Molecules

22 pages, 1449 KB

Open AccessArticle

Photocatalytic Evaluation of Fe₂O₃–TiO₂ Nanocomposites: Influence of TiO₂ Content on Their Structure and Activity

by Israel Águila-Martínez, Pablo Eduardo Cardoso-Avila, Isaac Zarazúa, Héctor Pérez Ladrón de Guevara, José Antonio Pérez-Tavares, Efrén González-Aguiñaga and Rita Patakfalvi

Molecules 2025, 30(21), 4309; https://doi.org/10.3390/molecules30214309 - 5 Nov 2025

Abstract

In this study, Fe₂O₃–TiO₂ nanocomposites with different TiO₂ contents (1–50%) were synthesized via a solvothermal method using pre-formed α-Fe₂O₃ nanoparticles as cores. We systematically evaluated the influence of TiO₂ loading on the nanocomposites’ [...] Read more.

In this study, Fe₂O₃–TiO₂ nanocomposites with different TiO₂ contents (1–50%) were synthesized via a solvothermal method using pre-formed α-Fe₂O₃ nanoparticles as cores. We systematically evaluated the influence of TiO₂ loading on the nanocomposites’ structural, morphological, optical, and photocatalytic properties. X-ray diffraction revealed the coexistence of hematite and anatase phases, with an increase in TiO₂ content inducing reduced crystallite size, enhanced dislocation density, and microstrain, indicating interfacial lattice distortion. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) showed a uniform elemental distribution at low TiO₂ contents, evolving into irregular agglomerates at higher loadings. Fourier-transform infrared (FTIR) spectra indicated the suppression of Fe–O vibrations and the appearance of hydroxyl-related bands with TiO₂ enrichment. Diffuse reflectance spectroscopy (DRS) analysis confirmed the simultaneous presence of hematite (~2.0 eV) and anatase (3.2–3.35 eV) absorption edges, with a slight blue shift in the TiO₂ band gap at higher concentrations. Photocatalytic activity, assessed using methylene blue degradation under xenon lamp irradiation, demonstrated a strong dependence on the TiO₂ fraction. The composite containing 33% TiO₂ achieved the best performance, with 98% dye removal and a pseudo-first-order rate constant of 0.045 min⁻¹, outperforming both pure hematite and commercial P25 TiO₂. These results highlight that intermediate TiO₂ content (~33%) provides an optimal balance between structural integrity and photocatalytic efficiency, making Fe₂O₃–TiO₂ heterostructures promising candidates for water purification under simulated solar irradiation. Full article

(This article belongs to the Special Issue Nanomaterials and Nanocomposites: Synthesis, Characterization and Applications in Environmental and Biomedical Sciences)

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12 pages, 1184 KB

Open AccessArticle

Racemosol Derivatives and Other Metabolites from Bauhinia malabarica Bark with Antibacterial Activity

by Wanchat Sirisarn, Apisara Somteds, Supachai Jadsadajerm, Sutin Kaennakam, Nuttapon Yodsin and Awat Wisetsai

Molecules 2025, 30(21), 4308; https://doi.org/10.3390/molecules30214308 - 5 Nov 2025

Abstract

Racemosol, a natural phenolic compound, is known for its antimicrobial potential, yet experimental studies remain limited. In this study, two new racemosol derivatives (4 and 5) and four known compounds (1–3, 6) were isolated from the [...] Read more.

Racemosol, a natural phenolic compound, is known for its antimicrobial potential, yet experimental studies remain limited. In this study, two new racemosol derivatives (4 and 5) and four known compounds (1–3, 6) were isolated from the bark of Bauhinia malabarica and structurally elucidated using spectroscopic analyses. Most of isolated compounds exhibited notable activity against Gram-positive bacteria, including Staphylococcus aureus, Bacillus subtilis, and Listeria monocytogenes, while showing limited effects on Gram-negative strains. Racemosol (1) and its derivatives (2, 4, and 6) displayed potent antibacterial activity with MIC values of 0.156–0.625 µg/µL and bactericidal properties confirmed by comparable MBCs. Compound 6 exhibited the highest potency, indicating that specific structural modifications enhance activity. These findings provide new insights into the structure activity relationships of racemosol derivatives and highlight B. malabarica as a promising natural source of phenolic antibacterial agents. Full article

(This article belongs to the Special Issue Phytochemicals and Bioactivity: Advances in Natural Product Chemistry and Applications)

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22 pages, 5222 KB

Open AccessArticle

Liquid Phase Catalytic Transfer Hydrogenation of Crotonaldehyde over ReO_x-Supported Catalysts Using Formic Acid as In Situ Hydrogen Donor

by Carlos Esteban Aristizábal-Alzate, Verónica Naharro-Ovejero, Manuel Romero-Sáez and Ana Belén Dongil

Molecules 2025, 30(21), 4307; https://doi.org/10.3390/molecules30214307 - 5 Nov 2025

Abstract

The selective hydrogenation of the C=O bond over the C=C bond in α,β-unsaturated aldehydes remains a well-known challenge. This work investigates the liquid-phase catalytic transfer hydrogenation of crotonaldehyde to crotyl alcohol over ReOx-based catalysts, using formic acid (FA) as an in situ hydrogen [...] Read more.

The selective hydrogenation of the C=O bond over the C=C bond in α,β-unsaturated aldehydes remains a well-known challenge. This work investigates the liquid-phase catalytic transfer hydrogenation of crotonaldehyde to crotyl alcohol over ReOx-based catalysts, using formic acid (FA) as an in situ hydrogen donor. A series of 10 wt% Re catalysts supported on G200, g-C₃N₄, TiO₂, and ZrO₂ were synthesized and tested in a batch reactor at 20 bar and temperatures of 140–180 °C. Catalysts were characterized by XRD, BET, NH₃-TPD, and XPS to correlate their physicochemical properties with catalytic behavior. Among the studied materials, ReO_x/ZrO₂ and ReO_x/g-C₃N₄ exhibited the highest crotyl alcohol selectivity above 57% for all reaction temperatures, evaluated at crotonaldehyde conversion of 25%. The nature of the support strongly influenced the dispersion and oxidation state of Re species, as well as the surface acidity, which governed the activation of both the carbonyl group and the FA decomposition. Compared with molecular hydrogen, FA improved both conversion and selectivity due to its superior hydrogen-donating ability in the aqueous phase. These findings demonstrate that tailoring the acid–base characteristics of ReO_x catalysts and employing biomass-derived hydrogen donors represent an effective strategy for selective hydrogenation of α,β-unsaturated aldehydes. Full article

(This article belongs to the Special Issue Recent Advances on Biomass Conversion and CO₂ Valorization: Steeping Towards a Circular Economy, 2nd Edition)

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20 pages, 2363 KB

Open AccessArticle

On the Question of the Application Potential and the Molecular Mechanism of the Formation of 1,3-Diaryl-5-Nitropyrazoles from Trichloromethylated Diarylnitropyrazolines

by Karolina Kula and Radomir Jasiński

Molecules 2025, 30(21), 4306; https://doi.org/10.3390/molecules30214306 - 5 Nov 2025

Abstract

The molecular mechanism of the formation of 1,3-diaryl-5-nitropyrazoles via a CHCl₃-elimination reaction was investigated using ωB97xD/6-31+G(d,p) (PCM) calculations. It was found that, regardless of the polarity of the reaction environment or the nature of the substituents on the phenyl rings of [...] Read more.

The molecular mechanism of the formation of 1,3-diaryl-5-nitropyrazoles via a CHCl₃-elimination reaction was investigated using ωB97xD/6-31+G(d,p) (PCM) calculations. It was found that, regardless of the polarity of the reaction environment or the nature of the substituents on the phenyl rings of the starting molecules, the elimination process proceeds through a single-step mechanism characterized by an extremely asynchronous transition state. The ELF (Electron Localization Function) analysis of selected critical structures confirms the proposed mechanism and reveals a pronounced reorganization of electrons within the heterocyclic ring. The in silico analysis based on ADME (Activity, Distribution, Metabolism, and Excretion) and PASS (Prediction of Activity Spectra for Substances) predictions indicates that the title 1,3-diaryl-5-nitropyrazoles exhibit promising biological potential, showing inhibitory activity against both oxidoreductases and proteases. The most consistent targets include hyponitrite reductase, (R)-6-hydroxynicotine oxidase, acrocylindropepsin, saccharopepsin, and chymosin. Thus, the presented CHCl₃-elimination provides an efficient and versatile route to functionalized pyrazoles, and, together with their promising bioactivity, confirms the utility of this approach for their synthesis. Full article

(This article belongs to the Special Issue Selectivity and Theoretical Studies of Cycloaddition Reactions)

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22 pages, 1127 KB

Open AccessArticle

Multiway Analysis of the Electrochemical Oxidation Pathway of a Lignin Using Chemometrics

by Gobind Sah, John A. Staser and Peter B. Harrington

Molecules 2025, 30(21), 4305; https://doi.org/10.3390/molecules30214305 - 5 Nov 2025

Abstract

The electrochemical oxidation mechanism of biopolymer lignin is challenging to characterize due to its complex structure. Controlling the oxidation process is crucial for ensuring the economic feasibility of electrochemical depolymerization of lignin, as it often generates numerous undesirable compounds. Regulating the depolymerization process [...] Read more.

The electrochemical oxidation mechanism of biopolymer lignin is challenging to characterize due to its complex structure. Controlling the oxidation process is crucial for ensuring the economic feasibility of electrochemical depolymerization of lignin, as it often generates numerous undesirable compounds. Regulating the depolymerization process can lead to the production of high-yield aromatic compounds, such as phenols and carboxylic acids. In addition to the depolymerization of lignin by the electrocatalyst, hydroxyl radicals (^•OH) during the electrochemical oxidation could also depolymerize lignin. Previous studies have reported that ^•OH forms during electrochemical oxidation; however, it is still uncertain whether these radicals or electrocatalysts are responsible for depolymerizing lignin. This study investigates the pivotal issue of whether the depolymerization process is driven by ^•OH or by a direct electrochemical route. In this study, lignin compounds were electrochemically oxidized using a nickel-cobalt (Ni-Co) electrocatalyst at several electrode potentials, and the oxidized products were analyzed using headspace solid-phase micro-extraction gas chromatography–mass spectrometry (SPME-GC-MS) and factor analysis (FA). Electrochemical depolymerization of lignin yielded mainly phenolic compounds (e.g., tert-butyl phenols), phthalate esters (e.g., dibutyl phthalate, bis(2-methylpropyl) phthalate), furan derivatives (e.g., 2-butyltetrahydrofuran), and short-chain carboxylic acid esters. This work has successfully predicted that both electrocatalyst and ^•OH radicals contribute to the electrochemical depolymerization of lignin. Radical-mediated depolymerization yielded a broader range of products. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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35 pages, 1832 KB

Open AccessReview

Recent Approaches for Bioactive Peptides Production from Pulses and Pseudocereals

by Manuel Martoccia, Vincenzo Disca, Yassine Jaouhari, Matteo Bordiga and Jean Daniel Coïsson

Molecules 2025, 30(21), 4304; https://doi.org/10.3390/molecules30214304 - 5 Nov 2025

Abstract

Pulses and pseudocereals are sustainable protein sources of bioactive peptides (BAPs) with potential antioxidant, antihypertensive, antidiabetic, antimicrobial, and immunomodulatory activities. BAPs are typically liberated during gastrointestinal digestion or through bio-based processes, among which enzymatic hydrolysis and microbial fermentation represent the most widely applied [...] Read more.

Pulses and pseudocereals are sustainable protein sources of bioactive peptides (BAPs) with potential antioxidant, antihypertensive, antidiabetic, antimicrobial, and immunomodulatory activities. BAPs are typically liberated during gastrointestinal digestion or through bio-based processes, among which enzymatic hydrolysis and microbial fermentation represent the most widely applied strategies. Enzymatic hydrolysis provides controlled and reproducible release of short peptide motifs; recent advances such as ultrasound- or high-pressure–assisted hydrolysis enhance yield and bioactivity. Fermentation exploits microbial proteolytic activity to generate complex peptide mixtures, while improving sensory quality, reducing antinutritional compounds, and responding to consumer demand for natural and “clean-label” products. In silico tools increasingly complement these approaches by accelerating peptide discovery, predicting interactions with molecular targets, and guiding process design. This review provides an updated overview of bio-based methods to produce BAPs from pulses and pseudocereals, emphasizing the comparative advantages of enzymatic and fermentation technologies and their integration with computational tools. Moreover, it examines regulatory frameworks in the European Union, the United States, Japan, and China, while discussing current challenges for industrial scale-up and application in functional foods and nutraceuticals. These combined strategies offer a promising pathway to unlock the health and sustainability potential of plant proteins. Full article

(This article belongs to the Special Issue Bioproducts for Health, 4th Edition)

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35 pages, 3381 KB

Open AccessReview

From Triads to Tools: A Comprehensive Review of the Expanding Roles of G-Triplex Structures

by Mitchell W. Myhre, Malay Kumar Das, Elizabeth P. Williams, Wendi M. David and Sean M. Kerwin

Molecules 2025, 30(21), 4303; https://doi.org/10.3390/molecules30214303 - 5 Nov 2025

Abstract

Interest in non-canonical DNA structures continues to grow, in part fueled by the recent discovery of a new structure, G-triplex DNA. Originally proposed as folding intermediates for G-quadruplex DNA, G-triplex DNA has more recently been shown to form from truncated G-quadruplex sequence oligonucleotides [...] Read more.

Interest in non-canonical DNA structures continues to grow, in part fueled by the recent discovery of a new structure, G-triplex DNA. Originally proposed as folding intermediates for G-quadruplex DNA, G-triplex DNA has more recently been shown to form from truncated G-quadruplex sequence oligonucleotides and other, specifically designed sequences. In this review, we provide the first, comprehensive survey of G-triplex DNA and RNA, covering the literature up to 2024. We include reports of G-triplex DNA from bulk solution and single-molecule approaches, the structural characterization of G-triplex DNA, and the breadth of oligonucleotide sequences that have been reported to form these structures. The formation of G-triplex RNA structures is also reviewed. The evolving understanding of sequence and environmental effects on G-triplex formation are presented together with challenges due to structural polymorphism and competing formation of multimeric G-quadruplex structures. Hints of the biological relevance of G-triplexes are provided by reports of protein recognition of these structures and their effects on DNA replication in vitro. Interaction of G-triplex DNA with a variety of ligands has been reported, although the search for selective ligands that can distinguish G-triplex from G-quadruplex is on-going. The vast majority of publications in the area have focused on the utilization of G-triplex in biosensing applications, which has shown some advantages compared to G-quadruplex-based systems. These results highlight the potential utility of G-triplex structures in a variety of domains and show its promise in applications in biotechnology, medicine, and research. Full article

(This article belongs to the Section Molecular Structure)

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44 pages, 3371 KB

Open AccessReview

Advances in Naturally and Synthetically Derived Bioactive Sesquiterpenes and Their Derivatives: Applications in Targeting Cancer and Neurodegenerative Diseases

by Liana R. Cutter, Alexandra R. Ren and Ipsita A. Banerjee

Molecules 2025, 30(21), 4302; https://doi.org/10.3390/molecules30214302 - 5 Nov 2025

Abstract

Sesquiterpenes are a diverse class of natural products that have garnered considerable interest for their potent bioactivity and structural variability. This review highlights advances in the derivatization of various sesquiterpene lactones, quinones, and alcohols, particularly in targeting cancer and neurodegenerative diseases. The structural [...] Read more.

Sesquiterpenes are a diverse class of natural products that have garnered considerable interest for their potent bioactivity and structural variability. This review highlights advances in the derivatization of various sesquiterpene lactones, quinones, and alcohols, particularly in targeting cancer and neurodegenerative diseases. The structural modifications discussed include the incorporation of triazole, arylidene, or thiol moieties with eudesmane, guaiane, and germacranolide-type sesquiterpenes, among others. In addition, the conjugation with chemotherapeutics, as well as the development of nanoscale therapeutics, is also discussed. Such modifications have expanded the pharmacological potential, enabling improved specificity, cytotoxicity profiles, and sensitization toward tumor cells. Additionally, sesquiterpenes such as parthenolide (20), pterosinsade A (176), and cedrol (186) have demonstrated potential in mitigating neurodegeneration via anti-inflammatory and antioxidant signaling pathway-modulation mechanisms, with potential applications in Alzheimer’s, Parkinson’s, and ALS diseases. Mechanistic insights into redox signaling modulation, NF-κB inhibition, ROS regulation, and disruption of aggregation underscore their multifaceted modes of action. This review highlights the translational promise of sesquiterpene derivatives as dual-action agents for potential drug development in a plethora of diseases that are caused by inflammation and free-radical damage. It provides a framework for future rational design of multifunctional drug candidates and therapeutics. Full article

(This article belongs to the Section Medicinal Chemistry)

36 pages, 1057 KB

Open AccessReview

Degradable Alternatives to Single-Use Plastics: Mechanisms, Materials, and Strategies for Sustainable Polyolefin Replacement

by Hamza Fakhrizada and Yaser Dahman

Molecules 2025, 30(21), 4301; https://doi.org/10.3390/molecules30214301 - 5 Nov 2025

Abstract

The widespread use of single-use plastics, particularly polyethylene (PE) and polypropylene (PP), has resulted in severe environmental pollution due to their durability and resistance to degradation. This report reviews current degradable alternatives to conventional polyolefins and strategies for enhancing their breakdown in natural [...] Read more.

The widespread use of single-use plastics, particularly polyethylene (PE) and polypropylene (PP), has resulted in severe environmental pollution due to their durability and resistance to degradation. This report reviews current degradable alternatives to conventional polyolefins and strategies for enhancing their breakdown in natural and managed environments. Mechanisms of abiotic and biotic degradation are examined alongside the influence of environmental factors and standardized testing protocols. Commercially available biodegradable polymers—such as polylactic acid (PLA), polyhydroxyalkanoates (PHAs), poly(butylene succinate) (PBS), poly(butylene adipate-co-terephthalate) (PBAT), starch-based plastics, cellulose derivatives, chitosan, and protein-based materials—are evaluated for their sources, degradation behavior, applications, scalability, and limitations. In addition, modification techniques for PE and PP, including copolymerization, pro-degradant additives, blending with biodegradable fillers, surface functionalization, enzyme-assisted degradation, and photocatalytic additives, are critically assessed for their potential to reduce environmental persistence. Key challenges such as performance trade-offs, incomplete degradation, ecotoxicity, cost, scalability, and end-of-life management are discussed within the context of circular economic integration. This report concludes with future research directions aimed at developing cost-effective, high-performance materials that degrade completely under real-world conditions while minimizing ecological impacts. Full article

(This article belongs to the Special Issue Bio-Based Polymers for Sustainable Future)

17 pages, 2153 KB

Open AccessArticle

Analytical Determination of the Lipid Fraction of Nigella sativa Fatty Oil by GC and NMR Analysis and Evaluation of Its Cytotoxic and Antioxidant Activity

by Martina Dentato, Antonella Porrello, Elena De Marino, Stefania Ponticelli, Alessia Postiglione, Alessandra Pollice, Maurizio Bruno, Natale Badalamenti, Giuseppe Bazan and Viviana Maresca

Molecules 2025, 30(21), 4300; https://doi.org/10.3390/molecules30214300 - 5 Nov 2025

Abstract

Nigella sativa, or black cumin, is used as a spice in cooking and as a food supplement like seeds or oil for its biological properties, including antioxidant capacity, anti-inflammatory action, and support for the immune system. In the present study, the chemical [...] Read more.

Nigella sativa, or black cumin, is used as a spice in cooking and as a food supplement like seeds or oil for its biological properties, including antioxidant capacity, anti-inflammatory action, and support for the immune system. In the present study, the chemical composition and biological activities of the Nigella sativa seeds’ fatty oil (NS) were investigated. The analytical composition was carried out by several techniques, such as GC-MS spectrometry and ¹H- and ¹³C-NMR spectroscopies using appropriate internal standards. The GC-MS analysis highlighted the presence of palmitic and linoleic acid as major compounds. The antioxidant potential was evaluated through the DPPH radical-scavenging assay, and, furthermore, the NS effect on intracellular reactive oxygen species (ROS) levels was assessed in HaCaT cells (non-tumorigenic human keratinocytes) under oxidative stress induced by hydrogen peroxide. The cytotoxic and genotoxic profiles were evaluated on Caco-2 cells (human colorectal adenocarcinoma cells) using the CCK-8 viability assay and the Comet assay, respectively. Overall, the results demonstrated that NS possessed antioxidant activity, as evidenced by concentration-dependent DPPH radical scavenging and reduced intracellular ROS levels in HaCaT cells under oxidative stress. In Caco-2 colorectal cancer cells, NS induced significant cytotoxicity and DNA damage at higher concentrations, suggesting potential genotoxic effects. These findings support the dual role of NS as a natural antioxidant and a promising candidate for nutraceutical and dermatological applications, including those targeting oxidative stress-related conditions and cancer. Full article

(This article belongs to the Special Issue Biological Evaluation of Plant Extracts)

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24 pages, 3795 KB

Open AccessArticle

A Controlled System for Parahydrogen Hyperpolarization Experiments

by Lorenzo Franco, Federico Floreani, Salvatore Mamone, Ahmed Mohammed Faramawy, Marco Ruzzi, Cristina Tubaro and Gabriele Stevanato

Molecules 2025, 30(21), 4299; https://doi.org/10.3390/molecules30214299 - 5 Nov 2025

Abstract

Parahydrogen-induced hyperpolarization (PHIP), introduced nearly four decades ago, provides an elegant solution to one of the fundamental limitations of nuclear magnetic resonance (NMR)—its notoriously low sensitivity. By converting the spin order of parahydrogen into nuclear spin polarization, NMR signals can be boosted by [...] Read more.

Parahydrogen-induced hyperpolarization (PHIP), introduced nearly four decades ago, provides an elegant solution to one of the fundamental limitations of nuclear magnetic resonance (NMR)—its notoriously low sensitivity. By converting the spin order of parahydrogen into nuclear spin polarization, NMR signals can be boosted by several orders of magnitude. Here we present a portable, compact, and cost-effective setup that brings PHIP and Signal Amplification by Reversible Exchange (SABRE) experiments within easy reach, operating seamlessly across ultra-low-field (0–10 μT) and high-field (>1 T) conditions at 50% parahydrogen enrichment. The system provides precise control over bubbling pressure, temperature, and gas flow, enabling systematic studies of how these parameters shape hyperpolarization performance. Using the benchmark Chloro(1,5-cyclooctadiene)[1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene]iridium(I) (Ir–IMes) catalyst, we explore the catalyst activation time and response to parahydrogen flow and pressure. Polarization transfer experiments from hydrides to [1-¹³C]pyruvate leading to the estimation of heteronuclear J-couplings are also presented. We further demonstrate the use of Chloro(1,5-cyclooctadiene)[1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene]iridium(I) (Ir–SIPr), a recently introduced catalyst that can also be used for pyruvate hyperpolarization. The proposed design is robust, reproducible, and easy to implement in any laboratory, widening the route to explore and expand the capabilities of parahydrogen-based hyperpolarization. Full article

(This article belongs to the Special Issue Emerging Horizons of Hyperpolarization in Chemistry and Biomedicine)

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15 pages, 1776 KB

Open AccessArticle

Selected Biochemical Properties of Medicinal Plant (Urtica dioica L.) Leaves in Relation to the Enzymatic Activity of Soils Exposed to the Impact of Road Traffic

by Joanna Lemanowicz and Iwona Jaskulska

Molecules 2025, 30(21), 4298; https://doi.org/10.3390/molecules30214298 - 5 Nov 2025

Abstract

This study examined the impact of distance from the road traffic on soil enzymatic activity, which we used as a tool to assess the relationship between soil and common nettle (Urtica dioica L.) used in herbalism and phytotherapy. A section of national [...] Read more.

This study examined the impact of distance from the road traffic on soil enzymatic activity, which we used as a tool to assess the relationship between soil and common nettle (Urtica dioica L.) used in herbalism and phytotherapy. A section of national road No. 10 (DK10) was selected for the study. Soil and common nettle leaf samples were collected from locations 5 m, 15 m, 25 m, and 100 m away from the road traffic and a control location (C). The activity of catalase (CAT), dehydrogenases (DEH), alkaline phosphatase (AlP), acid phosphatase (AcP), protease (PRO) and β-glucosidase (BG) was examined in the soil. Soil quality indices (RCh, RS, AlP/AcP, GMea, TEI) were calculated based on the enzyme activity results. The leaves of common nettles were tested for chlorophylls a and b (Chl a and b), carotenoids (Car), ascorbic acid (AAC), pH, relative water content (RWC), catalase (CATp) and superoxide dismutase (SOD) activity. Based on the values of Chl a+b, Car, pH, and RWC, the air pollution tolerance index (APTI) was calculated. The activity of the tested enzymes was statistically lowest in soil collected 5 m from traffic compared to the control (C), which was also confirmed by the results of the enzymatic soil quality indicators. In the case of CAT, AlP, AcP, and BG, based on the coefficient of determination (R2), it was found that over 70% of the variability of these enzymes was related to the distance from the road. It was found that the content of Ch a and b, Car, AAC, RWC, and pH was also lowest in soil 5 m away, whereas the activity of the antioxidant enzymes CATp and SOD was highest at this point. The ATPI values determined in common nettle leaf samples collected from locations 5 m, 15 m, 25 m, and 100 m from the road traffic were sensitive to pollution. The results indicate that the distance from the road strongly influenced the changes in the parameters studied. The enzymatic properties of the soil and selected biochemical parameters of common nettle leaves were similar at locations 15 m and 25 m, as well as 100 m and the control. The results of the enzymatic soil quality indicators show that soil 5 m from the road traffic is subject to degradation, and the nettles growing in this location are sensitive to road pollution. Therefore, it is not recommended to collect common nettle leaves from this location for medical or cosmetic purposes. Full article

(This article belongs to the Special Issue Biologically Active Molecules: Extraction Strategies, Therapeutic Potential and Biomedical Perspective)

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20 pages, 2408 KB

Open AccessArticle

Hydrothermal and Organosolv Treatments for Hydroxycinnamate Release from Corn Stover: Strong versus Mild Alkaline Catalysis

by Evangelia Brimo-Alevra, Marina Koutli, Elli Marielou, Theodoros Chatzimitakos and Dimitris P. Makris

Molecules 2025, 30(21), 4297; https://doi.org/10.3390/molecules30214297 - 5 Nov 2025

Abstract

Corn stover (CS) is an abundant biomaterial, which is regularly rejected during corn harvesting. This biowaste is a typical lignocellulosic source rich in hydroxycinnamates, which are mainly represented by p-coumaric acid and ferulic acid. These polyphenols are largely bound onto the lignocellulosic [...] Read more.

Corn stover (CS) is an abundant biomaterial, which is regularly rejected during corn harvesting. This biowaste is a typical lignocellulosic source rich in hydroxycinnamates, which are mainly represented by p-coumaric acid and ferulic acid. These polyphenols are largely bound onto the lignocellulosic complex and can be effectively liberated using alkaline catalysis. On this basis, the work described herein targeted at developing a high-performance process for producing hydroxycinnamate-enriched extracts, by deploying alkali-catalyzed hydrothermal and organosolv treatments. For this purpose, sodium carbonate was tested as a benign, natural alkali catalyst, along with the well-studied sodium hydroxide. The kinetic study demonstrated that both the alkali catalyst and the organic solvent (ethanol) may significantly affect polyphenol recovery, a fact further investigated by carrying out response surface optimization. The hydrothermal treatment was shown to be more efficacious than the organosolv one, with regard to total polyphenol recovery, while the sodium carbonate catalysis was less efficient compared to the sodium hydroxide one. Under optimized conditions, the hydrothermal treatment afforded 74.4 ± 3.6 mg gallic acid equivalents per g of dry CS mass. On the other hand, a more thorough investigation of the polyphenolic profile of the extracts obtained clearly demonstrated that the sodium hydroxide-catalyzed organosolv treatment provided almost 76 and 98% higher yields for p-coumaric and ferulic acid, respectively, compared to the hydrothermal treatment. Extract composition impacted the antioxidant activity, and it was revealed that the higher the p-coumaric acid/ferulic acid ratio, the stronger the antioxidant effect. It is proposed that the sodium hydroxide-catalyzed ethanol organosolv treatment of CS may be a particularly promising technique in a lignocellulose biorefinery frame, although improvements might be necessary to further increase treatment performance. Such a process might contribute to fully valorizing agricultural biowastes for the production of high value-added chemicals, in line with the “lignin first’ philosophy. Full article

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28 pages, 1127 KB

Open AccessReview

A Full-Spectrum Evaluation of Sigma-1 Receptor (S1R) Positron Emission Tomography (PET) Radioligands from Binding Affinity to Clinical Imaging

by Francesco Mastropasqua, Friedrich-Alexander Ludwig and Carmen Abate

Molecules 2025, 30(21), 4296; https://doi.org/10.3390/molecules30214296 - 5 Nov 2025

Abstract

Several pieces of evidence have demonstrated the sigma-1 receptor (S1R) as a druggable protein with important therapeutic potentials, including neurodegeneration, cancer, and neuropathic pain. The density of S1R is altered in pathological processes so that its imaging is under study for diagnostic purposes. [...] Read more.

Several pieces of evidence have demonstrated the sigma-1 receptor (S1R) as a druggable protein with important therapeutic potentials, including neurodegeneration, cancer, and neuropathic pain. The density of S1R is altered in pathological processes so that its imaging is under study for diagnostic purposes. Thus, research has been focused on the development of S1R positron emission tomography (PET) radioligands, not only as diagnostic tools but also as powerful means to assist in the drug-development process. Herein, we comprehensively review the most important S1R PET radiotracers belonging to different classes that have been developed in the last two decades. Starting from the structural modifications impacting on the S1R affinity and selectivity, we report (i) the differences in metabolism and pharmacokinetics, (ii) the in vivo behavior in different animal models, (iii) the in vitro autoradiography outcomes, and (iv) the dosimetric profiles. The successful use of the best-performing S1R PET radiotracers in the characterization of novel S1R drugs is also reported together with the approaches to assess the potential for clinical translation. What emerges from this review is that, although the development of reliable PET agents appears to be extremely challenging, these radiotracers hold incredible potential and play a fundamental role in the exploitation of S1R in health and disease. Full article

(This article belongs to the Section Medicinal Chemistry)

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23 pages, 4099 KB

Open AccessArticle

Hydrothermal Modification of Activated Carbon Enhances Acetaminophen Adsorption: Experimental and Computational Evidence of π–π Interaction Dominance

by Astrid G. Cortés-Cruz, Marta Adame-Pereira, Carlos J. Durán-Valle and Ignacio M. López-Coca

Molecules 2025, 30(21), 4295; https://doi.org/10.3390/molecules30214295 - 5 Nov 2025

Abstract

Acetaminophen (APAP) is a widely used pharmaceutical increasingly detected as a contaminant in aquatic environments due to its persistent nature and incomplete removal by conventional wastewater treatment. This study investigates the adsorption performance and mechanisms of commercial activated carbon (M) and its hydrothermally [...] Read more.

Acetaminophen (APAP) is a widely used pharmaceutical increasingly detected as a contaminant in aquatic environments due to its persistent nature and incomplete removal by conventional wastewater treatment. This study investigates the adsorption performance and mechanisms of commercial activated carbon (M) and its hydrothermally modified form (MH) for APAP removal. Characterization via elemental analysis, X-ray photoelectron spectroscopy (XPS), and N₂ adsorption isotherms revealed that hydrothermal treatment reduced oxygen content and enhanced micro- and mesopore volumes, resulting in a more homogeneous and carbon-rich surface. Batch adsorption experiments conducted under varying pH (5–7) and temperature (30–40 °C) conditions showed that MH achieved up to 94.3% APAP removal, outperforming the untreated carbon by more than 15%. Kinetic modeling indicated that adsorption followed a pseudo-second-order mechanism (R² > 0.99), and isotherm data fitted best to the Langmuir model for MH and the Freundlich model for M, reflecting their differing surface properties. Adsorption was enhanced at lower pH and higher temperatures, consistent with an endothermic and pH-dependent mechanism. Complementary density functional theory (DFT) simulations confirmed that π–π stacking is the dominant interaction between APAP and the carbon surface. The most favorable configuration involved coplanar stacking with non-oxidized graphene (ΔG = −33 kJ/mol), while oxidized graphene models exhibited weaker interactions. Natural Bond Orbital (NBO) analysis further supported the prevalence of π–π interactions over dipole interactions. These findings suggest that surface deoxygenation and improved pore architecture achieved via hydrothermal treatment significantly enhance APAP adsorption, offering a scalable strategy for pharmaceutical pollutant removal in water treatment applications. Full article

(This article belongs to the Special Issue New Insights into Porous Materials in Adsorption and Catalysis)

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26 pages, 2062 KB

Open AccessArticle

Screening of Cytotoxic and Genotoxic Activities of Subcritical Water Extracts from R. damascena and R. alba Flowers

by Tsvetelina Gerasimova, Svetla Gateva, Gabriele Jovtchev, Ana Dobreva, Milka Mileva, Zlatina Kokanova-Nedialkova, Milena Gospodinova, Tsveta Angelova and Paraskev Nedialkov

Molecules 2025, 30(21), 4294; https://doi.org/10.3390/molecules30214294 - 5 Nov 2025

Abstract

Regulatory changes in the EU for safety purposes require strict control and high safety standards for essential oils obtained by steam distillation, as they are classified as chemical mixtures with potential toxic effects. Subcritical water extracts (SWEs) are considered safer. This study evaluated [...] Read more.

Regulatory changes in the EU for safety purposes require strict control and high safety standards for essential oils obtained by steam distillation, as they are classified as chemical mixtures with potential toxic effects. Subcritical water extracts (SWEs) are considered safer. This study evaluated the cytotoxicity and genotoxicity of SWEs from Rosa damascena Mill. and Rosa alba L. in three test systems at different hierarchical levels: higher plants (root meristems of Hordeum vulgare), somatic cells of Mus musculus ICR strain, and human lymphocytes in vitro. The chromatographic fingerprint of the extracts revealed the presence of key components such as flavonoids, phenolic acids, and glycoside derivatives, with species-dependent variations and concentrations. No significant cytotoxicity was detected in the concentration range of 6–20%. SWE from R. alba showed a higher level of safety at high doses. Genotoxicity tests showed a weak, dose-dependent induction of chromosomal aberrations and micronuclei in barley and lymphocytes (greater in R. alba), a lack of genotoxicity in mouse bone marrow, and a slight increase in micronuclei in mouse erythrocytes after exposure to R. alba extract. The results highlight the suitability of SWEs from R. damascena and R. alba for safe application in the medical, food, and cosmetic industries. Full article

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15 pages, 2406 KB

Open AccessArticle

Chemical and Microscopic Characterization of the Yellow Passion Fruit Peel

by Daniel Arrieta-Baez, Denise Larissa Díaz de la Torre, Héctor Francisco Mendoza-León, María de Jesús Perea-Flores and Mayra Beatriz Gómez-Patiño

Molecules 2025, 30(21), 4293; https://doi.org/10.3390/molecules30214293 - 5 Nov 2025

Abstract

Passion fruit (Passiflora edulis f. flavicarpa), commonly known as yellow passion fruit, is widely grown across tropical and subtropical regions worldwide, with Brazil as one of the top producers. Mexico also produces a significant amount of this variety, mainly for juices, [...] Read more.

Passion fruit (Passiflora edulis f. flavicarpa), commonly known as yellow passion fruit, is widely grown across tropical and subtropical regions worldwide, with Brazil as one of the top producers. Mexico also produces a significant amount of this variety, mainly for juices, jams, or flavoring in desserts. Since this fruit is highly perishable with a short shelf life, it needs to be consumed or used quickly. Although different preservation methods have been suggested, no structural analyses of the peel have been performed to improve these processes. This study aimed to analyze the structural and chemical properties of the peel’s cuticular matrix to better understand water loss. CPMAS ¹³C NMR analysis revealed a matrix containing polysaccharides, a small amount of aliphatics, and a notable group of aromatic signals that may indicate lignin presence. This was supported by alkaline hydrolysis, which achieved only 30% hydrolysis. Soluble compounds identified included hexoses, palmitic acid, stearic acid, and derivatives of ferulic and caffeic acids, the latter being parts of lignin monomers. MCL and SEM analyses showed features similar to cutans, including pores along the structures. The BET surface area measurement indicated that the insoluble cuticular material (ICM) has a significant specific surface area. The lignin in the yellow passion fruit peel gives the shell toughness, which, along with its pores, may contribute to dehydration and a short shelf life. Full article

(This article belongs to the Section Natural Products Chemistry)

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16 pages, 3868 KB

Open AccessArticle

Glutathione-Responsive Folate-Targeted Prodrugs: Tumor-Specific PD-L1 and CD47 Blockade

by Jianfeng Wang, Lianqi Liu, Dian Xiao, Fei Xie and Xinbo Zhou

Molecules 2025, 30(21), 4292; https://doi.org/10.3390/molecules30214292 - 5 Nov 2025

Abstract

Immune checkpoint inhibitors (ICIs) targeting PD-L1 and CD47 are clinically limited by severe off-target toxicities. To address this issue, immunotherapeutic prodrug strategies have been developed, aimed at preventing antibodies from binding to targets in healthy tissues and thereby reducing systemic toxicity. Existing strategies [...] Read more.

Immune checkpoint inhibitors (ICIs) targeting PD-L1 and CD47 are clinically limited by severe off-target toxicities. To address this issue, immunotherapeutic prodrug strategies have been developed, aimed at preventing antibodies from binding to targets in healthy tissues and thereby reducing systemic toxicity. Existing strategies include prodrug technologies that mask the active sites of antibodies via peptide or polyethylene glycol (PEG) modification—yet these approaches also cause antibodies to lose their targeting ability. Herein, we propose an antibody prodrug strategy (termed FA-PEG-S-Ab) with active targeting capability. By modifying antibodies with folate-PEG-disulfide and PEG-disulfide linkages, we developed two novel prodrugs: FA-PEG-S-Atz (PD-L1-blocking prodrug) and FA-PEG-S-Hu5 (CD47-blocking prodrug). This strategy functions through two key steps: first, folate binding to folate receptor α (FRα)-mediated tumor-specific targeting enables the prodrugs to accumulate specifically in tumor tissues; subsequently, the high concentration of glutathione (GSH) in the tumor microenvironment (TME) specifically cleaves the disulfide bonds, removing the PEG shield, releasing the antibody, and restoring the antibody’s antigen-binding activity. In vitro experiments confirmed that the modified antibody prodrug FA-PEG-S-Hu5 exhibits high affinity for FRα (K_D = 4.02 × 10⁻⁹ M) and effectively masks the antibody’s binding activity (K_D from 1.05 × 10⁻¹¹ M to 2.10 × 10⁻⁸ M). Following activation by GSH in the TME, this masking effect is reversed, and the antibody regains its binding affinity (K_D = 2.14 × 10⁻¹⁰ M). Crucially, FA-PEG-S-Hu5 completely eliminates hemolytic toxicity. This “folate targeting delivery + TME activation” prodrug strategy is expected to provide a new solution for addressing the off-target toxicities of conventional ICIs. Full article

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23 pages, 1550 KB

Open AccessArticle

Kinetics and Isotherm Study of Ceftriaxone Removal Using Functionalized Biochar Combined with Photocatalysis

by Luísa Cruz-Lopes, Rodrigo Araújo, Ana Rita Lopes, Samuel Moles, Francisca Romero-Sarria and Bruno Esteves

Molecules 2025, 30(21), 4291; https://doi.org/10.3390/molecules30214291 - 5 Nov 2025

Abstract

The increasing presence of antibiotics such as cephalosporins in wastewater represents a significant environmental risk. These compounds are excreted in large quantities, and conventional wastewater treatment plants are often ineffective at their removal. Consequently, the development of more sustainable and efficient treatment technologies [...] Read more.

The increasing presence of antibiotics such as cephalosporins in wastewater represents a significant environmental risk. These compounds are excreted in large quantities, and conventional wastewater treatment plants are often ineffective at their removal. Consequently, the development of more sustainable and efficient treatment technologies is essential. In this study, the removal of cephalosporins from aqueous solutions was evaluated through adsorption using pine bark biochar, photocatalysis with TiO₂, and a combination of both processes. Kinetic experiments were conducted with cephalosporin solutions (15 mg/L), employing 150 mg/L of biochar, 100 mg/L TiO₂, or their combination, under continuous stirring and/or UV-vis irradiation. Samples were collected at 0 and 120 min and analyzed via UV-vis spectrophotometry. Adsorption isotherms were established for initial cephalosporin concentrations ranging from 5 to 50 mg/L. The biochar alone achieved a removal efficiency of 94.2% after 120 min. Photocatalysis with TiO₂ alone resulted in 75% removal, while the combined approach reached 95.9%, indicating a synergistic effect between adsorption and photodegradation mechanisms. Kinetic data fitted the pseudo-second-order model, and the Langmuir isotherm provided the best correlation, suggesting monolayer adsorption. These findings demonstrate that pine bark biochar, whether used independently or in combination with TiO₂, constitutes an eco-friendly, effective, and low-cost alternative for the removal of antibiotics from wastewater, while simultaneously contributing to the valorization of forestry residues. Full article

(This article belongs to the Special Issue Natural-Based Sorbents for Water Remediation)

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