump-forming or trailing perennial evergreen shrub native to China. The current analysis was designed to explore the chemical constituents and determine the in vitro antimicrobial, cytotoxic, and antioxidant properties of the essential oils (EOs) of the stems, [...] Read more.

Rosa bracteata J.C.Wendl. is a thorny, clump-forming or trailing perennial evergreen shrub native to China. The current analysis was designed to explore the chemical constituents and determine the in vitro antimicrobial, cytotoxic, and antioxidant properties of the essential oils (EOs) of the stems, leaves, and flowers of Rosa bracteata for the first time. The chemical composition of the essential oils obtained through hydro-distillation was characterized by means of gas chromatography–mass spectrometry (GC–MS) and gas chromatography with a flame ionization detector (GC–FID). Thirty-seven, thirty-six, and forty-two constituents were identified from leaf oil (LEO), stem oil (SEO), and flower oil (FEO), representing 96.3%, 95.9%, and 97.4% of the total oil constituents, respectively. The LEO was mainly composed of 1-pentadecene, α-cadinol, and hexadecanoic acid. However, the main identified components of SEO were (E)-nerolidol, phytol, and benzyl benzoate, and the main components of the flower oil were ethyl octanoate, octanoic acid, and α-cadinol. All of the EOs exhibited antibacterial activities against both Gram-positive and Gram-negative bacteria with MIC values ranging from 40.00 to 640.00 μg/mL. In addition, the checkerboard method demonstrates potent synergistic effects of Rosa bracteata EOs when combined with commercial antibiotics (chloramphenicol and streptomycin). In the MTT test, SEO (IC₅₀: 37.91 ± 2.10 to 51.15 ± 6.42 μg/mL) showed stronger cytotoxic activity against four cancer cell lines (MCF-7, A549, HepG2, and HCT-116) during the incubation time of 48 h in comparison to the EOs isolated from the other plant parts. Overall, these findings reveal the chemical composition and significant bioactivity of R. bracteata EOs for the first time, suggesting their potential as promising natural agents for therapeutic applications, especially in combination therapies to combat antibiotic resistance. Full article

(This article belongs to the Special Issue Chemical Composition and Biological Evaluation of Essential Oils)

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24 pages, 5285 KB

Open AccessArticle

Thermosetting Resins Based on Poly(Ethylene Glycol Fumarate) and Acrylic Acid: Rheological and Thermal Analysis

by Gulsym Burkeyeva, Anna Kovaleva, Zhansaya Ibrayeva, David Havlicek, Yelena Minayeva, Aiman Omasheva, Elmira Zhakupbekova and Margarita Nurmaganbetova

Molecules 2025, 30(19), 4020; https://doi.org/10.3390/molecules30194020 - 8 Oct 2025

Viewed by 566

Abstract

The rheological behavior and low-temperature curing kinetics of poly(ethylene glycol fumarate)–acrylic acid systems initiated by benzoyl peroxide/N,N-dimethylaniline have been investigated for the first time with a focus on the development of thermosetting binders with controllable properties. It has been established that both composition [...] Read more.

The rheological behavior and low-temperature curing kinetics of poly(ethylene glycol fumarate)–acrylic acid systems initiated by benzoyl peroxide/N,N-dimethylaniline have been investigated for the first time with a focus on the development of thermosetting binders with controllable properties. It has been established that both composition and temperature have a significant effect on rheological behavior and kinetic parameters. Rheological studies revealed non-Newtonian flow behavior and thixotropic properties, while oscillatory tests demonstrated structural transformations during curing. Increasing the temperature was found to accelerate gelation, whereas a higher polyester content retarded the process, which is crucial for controlling the pot life of the reactive mixture. DSC analysis indicated that isothermal curing at 30–40 °C can be satisfactorily described by the Kamal autocatalytic model, whereas at 20 °C, at later stages, and at higher polyester contents, diffusion control becomes significant. The thermal behavior of cured systems was investigated using thermogravimetry. Calculations using the isoconversional Kissinger–Akahira–Sunose and Friedman methods confirmed an increase in the apparent activation energy for thermal decomposition, suggesting a stabilizing effect of poly(ethylene glycol fumarate) in the polymer structure. The studied systems are characterized by controllable kinetics, tunable viscosity, and high thermal stability, making them promising thermosetting binders for applications in composites, construction, paints and coatings, and adhesives. Full article

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17 pages, 2115 KB

Open AccessReview

Recent Developments in Azomethine Ylide-Initiated Double Cycloadditions

by Tieli Zhou, Xiaofeng Zhang, Yan Jan Sheng, Desheng Zhan and Wei Zhang

Molecules 2025, 30(19), 4019; https://doi.org/10.3390/molecules30194019 - 8 Oct 2025

Viewed by 835

Abstract

Azomethine ylides (AMYs) have a nitrogen–carbon double bond and an electron lone pair on the nitrogen atom. They are essential 1,3-dipoles for [3+2] cycloadditions in the synthesis of pyrrolidine-containing heterocycles. Significant progress in 1,3-diplolar cycloadditions has been made in the construction of novel [...] Read more.

Azomethine ylides (AMYs) have a nitrogen–carbon double bond and an electron lone pair on the nitrogen atom. They are essential 1,3-dipoles for [3+2] cycloadditions in the synthesis of pyrrolidine-containing heterocycles. Significant progress in 1,3-diplolar cycloadditions has been made in the construction of novel heterocyclic scaffolds, with efforts to broaden substrate scope, enhance stereoselectivity, and integrate green chemistry principles. This article summarizes double cycloadditions of AMYs derived from amino esters and amino acids for the synthesis of novel polyheterocycles. The design of double cycloadditions through the pot, atom, and step economic (PASE) method to increase the reaction efficiency is discussed. The examples presented in this paper may be applied to the synthesis of biologically active molecules. Full article

(This article belongs to the Special Issue Cyclization Reactions in the Synthesis of Heterocyclic Compounds)

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20 pages, 2867 KB

Open AccessArticle

Aromaticity Tuning in Biaryl Monophosphines and Their Derivatives

by Barbara Miroslaw, Pawel Rejmak, Izabela Dybala, Urszula Kosikowska, Sylwia Andrzejczuk, Łukasz Świątek, Kinga Salwa and Oleg M. Demchuk

Molecules 2025, 30(19), 4018; https://doi.org/10.3390/molecules30194018 - 8 Oct 2025

Viewed by 1072

Abstract

Aromaticity tuning of biaryl monophosphines can significantly impact their catalytic performance. Biaryl monophosphines constitute a crucial class of compounds due to their potential as ligand precursors in asymmetric Pd-catalyzed cross-coupling and some other catalytic reactions. In this study, we investigate the tuning of [...] Read more.

Aromaticity tuning of biaryl monophosphines can significantly impact their catalytic performance. Biaryl monophosphines constitute a crucial class of compounds due to their potential as ligand precursors in asymmetric Pd-catalyzed cross-coupling and some other catalytic reactions. In this study, we investigate the tuning of aromaticity within a series of selected biaryl monophosphine derivatives exhibiting diverse steric and electronic properties. XRD structures and Hirshfeld surface analyses were complemented by DFT calculations. Aromaticity indices, such as geometric HOMA, HOMER, and magnetic NICS, were evaluated and correlated with ligand properties. NICS(1)zz was the most sensitive to aromaticity changes. The results showed that among the ring-activating substituents, methoxy groups were more beneficial than hydroxy ones. The hydroxy groups not only modulated the aromaticity but also induced unfavorable conformational changes of the catalyst precursors through strong inter- and intramolecular hydrogen bonding. The spatial arrangement of the P atom adjacent to the aryl ring system confers catalytic advantages by promoting the assembly of coordination compounds (catalysts) in which Pd—C bond formation occurs, yielding C,P-chelated five-membered palladacyclic structures. The hydroxy substituents blocked access to the P atom, thereby hindering catalytic performance. The studies show that even subtle changes in the monophosphine biaryl scaffold, especially aromaticity tuning should be carefully evaluated during the rational design of new efficient catalysts. The studied compounds were evaluated for their biological activity against three Gram-positive and four Gram-negative bacteria as model microorganisms. The research was supplemented by in vitro cytotoxicity evaluation. Full article

(This article belongs to the Special Issue The Preparations and Applications of Organophosphorus Compounds)

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15 pages, 4026 KB

Open AccessArticle

Novel Azaborine-Based Inhibitors of Histone Deacetylases (HDACs)

by Martin Behringer, Markus Schweipert, Enna E. Peters, Aleksandra Kopranovic and Franz-Josef Meyer-Almes

Molecules 2025, 30(19), 4017; https://doi.org/10.3390/molecules30194017 - 8 Oct 2025

Viewed by 637

Abstract

Aromatic ring systems appear ubiquitously in active pharmaceutical substances, such as FDA-approved histone deacetylase inhibitors. However, these rings reduce the water solubility of the molecules, which is a disadvantage during application. To address this problem, azaborine rings may be substituted for conventional aromatic [...] Read more.

Aromatic ring systems appear ubiquitously in active pharmaceutical substances, such as FDA-approved histone deacetylase inhibitors. However, these rings reduce the water solubility of the molecules, which is a disadvantage during application. To address this problem, azaborine rings may be substituted for conventional aromatic ring systems. These are obtained by replacing two adjacent carbon atoms with boron and nitrogen. Incorporating B–N analogs in place of aromatic rings not only enhances structural diversity but also provides a strategy to navigate around patent-protected scaffolds. We synthesized azaborines, which are isosteric to naphthalene and indole, and utilized them as capping units for HDAC inhibitors. These molecules were attached to various aliphatic and aromatic linkers with different zinc-binding units, used in established active compounds. Nearly half of the twenty-four molecules tested exhibited inhibitory activity against at least one of the enzymes HDAC1, HDAC4, or HDAC8, with three compounds displaying IC₅₀ values in the nanomolar range. We have therefore demonstrated that azaborine building blocks can be successfully incorporated into HDACis, resulting in a highly active profile. Consequently, it should be feasible to develop active substances containing azaborine rings against other targets. Full article

(This article belongs to the Special Issue Design, Synthesis and Biological Evaluation of Novel Small Molecules Inhibitors, 2nd Edition)

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31 pages, 910 KB

Open AccessReview

The Shift to Bio-Based Auxiliaries in Textile Wet Processing: Recent Advances and Industrial Potential

by Maria L. Catarino, Filipa Sampaio, Luísa Pacheco and Ana L. Gonçalves

Molecules 2025, 30(19), 4016; https://doi.org/10.3390/molecules30194016 - 8 Oct 2025

Viewed by 1358

Abstract

The textile industry is among the most resource-intensive sectors, heavily dependent on water, energy, and synthetic chemicals, particularly in wet processing stages such as desizing, scouring, bleaching, dyeing, printing, and finishing. Conventional practices generate vast amounts of contaminated wastewater, posing severe risks to [...] Read more.

The textile industry is among the most resource-intensive sectors, heavily dependent on water, energy, and synthetic chemicals, particularly in wet processing stages such as desizing, scouring, bleaching, dyeing, printing, and finishing. Conventional practices generate vast amounts of contaminated wastewater, posing severe risks to ecosystems and human health. In recent years, growing environmental concerns and stricter regulations have accelerated the search for sustainable alternatives. Biotechnology offers promising solutions, including enzymes, biopolymers, plant- and agrowaste-derived materials, and microbial metabolites, which can replace conventional auxiliaries and reduce the ecological footprint of textile processing. This review provides a structured overview of recent advances in bio-based compounds applied across different stages of textile wet processing. Applications are critically assessed in terms of performance, efficiency, environmental benefits, and potential for industrial adoption. Current limitations, future outlooks, and examples of commercially available products are also discussed. By highlighting the most recent progress, this review underscores the potential of bio-based innovations to support the transition toward more sustainable and resource-efficient textile manufacturing. Full article

(This article belongs to the Special Issue Advances in Biomass Chemicals: Transformation and Valorization)

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34 pages, 3377 KB

Open AccessReview

Progress in the Study of Extraction Methods and Pharmacological Effects of Traditional Chinese Medicine-Derived Carbon Dots

by Xiaohang Zhou, Junxiang Zhou, Junling Ren, Zhongyuan Qu and Tianlei Zhang

Molecules 2025, 30(19), 4015; https://doi.org/10.3390/molecules30194015 - 8 Oct 2025

Cited by 1 | Viewed by 1537

Abstract

Traditional Chinese medicine-derived carbon dots (TCM-CDs) are prepared by top-down or bottom-up synthesis methods using TCM or their active ingredients as precursors, and the size of TCM-CDs is usually less than 10 nm. It has the advantages of easy preparation, low toxicity, and [...] Read more.

Traditional Chinese medicine-derived carbon dots (TCM-CDs) are prepared by top-down or bottom-up synthesis methods using TCM or their active ingredients as precursors, and the size of TCM-CDs is usually less than 10 nm. It has the advantages of easy preparation, low toxicity, and high compatibility. Compared with traditional Chinese medicines, it shows more outstanding performance in antioxidant, hemostatic, antibacterial, and other aspects, thus having good development prospects. This paper systematically reviews the synthesis methods of carbon dots, focusing on the influence of different traditional Chinese medicine precursors on the formation of carbon dots during the processing process, and analyzes the performance of carbon dots in enhancing the efficacy of original medicinal materials, exerting multi-target synergistic effects, improving bioavailability, and generating new medicinal effects. It is expected to provide a theoretical basis and reference direction for the in-depth research and development of traditional Chinese medicine carbon dots in the field of medicinal value. Full article

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21 pages, 850 KB

Open AccessArticle

From Chemistry to Bioactivity: HS-SPME-GC-MS Profiling and Bacterial Growth Inhibition of Three Different Propolis Samples from Romania, Australia, and Uruguay

by Radosław Balwierz, Katarzyna Kasperkiewicz, Martyna Straszak, Daria Siodłak, Katarzyna Pokajewicz, Ibtissem Ben Hammouda, Piotr P. Wieczorek, Anna Kurek-Górecka, Zenon P. Czuba and Tomasz Baj

Molecules 2025, 30(19), 4014; https://doi.org/10.3390/molecules30194014 - 8 Oct 2025

Cited by 1 | Viewed by 673

Abstract

Propolis is a valuable natural product whose chemical composition and bioactivity are strongly dependent on its geographical and botanical origin. This study presents a comprehensive comparative analysis of the volatile profiles and antibacterial properties of propolis from Romania, Australia, and Uruguay, benchmarked against [...] Read more.

Propolis is a valuable natural product whose chemical composition and bioactivity are strongly dependent on its geographical and botanical origin. This study presents a comprehensive comparative analysis of the volatile profiles and antibacterial properties of propolis from Romania, Australia, and Uruguay, benchmarked against previously published data from samples from Poland and Turkey. Volatile compounds were profiled using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. The resulting data were interrogated using multivariate chemometric analyses (HCA, PCA), and antibacterial activity was assessed via the disk diffusion method against five bacterial strains. Chemometric analysis revealed a clear demarcation into two primary chemotypes: a European type (Poland, Romania, Turkey) dominated by aromatic compounds such as benzoic acid, and a non-European type (Australia, Uruguay) characterized by a high abundance of terpenes. The Australian propolis exhibited a complex terpene profile rich in α-copaene and pinenes, while the Uruguayan sample was distinguished by an exceptionally high concentration of α-pinene. All active extracts showed selective, concentration-dependent inhibition against Gram-positive Staphylococcus aureus and Streptococcus mutans. The terpene-rich Australian propolis displayed the highest antibacterial potency, particularly against S. mutans. Crucially, Pearson correlation analysis revealed a counter-intuitive relationship: the most abundant terpenes in the non-European samples (e.g., α-pinene, verbenone) were significantly negatively correlated with antibacterial activity (r ≈ −0.99). Conversely, less abundant compounds, including linalool and acetic acid, were identified as strong positive predictors of inhibition (r > 0.90). These findings underscore a complex geography-chemotype-bioactivity relationship, where the overall synergistic effect of a mixed chemical profile, rather than the dominance of a single compound, determines antibacterial potency. The initially proposed markers provide a basis for origin-based standardization and highlight Australian propolis as a promising source of natural antibacterial agents. Full article

(This article belongs to the Special Issue Bee Products: Recent Progress in Health Benefits Studies, 2nd Edition)

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22 pages, 4924 KB

Open AccessArticle

Novel Isolongifolenone-Based Caprolactam Derivatives as Potential Anticancer Agents via the p53/mTOR/Autophagy Pathway

by Yunyun Wang, Min Hu, Jiale Han, Yuxun Zhao, Biao Xiong, Peihai Li and Shifa Wang

Molecules 2025, 30(19), 4013; https://doi.org/10.3390/molecules30194013 - 8 Oct 2025

Viewed by 709

Abstract

Isolongifolenone, a natural sesquiterpenoid widely used in food additives and perfume, demonstrates a range of biological activities. In this study, a series of isolongifolenone-based caprolactam derivatives (E1–E19) were designed, synthesized, and evaluated for their anticancer activities in vitro. Most [...] Read more.

Isolongifolenone, a natural sesquiterpenoid widely used in food additives and perfume, demonstrates a range of biological activities. In this study, a series of isolongifolenone-based caprolactam derivatives (E1–E19) were designed, synthesized, and evaluated for their anticancer activities in vitro. Most of the synthesized compounds significantly inhibited the proliferation of cultured cancer cells. Compound E10, containing an m-trifluoromethyl group, demonstrated the strongest anti-proliferation activities against MCF-7 (IC₅₀ = 0.32 µM), HepG2 (IC₅₀ = 1.36 µM), and A549 (IC₅₀ = 1.39 µM) cells. Moreover, E10 was shown to increase intracellular ROS, reduce mitochondrial function, and induce cancer cell apoptosis via the p53/mTOR/autophagy pathway. Together, these results indicate that compound E10 induced autophagy-associated cell apoptosis in MCF-7 cancer cells. Additionally, the antitumor activity of E10 was validated in a zebrafish MCF-7 xenograft model. The observation that E10 exhibits potent antitumor activity in both a three-dimensional (3D) cell culture model and the zebrafish xenograft model supports the development of E10 as a potential drug candidate for cancer therapy. Full article

(This article belongs to the Section Natural Products Chemistry)

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17 pages, 677 KB

Open AccessArticle

The Therapeutic Potential of Laurus nobilis L. Leaves Ethanolic Extract in Cancer Therapy

by Farah Al-Mammori, Ashraf M. A. Qasem, Deniz Al-Tawalbeh, Duaa Abuarqoub and Ali Hmedat

Molecules 2025, 30(19), 4012; https://doi.org/10.3390/molecules30194012 - 7 Oct 2025

Viewed by 1102

Abstract

This study explores the anticancer, antioxidant, and phytochemical activities of Laurus nobilis L. ethanolic leaf extract. The extract demonstrated selective cytotoxicity against four human cancer cell lines, showing strong cytotoxic effect against ovarian (ES2), head and neck (SAS), and colorectal (HT-29) cancer cells, [...] Read more.

This study explores the anticancer, antioxidant, and phytochemical activities of Laurus nobilis L. ethanolic leaf extract. The extract demonstrated selective cytotoxicity against four human cancer cell lines, showing strong cytotoxic effect against ovarian (ES2), head and neck (SAS), and colorectal (HT-29) cancer cells, with IC₅₀ values ranging from 3.8 ± 0.3 to 4.4 ± 0.6 µg/mL. Notably, it exhibited only moderate inhibition of the MDA-MB-231 breast cancer cell line (IC₅₀ = 18.5 ± 0.8 µg/mL), possibly reflecting intrinsic differences in cell line sensitivity. Importantly, the extract showed low toxicity toward normal human fibroblasts (HDF), with an IC₅₀ value exceeding 100 µg/mL, indicating a favorable selectivity profile. The flow cytometry analysis showed that the extract caused cell death and stopped the cell cycle in both SAS and ES2 cancer cell lines. In SAS cells, extract treatment significantly increased apoptotic cells (21.1% ± 0.3%) compared to the control (6.3% ± 0.4%), along with G2 phase accumulation, indicating G2 arrest. Similarly, in ES2 cells, apoptosis increased (16.2% ± 1.3% vs. control 8.1% ± 1.0%), and a significant cell accumulation in the S phase was observed, suggesting disruption of cell cycle progression. Antioxidant screenings showed impressive dose-dependent DPPH radical scavenging activity (25–2000 µg/mL), although less potent than ascorbic acid (2.6 µg/mL). UPLC-QTOF/MS phytochemical analysis revealed various phenolic constituents, such as flavonoids and phenolic acids, and an inferred association with the recorded bioactivities. This preliminary work indicates that L. nobilis extracts may act as natural anticancer and antioxidant agents; however, it was limited to in vitro testing with non-standardized samples, underscoring the need for further research to validate and extend these findings for future applications. Full article

(This article belongs to the Special Issue Advances in Plant-Sourced Natural Compounds as Anticancer Agents)

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15 pages, 1112 KB

Open AccessArticle

Synthesis of New Brassinosteroid Analogs with Androstane Skeleton and Heterocyclic Acyl Side Chains: Preliminary Molecular Docking Studies

by Omara Araya, María Núñez, Marco Mellado, Andrés F. Olea and Luis Espinoza-Catalán

Molecules 2025, 30(19), 4011; https://doi.org/10.3390/molecules30194011 - 7 Oct 2025

Viewed by 585

Abstract

Brassinosteroid analogs with heterocyclic rings in the side chain are interesting because important biological activity has been shown by these compounds. Thus, herein, five 23-24-dinorcholane BR analogs with a heterocyclic ester function at C-22 were synthesized and fully characterized by different spectroscopic techniques. [...] Read more.

Brassinosteroid analogs with heterocyclic rings in the side chain are interesting because important biological activity has been shown by these compounds. Thus, herein, five 23-24-dinorcholane BR analogs with a heterocyclic ester function at C-22 were synthesized and fully characterized by different spectroscopic techniques. The acylation reaction at C-22, which is a key synthetic step, was carried out by two different methods, namely acylation with heterocyclic acid chlorides and Steglich esterification reaction. In both cases, the acyl derivatives were obtained with good yields. Additionally, a preliminary molecular docking study of BRI1–BAK1 complexes formed by these analogs and brassinolide was performed to estimate what their biological activity would be. Results indicate that the complex formed by the analog 36, which has an indole group in the side chain, within the active site of BRI1–BAK1 is more stable than that formed by brassinolide. Additionally, molecular docking of a derivative having a benzoate function at C-22 and a F atom in the ortho position, 23, shows a similar pose and interactions at the active site but the highest binding energy. As 23 has shown similar activity to brassinolide in the Rice Lamina Inclination Test, it is expected that 36 will also exhibit similar behavior. Full article

(This article belongs to the Special Issue Heterocyclic Compounds: Synthesis, Application and Theoretical Study)

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23 pages, 3836 KB

Open AccessArticle

Kinetically Assisted Chemical Removal of Organic Contaminants by Reactive Oxygen Species: Insights from ReaxFF Molecular Dynamics Simulations

by Zixu Wang, Yuhai Li, Peng Zhang, Fei Wang, Laixi Sun, Qingshun Bai, Mingzhi Zhu and Baoxu Wang

Molecules 2025, 30(19), 4010; https://doi.org/10.3390/molecules30194010 - 7 Oct 2025

Viewed by 609

Abstract

Organic contaminants on optical components critically impair intense laser systems. Oxygen plasma cleaning is a promising non-contact method, yet the mechanism by which the initial kinetic energy of reactive oxygen species assists chemically driven removal remains unclear. This study employs ReaxFF molecular dynamics [...] Read more.

Organic contaminants on optical components critically impair intense laser systems. Oxygen plasma cleaning is a promising non-contact method, yet the mechanism by which the initial kinetic energy of reactive oxygen species assists chemically driven removal remains unclear. This study employs ReaxFF molecular dynamics to elucidate how reactive oxygen species chemically decompose dibutyl phthalate and how kinetic energy assists chemical reactions by enhancing transport, penetration, and energy transfer. While the core removal mechanism is chemical, kinetic energy promotes plasma-contaminant encounters and facilitates access to otherwise sluggish pathways. The results show that kinetic energy is a key promoter that enhances chemical decomposition, with the contaminant decomposition rate enhanced by up to 1310% and residues reduced by 81.13% compared to pure chemical reactions. This study identifies and quantifies two dominant reaction pathways (butyl chain cleavage & benzene ring cleavage). The analysis of diffusion and energy transfer reveals that higher kinetic energy improves reactive oxygen species transport, enables deeper penetration, and selectively activates specific reaction pathways by overcoming energy barriers. Synergy with flux, dose, and temperature is also demonstrated. This work provides atomic-level insights into kinetic promotion mechanisms, supporting optimized plasma cleaning processes and contributing to the performance stability and operational longevity of intense laser systems. Full article

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24 pages, 2338 KB

Open AccessArticle

Comparative (Bio)monitoring of Airborne PAHs Using Mosses and Filters

by Małgorzata Rajfur, Paweł Świsłowski, Tymoteusz Turlej, Oznur Isinkaralar, Kaan Isinkaralar, Sara Almasi, Arianna Callegari and Anca-Iulia Stoica

Molecules 2025, 30(19), 4009; https://doi.org/10.3390/molecules30194009 - 7 Oct 2025

Viewed by 853

Abstract

The present investigation provides a comparative six-month analysis of atmospheric pollution by polycyclic aromatic hydrocarbons (PAHs) in the urban region of Opole, Poland. The study employs dual monitoring methods: traditional quartz filter-based active air sampling and active moss biomonitoring using Pleurozium schreberi, [...] Read more.

The present investigation provides a comparative six-month analysis of atmospheric pollution by polycyclic aromatic hydrocarbons (PAHs) in the urban region of Opole, Poland. The study employs dual monitoring methods: traditional quartz filter-based active air sampling and active moss biomonitoring using Pleurozium schreberi, Sphagnum fallax, and Dicranum polysetum mosses. The experimental campaign took place from August 2021 to February 2022, spanning the autumn and winter seasons. PAH concentrations were measured using gas chromatography–mass spectrometry (GC-MS) following methodical sample extraction protocols. Filters documented transient air changes in PAHs, particularly high-molecular-weight (HMW) components such as benzo[a]pyrene (BaP), which exhibited considerable increases during the colder months due to heightened heating activities and less dispersion. The size of particles deposited on the filters varied from 0.16 to 73.6 μm, with an average size of 0.71 μm. Mosses exhibited cumulative uptake trends, with D. polysetum showing the greatest bioaccumulation efficiency, particularly for low- and medium-molecular-weight PAHs, followed by P. schreberi and S. fallax. Meteorological indices, including sun radiation and air temperature, demonstrated significant negative relationships with PAH buildup in mosses. Diagnostic ratio analysis verified primarily pyrogenic sources (e.g., fossil fuel burning), although petrogenic contributions were detected in D. polysetum, indicating its increased sensitivity to evaporative emissions. The study shows that the integration of moss biomonitoring with traditional filter samples provides a strong, complementary framework for assessing air quality, particularly in fluctuating meteorological settings. The results advocate for the integration of moss-based methodologies into environmental monitoring initiatives and provide significant insights into contaminant dynamics influenced by seasonal and meteorological factors. Full article

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20 pages, 2545 KB

Open AccessArticle

Impacts of Tween-20, Glycerol, and Trehalose on Hyaluronidase Activity: Insights from Microscale Thermophoresis and Capillary Electrophoresis

by Rouba Nasreddine, Josipa Cecić Vidoš, Alexandra Launay and Reine Nehmé

Molecules 2025, 30(19), 4008; https://doi.org/10.3390/molecules30194008 - 7 Oct 2025

Viewed by 993

Abstract

Additives such as surfactants (Tween-20) and cryoprotectants (glycerol and trehalose) are often used in enzymatic assays to improve the quality and long-term stabilization of proteins. However, these additives can affect the enzymatic activity and the enzyme’s affinity for active compounds, such as inhibitors, [...] Read more.

Additives such as surfactants (Tween-20) and cryoprotectants (glycerol and trehalose) are often used in enzymatic assays to improve the quality and long-term stabilization of proteins. However, these additives can affect the enzymatic activity and the enzyme’s affinity for active compounds, such as inhibitors, and must be considered during assay design since a slight shift in enzyme behavior may compromise the reliability of the results. In this study, the effects of Tween-20, glycerol, and trehalose on hyaluronidase (Hyal) were systematically evaluated by assessing their influence both directly—through microscale thermophoresis (MST) signals of the labeled enzyme (Hyal*)—and indirectly, by monitoring the formation of the final product of the degradation of hyaluronic acid, tetrasaccharide (Tet), using capillary electrophoresis (CE/UV). Hyal was labeled for the first time with ATTO-647 NHS ester, a commercial dye compatible with MST. Efficient labeling was achieved in a phosphate-based buffer without loss of catalytic activity. Tween-20 showed no impact on MST signals nor on enzymatic performance when used between 0.005 and 0.05% (v/v). Glycerol also did not interfere with MST measurements; however, it significantly reduced catalytic activity at concentrations above 2% (v/v). Trehalose affected Hyal* fluorescence in a concentration-dependent manner and enhanced catalytic activity even at 0.02% (v/v). Full article

(This article belongs to the Special Issue Peptide and Protein-Based Materials: Technology and Applications)

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30 pages, 3795 KB

Open AccessArticle

Alpha-Lipoic Acid in Early-Stage Alcohol-Related Brain Damage in Rats: A Comparative Pilot Study

by Hristian Staykov, Stela Dragomanova, Yordan Hodzhev, Valya Grigorova, Borislav Minchev, Diamara Uzunova, Ani Georgieva, Inna Sulikovska, Katerina Todorova, Elina Tsvetanova, Almira Georgieva, Miroslava Stefanova, Pendar Valadbeigi, Reni Kalfin, Rumen Nikolov and Lyubka Tancheva

Molecules 2025, 30(19), 4007; https://doi.org/10.3390/molecules30194007 - 7 Oct 2025

Viewed by 2015

Abstract

Alcohol misuse can lead to alcohol-related brain damage (ARBD), a condition linked to long-term cognitive impairment and considerable disease burden. The pharmacological characteristics of alpha-lipoic acid (ALA) make it a promising candidate for the treatment of ARBD. In this study, adult male Wistar [...] Read more.

Alcohol misuse can lead to alcohol-related brain damage (ARBD), a condition linked to long-term cognitive impairment and considerable disease burden. The pharmacological characteristics of alpha-lipoic acid (ALA) make it a promising candidate for the treatment of ARBD. In this study, adult male Wistar rats were divided into eight experimental groups. Four groups received a 20% (v/v) ethanol–tap water solution ad libitum for 15 weeks to induce early-stage ARBD, while the remaining received only tap water. After 14 weeks, all groups were administered daily injections for one week with either ALA, rivastigmine, or memantine. Behavioral testing included the step-through passive avoidance and rotarod performance tests. Whole-brain biochemical analyses assessed acetylcholinesterase activity, brain-derived neurotrophic factor, and oxidative stress biomarkers. Brain weight, relative brain weight, and brain histopathological changes were also evaluated. Results showed that, similar to memantine and rivastigmine, ALA improved STL at both 24 h and 8 days and reduced ethanol-induced Purkinje cell damage. It also decreased lipid peroxidation levels by 44%, unlike the reference drugs, and superoxide dismutase activity by 33%, similar to them. No other significant changes were detected. Albeit several limitations, this is the first study comparing ALA with rivastigmine and memantine in this experimental context. Full article

(This article belongs to the Section Medicinal Chemistry)

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15 pages, 3066 KB

Open AccessArticle

Optimal Extraction of Antioxidants, Flavonoids, and Phenolic Acids from the Leaves of Apocynum venetum L. by Response Surface Methodology with Integrated Chemical Profiles and Bioactivity Evaluation

by Rulan Qin, Jinhang Song, Qiang Wang, Yingli Guan and Chongning Lv

Molecules 2025, 30(19), 4006; https://doi.org/10.3390/molecules30194006 - 7 Oct 2025

Viewed by 764

Abstract

The leaves of Apocynum venetum L. (A. venetum L.) are a functional food that plays an important role in antioxidation due to its high content of flavonoids and phenolic acids. Therefore, the extraction process of leaves of A. venetum L. is closely [...] Read more.

The leaves of Apocynum venetum L. (A. venetum L.) are a functional food that plays an important role in antioxidation due to its high content of flavonoids and phenolic acids. Therefore, the extraction process of leaves of A. venetum L. is closely related to their activity. In this study, ultra-high-performance liquid chromatography (UHPLC) coupled with diode array detector (DAD), electrospray ionization (ESI), and quadrupole time-of-flight mass spectrometry (QTOF/MS) techniques has been established for qualitative and quantitative analysis of three phenolic acids and six flavonoids in the leaves of A. venetum L. Ultrasonic-assisted extraction conditions for the maximum recovery of phenolic and flavonoid compounds with a high antioxidation effect were optimized by response surface methodology (RSM). The optimum extraction conditions were as follows: ethanol concentration 64%, extraction time 20 min, and liquid-to-solid ratio 16:1 mL/g. The yields of three phenolic acids and six flavonoids under the optimal process were found to be 8.932 ± 0.091 and 20.530 ± 0.198 mg/g, respectively, which matched with those predicted (8.751 and 20.411 mg/g) within a 95% confidence level. Antioxidant activities based on ABTS and DPPH assays showed that the optimal extracts had strong activities compared with those of conventional reflux extraction methods. Moreover, the contribution of total and individual phenolic acids and flavonoids to antioxidant activity was also estimated by Pearson correlation analysis. Full article

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14 pages, 1955 KB

Open AccessArticle

Investigation of Photorecoordination Kinetics for Complexes of Bis(aza-18-crown-6)-Containing Dienones with Alkali and Alkaline-Earth Metal Cations via Time-Resolved Absorption Spectroscopy: Structure vs. Properties

by Oleg A. Alatortsev, Valeriy V. Volchkov, Mikhail N. Khimich, Ivan D. Sorokin, Mikhail Ya. Melnikov, Fedor E. Gostev, Ivan V. Shelaev, Victor A. Nadtochenko, Marina V. Fomina and Sergey P. Gromov

Molecules 2025, 30(19), 4005; https://doi.org/10.3390/molecules30194005 - 7 Oct 2025

Viewed by 514

Abstract

The analysis of time-resolved S₁–S_n absorption spectra in the 0–500 ps range, together with quantum-chemical calculations, uncovered a photorecoordination reaction for the following complexes of CD6 (a bis(aza-18-crown-6)-containing dienone (ketocyanine dye) with a central cyclohexanone fragment): CD6·(Mⁿ⁺)₂ [...] Read more.

The analysis of time-resolved S₁–S_n absorption spectra in the 0–500 ps range, together with quantum-chemical calculations, uncovered a photorecoordination reaction for the following complexes of CD6 (a bis(aza-18-crown-6)-containing dienone (ketocyanine dye) with a central cyclohexanone fragment): CD6·(Mⁿ⁺)₂ (M = Ba²⁺, Sr²⁺, Ca²⁺, K⁺). This process takes place over hundreds of fs and involves an “axial-to-equatorial” conformational change, with the solvation shell undergoing rearrangement as well. The characteristic photorecoordination times were found to correlate with the stability constants of the complexes. The lifetimes for the fluorescent states of CD6 and its complexes, namely CD6·(Mⁿ⁺)₂ (M = Ba²⁺, Sr²⁺, Ca²⁺, K⁺), are different; ergo, there is no photoejection of crowned cations into the solution. The calculated conformational profiles in the ground and excited states indicate the presence of an energy barrier in this process. A general photorelaxation pathway is suggested for CD6·(Mⁿ⁺)₂ metal complexes (M = Ba²⁺, Sr²⁺, Ca²⁺, K⁺). The coordination of cations via the carbonyl moiety in the dye molecule promotes photorecoordination of metal cations in the cavities of the azacrown ether fragment. Photorecoordination times were found to correlate with the degree of conjugation between the lone pairs in the N atoms of the aza-18-crown-6 ether and the π subsystem in the dye molecules (established for the CD4–CD6 metal–dye complex series, where CD4 and CD5 are related dyes with central cyclobutanone and cyclopentanone fragments, respectively). Full article

(This article belongs to the Section Macromolecular Chemistry)

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20 pages, 3137 KB

Open AccessArticle

HX-Linear and Nonlinear Optical Responsiveness of Rationally Designed Heteroleptic d⁸-Metallo-dithiolene Complexes

by Salahuddin S. Attar, Flavia Artizzu, Luca Pilia, Angela Serpe, Alessia Colombo, Claudia Dragonetti, Francesco Fagnani, Dominique Roberto, Daniele Marinotto and Paola Deplano

Molecules 2025, 30(19), 4004; https://doi.org/10.3390/molecules30194004 - 7 Oct 2025

Viewed by 533

Abstract

This work presents the HX-responsiveness of the following heteroleptic donor–M–acceptor dithiolene complexes: Bu4N[MII(L1)(L2)] [M = Ni(1), Pd(2), Pt(3)], where L1 is the chiral acceptor ligand [(R)-α-MBAdto = chiral (R)-(+)α-methylbenzyldithio-oxamidate] and L2 is the donor ligand (tdas = [...] Read more.

This work presents the HX-responsiveness of the following heteroleptic donor–M–acceptor dithiolene complexes: Bu4N[MII(L1)(L2)] [M = Ni(1), Pd(2), Pt(3)], where L1 is the chiral acceptor ligand [(R)-α-MBAdto = chiral (R)-(+)α-methylbenzyldithio-oxamidate] and L2 is the donor ligand (tdas = 1,2,5-thiadiazole-3,4-dithiolato). Addition of hydrohalic acids induces a strong bathochromic shift and visible color change, which is fully reversed by ammonia (NH₃). Moreover, the sensing capability of 1 was further evaluated by deposition on a cellulose substrate. Exposure to HCl vapors induces an evident color change from purple to green, whereas successive exposure to NH₃ vapors fully restores the purple color. Remarkably, cellulose films of 1 were revealed to be excellent optical sensors against the response to triethylamine, which is a toxic volatile amine. Moreover, the HCl-responsiveness of the nonlinear optical properties of complexes 1, 2, and 3 embedded into a poly(methyl methacrylate) poled matrix was demonstrated. Reversible chemical second harmonic generation (SHG) switching is achieved by exposing the poled films to HCl vapors and then to NH₃ vapors. The SHG response ratio HCl–adduct/complex is significant (around 1.5). Remarkably, the coefficients of the susceptibility tensor for the HCl–adduct films are always larger than those of the respective free-complex films. Density Functional Theory (DFT) and time-dependent DFT calculations help in highlighting the structure–properties relationship. Full article

(This article belongs to the Special Issue Functional Coordination Compounds: Design, Synthesis and Applications)

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67 pages, 2023 KB

Open AccessReview

Therapeutic Bioactivity Exerted by the Apis mellifera Bee Venom and Its Major Protein Melittin: A Scoping Review

by Perihan Mutlu Erdoğan, Funda Bilgili-Tetikoğlu, Selcen Çelik-Uzuner, Oktay Yıldız, Sevgi Kolayli and Dimitris Mossialos

Molecules 2025, 30(19), 4003; https://doi.org/10.3390/molecules30194003 - 7 Oct 2025

Viewed by 3584

Abstract

Honey bee (Apis mellifera) products have been extensively utilized in traditional medicine. Bee venom (BV) is one of the major bee products with a high concentration of the small peptide melittin (MEL) and exerts bioactivity ranging from anti-microbial to anti-inflammatory and [...] Read more.

Honey bee (Apis mellifera) products have been extensively utilized in traditional medicine. Bee venom (BV) is one of the major bee products with a high concentration of the small peptide melittin (MEL) and exerts bioactivity ranging from anti-microbial to anti-inflammatory and anti-cancer. This scoping review aims to sum up research articles on the bioactivity exerted by BV and MEL published in PubMed and Scopus from 2010 onwards. PRISMA guidelines were implemented to analyze the relevant literature; we ended up with 425 research articles. Bioactivity of BV and MEL was grouped as (i) anti-inflammatory (85), (ii) immunomodulatory (37), (iii) anti-microbial (179), (iv) anti-cancer (170), and (v) anti-oxidant (32). Although there is a significant body of research on the anti-cancer and anti-microbial activity of BV and MEL, their anti-oxidant, anti-inflammatory and immunomodulatory properties have received comparatively less attention. Many studies on the immunomodulatory effects of BV or MEL have focused on cancer. However, the effects on Parkinson’s and Alzheimer’s disease have not been extensively studied regarding the anti-inflammatory effects. Given the critical role of the immune system and inflammatory response in cancer, neurodegenerative diseases, senescence and against infections, it is paramount to further explore the immunomodulatory and anti-inflammatory potential of BV and MEL. Full article

(This article belongs to the Special Issue Bee Products: Recent Progress in Health Benefits Studies, 2nd Edition)

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