Molecules

16 pages, 1196 KiB

Open AccessReview

Peptide with Dual Roles in Immune and Metabolic Regulation: Liver-Expressed Antimicrobial Peptide-2 (LEAP-2)

by Yitong Li, Ying Liu and Meng Gou

Molecules 2025, 30(2), 429; https://doi.org/10.3390/molecules30020429 - 20 Jan 2025

Liver-expressed antimicrobial peptide 2 (LEAP-2) was originally discovered as an antimicrobial peptide that plays a vital role in the host innate immune system of various vertebrates. Recent research discovered LEAP-2 as an endogenous antagonist and inverse agonist of the GHSR1a receptor. By acting [...] Read more.

Liver-expressed antimicrobial peptide 2 (LEAP-2) was originally discovered as an antimicrobial peptide that plays a vital role in the host innate immune system of various vertebrates. Recent research discovered LEAP-2 as an endogenous antagonist and inverse agonist of the GHSR1a receptor. By acting as a competitive antagonist to ghrelin, LEAP-2 influences energy balance and metabolic processes via the ghrelin–GHSR1a signaling pathway. LEAP-2 alone or the LEAP-2/ghrelin molar ratio showed potential as therapeutic targets for obesity, diabetes, and metabolic disorders. This review explores the recent advances of LEAP-2 in immune modulation and energy regulation, highlighting its potential in treating the above diseases. Full article

(This article belongs to the Topic Peptoids and Peptide Based Drugs)

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18 pages, 7621 KiB

Open AccessArticle

The Synthesis, Crystal Structure, Modification, and Cytotoxic Activity of α-Hydroxy-Alkylphosphonates

by Zsuzsanna Szalai, Anna Sára Kis, Angéla Takács, László Kőhidai, Konstantin Karaghiosoff, Mátyás Czugler, László Drahos and György Keglevich

Molecules 2025, 30(2), 428; https://doi.org/10.3390/molecules30020428 - 20 Jan 2025

Abstract

A series of α-hydroxy-alkylphosphonates and α-hydroxy-alkylphosphine oxides were synthesized by the Pudovik reaction of acetaldehyde and acetone with dialkyl phosphites or diarylphosphine oxides. The additions were performed in three different ways: in liquid phase using triethylamine as the catalyst (1), on the surface [...] Read more.

A series of α-hydroxy-alkylphosphonates and α-hydroxy-alkylphosphine oxides were synthesized by the Pudovik reaction of acetaldehyde and acetone with dialkyl phosphites or diarylphosphine oxides. The additions were performed in three different ways: in liquid phase using triethylamine as the catalyst (1), on the surface of Al₂O₃/KF solid catalyst (2), or by a MW-assisted Na₂CO₃-catalyzed procedure (3). In most of the cases, our methods were more efficient and more robust than those applied in the literature. Two of the α-hydroxy-alkylphosphonates were subjected to single-crystal X-ray analysis, suggesting a dimeric and a chain supramolecular buildup in their respective crystals. Four α-hydroxy-alkylphosphonates and one α-hydroxy-ethylphosphine oxide were reacted with different acid chlorides to afford ten α-acyloxyphosphonates. Diethyl α-hydroxy-ethylphosphonate was transformed to the methanesulfonyloxy derivative that was useful in the Michaelis–Arbuzov reaction with triethyl phosphite and ethyl diphenylphosphinite to afford tetraethyl ethylidenebisphosphonate and diethyl α-(diphenylphosphinoyl)-ethylphosphonate, respectively. The α-hydroxyphosphonates and α-hydroxyphosphine oxides prepared were subjected to bioactivity studies, and the compounds tested exhibited limited cytotoxic effects on U266 cells with modest reductions in viability at a concentration of 100 μM. Full article

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

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22 pages, 826 KiB

Open AccessArticle

Effect of Glycoconjugation on Cytotoxicity and Selectivity of 8-Aminoquinoline Derivatives Compared to 8-Hydroxyquinoline

by Gabriela Pastuch-Gawołek and Julia Szreder

Molecules 2025, 30(2), 427; https://doi.org/10.3390/molecules30020427 - 20 Jan 2025

Abstract

Numerous emerging chemotherapeutic agents incorporate N-heterocyclic fragments in their structures, with the quinoline skeleton being particularly significant. Our recent works have focused on glycoconjugates of 8-hydroxyquinoline (8-HQ), which demonstrated enhanced bioavailability and solubility compared to their parent compounds, although they fell short [...] Read more.

Numerous emerging chemotherapeutic agents incorporate N-heterocyclic fragments in their structures, with the quinoline skeleton being particularly significant. Our recent works have focused on glycoconjugates of 8-hydroxyquinoline (8-HQ), which demonstrated enhanced bioavailability and solubility compared to their parent compounds, although they fell short in selectivity. In this study, our objective was to improve the selectivity of glycoconjugates by replacing the oxygen atom with nitrogen by substituting the 8-HQ moiety with 8-aminoquinoline (8-AQ). The 8-AQ derivatives were functionalized through the amino group and linked to sugar derivatives (D-glucose or D-galactose) that were modified with an azide, alkylazide, or propargyl group at the anomeric position by copper(I)-catalyzed 1,3-dipolar azido-alkyne cycloaddition (CuAAC). The resulting glycoconjugates, as well as their potential metabolites, were evaluated for their ability to inhibit the proliferation of cancer cell lines (including HCT 116 and MCF-7) and a healthy cell line (NHDF-Neo). Two of the synthesized glycoconjugates (17 and 18) demonstrated higher cytotoxicity than their oxygen-containing counterparts and showed improved selectivity for cancer cells, thus enhancing their anticancer potential. Furthermore, it was found that glycoconjugates exhibited greater cytotoxicity in comparison to their potential metabolites. Full article

(This article belongs to the Special Issue Bioorganic Chemistry in Europe)

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15 pages, 2961 KiB

Open AccessArticle

Sustainable CO₂ Capture: N,S-Codoped Porous Carbons Derived from Petroleum Coke with High Selectivity and Stability

by Jiawei Shao, Yingyi Wang, Mingyang Che, Ya Liu, Yongfu Jiang, Qiang Xiao, Muslum Demir, Linlin Wang and Xin Hu

Molecules 2025, 30(2), 426; https://doi.org/10.3390/molecules30020426 - 20 Jan 2025

Abstract

CO₂ capture from the flue gas is a promising approach to mitigate global warming. However, regulating the carbon-based adsorbent in terms of textural and surface modification is still a challenge. To overcome this issue, the present study depicts the development of cost-effective [...] Read more.

CO₂ capture from the flue gas is a promising approach to mitigate global warming. However, regulating the carbon-based adsorbent in terms of textural and surface modification is still a challenge. To overcome this issue, the present study depicts the development of cost-effective and high-performance CO₂ adsorbents derived from petroleum coke, an industrial by-product, using a two-step process involving thiourea modification and KOH activation. A series of N,S-codoped porous carbons was synthesized by varying activation temperatures and KOH quantity. The optimized sample exhibited a high specific surface area of 1088 m²/g, a narrow micropore volume of 0.52 cm³/g, and considerable heteroatom doping (1.57 at.% nitrogen and 0.19 at.% sulfur). The as-prepared adsorbent achieved a CO₂ adsorption capacity of 3.69 and 5.08 mmol/g at 1 bar, 25 °C and 0 °C, respectively, along with a CO₂/N₂ selectivity of 17. Adsorption kinetics showed 90% of equilibrium uptake was achieved within 5 min, while cyclic studies revealed excellent stability with 97% capacity retention after five cycles. Thermodynamic analysis indicated moderate isosteric heat of adsorption (Q_st) values ranging from 18 to 47 kJ/mol, ensuring both strong adsorption and efficient desorption. These findings highlight the potential of petroleum coke-derived porous carbons for sustainable and efficient CO₂ capture applications. Full article

(This article belongs to the Special Issue Porous Carbons for Gas Adsorption and Capture)

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14 pages, 4274 KiB

Open AccessArticle

Dissolution Mechanism of YbOF in (LiF-CaF₂)_eut. Molten Salt

by Linsheng Luo, Kailei Sun and Xu Wang

Molecules 2025, 30(2), 425; https://doi.org/10.3390/molecules30020425 - 20 Jan 2025

Abstract

The dissolution mechanism of YbOF in a fluoride-containing (LiF-CaF₂)_eut. molten salt is the basis for analyzing the structure of the resulting medium and optimizing the electrolytic preparation of rare-earth Yb alloys. In this study, isothermal saturation was used to analyze [...] Read more.

The dissolution mechanism of YbOF in a fluoride-containing (LiF-CaF₂)_eut. molten salt is the basis for analyzing the structure of the resulting medium and optimizing the electrolytic preparation of rare-earth Yb alloys. In this study, isothermal saturation was used to analyze solubility changes of YbOF in the (LiF-CaF₂)_eut. system. Quantum chemical and molecular dynamics ab initio methods were used to study the basic properties of the components of the (LiF-CaF₂)_eut.-YbOF system and the microscopic structural changes during the dissolution process. In addition, structural changes in the YbOF-saturated (LiF-CaF₂)_eut. system were analyzed by combining cryogenic-temperature Raman spectroscopy with experimental methods. The results show the solubility of YbOF increased linearly in the temperature range of 1073–1323 K. As the melting temperature exceeded 1073 K, LiF and CaF₂ gradually dissociated into Li⁺, Ca²⁺, and F⁻. In the initial stages of YbOF dissolution (1073–1173 K), the Yb–F bond was less stable than the Yb–O bond; YbOF dissociated into YbO⁺ and F⁻ in this temperature range. When the temperature was increased above 1173 K, YbO⁺ further dissociated into Yb³⁺ and O²⁻. Overall, the dissolution of YbOF did not affect the main structure of the (LiF-CaF₂)_eut. system. Full article

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17 pages, 8844 KiB

Open AccessArticle

From Anatase TiO₂ Nano-Cuboids to Nano-Bipyramids: Influence of Particle Shape on the TiO₂ Photocatalytic Degradation of Emerging Contaminants in Contrasted Water Matrices

by Humaira Asghar, Daphne Hermosilla, Francesco Pellegrino, Virginia Muelas-Ramos, Christian de los Ríos, Antonio Gascó, Valter Maurino and Muhammad Ahsan Iqbal

Molecules 2025, 30(2), 424; https://doi.org/10.3390/molecules30020424 - 20 Jan 2025

Abstract

Water pollution, resulting from industrial effluents, agricultural runoff, and pharmaceutical residues, poses serious threats to ecosystems and human health, highlighting the need for innovative approaches to effective remediation, particularly for non-biodegradable emerging pollutants. This research work explores the influence of shape-controlled nanocrystalline titanium [...] Read more.

Water pollution, resulting from industrial effluents, agricultural runoff, and pharmaceutical residues, poses serious threats to ecosystems and human health, highlighting the need for innovative approaches to effective remediation, particularly for non-biodegradable emerging pollutants. This research work explores the influence of shape-controlled nanocrystalline titanium dioxide (TiO₂ NC), synthesized by a simple hydrothermal method, on the photodegradation efficiency of three different classes of emerging environmental pollutants: phenol, pesticides (methomyl), and drugs (sodium diclofenac). Experiments were conducted to assess the influence of the water matrix on treatment efficiency by using ultrapure water and stormwater (basic) collected from an urban drainage system as matrices. The size and shape of the nano-cuboids were accurately controlled during synthesis to assess their impact on photoactivity and selectivity. Regarding total organic carbon removal using TiO₂ nano-cuboids in basic environments, the results were particularly remarkable. TiO₂ nano-cuboids and truncated bipyramids synthesized in the 200–250 °C temperature range showed an enhanced photocatalytic efficiency when compared to alternative formulations. Diclofenac, methomyl, and phenol were fully mineralized from ultrapure water and basic stormwater. The TiO₂ nano-cuboids/nano-bipyramids demonstrated better selectivity and photoactivity in comparison to irregular TiO₂ nanoparticles. The differences in photoactivity and selectivity are explained in terms of charge carrier separation and trapping on the different crystal facets. Their performance demonstrates their potential as sustainable materials for the photodegradation of emerging pollutants in various water matrices. Full article

(This article belongs to the Special Issue New Research on Novel Photo-/Electrochemical Materials)

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15 pages, 2047 KiB

Open AccessArticle

Colorimetric Detection of Dopamine Based on Peroxidase-like Activity of β-CD Functionalized AuNPs

by Sara Anderson, Hamish Shepherd, Kiran Boggavarapu and Janak Paudyal

Molecules 2025, 30(2), 423; https://doi.org/10.3390/molecules30020423 - 20 Jan 2025

Abstract

Catalytically active nanomaterials, or nanozymes, have gained significant attention as alternatives to natural enzymes due to their low cost, ease of preparation, and enhanced stability. Because of easy preparation, excellent biocompatibility, and unique optoelectronic properties, gold nanoparticles (AuNPs) have attracted increasing attention in [...] Read more.

Catalytically active nanomaterials, or nanozymes, have gained significant attention as alternatives to natural enzymes due to their low cost, ease of preparation, and enhanced stability. Because of easy preparation, excellent biocompatibility, and unique optoelectronic properties, gold nanoparticles (AuNPs) have attracted increasing attention in many fields, including nanozymes. In this work, we demonstrated the applicability of beta-cyclodextrin functionalized gold nanoparticles (β-CD-AuNPs) as enzyme mimics for different substances, including TMB and DA. We found that β-CD-AuNPs can catalyze the H₂O₂-mediated oxidation of DA. The dopamine signal-off sensor was developed by taking advantage of the peroxidase-like activity of β-CD-AuNPs towards TMB and DA, where both 3,3′,5,5′-tetramethylbenzidine (TMB) and dopamine (DA) may compete for the binding sites with β-CD-AuNPs. As a result, the presence of dopamine can be detected even through the naked eye (up to the concentration of 3.75 µM) and using a spectrophotometer (up to the concentration of 1.0 µM) by monitoring the disappearance of the blue color of the oxidized form of TMB in the presence of dopamine. Furthermore, no obvious disappearance of color was observed at lower concentrations of interferences including ascorbic and uric acid. Given the versatility of cyclodextrin to host large numbers of analyte molecules, we envision that a similar principle can be applied for the detection of other analyte molecules of biological, medical, and environmental significance. Full article

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18 pages, 5079 KiB

Open AccessArticle

Epigynum auritum-Derived Near-Infrared Carbon Dots for Bioimaging and Antimicrobial Applications

by Wenfeng Shi, Jiahui Li, Junmei Pu, Guiguang Cheng, Yaping Liu, Shanshan Xiao and Jianxin Cao

Molecules 2025, 30(2), 422; https://doi.org/10.3390/molecules30020422 - 20 Jan 2025

Abstract

The use of biomass feedstocks for producing high-value-added chemicals is gaining significant attention in the academic community. In this study, near-infrared carbon dots (NIR-CDs) with antimicrobial and bioimaging functions were prepared from Epigynum auritum branches and leaves using a novel green synthesis approach. [...] Read more.

The use of biomass feedstocks for producing high-value-added chemicals is gaining significant attention in the academic community. In this study, near-infrared carbon dots (NIR-CDs) with antimicrobial and bioimaging functions were prepared from Epigynum auritum branches and leaves using a novel green synthesis approach. The spectral properties of the synthesized NIR-CDs were characterized by ultraviolet–visible (UV-Vis) absorption and fluorescence spectroscopy. The crystal structures of the NIR-CDs were further characterized by high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), and X-ray diffraction (XRD). The NIR-CDs exhibited minimal toxicity, excellent biocompatibility, and high penetrability in both in vivo and in vitro environments, making them ideal luminescent probes for bioimaging applications. Moreover, the antimicrobial activity of NIR-CDs was tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), showing significant bacterial growth inhibition. The antimicrobial effect is likely attributed to the NIR-CDs disrupting the cell membrane integrity, leading to the leakage of the intracellular contents. Therefore, NIR-CDs hold promise as fluorescent bioimaging probes and antimicrobial agents. Full article

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12 pages, 4615 KiB

Open AccessArticle

Water-Resistant Poly(ethylene oxide) Electrospun Membranes Enabled by In Situ UV-Cross-Linking for Efficient Daytime Radiative Cooling

by Haiyan Zhang, Qingpeng Wang, Zhiguang Xu and Yan Zhao

Molecules 2025, 30(2), 421; https://doi.org/10.3390/molecules30020421 - 20 Jan 2025

Abstract

Daytime radiative cooling, based on selective infrared emissions through atmospheric transparency windows to outer space and the reflection of solar irradiance, is a zero-energy and environmentally friendly cooling technology. Poly(ethylene oxide) (PEO) electrospun membranes have both selective mid-infrared emissions and effective sunlight reflection, [...] Read more.

Daytime radiative cooling, based on selective infrared emissions through atmospheric transparency windows to outer space and the reflection of solar irradiance, is a zero-energy and environmentally friendly cooling technology. Poly(ethylene oxide) (PEO) electrospun membranes have both selective mid-infrared emissions and effective sunlight reflection, inducing excellent daytime radiative cooling performance. However, PEO is highly water soluble, which makes electrospun PEO membranes unable to cope with rainy conditions when used for outdoor daytime radiative cooling. Herein, we report an in situ UV-crosslinking strategy for preparing PEO electrospun membranes with water resistance for the application of daytime radiative cooling. Acrylate-terminated PEO was synthesized and mixed together with cross-linking agents and photoinitiators to prepare the electrospinning solution. During electrospinning, the nanofibers were irradiated with UV light to initiate the cross-linking. For a membrane with a thickness of 200 μm, the average solar reflectance was 89.6%, and the infrared emissivity (8–13 μm) was 96.3%. Although slight swelling happens to the cross-linked membrane once it comes into contact with water, the fibrous morphology shows no obvious change when prolonging the water soaking time, indicating excellent water resistance. The outdoor cooling performance test results showed that compared to the average temperature of the air in the test box, the average temperature drop in the membrane before and after water soaking was 13.8 °C and 11.5 °C, respectively. Crosslinked PEO-based electrospun membranes with both water resistance and radiative cooling performance may have real applications for outdoor daytime radiative cooling. Full article

(This article belongs to the Special Issue Preparation, Characterization, and Application of Electrospun Nanofibers)

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15 pages, 3754 KiB

Open AccessArticle

The Effect of Zeolite Na-X and Clinoptilolite as Functional Fillers on the Mechanical, Thermal and Barrier Properties of Thermoplastic Polyurethane

by Nello Russo, Letizia Verdolotti, Giuseppe Cesare Lama, Federica Recupido, Barbara Liguori and Maria Oliviero

Molecules 2025, 30(2), 420; https://doi.org/10.3390/molecules30020420 - 20 Jan 2025

Abstract

To obtain sustainable food packaging materials, alternatives to traditional ones must be researched. In this work, two different kinds of zeolites, i.e., a natural one, Clinoptilolite, and a synthetic one, Zeolite Na-X, were mixed with thermoplastic polyurethane for the fabrication of composites. Composite [...] Read more.

To obtain sustainable food packaging materials, alternatives to traditional ones must be researched. In this work, two different kinds of zeolites, i.e., a natural one, Clinoptilolite, and a synthetic one, Zeolite Na-X, were mixed with thermoplastic polyurethane for the fabrication of composites. Composite films were prepared via a hot mixing stage and then by means of a hot compression molding process. Several TPU/zeolite composites were produced with a filler concentration ranging from 5% to 10%wt. Finally, the obtained films were characterized by Fourier Transform Spectroscopy (FT-IR, ATR), thermal analysis (TGA and DSC), frequency sweep test, scanning electron microscopy (SEM), mechanical tensile test and oxygen permeability test. For both fillers and at all concentrations, the inclusion of zeolites significantly influenced the analyzed properties. In the TPU/zeolite composites, an overall enhancement was observed compared to the neat polymer, attributed to improved processability, superior barrier properties and the potential to create active materials by loading zeolite combined with various chemicals for specific applications. These findings suggest that the resulting composites hold considerable promise for applications in the food packaging sector. Full article

(This article belongs to the Special Issue Zeolites and Related Materials)

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12 pages, 2191 KiB

Open AccessArticle

Phenolic and Iridoid Glycosides from Leonurus cardiaca L. and Their Effects on the α, δ, and γ Subtypes of the PPAR System—Including the Discovery of the Novel Phenylethanoid Cardiaphenyloside A and the Most Active 7-Chloro-6-desoxy-harpagide

by Kenny Kuchta, Nobuyasu Matsuura, Tung Huu Nguyen, Christian Rusch, Munekazu Iinuma, Yukihiro Shoyama and Hans Wilhelm Rauwald

Molecules 2025, 30(2), 419; https://doi.org/10.3390/molecules30020419 - 20 Jan 2025

Abstract

Leonurus cardiaca L. is known in Europe for its cardioactivity—also in interrelation with known risk factors of the metabolic syndrome—just as L. japonicus Houtt. in East Asia; however, up to now, no active constituents could be identified. The three sub-types of PPARs (α, [...] Read more.

Leonurus cardiaca L. is known in Europe for its cardioactivity—also in interrelation with known risk factors of the metabolic syndrome—just as L. japonicus Houtt. in East Asia; however, up to now, no active constituents could be identified. The three sub-types of PPARs (α, δ, and γ), are involved in controlling the lipid metabolism in the liver and skeletal muscles. Although PPARδ especially is a potential therapeutic target for the metabolic syndrome, insulin resistance, and obesity, no PPARδ agonists with clinical potential have presently been developed. Therefore, nineteen dominant isolated constituents of both species were screened for activity on the metabolic syndrome related PPAR α, δ, and γ in a newly developed luciferase reporter gene assay. Eight phenylethanoid glycosides not previously detected in L. cardiaca, including the novel cardiaphenyloside A, as well as the iridoids ajugol and harpagide were found via bioassay-guided isolation and structural elucidation of spectroscopic and chemical evidence. For the PPARδ experiment, all nineteen isolated constituents and GW0742 (positive control) were added to the medium of transfected COS-1 cells and further processed according to a standardized luciferase assay protocol. Only the major iridoid 7-chloro-6-desoxy-harpagide displayed significant activity in the PPARδ assay at 50 μg/mL, while the result for 100 μg/mL was higher than for the GW0742 positive control. Rutin, chicoric acid, and cardiaphenyloside A at 100 μg/mL showed PPARα agonistic activity. For PPARγ, no significant effects were observed. This activity of Leonurus extracts and especially of their active constituent 7-chloro-6-desoxy-harpagide on the δ subtype of the PPAR system strongly indicates their potential for anti-obesity therapy. Full article

(This article belongs to the Special Issue Bioactivity of Natural Compounds: From Plants to Humans)

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17 pages, 7586 KiB

Open AccessArticle

Corrosion of Low-Alloy Steel in Ethanolamine Steam Generator Chemistry—The Effect of Temperature and Flow Rate

by Iva Betova, Martin Bojinov and Vasil Karastoyanov

Molecules 2025, 30(2), 418; https://doi.org/10.3390/molecules30020418 - 20 Jan 2025

Abstract

The corrosion of low-alloy steel in ethanolamine solution, simulating steam generator chemistry, is studied by in situ chronopotentiometry and electrochemical impedance spectroscopy combined with ex situ analysis of the obtained oxide films and model calculations. Hydrodynamic calculations of the proposed setup to study [...] Read more.

The corrosion of low-alloy steel in ethanolamine solution, simulating steam generator chemistry, is studied by in situ chronopotentiometry and electrochemical impedance spectroscopy combined with ex situ analysis of the obtained oxide films and model calculations. Hydrodynamic calculations of the proposed setup to study flow-assisted corrosion demonstrate that turbulent conditions are achieved. Quantum chemical calculations indicate the adsorption orientation of ethanolamine on the oxide surface. Interpretation of impedance spectra with a kinetic approach based on the mixed-conduction model enabled estimating the rate constants of oxidation at the alloy–oxide interface, as well as charge transfer and ionic transport resistances of the corrosion process. In turbulent conditions, the dissolution of Fe oxide and ejection of Fe cations are enhanced, leading to Cr enrichment in the oxide and alteration of its electronic and electrochemical properties that influence the corrosion rate. Full article

(This article belongs to the Section Electrochemistry)

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28 pages, 4327 KiB

Open AccessFeature PaperReview

Recent Advances in Paper Conservation Using Nanocellulose and Its Composites

by Mei Jiang, Jingjing Yao, Qiang Guo, Yueer Yan, Yi Tang and Yuliang Yang

Molecules 2025, 30(2), 417; https://doi.org/10.3390/molecules30020417 - 19 Jan 2025

Abstract

Paper-based cultural relics experience aging and deterioration during their long-term preservation, which poses a serious threat to their lifetime. The development of conservation materials with high compatibility and low intervention has been expected to extend the lifetime of paper artifacts. As a new [...] Read more.

Paper-based cultural relics experience aging and deterioration during their long-term preservation, which poses a serious threat to their lifetime. The development of conservation materials with high compatibility and low intervention has been expected to extend the lifetime of paper artifacts. As a new type of biological macromolecule, nanocellulose has been extensively utilized in paper conservation, attributed to its excellent paper compatibility, high optical transparency, outstanding mechanical strength, and large specific surface area with abundant hydroxyl groups. This review systematically summarizes the latest development of three kinds of nanocellulose (cellulose nanofibril, cellulose nanocrystal, and bacterial nanocellulose) and their composites used for the multifunctional conservation of paper relics. Owing to the strong hydrogen bond interactions between hydroxyls of nanocellulose and paper fibers, nanocellulose can effectively consolidate paper without adding adhesives. The composite of nanocellulose with other functional materials greatly expands its application scope, and the superior performance has been emphasized in paper deacidification, consolidation, antimicrobial effect, antioxidation, UV resistance, self-cleaning, promotion of printing property, reduction in air permeability, and flame retardancy. The application characteristics and future prospects of nanocellulose composites are highlighted in the conservation of paper-based cultural relics. Full article

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21 pages, 2172 KiB

Open AccessArticle

Crude Drugs for Clearing Heat Contain Compounds Exhibiting Anti-Inflammatory Effects in Interleukin-1β-Treated Rat Hepatocytes

by Airi Fujii, Saki Onishi, Nodoka Watanabe, Mizuki Kajimura, Kentaro Ito, Keita Minamisaka, Yuto Nishidono, Saki Shirako, Yukinobu Ikeya and Mikio Nishizawa

Molecules 2025, 30(2), 416; https://doi.org/10.3390/molecules30020416 - 19 Jan 2025

Abstract

Traditional Japanese medicines, i.e., Kampo medicines, consist of crude drugs (mostly plants) that have empirical pharmacological functions (‘Yakuno’ in Japanese), such as clearing heat. Crude drugs with cold properties, such as Phellodendron bark, have the empirical function of clearing heat as [...] Read more.

Traditional Japanese medicines, i.e., Kampo medicines, consist of crude drugs (mostly plants) that have empirical pharmacological functions (‘Yakuno’ in Japanese), such as clearing heat. Crude drugs with cold properties, such as Phellodendron bark, have the empirical function of clearing heat as they cool the body. Because we found that anti-inflammatory compounds were present in several crude drugs for clearing heat, it is speculated that the empirical function of clearing heat may be linked to anti-inflammatory activities. When 10 typical crude drugs were selected from 22 herbal crude drugs for clearing heat, we identified anti-inflammatory compounds in five crude drugs, including Phellodendron bark. In this study, the other crude drugs were extracted and partitioned with ethyl acetate (EtOAc) and n-butanol to obtain three crude fractions. All the EtOAc-soluble fractions, except that from Forsythia fruits, inhibited interleukin (IL)-1β-induced nitric oxide (NO) production in primary-cultured rat hepatocytes. Anti-inflammatory compounds were identified from these EtOAc-soluble fractions: baicalein from Scutellaria roots, (−)-nyasol from Anemarrhena rhizomes, and loniflavone from Lonicera leaves and stems. (+)-Phillygenin was purified from Forsythia fruits by removing cytotoxic oleanolic and betulinic acids. These compounds suppressed the production of NO and cytokines in hepatocytes. Anti-inflammatory compounds were not purified from the EtOAc-soluble fraction of Rehmannia roots because of their low abundance. Collectively, these findings indicate that anti-inflammatory compounds are present in all 10 crude drugs for clearing heat, confirming that these anti-inflammatory compounds in crude drugs provide the empirical functions for clearing heat. Other empirical functions of Kampo medicine can also be explained by modern pharmacological activities. Full article

(This article belongs to the Special Issue Natural Bioactive Compounds from Traditional Asian Plants)

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14 pages, 1435 KiB

Open AccessArticle

Concise Synthesis of Naphthalene-Based 14-Aza-12-Oxasteroids

by Smriti Srivastava, Jun Luo, Daniel Whalen, Katherine N. Robertson and Amitabh Jha

Molecules 2025, 30(2), 415; https://doi.org/10.3390/molecules30020415 - 19 Jan 2025

Abstract

A concise, transition metal-free four-step synthetic pathway has been developed for the synthesis of tetracyclic heterosteroidal compounds, 14-aza-12-oxasteroids, starting from readily available 2-naphthol analogues. After conversion of 2-naphthols to 2-naphthylamines by the Bucherer reaction, subsequent selective C-acetylation was achieved via the Sugasawa reaction [...] Read more.

A concise, transition metal-free four-step synthetic pathway has been developed for the synthesis of tetracyclic heterosteroidal compounds, 14-aza-12-oxasteroids, starting from readily available 2-naphthol analogues. After conversion of 2-naphthols to 2-naphthylamines by the Bucherer reaction, subsequent selective C-acetylation was achieved via the Sugasawa reaction and reduction of the acetyl group using borohydride, which resulted into the corresponding amino-alcohols. The naphthalene-based amino-alcohols underwent double dehydrations and double intramolecular cyclization with oxo-acids leading to one-pot formation of a C-N bond, a C-O bond and an amide bond in tandem, to generate two additional rings completing the steroidal framework. A series of 14-aza-12-oxasteroids were synthesized using our developed synthetic strategy in moderate yields, and the structure of one of the final products, 12a-Methyl-11-phenyl-11,12a-dihydro-1H-naphtho[2,1-d]pyrrolo[2,1-b][1,3]oxazin-3(2H)-one, was further confirmed by single crystal X-ray crystallography. Full article

(This article belongs to the Special Issue Advances in the Synthesis of Heterocyclic Compounds and Their Applications)

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12 pages, 1455 KiB

Open AccessFeature PaperArticle

Enzymatic β-Mannosylation of Phenylethanoid Alcohols

by Lucia Černáková, Peter Haluz, Vladimír Mastihuba, Zuzana Košťálová, Elena Karnišová Potocká and Mária Mastihubová

Molecules 2025, 30(2), 414; https://doi.org/10.3390/molecules30020414 - 19 Jan 2025

Abstract

Phenylethanoid glycosides (PhGs) are widely occurring secondary metabolites of medicinal plants with interesting biological activities such as antioxidant, anti-inflammatory, neuroprotective, antiviral, hepatoprotective, immunomodulatory, etc. They are characterized by a structural core formed by a phenethyl alcohol, usually tyrosol or hydroxytyrosol, attached to β-D-glucopyranose [...] Read more.

Phenylethanoid glycosides (PhGs) are widely occurring secondary metabolites of medicinal plants with interesting biological activities such as antioxidant, anti-inflammatory, neuroprotective, antiviral, hepatoprotective, immunomodulatory, etc. They are characterized by a structural core formed by a phenethyl alcohol, usually tyrosol or hydroxytyrosol, attached to β-D-glucopyranose via a glycosidic bond. This core is usually further decorated by attached phenolic acids or another saccharide. Several studies suggest an important role of the saccharidic fragment in the biological activities of PhGs, provoking demand for new glycovariants of natural PhGs. This study presents the preparation of β-mannosylated analogs of tyrosol β-D-glucopyranoside (salidroside) and hydroxytyrosol β-D-glucopyranoside (hydroxysalidroside). While the chemical synthesis of β-D-mannopyranosides is rather challenging, they can be prepared by enzymatic catalysis. We found that Novozym 188, an industrial β-glucosidase, also contains β-mannosidase and used this enzyme in the preparation of tyrosol β-D-mannopyranoside and hydroxytyrosol β-D-mannopyranoside in 12 and 16% chemical yields, respectively, by transglycosylation from β-D-mannopyranosyl-(1→4)-D-mannose. The mannosylation was chemoselective and occurred exclusively on the primary hydroxyls of tyrosol and hydroxytyrosol, and the glycosylation of phenolic moieties of the aglycons was observed. Full article

(This article belongs to the Section Natural Products Chemistry)

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12 pages, 592 KiB

Open AccessArticle

An Electrochemical Dopamine Assay with Cobalt Oxide Palatinose Carbon Dots

by Ram Chandra Nepal, Elif S. Seven, Roger M. Leblanc and Charles C. Chusuei

Molecules 2025, 30(2), 413; https://doi.org/10.3390/molecules30020413 - 19 Jan 2025

Abstract

Elevated dopamine (DA) levels in urine denote neuroblastoma, a pediatric cancer. Saccharide-derived carbon dots (CDs) were applied to assay DA detection in simulated urine (SU) while delineating the effects of graphene defect density on electrocatalytic activity. CDs were hydrothermally synthesized to vary graphene [...] Read more.

Elevated dopamine (DA) levels in urine denote neuroblastoma, a pediatric cancer. Saccharide-derived carbon dots (CDs) were applied to assay DA detection in simulated urine (SU) while delineating the effects of graphene defect density on electrocatalytic activity. CDs were hydrothermally synthesized to vary graphene defect densities using sucrose, raffinose, and palatinose, depositing them onto glassy carbon electrodes (GCEs). Co₃O₄ nanoparticles (NPs) were encapsulated by the CDs. Cyclic (CV) and linear sweep (LSV) voltammetry measurements were obtained, drop-casting the CDs onto GCEs and measuring DA in a phosphate-buffer solution (pH = 7). DA had an oxidation peak at +0.2 V with SucCDs, with the highest current correlating with the highest defect density. PalCD-Co₃O₄ exhibited the largest signal for DA detection in simulated urine (SU) using the oxidation peak at +0.5 V; the composite had a lower defect density compared to SucCD-Co₃O₄. The Co₃O₄-PalCDs had a DA detection range of 1 to 90 µM with an LOD of 0.88 μM in SU. SEM-EDX analysis of the electrode surface revealed semi-spherical structures with an average particle diameter of 80 ± 19 nm (n = 347) with PalCDs decorating the Co₃O₄ NPs. XRD characterization showed the incorporation of PalCD and Co₃O₄ within the composite. XPS showed electron density donation from the PalCD to Co₃O₄. Full article

(This article belongs to the Section Electrochemistry)

19 pages, 4186 KiB

Open AccessArticle

Thiamine and Thiamine Pyrophosphate as Non-Competitive Inhibitors of Acetylcholinesterase—Experimental and Theoretical Investigations

by Łukasz Szeleszczuk, Dariusz Maciej Pisklak and Błażej Grodner

Molecules 2025, 30(2), 412; https://doi.org/10.3390/molecules30020412 - 19 Jan 2025

Abstract

Vitamin B₁ (thiamine) plays an important role in human metabolism. It is essential for the proper growth and development of the body and has a positive effect on the functioning of the digestive, cardiovascular, and nervous systems. Additionally, it stimulates the brain [...] Read more.

Vitamin B₁ (thiamine) plays an important role in human metabolism. It is essential for the proper growth and development of the body and has a positive effect on the functioning of the digestive, cardiovascular, and nervous systems. Additionally, it stimulates the brain and improves the psycho-emotional state. In vivo, vitamin B₁ occurs in free form as thiamine or as its ester with phosphate residue(s), i.e., as mono-, di-, or triphosphate. It has been proven that supportive therapy with vitamin B₁ can not only provide neuroprotection but also has a positive effect on advanced neurodegenerative diseases, such as Parkinson’s disease, Alzheimer’s disease, Wernicke–Korsakoff syndrome, or Huntington’s disease. This paper presents studies on the effect of free thiamine (T) and thiamine pyrophosphate (TPP) on the activity of acetylcholinesterase (AChE), which is an enzyme considered to play an important role in the therapies for neurodegenerative diseases, especially Alzheimer’s disease. The mechanisms of action of these compounds as potential inhibitors of AChE were evaluated using both experimental (enzymatic activity) as well as computational (molecular docking, molecular dynamics simulations, and MM-GBSA calculations) methods. The results of the current study indicate a non-competitive type of enzyme inhibition, in contrast to the previously published works suggesting a competitive one. Full article

(This article belongs to the Special Issue Enzyme Inhibitors: Design, Synthesis and Biological Evaluation, 2nd Edition)

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22 pages, 3257 KiB

Open AccessReview

Compounds Involved in the Invasive Characteristics of Lantana camara

by Hisashi Kato-Noguchi and Midori Kato

Molecules 2025, 30(2), 411; https://doi.org/10.3390/molecules30020411 - 19 Jan 2025

Abstract

Lantana camara L. is native to tropical America and has naturalized in many other tropical, subtropical, and temperate regions in Asia, Africa, Oceania, North and South America, and Europe. L. camara infests diverse habitats with a wide range of climatic factors, and its [...] Read more.

Lantana camara L. is native to tropical America and has naturalized in many other tropical, subtropical, and temperate regions in Asia, Africa, Oceania, North and South America, and Europe. L. camara infests diverse habitats with a wide range of climatic factors, and its population increases aggressively as one of the world’s 100 worst invasive alien species. Its infestation reduces species diversity and abundance in the natural ecosystems and reduces agricultural production. The life history characteristics of L. camara, such as its high reproductive ability and high adaptive ability to various environmental conditions, may contribute to its ability to infest and increase its population. Possible evidence of the compounds involved in the defense functions of L. camara against natural enemies, such as herbivore mammals and insects, parasitic nematodes, pathogenic fungi and bacteria, and the allelochemicals involved in its allelopathy against neighboring competitive plant species, have accumulated in the literature over three decades. Lantadenes A and B, oleanonic acid, and icterogenin are highly toxic to herbivore mammals, and β-humulene, isoledene, α-copaene thymol, and hexadecanoic acid have high insecticidal activity. β-Caryophyllene and cis-3-hexen-1-ol may function as herbivore-induced plant volatiles which are involved in sending warning signals to undamaged tissues and the next plants of the same species. Farnesol and farnesal may interrupt insect juvenile hormone biosynthesis and cause abnormal metamorphosis of insects. Several triterpenes, such as lantanolic acid, lantoic acid, pomolic acid, camarin, lantacin, camarinin, ursolic acid, and oleanonic acid, have demonstrated nematocidal activity. Lantadene A, β-caryophyllene, germacrene-D, β-curcumene, eicosapentaenoic acid, and loliolide may possess antimicrobial activity. Allelochemicals, such as caffeic acid, ferulic acid, salicylic acid, α-resorcylic acid, p-hydroxybenzoic acid, vanillic acid, unbelliferone, and quercetin, including lantadenes A and B and β-caryophyllene, suppress the germination and growth of neighboring plant species. These compounds may be involved in the defense functions and allelopathy and may contribute to L. camara’s ability to infest and to expand its population as an invasive plant species in new habitats. This is the first review to focus on how compounds enhance the invasive characteristics of L. camara. Full article

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