Molecules

23 pages, 8012 KiB

Open AccessArticle

Phenolic Compounds in Flowers and Herb of Achillea millefolium L.: Histochemical and Phytochemical Studies

by Agata Konarska, Elżbieta Weryszko-Chmielewska, Małgorzata Materska, Aneta Sulborska-Różycka, Marta Dmitruk and Barbara Chilczuk

Molecules 2025, 30(9), 2084; https://doi.org/10.3390/molecules30092084 - 7 May 2025

Viewed by 188

Abstract

The herb and flowers of yarrow (Achillea millefolium) are sources of multiple bioactive secondary metabolites used in medicine and cosmetology. This study aimed to establish the location of phenolic compounds in tissues of flowers and stems of A. millefolium via light [...] Read more.

The herb and flowers of yarrow (Achillea millefolium) are sources of multiple bioactive secondary metabolites used in medicine and cosmetology. This study aimed to establish the location of phenolic compounds in tissues of flowers and stems of A. millefolium via light and fluorescence microscopy and histochemical assays. The spectrophotometric and HPLC methods were deployed to quantify total phenolic compounds (PC), phenolic acids, and flavonoids in extracts from flowers and herb, whereas the LC-QTOF-MS method was used for their qualitative analysis. The results demonstrated that PC occurred in external and internal tissues of yarrow stems, petals, and other parts of the flower, as well as in involucral bracts. Qualitative phytochemical analyses demonstrated ca. 16% more PC and flavonoids in flowers than in the herb. This analysis allowed identifying 48 PC. A higher number of PC was identified in flowers than in herbs, with rosmarinic acid followed by chlorogenic acid being the major polyphenols found in both sample types. One of the flavonoids, namely luteolin, was detected in significantly higher quantities in the flowers than in the herb. This study results provide new data on the location of PC in flowers and stems of A. millefolium as well as extend knowledge on their contents in the raw material of yarrow. Full article

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14 pages, 3740 KiB

Open AccessArticle

Structure of a DNA Glycosylase Bound to a Nicked T:G Mismatch-Containing DNA

by Hala Ouzon-Shubeita, Rebecca Barnes, Lillian F. Schmaltz and Seongmin Lee

Molecules 2025, 30(9), 2083; https://doi.org/10.3390/molecules30092083 - 7 May 2025

Viewed by 144

Abstract

Mismatched T:G base pairs can arise during de novo replication as well as base excision repair (BER). In particular, the action of the gap-filling polymerase β (Polβ) can generate a T:G pair as well as a nick in the DNA backbone. The processing [...] Read more.

Mismatched T:G base pairs can arise during de novo replication as well as base excision repair (BER). In particular, the action of the gap-filling polymerase β (Polβ) can generate a T:G pair as well as a nick in the DNA backbone. The processing of a nicked T:G mispair is poorly understood. We are interested in understanding whether the T:G-specific DNA glycosylase MBD4 can recognize and process nicked T:G mismatches. We have discovered that MBD4 binds a nicked T:G-containing DNA, but does not cleave thymine opposite guanine. To gain insight into this, we have determined a crystal structure of human MBD4 bound to a nicked T:G-containing DNA. This structure displayed the full insertion of thymine into the catalytic site and the recognition of thymine based on the catalytic site’s amino acid residues. However, thymine excision did not occur, presumably due to the inactivation of the catalytic D560 carboxylate nucleophile via a polar interaction with the 5′-hydrogen phosphate of the nicked DNA. The nicked complex was greatly stabilized by an ordered water molecule that formed four hydrogen bonds with the nicked DNA and MBD4. Interestingly, the arginine finger R468 did not engage in the phosphate pinching that is commonly observed in T:G mismatch recognition complex structures. Instead, the guanidinium moiety of R468 made bifurcated hydrogen bonding interactions with O6 of guanine, thereby stabilizing the estranged guanine. These observations suggest that R468 may sense and disrupt T:G pairs within the DNA duplex and stabilize the flipped-out thymine. The structure described here would be a close mimic of an intermediate in the base extrusion pathway induced by DNA glycosylase. Full article

(This article belongs to the Section Bioorganic Chemistry)

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17 pages, 18705 KiB

Open AccessArticle

A Cost-Effective Treatment of Spin–Orbit Couplings in the State-Averaged Driven Similarity Renormalization Group Second-Order Perturbation Theory

by Meng Wang and Chenyang Li

Molecules 2025, 30(9), 2082; https://doi.org/10.3390/molecules30092082 - 7 May 2025

Viewed by 145

Abstract

We present an economical approach to treat spin–orbit coupling (SOC) in the state-averaged driven similarity renormalization group second-order perturbation theory (SA-DSRG-PT2). The electron correlation is first introduced by forming the SA-DSRG-PT2 dressed spin-free Hamiltonian. This Hamiltonian is then augmented with the Breit–Pauli Hamiltonian [...] Read more.

We present an economical approach to treat spin–orbit coupling (SOC) in the state-averaged driven similarity renormalization group second-order perturbation theory (SA-DSRG-PT2). The electron correlation is first introduced by forming the SA-DSRG-PT2 dressed spin-free Hamiltonian. This Hamiltonian is then augmented with the Breit–Pauli Hamiltonian and diagonalized using spin-pure reference states to obtain the SOC-corrected energy spectrum. The spin–orbit mean-field approximation is also assumed to reduce the cost associated with the two-electron spin–orbit integrals. The resulting method is termed BP1-SA-DSRG-PT2c, and it possesses the same computational scaling as the non-relativistic counterpart, where only the one- and two-body density cumulants are required to obtain the vertical transition energy. The accuracy of BP1-SA-DSRG-PT2c is assessed on a few atoms and small molecules, including main-group diatomic molecules, transition-metal atoms, and actinide dioxide cations. Numerical results suggest that BP1-SA-DSRG-PT2c performs comparably to other internally contracted multireference perturbation theories with SOC treated using the state interaction scheme. Full article

(This article belongs to the Special Issue Multiconfigurational and DFT Methods Applied to Chemical Systems—2nd Edition)

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24 pages, 8965 KiB

Open AccessArticle

Nitrogen-Doped Hollow Carbon Spheres-Decorated Co₂SnO₄/WS₂ Heterostructures with Improved Visible-Light Photocatalytic Degradation of Organic Dye

by Muthuraj Arunpandian and Tae Hwan Oh

Molecules 2025, 30(9), 2081; https://doi.org/10.3390/molecules30092081 - 7 May 2025

Viewed by 144

Abstract

Advanced photocatalytic materials for environmental cleanup need to be developed in response to growing concerns about water pollution. This paper presents a novel N-doped hollow carbon spheres (NHCSs)-supported Co₂SnO₄/WS₂ heterostructure synthesized using a hydrothermal approach and examined using [...] Read more.

Advanced photocatalytic materials for environmental cleanup need to be developed in response to growing concerns about water pollution. This paper presents a novel N-doped hollow carbon spheres (NHCSs)-supported Co₂SnO₄/WS₂ heterostructure synthesized using a hydrothermal approach and examined using various characterization techniques to evaluate the crystal structures, functional groups, surface morphology, chemical properties, and optical characteristics. The photocatalytic performance of the Co₂SnO₄/WS₂@NHCSs composite was assessed by degrading Congo red (CR) under visible light, resulting in a notable degradation rate of 87.22% in 60 min. The enhanced degradation efficiency is ascribed to the Z-scheme heterojunction charge-transfer mechanism, which augments sustained charge separation while suppressing recombination under visible-light irradiation. Furthermore, the quenching experiments revealed that specific superoxide radicals (^•O₂^-) and hydroxyl radicals (^•OH) were integral to the degradation reaction, and a potential Z-scheme charge-transfer pathway mechanism for the effective Co₂SnO₄/WS₂@NHCSs photocatalysts was also suggested. The potential degradation mechanism was suggested using LC-MS analysis. This study highlights the promise of Co₂SnO₄/WS₂@NHCSs composites for practical wastewater treatment applications, providing a sustainable and effective solution for environmental remediation. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal, 2nd Edition)

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23 pages, 23181 KiB

Open AccessArticle

Ultrasound-Assisted Ferritin Extraction from Northern Pike Liver: An Innovative Approach for Chlorogenic Acid Encapsulation with Enhanced Thermal Stability

by Zhikun Xing, Yi Wang, Yabo Wei, Xin Guo, Xiaoyue Liang, Xiaorong Deng, Lianfu Zhang and Jian Zhang

Molecules 2025, 30(9), 2080; https://doi.org/10.3390/molecules30092080 - 7 May 2025

Viewed by 173

Abstract

Ferritin, an emerging protein resource, has garnered significant attention in scientific research due to its biocompatibility and unique cavity structure capable of encapsulating bioactive compounds. This study aimed to optimize ultrasound-assisted extraction (UAE) for enhancing ferritin yield from northern pike liver byproducts and [...] Read more.

Ferritin, an emerging protein resource, has garnered significant attention in scientific research due to its biocompatibility and unique cavity structure capable of encapsulating bioactive compounds. This study aimed to optimize ultrasound-assisted extraction (UAE) for enhancing ferritin yield from northern pike liver byproducts and evaluate its potential as a nanocarrier for chlorogenic acid (CA). Through response surface methodology (RSM), the optimal UAE parameters were established as 200 W ultrasonic power, 1:3 solid–liquid ratio, and 25 min extraction time. Under these conditions, the ferritin extraction yield reached 139.46 mg/kg, representing a 4.02-fold increase compared to conventional methods (34.65 mg/mL). Electrophoretic analysis confirmed the electrophoretic purity of the extracted liver ferritin. Comprehensive characterization using UV-vis spectroscopy, FTIR, and fluorescence spectroscopy revealed preserved structural integrity of UAE-extracted ferritin. Homology modeling provided molecular insights into the ferritin architecture. Successful encapsulation of CA was achieved with an encapsulation efficiency of 13.25%, as quantified by HPLC. Analysis by DLS and ζ potential as well as TG and DSC showed that not only the thermal stability of CA was enhanced after ferritin encapsulation, but also that the ferritin remained stable with a cage-like structure. This investigation establishes UAE as an effective strategy for valorizing fish processing byproducts through high-yield ferritin extraction while demonstrating the protein’s functional capacity as a nanocarrier for bioactive compound delivery. The findings highlight the dual advantage of sustainable resource utilization and advanced delivery system development through this biotechnological approach. Full article

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14 pages, 2913 KiB

Open AccessArticle

Selective Extraction of Aromatics from Slurry Oil with Subcritical Water

by Nuo-Xin Zhou, Zhu-Qi Liu, Meng-Han Zhu, Zi-Bin Huang, Jing-Yi Yang, Li-Tao Wang and Pei-Qing Yuan

Molecules 2025, 30(9), 2079; https://doi.org/10.3390/molecules30092079 - 7 May 2025

Viewed by 146

Abstract

The selective separation of aromatics from slurry oil (SLO)—a low-value byproduct of fluid catalytic cracking—remains a major industrial challenge. This study investigates the use of subcritical water (Sub-CW) as a green and tunable solvent to extract aromatics from SLO in a semi-batch system [...] Read more.

The selective separation of aromatics from slurry oil (SLO)—a low-value byproduct of fluid catalytic cracking—remains a major industrial challenge. This study investigates the use of subcritical water (Sub-CW) as a green and tunable solvent to extract aromatics from SLO in a semi-batch system operating at 250–325 °C. At 325 °C and a water-to-oil mass ratio of 6:1, the extract yield reaches 16 wt%, with aromatic hydrocarbons accounting for over 90 wt% of the extract, predominantly composed of 3- to 4-ring polycyclic aromatic hydrocarbons. Comprehensive characterization via simulated distillation, SARA analysis, FT-IR, and ¹H-NMR confirms the selective enrichment of aromatics and effective separation from saturates and asphaltenes. To elucidate the molecular basis of this selectivity, principal component analysis of Hansen solubility parameters was performed. The results revealed a temperature-dependent solubility trend in Sub-CW, whereby the affinity for hydrocarbons follows the order aromatics > cycloalkanes > alkanes. This solubility preference, supported by both experimental data and theoretical analysis, offers new insight into subcritical solvent design and provides a basis for process intensification in SLO valorization. Full article

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18 pages, 2382 KiB

Open AccessArticle

Synthesis of Diversely Substituted Diethyl (Pyrrolidin-2-Yl)Phosphonates

by Andrea Bagán, Alba López-Ruiz, Sònia Abás, Elies Molins, Belén Pérez, Itziar Muneta-Arrate, Luis F. Callado and Carmen Escolano

Molecules 2025, 30(9), 2078; https://doi.org/10.3390/molecules30092078 - 7 May 2025

Viewed by 187

Abstract

Imidazoline I₂ receptors (I₂-IR) are untapped therapeutic targets lacking a structural description. Although the levels of I₂-IR are dysregulated in a plethora of illnesses, the arsenal of ligands that can modulate I₂-IR is limited. In this [...] Read more.

Imidazoline I₂ receptors (I₂-IR) are untapped therapeutic targets lacking a structural description. Although the levels of I₂-IR are dysregulated in a plethora of illnesses, the arsenal of ligands that can modulate I₂-IR is limited. In this framework, we have reported several new structural families embodying the iminophosphonate functional group that have an excellent affinity and selectivity for I₂-IR, and selected members have demonstrated relevant pharmacological properties in murine models of neurodegeneration and Alzheimer’s disease. Starting with these iminophosphonates, we continued to exploit their high degree of functionalization through a short and efficient synthesis to access unprecedented 2,3-di, 2,2,3-tri, 2,3,4-tri, and 2,2,3,4-tetrasubstituted diethyl (pyrrolidine-2-yl) phosphonates. The stereochemistry of the new compounds was unequivocally characterized by X-ray crystallographic analyses. Two selected compounds with structural features shared with the starting products were pharmacologically evaluated, allowing us to deduce the required key structural motifs for biologically active aminophosphonate derivatives. Full article

(This article belongs to the Special Issue Heterocycles: Design, Synthesis and Biological Evaluation, 3rd Edition)

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45 pages, 20859 KiB

Open AccessReview

Thiosemicarbazone-Based Compounds: Cancer Cell Inhibitors with Antioxidant Properties

by Olga Garbuz, Emil Ceban, Dorin Istrati, Nadejda Railean, Ion Toderas and Aurelian Gulea

Molecules 2025, 30(9), 2077; https://doi.org/10.3390/molecules30092077 - 7 May 2025

Viewed by 212

Abstract

Thiosemicarbazone-based compounds have attracted significant attention in recent years due to their potential as inhibitors of cancer cell proliferation. They not only exhibit strong antiproliferative effects but also possess antioxidant properties that are crucial in combating oxidative stress linked to cancer progression. This [...] Read more.

Thiosemicarbazone-based compounds have attracted significant attention in recent years due to their potential as inhibitors of cancer cell proliferation. They not only exhibit strong antiproliferative effects but also possess antioxidant properties that are crucial in combating oxidative stress linked to cancer progression. This review highlights specific compounds that not only exhibit significantly higher antiproliferative activities but also demonstrate lower toxicity compared to traditional chemotherapy agents. This is important because it suggests that these compounds could provide better treatment options while reducing the side effects often associated with chemotherapy. A detailed analysis of the structure–activity relationships (SARs) reveals that the unique structural features of these compounds play a crucial role in their enhanced effectiveness. Understanding which molecular characteristics contribute to improved activity will be key for future compound design. The findings from this study emphasize the need for further exploration and development of these novel agents. By investigating their biological mechanisms and optimizing their structures, researchers can improve cancer treatment strategies, providing safer and more effective options for patients. Despite substantial previous research on thiosemicarbazones and isothiosemicarbazones, the field still holds many unknowns and opportunities for discovery. Studying coordination chemistry with 3d metal ions and strategically modifying their inner structures may lead to new compounds with promising biological activities and selectivity. Overall, exploring thiosemicarbazones and isothiosemicarbazones as innovative pharmacological agents against cancer could unlock their full potential, significantly enhancing cancer treatment protocols and improving patient survival rates. Full article

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12 pages, 826 KiB

Open AccessArticle

Magnetic Solid-Phase Extraction Based on C18 Nanoparticles for the Determination of Pesticides in Aquaculture Water Samples

by Margarita Kapsi, Vasileios Sakkas, Vasiliki Boti and Triantafyllos Albanis

Molecules 2025, 30(9), 2076; https://doi.org/10.3390/molecules30092076 - 7 May 2025

Viewed by 156

Abstract

In this study, C18-functionalized magnetic silica nanoparticles (Fe₃O₄@SiO₂@C18) were used as adsorbents for the magnetic solid-phase extraction (MSPE) of organic contaminants commonly applied to aquaculture water (organic booster biocides, herbicides, and insecticides) followed by Gas Chromatography coupled [...] Read more.

In this study, C18-functionalized magnetic silica nanoparticles (Fe₃O₄@SiO₂@C18) were used as adsorbents for the magnetic solid-phase extraction (MSPE) of organic contaminants commonly applied to aquaculture water (organic booster biocides, herbicides, and insecticides) followed by Gas Chromatography coupled to Mass Spectrometry (GC–MS). The extraction conditions and efficiency of the nanoparticles for the determination of ten pesticides (atrazine, ethoxyquine, chlorothalonil, chlorpyriphos methyl, methyl parathion, chlorpyriphos, resmethrin, λ-cyhalothrin, permethrin, and irgarol) were thoroughly investigated. Several experimental parameters affecting the extraction efficiency such as the amount of sorbent, extraction time, and elution time were optimized by employing experimental designs as response surface methodology. Validation experiments showed that the average recoveries of target analytes were in the range of 60% to 99%. The optimized method exhibited good linearity (R² > 0.9901) and satisfactory precision (Relative Standard deviations, RSDs < 15%). The method detection limits ranged between 1.9 ng L⁻¹ and 62 ng L⁻¹. Finally, the MSPE method was successfully applied to aquaculture water samples collected from the Thesprotia region (N.W. Greece), Thermaikos Gulf (N. Greece) and Butrint (S.W. Albania). Full article

(This article belongs to the Special Issue Green Chemistry Approaches to Analysis and Environmental Remediation)

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9 pages, 3016 KiB

Open AccessArticle

Synthesis, Structure and Dye Adsorption Properties of Wine-Rack-Type Supramolecular Macrocycles Based on Polyoxovanadate

by Nasen Bate, Baoshan Hou and Hongmei Gan

Molecules 2025, 30(9), 2075; https://doi.org/10.3390/molecules30092075 - 7 May 2025

Viewed by 131

Abstract

The precise construction and programmable assembly of structures with specific topologies remain persistent challenges in crystal engineering, primarily constrained by the limited availability of building blocks. Utilizing a synergistic approach that combines an in situ-formed concave polyoxovanadate (POV) cluster {VV₄} with [...] Read more.

The precise construction and programmable assembly of structures with specific topologies remain persistent challenges in crystal engineering, primarily constrained by the limited availability of building blocks. Utilizing a synergistic approach that combines an in situ-formed concave polyoxovanadate (POV) cluster {VV₄} with specifically designed 120° ditopic carboxylic acid bridging ligands, we successfully synthesized a series of wine-rack-type supramolecular macrocycles characterized by the general formula [(V₅O₉Cl)₄(L)₈]⁸⁻. The experimental results demonstrate that the introduction of sulfonic acid groups enables controlled structural extension into 1D chain and 2D layer architectures, manifesting the unique advantages of POV-based wine-rack units in constructing framework-based porous materials. This work significantly contributes to the structural diversity of wine-rack-type supramolecular architectures while simultaneously highlighting the great potential of polyoxometalate-driven supramolecular assemblies in materials science. Full article

(This article belongs to the Special Issue Inorganic Chemistry in Asia)

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21 pages, 8372 KiB

Open AccessArticle

Sodium-Intercalated Vanadium Oxide Coated on Carbon Cloth for Electrode Materials in High-Performance Aqueous Zinc-Ion Batteries

by Chen Chen, Baoxuan Hou, Ting Cheng, Fei Wu, Yulin Hu, Youzhi Dai, Xiao Zhang, Yuan Tian, Xin Zhao and Lei Wang

Molecules 2025, 30(9), 2074; https://doi.org/10.3390/molecules30092074 - 7 May 2025

Viewed by 150

Abstract

In this work, novel sodium-intercalated vanadium oxide nanowire electrode materials (NaXV@CC) were successfully designed as cathode materials for Aqueous Zinc-Ion Batteries (AZIBs) through a two-step electrochemical process. The optimized electrode material, Na30V@CC, exhibited superior capacity, excellent rate capability, and outstanding stability. The intercalation [...] Read more.

In this work, novel sodium-intercalated vanadium oxide nanowire electrode materials (NaXV@CC) were successfully designed as cathode materials for Aqueous Zinc-Ion Batteries (AZIBs) through a two-step electrochemical process. The optimized electrode material, Na30V@CC, exhibited superior capacity, excellent rate capability, and outstanding stability. The intercalation of sodium ions into the nanowire lattice induced a significant transformation in the overall nanostructure, leading to altered nanowire morphology. This unique structural design provided abundant active sites and efficient ion transport pathways, thereby enhancing the overall electrochemical performance. The charging and discharging capacities were 343.3 and 330.4 mAh·g⁻¹ at 0.2 A·g⁻¹, respectively, and the capacity was maintained at 90 mAh·g⁻¹ at 8 A·g⁻¹. The battery demonstrated exceptional capacity retention over 3000 cycles at 5 A·g⁻¹, highlighting its long-term electrochemical stability. Moreover, the overall battery reaction was governed by a combination of diffusion and surface processes. The Na30V@CC battery system demonstrated reduced reaction impedance and improved zinc ion diffusion rates. This study offers valuable insights into enhancing the electrochemical performance of vanadium-based cathodes in AZIBs. Full article

(This article belongs to the Special Issue New Insights into Electrochemical Energy Storage and Conversion: Aqueous Rechargeable Batteries)

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16 pages, 2040 KiB

Open AccessArticle

Morus alba L. Cell Cultures as Sources of Antioxidant and Anti-Inflammatory Stilbenoids for Food Supplement Development

by Vanessa Dalla Costa, Anna Piovan, Paola Brun and Raffaella Filippini

Molecules 2025, 30(9), 2073; https://doi.org/10.3390/molecules30092073 - 7 May 2025

Viewed by 156

Abstract

Morus alba L. (Moraceae), white mulberry, is an ancient, well-known source of several compounds with potent biological activities and beneficial effects on human health. In this study, the juices of three stabilised undifferentiated cell lines, calli maintained in light and dark conditions, and [...] Read more.

Morus alba L. (Moraceae), white mulberry, is an ancient, well-known source of several compounds with potent biological activities and beneficial effects on human health. In this study, the juices of three stabilised undifferentiated cell lines, calli maintained in light and dark conditions, and suspensions maintained in dark condition of M. alba were investigated for their phytochemical content and biological activity. The results highlighted the main presence of oxyresveratrol and resveratrol-backbone glucosides, together with benzofuran derivatives. Oxyresveratrol triglucoside was found for the first time in M. alba in vitro cultures, where it represents the main compound, accounting for almost 90 µg/mL in all the juices. The total stilbenoid content resulted significantly higher in calli juices during the logarithmic phase of the growth cycle, and cell suspension juice exhibited the statistically highest total content (313.21 µg/mL of juice). Only cell suspension juice showed ROS reduction in Caco-2 cells, whereas all the juices reduced IL-1β and TNF-α levels in Caco-2 cells stimulated with LPS. These results lay the groundwork for the future exploitation of M. alba dedifferentiated cultures as sustainable resources of stilbenoid compounds to be used in the nutraceutical, cosmetic, and pharmaceutical industries. Full article

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

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27 pages, 2345 KiB

Open AccessArticle

Can Provence Flora Offer Effective Alternatives to Widely Used Medicinal Plants? A Comparative Study of Antioxidant Activity and Chemical Composition Using Molecular Networking

by Clémentine Achard-Baccati, Elnur Garayev, Charifat Saïd Hassane, Célia Breaud, Eldar Garaev, Myriam Bertolotti, Fathi Mabrouki, Sok-Siya Bun-Llopet and Béatrice Baghdikian

Molecules 2025, 30(9), 2072; https://doi.org/10.3390/molecules30092072 - 7 May 2025

Viewed by 165

Abstract

This study compares the antioxidant properties and phytochemical profiles of three pairs of widely used medicinal plant species to their counterparts from Provence, France: Arnica montana with Pentanema montanum (formerly known as Inula montana), Helichrysum italicum with Helichrysum stoechas, and Satureja hortensis [...] Read more.

This study compares the antioxidant properties and phytochemical profiles of three pairs of widely used medicinal plant species to their counterparts from Provence, France: Arnica montana with Pentanema montanum (formerly known as Inula montana), Helichrysum italicum with Helichrysum stoechas, and Satureja hortensis with Satureja montana. Phytochemical composition has been investigated using UHPLC-HRMS/MS and molecular networking, revealing chemical profiles dominated by phenylpropanoids and flavonoids, with lignans, sesquiterpene lactones, or polyketides aside. Well-plate DPPH/ABTS assays were used to evaluate the antioxidant activity of extracts, and post-column assays were used to identify antioxidant compounds. The three Provence species demonstrated comparable or superior antioxidant activities to their counterparts, primarily attributed to phenolic compounds such as mono- and di-caffeoylquinic acids, quercetagetin-7-O-glucoside, and myricetin acetylhexoside. These findings show the potential of Provence species to be substituted for some overharvested medicinal plants. This research supports biodiversity conservation while promoting the integration of these local species into pharmaceutical, nutraceutical, cosmetic, and food industries. Full article

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15 pages, 1998 KiB

Open AccessArticle

Rationally Designed Pentapeptide Analogs of Aβ19–23 Fragment as Potent Inhibitors of Aβ42 Aggregation

by Sachin B. Baravkar, Yan Lu, Qi Zhao, Hongying Peng, Weilie Zhou and Song Hong

Molecules 2025, 30(9), 2071; https://doi.org/10.3390/molecules30092071 - 7 May 2025

Viewed by 167

Abstract

Amyloid beta (Aβ42 and Aβ40) aggregation, along with neurofibrillary tangles, is one of the major neurotoxic events responsible for the onset of Alzheimer’s disease. Many potent peptide-based inhibitors mainly focusing on central hydrophobic core Aβ16–20 (KLVFF) have been reported in recent years. Herein, [...] Read more.

Amyloid beta (Aβ42 and Aβ40) aggregation, along with neurofibrillary tangles, is one of the major neurotoxic events responsible for the onset of Alzheimer’s disease. Many potent peptide-based inhibitors mainly focusing on central hydrophobic core Aβ16–20 (KLVFF) have been reported in recent years. Herein, we report pentapeptides 1–4, based on the β-turn-inducing fragment Aβ19–23 (FFAED). The synthesis of peptides 1–4 was carried out using Fmoc/tBu-based solid-phase peptide synthesis technique, and it was found that pentapeptide 3 potently inhibit the aggregation propensity of Aβ42, when incubated with it at 37 °C for 48 h. The aggregation inhibition study was conducted using thioflavin T-based fluorescence assay and circular dichroism spectroscopy, and supported by transmission electron microscope imaging. The conformational change on the aggregation of Aβ42 and aggregation inhibition by peptides 1–4 was further evaluated using ¹H–¹⁵N HSQC NMR spectroscopy. The results demonstrated that the most potent analog, peptide 3, effectively disrupts the aggregation process. This study is the first to demonstrate that an Aβ19–23 fragment mimic can disrupt the aggregation propensity of Aβ42. Full article

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

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18 pages, 2356 KiB

Open AccessArticle

Effect of Auxins on the Accumulation of Alkaloids in Ungrafted Annona emarginata (Schltdl.) H. Rainer and Annona emarginata (Schltdl.) H. Rainer Grafted with Annona atemoya Mabb.

by Carolina Ovile Mimi, Iván De-la-Cruz-Chacón, Felipe Moura Araujo da Silva, Victor Cauan Rocha Roberto and Gisela Ferreira

Molecules 2025, 30(9), 2070; https://doi.org/10.3390/molecules30092070 - 7 May 2025

Viewed by 133

Abstract

Plant regulators, such as auxins, modulate the synthesis of specialized metabolites and aid in the bioprospection of molecules. Annona emarginata is known to produce antifungal alkaloids and serves as a rootstock for Annona atemoya. This study evaluated the effects of indoleacetic acid [...] Read more.

Plant regulators, such as auxins, modulate the synthesis of specialized metabolites and aid in the bioprospection of molecules. Annona emarginata is known to produce antifungal alkaloids and serves as a rootstock for Annona atemoya. This study evaluated the effects of indoleacetic acid (IAA), indolebutyric acid (IBA), and naphthaleneacetic acid (NAA) applications on the accumulation of alkaloids in ungrafted A. emarginata and grafted with A. atemoya. Total alkaloids were analyzed by spectrophotometry, and alkaloid profiles were analyzed by DI-MS at 8, 14, and 20 days after treatments (DAT). The results indicated that IAA and NAA had the strongest effects on increasing the synthesis of alkaloids in the roots of ungrafted seedlings. In grafted plants, IBA had a more pronounced effect on roots; however, at final evaluation, all three auxins had an impact on both roots and leaves. Chemometric analysis revealed that auxins also altered the alkaloid composition in both seedling types. Nineteen alkaloids were identified regardless of treatment and harvest time. Eight alkaloids were identified for the first time in A. emarginata and nine were identified in A. atemoya. The main alkaloids found in ungrafted seedlings treated with IAA, IBA, and NAA were liriodenine and lanuginosine. In grafted seedlings, liriodenine and reticuline were the primary alkaloids found in roots, whereas liriodenine, lanuginosine, and reticuline were significantly present in leaves. The use of auxins to enhance alkaloid biosynthesis demonstrates their potential for bioprospection and the development of crops tolerant to biotic stress. Full article

(This article belongs to the Special Issue Synthesis, Characterization, and Biological Evaluation of Alkaloids)

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12 pages, 5202 KiB

Open AccessArticle

Reduced Graphene Oxide-Coated Iridium Oxide as a Catalyst for the Oxygen Evolution Reaction in Alkaline Water Electrolysis

by Shengyin Luo, Ziqing Zuo and Hongbin Sun

Molecules 2025, 30(9), 2069; https://doi.org/10.3390/molecules30092069 - 7 May 2025

Viewed by 175

Abstract

Producing hydrogen by water electrolysis has attracted significant attention as a potential renewable energy solution. In this work, a catalyst with reduced graphene oxide (rGO) loaded on IrO₂/TiO₂ (called rGO/IrO₂/TiO₂) was designed for the catalytic oxygen [...] Read more.

Producing hydrogen by water electrolysis has attracted significant attention as a potential renewable energy solution. In this work, a catalyst with reduced graphene oxide (rGO) loaded on IrO₂/TiO₂ (called rGO/IrO₂/TiO₂) was designed for the catalytic oxygen evolution reaction (OER). The catalyst was synthesized by coating graphene oxide onto a pretreated IrO₂/TiO₂ precursor, followed by thermal treatment at 450 °C to achieve reduction and the adhesion of graphene to the substrate. The graphene support retained its intact sp² carbon framework with minor oxygen-containing functional groups, which enhanced electrical conductivity and hydrophilicity. Benefiting from the synergistic effect of an rGO, IrO₂, and TiO₂ matrix, the rGO/IrO₂/TiO₂ catalyst only needed overpotentials of 240 mV and 320 mV to reach 10 mA cm⁻² and 100 mA cm⁻² in the OER, along with excellent stability over 50 h. Its morphology and crystalline structure were characterized by SEM and XRD spectroscopy, and its electrochemical performance was tested by LSV analysis, EIS impedance spectrum, and double-layer capacitance (C_dl) measurements. This work introduces an innovative and eco-friendly strategy for constructing a high-performance, functionalized Ir-based catalyst. Full article

(This article belongs to the Special Issue Design and Mechanisms of Photo(electro)catalysts for Water Splitting)

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12 pages, 3401 KiB

Open AccessArticle

Synthesis and Fluorescence Mechanism of Nitrogen-Doped Carbon Dots Utilizing Biopolymer and Urea

by Hikaru Yorozuya, Noor E Ashrafi, Kazuya Sato, Ahatashamul Islam, Rikuto Fukae, Yusuke Tagashira and Toshifumi Iimori

Molecules 2025, 30(9), 2068; https://doi.org/10.3390/molecules30092068 - 7 May 2025

Viewed by 174

Abstract

Fluorescent carbon dots are nontoxic nanoparticles composed of carbon, exhibiting advantageous properties for applications in bioimaging and functional materials. We present a methodology for synthesizing fluorescent nitrogen-doped carbon dots (N-CDs) using starch, a biopolymer, and urea as the sources of nitrogen, via the [...] Read more.

Fluorescent carbon dots are nontoxic nanoparticles composed of carbon, exhibiting advantageous properties for applications in bioimaging and functional materials. We present a methodology for synthesizing fluorescent nitrogen-doped carbon dots (N-CDs) using starch, a biopolymer, and urea as the sources of nitrogen, via the microwave-assisted hydrothermal method. Furthermore, the dependence of the fluorescence spectra and fluorescence quantum yield of N-CDs on the initial concentration of urea in the reactant solution was examined, thereby providing a comprehensive understanding of the influence of nitrogen doping on the CDs. The fluorescence of N-CDs was tunable by varying the excitation wavelength. Stronger fluorescence intensity was observed for a moist phosphate salt/N-CD composite, in contrast to the weaker fluorescence exhibited by a dried one. Fluorescence lifetime measurements revealed that the change in fluorescence intensity can be attributed to the suppression of the non-radiative deactivation process. This observation highlights the critical importance of the interaction between water molecules and surface functional groups in controlling the photophysics of the excited state of N-CDs. Full article

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16 pages, 5651 KiB

Open AccessArticle

Surface-Dependent Isotopic Adsorption of CO on α-Al₂O₃: Role of Weak Interactions and Zero-Point Energy

by Qun Yang, Xiyue Cheng, Qian Xu and Shuiquan Deng

Molecules 2025, 30(9), 2067; https://doi.org/10.3390/molecules30092067 - 6 May 2025

Viewed by 198

Abstract

Carbon isotopes, particularly ¹³C, are critical for applications in food authentication, biomedical diagnostics, and metabolic research; however, their efficient separation remains challenging due to their low natural abundance. This study investigates the adsorption behavior of ¹²CO and ¹³CO on various [...] Read more.

Carbon isotopes, particularly ¹³C, are critical for applications in food authentication, biomedical diagnostics, and metabolic research; however, their efficient separation remains challenging due to their low natural abundance. This study investigates the adsorption behavior of ¹²CO and ¹³CO on various low-index

α

-Al₂O₃ surfaces as a strategy for isotope separation. Density functional theory (DFT) calculations with D3 (BJ) dispersion corrections were employed to optimize surface models for five representative

α

-Al₂O₃ facets. Nine adsorption configurations were systematically evaluated by optimizing geometric structures, computing adsorption enthalpies with zero-point energy corrections, and performing Bader charge and charge density difference analyses to elucidate interfacial interactions. The results reveal that CO preferentially adsorbs in a vertical configuration via its carbon end at Al sites, with the (0001) surface exhibiting the lowest surface energy and most favorable adsorption characteristics. Furthermore, we found that facets with lower surface energy not only facilitate stronger CO adsorption but also demonstrate pronounced adsorption enthalpy differences between ¹²CO and ¹³CO, driven by vibrational zero-point energy disparities. These findings highlight the potential of low adsorption enthalpy surfaces, particularly (0001), (

01 \bar{1} 2

), and (

11 \bar{2} 0

), for enhancing isotope separation efficiency, providing valuable insights for the design of advanced separation materials. Full article

(This article belongs to the Special Issue Exclusive Contributions by the Editorial Board Members (EBMs) of the Inorganic Chemistry Section of Molecules 2025)

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16 pages, 2967 KiB

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Geometrical Evolution Pattern and Spectroscopic Properties of Terbium-Doped Germanium Anionic TbGe_n (n = 6–17) Nanoclusters: From Tb-Lined to Tb-Encapsulated Structures

by Chenliang Hao and Jucai Yang

Molecules 2025, 30(9), 2066; https://doi.org/10.3390/molecules30092066 - 6 May 2025

Viewed by 179

Abstract

Developing advanced materials with enhanced performance through the doping of nanoclusters is a promising strategy. However, there remains an insufficient understanding of the specific effects induced by such doped nanoclusters, particularly regarding the structural evolution pattern after doping with rare-earth elements and their [...] Read more.

Developing advanced materials with enhanced performance through the doping of nanoclusters is a promising strategy. However, there remains an insufficient understanding of the specific effects induced by such doped nanoclusters, particularly regarding the structural evolution pattern after doping with rare-earth elements and their impact on performance. To solve this problem, we used first-principles calculation to study the structural evolution pattern and spectroscopic properties of anionic TbGe_n (n = 6–17) nanoclusters through the ABCluster global search technique coupled with the mPW2PLYP double-hybrid density functional theory. The results revealed that the geometrical evolution pattern is from the typical Tb-linked structures (for n = 10–13, in which Tb acts as a linker connecting two germanium sub-clusters) to Tb-centered cage configurations (for n = 14–17). The simulated photoelectron spectroscopy of anionic TbGe₁₆ agrees well with its experimental counterpart. Furthermore, we calculated properties such as infrared spectroscopy, Raman spectroscopy, ultraviolet–visible (UV–vis) spectra, magnetism, charge transfer, the HOMO-LUMO gap, and relative stability. The results suggest that TbGe₁₂⁻ and TbGe₁₆⁻ clusters, with their remarkable stability and tunable photothermal properties, can serve as ideal building blocks for developing novel functional nanomaterials. These clusters demonstrate promising applications in solar photothermal conversion, photoelectric conversion, and infrared imaging technologies through their distinct one- and three-dimensional architectures, respectively. Full article

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

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14 pages, 2768 KiB

Open AccessArticle

Vanadyl Phthalocyanine as a Low-Temperature/Low-Pressure Catalyst for the Conversion of Fructose to Methyl Levulinate

by Juan Luna, Mataz Alcoutlabi, Elizabeth Fletes, Helia Morales and Jason G. Parsons

Molecules 2025, 30(9), 2065; https://doi.org/10.3390/molecules30092065 - 6 May 2025

Viewed by 163

Abstract

In this study, a vanadyl phthalocyanine was synthesized and characterized using XRD, FTIR, and XPS, confirming the successful metalation of the phthalocyanine ring. XRD analysis showed the vanadyl phthalocyanine crystallized in the P-1 crystal lattice, with unit cell parameters a = 12.058 Å, [...] Read more.

In this study, a vanadyl phthalocyanine was synthesized and characterized using XRD, FTIR, and XPS, confirming the successful metalation of the phthalocyanine ring. XRD analysis showed the vanadyl phthalocyanine crystallized in the P-1 crystal lattice, with unit cell parameters a = 12.058 Å, b = 12.598 Å, and c = 8.719 Å, and the lattice angels were 96.203°, 94.941°, and 68.204°. FTIR spectroscopy supported the metalation by the disappearance of the N-H stretch of the non-metalated phthalocyanine. The vanadyl phthalocyanine was tested as a heterogenous catalyst for the conversion of fructose into methyl levulinate in H₂SO₄–methanol and HCl–methanol systems. The H₂SO₄–methanol reaction system catalyzed with the vanadyl phthalocyanine, and a zeroth-order rate constant of 1.10 × 10⁻⁶ M/s was observed, which was 1.74 times faster than sulfuric acid alone. The HCl–methanol system showed a zeroth-order of reaction with a rate constant of 2.33 × 10⁻⁶ M/s, which was 1.3 times faster than the HCl–methanol alone. While the HCl–methanol system showed a faster reaction rate, product distribution favored methyl levulinate formation in the H₂SO₄–methanol system. The main products identified were methyl levulinate and hepta-2,4-dienoic acid methyl ester, with a minor amount of hydroxymethylfurfural formed. These results suggest that vanadyl phthalocyanine can be effectively used as a catalyst to increase the rate of fructose conversion to methyl levulinate in either H₂SO₄ or HCl–methanol. Full article

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

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13 pages, 1034 KiB

Open AccessArticle

Diffusion Coefficients and Activation Energies of Diffusion of Organic Molecules in Poly(lactic acid) Films

by Johann Ewender, Rafael Auras, Uruchaya Sonchaeng and Frank Welle

Molecules 2025, 30(9), 2064; https://doi.org/10.3390/molecules30092064 - 6 May 2025

Viewed by 156

Abstract

Poly(lactic acid) (PLA) is one of the most important bio-based and industrial compostable materials in food packaging. Its barrier properties towards oxygen and moisture are well documented. However, data on barrier properties of PLA towards organic molecules are scarce in the literature. This [...] Read more.

Poly(lactic acid) (PLA) is one of the most important bio-based and industrial compostable materials in food packaging. Its barrier properties towards oxygen and moisture are well documented. However, data on barrier properties of PLA towards organic molecules are scarce in the literature. This study investigated the diffusion of various organic molecules, including n-alkanes, 1-alcohols, 2-ketones, ethers, esters, amines, and aromatics, in two commercial PLA films with thicknesses of 20 µm and 30 µm. The diffusion coefficient (D_P) values were determined from lag time in permeation tests conducted at temperatures ranging from 20 °C to 90 °C. The films were also characterized in terms of crystallinity, rigid and mobile amorphous fractions, and molecular weight. Activation energies (E_A) were calculated based on the temperature dependence of the D_P using the Arrhenius approach. In total, 290 D_P values for 55 individual substances were determined, and 38 E_A values were derived from these data. The E_A correlated well with the molecular volume of the investigated substances. Moreover, the pre-exponential factor D₀ showed a correlation with E_A. These correlations enabled the establishment of diffusion modeling parameters for PLA, allowing the prediction of D_P for untested substances. The diffusion behavior of PLA was further compared with the literature data for polyethylene terephthalate and polyethylene naphthalate, providing insights into the relative performance of these materials. Full article

(This article belongs to the Special Issue Advanced Materials, Technologies, and Innovations in Food Packaging towards Sustainability)

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12 pages, 2060 KiB

Open AccessArticle

In Vitro Anti-Hepatitis B Virus Activity of Hydroxytyrosol from Lindernia ruellioides

by Tong-Shi-Yao Zhao, Kang-Zhi Li, He-Ling Su, Bin Liang, Cheng-Qin Liang, Jin-Tao Gao and Xian-Li Zhou

Molecules 2025, 30(9), 2063; https://doi.org/10.3390/molecules30092063 - 6 May 2025

Viewed by 190

Abstract

Hepatitis B is a serious infectious disease that threatens the health of all mankind. In this study, we isolated and extracted hydroxytyrosol from Lindernia ruellioides with anti-hepatitis B virus (HBV) activity. The structure of hydroxytyrosol was identified by the nuclear magnetic resonance technique. [...] Read more.

Hepatitis B is a serious infectious disease that threatens the health of all mankind. In this study, we isolated and extracted hydroxytyrosol from Lindernia ruellioides with anti-hepatitis B virus (HBV) activity. The structure of hydroxytyrosol was identified by the nuclear magnetic resonance technique. HepG2.2.15 cell models were used to detect the anti-HBV activity and liver protection of hydroxytyrosol in vitro. Hydroxytyrosol can inhibit hepatitis B surface antigen (HBsAg) and hepatitis B e-antigen (HBeAg). The IC₅₀ values of HBsAg and HBeAg were 4.02 mg/L and 5.19 mg/L, respectively. At the highest concentration of hydroxytyrosol, the inhibition rates of supernatant and intracellular HBV DNA were 75.99% and 66.33%, respectively. Hydroxytyrosol was less toxic to normal human hepatocytes. Molecular docking showed that hydroxytyrosol was bound to three amino acid residues of HBV polymerase with a binding energy of −7.0 kcal/mol. This study provided data for the development and utilization of Lindernia ruellioides and the research and development of anti-hepatitis B virus drugs. Full article

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22 pages, 5900 KiB

Open AccessReview

Challenges in the Measurement of the Volume of Phases for HPLC Columns

by Victor David, Jana Petre and Serban C. Moldoveanu

Molecules 2025, 30(9), 2062; https://doi.org/10.3390/molecules30092062 - 6 May 2025

Viewed by 171

Abstract

The evaluation of the time spent by a solute exclusively in the mobile phase (dead time) is of fundamental interest for the interpretation of the retention data and obtainment of thermodynamic parameters for the HPLC process. This parameter depends on the volume occupied [...] Read more.

The evaluation of the time spent by a solute exclusively in the mobile phase (dead time) is of fundamental interest for the interpretation of the retention data and obtainment of thermodynamic parameters for the HPLC process. This parameter depends on the volume occupied by the mobile phase and on the volume of the effective stationary phase from the HPLC column, and the measurement of these volumes poses a real challenge. This review discusses the evaluation of volumes of various phases involved in the retention process of solutes, which are related to the dead time, and the phase ratio for the separation. This paper attempts to cover as many points of view as possible regarding this topic in liquid chromatography, which is of importance for almost all separation mechanisms. Full article

(This article belongs to the Section Analytical Chemistry)

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20 pages, 3647 KiB

Open AccessArticle

Electronic Interactions Between the Receptor-Binding Domain of Omicron Variants and Angiotensin-Converting Enzyme 2: A Novel Amino Acid–Amino Acid Bond Pair Concept

by Puja Adhikari, Bahaa Jawad and Wai-Yim Ching

Molecules 2025, 30(9), 2061; https://doi.org/10.3390/molecules30092061 - 6 May 2025

Viewed by 194

Abstract

SARS-CoV-2 remains a severe threat to worldwide public health, particularly as the virus continues to evolve and diversify into variants of concern (VOCs). Among these VOCs, Omicron variants exhibit unique phenotypic traits, such as immune evasion, transmissibility, and severity, due to numerous spike [...] Read more.

SARS-CoV-2 remains a severe threat to worldwide public health, particularly as the virus continues to evolve and diversify into variants of concern (VOCs). Among these VOCs, Omicron variants exhibit unique phenotypic traits, such as immune evasion, transmissibility, and severity, due to numerous spike protein mutations and the rapid subvariant evolution. These Omicron subvariants have more than 15 mutations in the receptor-binding domain (RBD), a region of the SARS-CoV-2 spike protein that is important for recognition and binding with the angiotensin-converting enzyme 2 (ACE2) human receptor. To address the impact of these high numbers of Omicron mutations on the binding process, we have developed a novel method to precisely quantify amino acid interactions via the amino acid–amino acid bond pair (AABP). We applied this concept to investigate the interface interactions of the RBD–ACE2 complex in four Omicron Variants (BA.1, BA.2, BA.5, and XBB.1.16) with its Wild Type counterpart. Based on the AABP analysis, we have identified all the sites that are affected by mutation and have provided evidence that unmutated sites are also impacted by mutation. We have calculated that the binding between RBD and ACE2 is strongest in OV BA.1, followed by OV BA.2, WT, OV BA.5, and OV XBB.1.16. We also present the partial charge values for all 311 residues across these five models. Our analysis provides a detailed understanding of changes caused by mutation in each Omicron interface complex. Full article

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18 pages, 3654 KiB

Open AccessArticle

Quantitative ¹H and ¹³C NMR and Chemometric Assessment of ¹³C NMR Data: Application to Anabolic Steroid Formulations

by Stéphane Balayssac, Gaëtan Assemat, Saïda Danoun, Myriam Malet-Martino and Véronique Gilard

Molecules 2025, 30(9), 2060; https://doi.org/10.3390/molecules30092060 - 6 May 2025

Viewed by 228

Abstract

This study investigates the potential of ¹H and ¹³C NMR for the characterization and classification of anabolic androgenic steroids (AASs) in various formulations. First, twenty AAS formulations, including tablets, capsules, and injectable solutions, were analyzed using ¹H NMR for the [...] Read more.

This study investigates the potential of ¹H and ¹³C NMR for the characterization and classification of anabolic androgenic steroids (AASs) in various formulations. First, twenty AAS formulations, including tablets, capsules, and injectable solutions, were analyzed using ¹H NMR for the qualitative identification and quantification of active compounds. The results revealed discrepancies between the labeled and detected substances in several samples, highlighting issues related to product mislabeling and potential health risks. Then, twelve oil-based injectable formulations were examined using ¹³C NMR, demonstrating its effectiveness in differentiating and quantifying closely related steroid structures that cannot be discriminated with ¹H NMR. A chemometric approach from ¹³C NMR data, based on a principal component analysis (PCA) and hierarchical cluster analysis (HCA), enabled the classification of samples and the identification of key active ingredients. Full article

(This article belongs to the Special Issue New Trends of Nuclear Magnetic Resonance Spectroscopy (NMR) in Chemical and Biomolecular Studies)

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19 pages, 2890 KiB

Open AccessArticle

Visible Light-Driven Phenol Degradation via Advanced Oxidation Processes with Ferrous Oxalate Obtained from Black Sands: A Kinetics Study

by Salomé Galeas, Víctor H. Guerrero, Patricia I. Pontón and Vincent Goetz

Molecules 2025, 30(9), 2059; https://doi.org/10.3390/molecules30092059 - 6 May 2025

Viewed by 1098

Abstract

Ferrous oxalate dihydrate (α-FOD) was synthesized from Ecuadorian black sands for phenol removal from aqueous solutions. Visible light-driven photodegradation kinetics were studied by varying the initial pollutant concentration, solution pH, and α-FOD dosage and by adding peroxydisulfate (PDS), including quenching tests. A representative [...] Read more.

Ferrous oxalate dihydrate (α-FOD) was synthesized from Ecuadorian black sands for phenol removal from aqueous solutions. Visible light-driven photodegradation kinetics were studied by varying the initial pollutant concentration, solution pH, and α-FOD dosage and by adding peroxydisulfate (PDS), including quenching tests. A representative model of phenol photodegradation was obtained by the Langmuir–Hinshelwood mechanism over a large range of concentrations (apparent kinetic constant, k = 0.524 h⁻¹). Almost complete removal was reached within 1 h under dark + 9 h under visible irradiation. The degradation rate was slightly affected by pH in the range of 3 to 9, with a significant improvement at pH 11 (k = 1.41-fold higher). The optimal α-FOD dosage was ~0.5 g/L. Two regimes were observed when using PDS: first, a heterogeneous Fenton-like process during the first few minutes after PDS addition; second, pure photocatalysis to completely remove the phenol. When comparing the two systems, without and with PDS, the half-life time for pure photocatalysis was 2.5 h (after the lamp was switched on). When adding PDS (1.0 mM), the half-life time was reduced to a few minutes (5 min after PDS addition, phenol removal was 66%). The photocatalyst presented remarkable degradation efficiency up to five repeated cycles. Full article

(This article belongs to the Special Issue Materials in the Application of Adsorption, Degradation, Catalysis and Water Treatment)

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14 pages, 5118 KiB

Open AccessArticle

Experimental Study of the Reactions of Br Atoms with Thiirane and Nitrosyl Chloride

by Yuri Bedjanian

Molecules 2025, 30(9), 2058; https://doi.org/10.3390/molecules30092058 - 6 May 2025

Viewed by 184

Abstract

The kinetics of Br-atom reactions with C₂H₄S and ClNO were studied as a function of temperature at a total pressure of 2 Torr of helium using a discharge–flow system combined with mass spectrometry: Br + C₂H₄ [...] Read more.

The kinetics of Br-atom reactions with C₂H₄S and ClNO were studied as a function of temperature at a total pressure of 2 Torr of helium using a discharge–flow system combined with mass spectrometry: Br + C₂H₄S → SBr + C₂H₄ (1) and Br + ClNO →BrCl + NO (2). The rate constant of reaction (1) was determined at T = 340–920 K by absolute measurements under pseudo-first-order conditions, either by monitoring the kinetics of Br-atom or C₂H₄S consumption in excess of C₂H₄S or of Br atoms, respectively, and by using a relative rate method: k₁ = (6.6 ± 0.7) × 10⁻¹¹ exp(−(2946 ± 60)/T) cm³molecule⁻¹s⁻¹ (where the uncertainties represent the precision at the 2σ level, the estimated total uncertainty on k₁ being 15% at all temperatures). The rate coefficient of reaction (2), determined either from the kinetics of the formation of the reaction product, BrCl, or from the decays of Br-atoms in an excess of ClNO, showed non-Arrhenius behavior, being practically independent of temperature below 400 K and increasing significantly at temperatures above 500 K. The measured rate constant is well reproduced by a sum of two exponential functions: k₂ = 1.2 × 10⁻¹¹ exp(−19/T) + 8.0 × 10⁻¹¹ exp(−1734/T) cm³ molecule⁻¹ s⁻¹ (with an estimated overall temperature-independent uncertainty of 15%) at T = 225–960 K. Full article

(This article belongs to the Section Physical Chemistry)

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13 pages, 10248 KiB

Open AccessArticle

Formation, Structure, and Thermal Annealing Effects of Ordered Self-Assembled Monolayers of 4-Fluorobenzeneselenol on Au(111)

by Sicheon Seong, Jin Wook Han, Gayeong Joo, Hyun Sun Sung, Hong Kyu Park and Jaegeun Noh

Molecules 2025, 30(9), 2057; https://doi.org/10.3390/molecules30092057 - 5 May 2025

Viewed by 255

Abstract

The formation, surface structure, and thermal annealing effects of self-assembled monolayers (SAMs) via vapor deposition of 4-fluorobenzeneselenol (4-FBSeH) on Au(111) at room temperature were investigated using scanning tunneling microscopy (STM). The most prominent structural feature is that 4-fluorobenzeneselenolate (4-FBSe) SAMs on Au(111) are [...] Read more.

The formation, surface structure, and thermal annealing effects of self-assembled monolayers (SAMs) via vapor deposition of 4-fluorobenzeneselenol (4-FBSeH) on Au(111) at room temperature were investigated using scanning tunneling microscopy (STM). The most prominent structural feature is that 4-fluorobenzeneselenolate (4-FBSe) SAMs on Au(111) are composed of numerous SAM-covered Au adatom islands, regardless of the deposition time. High-resolution STM observations revealed that the ordered phase of 4-FBSe SAMs was formed after very short deposition times of 30 s and 3 min, whereas the disordered phase was formed after long deposition times of 1 h and 24 h. The ordered phase can be described as a (4 × 2√3) structure, and the average areal molecular density of the SAMs was calculated to be 29.0 Å²/molecule, suggesting the formation of densely packed monolayers with a standing-up adsorption structure. Interestingly, after thermal annealing at 373 K for 30 min, the (4 × 2√3) ordered phase of the SAMs was transformed to randomly distributed, short, single-molecular rows ranging from several nanometers to approximately ten nanometers in length, which has not been observed previously in organic thiolate SAMs. The high-resolution STM results of this study can provide very meaningful information for understanding the formation, surface structure, and thermal annealing effects of 4-FBSe SAMs on Au(111). Full article

(This article belongs to the Special Issue Molecular Self-Assembly in Interfacial Chemistry)

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20 pages, 6091 KiB

Open AccessArticle

Foaming of Bio-Based PLA/PBS/PBAT Ternary Blends with Added Nanohydroxyapatite Using Supercritical CO₂: Effect of Operating Strategies on Cell Structure

by Pei-Hua Chen, Chin-Wen Chen, Tzu-Hsien Chan, Hsin-Ying Lin, Ke-Ling Tuan, Chie-Shaan Su, Jung-Chin Tsai and Feng-Huei Lin

Molecules 2025, 30(9), 2056; https://doi.org/10.3390/molecules30092056 - 5 May 2025

Viewed by 254

Abstract

This study explored the innovative foaming behavior of a novel biodegradable polymer blend consisting of polylactic acid/poly(butylene succinate)/poly(butylene adipate-co-terephthalate) (PLA/PBS/PBAT) enhanced with nanohydroxyapatite (nHA), using supercritical carbon dioxide (SCCO₂) as an environmentally friendly physical foaming agent. The aim was to investigate [...] Read more.

This study explored the innovative foaming behavior of a novel biodegradable polymer blend consisting of polylactic acid/poly(butylene succinate)/poly(butylene adipate-co-terephthalate) (PLA/PBS/PBAT) enhanced with nanohydroxyapatite (nHA), using supercritical carbon dioxide (SCCO₂) as an environmentally friendly physical foaming agent. The aim was to investigate the effects of various foaming strategies on the resulting cell structure, aiming for potential applications in tissue engineering. Eight foaming strategies were examined, starting with a basic saturation process at high temperature and pressure, followed by rapid decompression to ambient conditions, referred to as the (1T-1P) strategy. Intermediate temperature and pressure variations were introduced before the final decompression to evaluate the impact of operating parameters further. These strategies included intermediate-temperature cooling (2T-1P), intermediate-temperature cooling with rapid intermediate decompression (2T-2P), and intermediate-temperature cooling with gradual intermediate decompression (2T-2P, stepwise ΔP). SEM imaging revealed that the (2T-2P, stepwise ΔP) strategy produced a bimodal cell structure featuring small cells ranging from 105 to 164 μm and large cells between 476 and 889 μm. This study demonstrated that cell size was influenced by the regulation of intermediate pressure reduction and the change in intermediate temperature. The results were interpreted based on classical nucleation theory, the gas solubility principle, and the effect of polymer melt strength. Foaming results of average cell size, cell density, expansion ratio, porosity, and opening cell content are reported. The hydrophilicity of various foamed polymer blends was evaluated by measuring the water contact angle. Typical compressive stress–strain curves obtained using DMA showed a consistent trend reflecting the effect of foam stiffness. Full article

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34 pages, 2698 KiB

Open AccessReview

Microalgae: A Promising Source of Bioactive Polysaccharides for Biotechnological Applications

by Chiara Magnabosco, Giovanna Santaniello and Giovanna Romano

Molecules 2025, 30(9), 2055; https://doi.org/10.3390/molecules30092055 - 5 May 2025

Viewed by 425

Abstract

Polysaccharides (PSs) are the most abundant carbohydrates in nature, performing essential biological functions such as immune system regulation, structural support, and cell communication. PSs from marine microalgae have gained increasing attention due to their diverse biological activities and potential applications in various fields, [...] Read more.

Polysaccharides (PSs) are the most abundant carbohydrates in nature, performing essential biological functions such as immune system regulation, structural support, and cell communication. PSs from marine microalgae have gained increasing attention due to their diverse biological activities and potential applications in various fields, including the human health sector. These natural macromolecules, primarily composed of glucose, xylose, galactose, rhamnose, and fucose, exhibit bioactive properties influenced by their molecular weight, sulfation degree, and structural complexity. Microalgal PSs can function as antiviral, antimicrobial, antioxidant, immunomodulatory, and antitumor agents, making them promising candidates for pharmaceutical and nutraceutical applications. Additionally, their physicochemical properties make them valuable as bioactive ingredients in cosmetics, serving as hydrating agents, UV protectants, and anti-ageing compounds. The production of PSs from microalgae presents a sustainable alternative to terrestrial plants, as microalgae can be cultivated under controlled conditions, ensuring high yield and purity while minimizing environmental impact. Despite their potential, challenges remain in optimizing extraction techniques, enhancing structural characterization, and scaling up production for commercial applications. This review provides an overview of the principal biological activities of PSs from eukaryotic microalgae and their possible use as ingredients for cosmetic applications. Challenges to address to implement their use as products to improve human health and wellbeing are also discussed. Full article

(This article belongs to the Special Issue Metabolites from Algae: Discovery, Identification and Multifaceted Applications)

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