Molecules

13 pages, 934 KiB

Open AccessArticle

Fluorescence of Half-Twisted 10-Acyl-1-methyltetrahydrobenzoquinolines

by Christopher Abelt, Ian Day, Junkai Zhao and Robert Pike

Molecules 2024, 29(13), 3016; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133016 (registering DOI) - 25 Jun 2024

Abstract

The steric interference of proximal dialkyl amino and acyl groups at the peri (1,8) positions of naphthalene affects the intramolecular charge transfer fluorescence. Previous studies indicate that acyl and freely rotating dimethyl amino groups twist toward coplanarity with the naphthalene ring in the [...] Read more.

The steric interference of proximal dialkyl amino and acyl groups at the peri (1,8) positions of naphthalene affects the intramolecular charge transfer fluorescence. Previous studies indicate that acyl and freely rotating dimethyl amino groups twist toward coplanarity with the naphthalene ring in the excited state. The present study examines the effect of constraining the amino group in a ring. The photophysical properties of 2,2-dimethyl-1-(1-methyl-1,2,3,4-tetrahydrobenzo[h]quinolin-10-yl)propan-1-one (4), ethyl 1-methyl-1,2,3,4-tetrahydrobenzo[h]quinoline-10-carboxylate (5), and 1-methyl-1,2,3,4-tetrahydrobenzo[h]quinoline-10-carbaldehyde (6) are compared with the dimethyl amino derivatives 2 and 3. Crystal structures of 4–6 show that the amine ring adopts a chair conformation, where the N-methyl group is axial. Computational results suggest that the pyramidal amino group planarizes and twists together with the acyl toward coplanarity in the excited state. The ring structure does not thwart the formation of a planar intramolecular charge transfer (PICT) state. Full article

(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)

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57 pages, 1804 KiB

Open AccessArticle

Synthesis and Enzymatic Evaluation of a Small Library of Substituted Phenylsulfonamido-Alkyl Sulfamates towards Carbonic Anhydrase II

by Toni C. Denner, Niels V. Heise, Ahmed Al-Harrasi and René Csuk

Molecules 2024, 29(13), 3015; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133015 (registering DOI) - 25 Jun 2024

Abstract

A small library of 79 substituted phenylsulfonamidoalkyl sulfamates, 1b–79b, was synthesized starting from arylsulfonyl chlorides and amino alcohols with different numbers of methylene groups between the hydroxyl and amino moieties yielding intermediates 1a–79a, followed by the reaction [...] Read more.

A small library of 79 substituted phenylsulfonamidoalkyl sulfamates, 1b–79b, was synthesized starting from arylsulfonyl chlorides and amino alcohols with different numbers of methylene groups between the hydroxyl and amino moieties yielding intermediates 1a–79a, followed by the reaction of the latter with sulfamoyl chloride. All compounds were screened for their inhibitory activity on bovine carbonic anhydrase II. Compounds 1a–79a showed no inhibition of the enzyme, in contrast to sulfamates 1b–79b. Thus, the inhibitory potential of compounds 1b–79b towards this enzyme depends on the substituent and the substitution pattern of the phenyl group as well as the length of the spacer. Bulkier substituents in the para position proved to be better for inhibiting CAII than compounds with the same substituent in the meta or ortho position. For many substitution patterns, compounds with shorter spacer lengths were superior to those with long chain spacers. Compounds with shorter spacer lengths performed better than those with longer chain spacers for a variety of substitution patterns. The most active compound held inhibition constant as low as K_i = 0.67 μM (for 49b) and a tert-butyl substituent in para position and acted as a competitive inhibitor of the enzyme. Full article

(This article belongs to the Section Medicinal Chemistry)

17 pages, 1587 KiB

Open AccessArticle

Research on the Interaction Mechanisms between ScCO₂and Low-Rank/High-Rank Coal with the ReaxFF-MD Force Field

by Kui Dong, Shaoqi Kong, Zhiyu Niu and Bingyi Jia

Molecules 2024, 29(13), 3014; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133014 (registering DOI) - 25 Jun 2024

Viewed by 56

Abstract

CO₂ geological sequestration in coal seams can be carried out to achieve the dual objectives of CO₂ emission reduction and enhanced coalbed methane production, making it a highly promising carbon capture and storage technology. However, the injection of CO₂ into [...] Read more.

CO₂ geological sequestration in coal seams can be carried out to achieve the dual objectives of CO₂ emission reduction and enhanced coalbed methane production, making it a highly promising carbon capture and storage technology. However, the injection of CO₂ into coal reservoirs in the form of supercritical fluid (ScCO₂) leads to complex physicochemical reactions with the coal seam, altering the properties of the coal reservoir and impacting the effectiveness of CO₂ sequestration and methane production enhancement. In this paper, theoretical calculations based on ReaxFF-MD were conducted to study the interaction mechanism between ScCO₂ and the macromolecular structures of both low-rank and high-rank coal, to address the limitations of experimental methods. The reaction of ScCO₂ with low-rank coal and high-rank coal exhibited significant differences. At the swelling stage, the low-rank coal experienced a decrease in aromatic structure and aliphatic structure, and high-rank coal showed an increase in aromatic structure and a decrease in aliphatic structure, while the swelling phenomenon was more pronounced in high-rank coal. At the dissolution stage, low-rank coal was initially decomposed into two secondary molecular fragments, and then these recombined to form a new molecular structure; the aromatic structure increased and the aliphatic structure decreased. In contrast, high-rank coal showed the occurrence of stretches–breakage–movement–reconnection, a reduction in aromatic structure, and an increase in aliphatic structure. The primary reasons for these variations lie in the distinct molecular structure compositions and the properties of ScCO₂, leading to different reaction pathways of the functional group and aromatic structure. The reaction pathways of functional groups and aromatic structures in coal can be summarized as follows: the breakage of the O–H bond in hydroxyl groups, the breakage of the C–OH bond in carboxyl groups, the transformation of aliphatic structures into smaller hydrocarbon compounds or the formation of long-chain alkenes, and various pathways involving the breakage, rearrangement, and recombination of aromatic structures. In low-rank coal, there is a higher abundance of oxygen-containing functional groups and aliphatic structures. The breakage of O–H and C–OH chemical bonds results in the formation of free radical ions, while some aliphatic structures detach to produce hydrocarbons. Additionally, some of these aliphatic structures combine with carbonyl groups and free radical ions to generate new aromatic structures. Conversely, in high-rank coal, a lower content of oxygen-containing functional groups and aliphatic structures, along with stronger intramolecular forces, results in fewer chemical bond breakages and makes it less conducive to the formation of new aromatic structures. These results elucidate the specific deformations of different chemical groups, offering a molecular-level understanding of the interaction between CO₂ and coal. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

13 pages, 2287 KiB

Open AccessArticle

Self-Responsive Fluorescence Aptasensor for Lactoferrin Determination in Dairy Products

by Hao Liu, Xibao Gao, Hongwei Qin, Mengmeng Yan, Chao Zhu, Linsen Li and Feng Qu

Molecules 2024, 29(13), 3013; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133013 (registering DOI) - 25 Jun 2024

Viewed by 57

Abstract

In this study, a self-responsive fluorescence aptasensor was established for the determination of lactoferrin (Lf) in dairy products. Herein, the aptamer itself functions as both a recognition element that specifically binds to Lf and a fluorescent signal reporter in conjunction with fluorescent moiety. [...] Read more.

In this study, a self-responsive fluorescence aptasensor was established for the determination of lactoferrin (Lf) in dairy products. Herein, the aptamer itself functions as both a recognition element that specifically binds to Lf and a fluorescent signal reporter in conjunction with fluorescent moiety. In the presence of Lf, the aptamer preferentially binds to Lf due to its specific and high-affinity recognition by folding into a self-assembled and three-dimensional spatial structure. Meanwhile, its reduced spatial distance in the aptamer–Lf complex induces a FRET phenomenon based on the quenching of 6-FAM by amino acids in the Lf protein, resulting in a turn-off of the fluorescence of the system. As a result, the Lf concentration can be determined straightforwardly corresponding to the change in the self-responsive fluorescence signal. Under the optimized conditions, good linearities (R² > 0.99) were achieved in an Lf concentration range of 2~10 μg/mL for both standard solutions and the spiked matrix, as well as with the desirable detection limits of 0.68 μg/mL and 0.46 μg/mL, respectively. Moreover, the fluorescence aptasensor exhibited reliable recoveries (89.5–104.3%) in terms of detecting Lf in three commercial samples, which is comparable to the accuracy of the HPCE method. The fluorescence aptasensor offers a user-friendly, cost-efficient, and promising sensor platform for point-of-need detection. Full article

(This article belongs to the Special Issue Analytical Chemistry Presents with State-of-the-Art Molecular Recognition and Interaction, 2nd Edition)

16 pages, 2847 KiB

Open AccessArticle

Self-Association and Microhydration of Phenol: Identification of Large-Amplitude Hydrogen Bond Librational Modes

by Dmytro Mihrin, Karen Louise Feilberg and René Wugt Larsen

Molecules 2024, 29(13), 3012; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133012 (registering DOI) - 25 Jun 2024

Viewed by 45

Abstract

The self-association mechanisms of phenol have represented long-standing challenges to quantum chemical methodologies owing to the competition between strongly directional intermolecular hydrogen bonding, weaker non-directional London dispersion forces and C–H⋯

π

interactions between the aromatic rings. The present work explores these subtle self-association [...] Read more.

The self-association mechanisms of phenol have represented long-standing challenges to quantum chemical methodologies owing to the competition between strongly directional intermolecular hydrogen bonding, weaker non-directional London dispersion forces and C–H⋯

π

interactions between the aromatic rings. The present work explores these subtle self-association mechanisms of relevance for biological molecular recognition processes via spectroscopic observations of large-amplitude hydrogen bond librational modes of phenol cluster molecules embedded in inert neon “quantum” matrices complemented by domain-based local pair natural orbital-coupled cluster DLPNO-CCSD(T) theory. The spectral signatures confirm a primarily intermolecular O-H⋯H hydrogen-bonded structure of the phenol dimer strengthened further by cooperative contributions from inter-ring London dispersion forces as supported by DLPNO-based local energy decomposition (LED) predictions. In the same way, the hydrogen bond librational bands observed for the trimeric cluster molecule confirm a pseudo-C

_{3}

symmetric cyclic cooperative hydrogen-bonded barrel-like potential energy minimum structure. This structure is vastly different from the sterically favored “chair” conformations observed for aliphatic alcohol cluster molecules of the same size owing to the additional stabilizing London dispersion forces and C–H⋯

π

interactions between the aromatic rings. The hydrogen bond librational transition observed for the phenol monohydrate finally confirms that phenol acts as a hydrogen bond donor to water in contrast to the hydrogen bond acceptor role observed for aliphatic alcohols. Full article

(This article belongs to the Special Issue Gulliver in the Country of Lilliput: An Interplay of Noncovalent Interactions (Volume II))

7 pages, 301 KiB

Open AccessArticle

Facile Access to Solifenacin Impurity K: One-Step Synthesis and an HPLC-MS Method for Its Determination

by Raúl Xifra, Andrés E. Lukach and Andreea L. Turcu

Molecules 2024, 29(13), 3011; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133011 (registering DOI) - 25 Jun 2024

Viewed by 68

Abstract

Solifenacin (SFC) is a potent muscarinic antagonist that effectively reduces bladder muscle contraction, thereby alleviating symptoms such as frequency of micturition and urgency. Oxidation of SFC leads to the formation of impurities like Impurity K. Effective analysis and control of this impurity is [...] Read more.

Solifenacin (SFC) is a potent muscarinic antagonist that effectively reduces bladder muscle contraction, thereby alleviating symptoms such as frequency of micturition and urgency. Oxidation of SFC leads to the formation of impurities like Impurity K. Effective analysis and control of this impurity is crucial for ensuring compliance with regulatory standards and safeguarding patient health. To address these challenges, we propose a novel one-step synthesis of Impurity K from SFC. Impurity K was synthesized using cerium (IV) ammonium nitrate (CAN) in water/acetonitrile as the solvent. Additionally, we describe a new HPLC-MS method for the detection of Impurity K in solifenacin succinate tablets. Full article

(This article belongs to the Section Medicinal Chemistry)

14 pages, 1116 KiB

Open AccessArticle

Synthesis, Anticancer Activity, and Molecular Docking of New 1,2,3-Triazole Linked Tetrahydrocurcumin Derivatives

by Meitao Duan, Ahmed Mahal, Anas Alkouri, Chen Wang, Zhiqiang Zhang, Jungang Ren and Ahmad J. Obaidullah

Molecules 2024, 29(13), 3010; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133010 (registering DOI) - 25 Jun 2024

Viewed by 88

Abstract

Cancer is one of the deadliest diseases to humanity. There is significant progress in treating this disease, but developing some drugs that can fight this disease remains a challenge in the field of medical research. Thirteen new 1,2,3-triazole linked tetrahydrocurcumin derivatives were synthesized [...] Read more.

Cancer is one of the deadliest diseases to humanity. There is significant progress in treating this disease, but developing some drugs that can fight this disease remains a challenge in the field of medical research. Thirteen new 1,2,3-triazole linked tetrahydrocurcumin derivatives were synthesized by click reaction, including a 1,3-dipolar cycloaddition reaction of tetrahydrocurcumin baring mono-alkyne with azides in good yields, and their in vitro anticancer activity against four cancer cell lines, including human cervical carcinoma (HeLa), human lung adenocarcinoma (A549), human hepatoma carcinoma (HepG2), and human colon carcinoma (HCT-116) were investigated using MTT(3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetraz-olium bromide) assay. The newly synthesized compounds had their structures identified using NMR HRMS and IR techniques. Some of prepared compounds, including compounds 4g and 4k, showed potent cytotoxic activity against four cancer cell lines compared to the positive control of cisplatin and tetrahydrocurcumin. Compound 4g exhibited anticancer activity with a IC₅₀value of 1.09 ± 0.17 μM against human colon carcinoma HCT-116 and 45.16 ± 0.92 μM against A549 cell lines compared to the positive controls of tetrahydrocurcumin and cisplatin. Moreover, further biological examination in HCT-116 cells showed that compound 4g can arrest the cell cycle at the G1 phase. A docking study revealed that the potential mechanism by which 4g exerts its anti-colon cancer effect may be through inhabiting the binding of APC–Asef. Compound 4g can be used as a promising lead for further exploration of potential anticancer agents. Full article

(This article belongs to the Special Issue Synthesis of Heterocyclic Compounds via Cycloadditions: Applications in Medicinal Chemistry)

11 pages, 517 KiB

Open AccessArticle

Effective Transport Recovery of Palladium(II) from Hydrochloric Acid Solutions Using Polymer Inclusion Membrane with Tetrabutylammonium Bromide

by Beata Pospiech

Molecules 2024, 29(13), 3009; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133009 (registering DOI) - 25 Jun 2024

Viewed by 76

Abstract

This article reports on the extraction of palladium(II) from hydrochloric acid (HCl) solutions using polymer inclusion membranes (PIMs) containing tetrabutylammonium bromide (TBAB) as the ion carrier. The membranes were based on cellulose triacetate (CTA) as the polymer support. The main aim of this [...] Read more.

This article reports on the extraction of palladium(II) from hydrochloric acid (HCl) solutions using polymer inclusion membranes (PIMs) containing tetrabutylammonium bromide (TBAB) as the ion carrier. The membranes were based on cellulose triacetate (CTA) as the polymer support. The main aim of this study is to determine the possibility of TBAB’s application as the effective ion carrier/extractant of Pd(II) from hydrochloric acid solutions. At first, the effect of the hydrochloric acid concentration in the aqueous phase on palladium(II) extraction was investigated. Next, cellulose triacetate membranes with TBAB as the carrier were prepared and applied for the recovery of Pd(II) from HCl solutions. As a result of the investigations, the optimal composition of the receiving phase was determined to be 0.5 M thiourea in 0.1 M hydrochloric acid. The effect of the acid concentration in the source phase was investigated. The results show a linear decrease in the permeability coefficient and initial flux of palladium(II) with an increase in the hydrochloric acid concentration in the source phase. The separation of Pd(II) from Pt(IV) from the hydrochloric acid solution was also studied. The transport rate of Pd(II) was higher than Pt(IV). The separation coefficient S_Pd/Ptwas 1.3. The results show that transport through PIMs with TBAB can be used as an effective method to recover Pd(II) from hydrochloric acid, especially at a low concentration of this acid. Full article

(This article belongs to the Special Issue Functional Polymers in Separation Science)

14 pages, 959 KiB

Open AccessArticle

Molecular Weight Distribution of Humic Acids Isolated from Calcic Cryosol in Central Yakutia, Russia

by Vyacheslav Polyakov, Evgeny Abakumov, Evgeny Lodygin, Roman Vasilevich and Alexey Petrov

Molecules 2024, 29(13), 3008; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133008 (registering DOI) - 25 Jun 2024

Viewed by 80

Abstract

The transition of soils into fallow state has a significant impact on the accumulation and transformation of soil organic matter (SOM). However, the issue of SOM transformation as a result of soil transition to fallow state in cryolithozone conditions is insufficiently studied. The [...] Read more.

The transition of soils into fallow state has a significant impact on the accumulation and transformation of soil organic matter (SOM). However, the issue of SOM transformation as a result of soil transition to fallow state in cryolithozone conditions is insufficiently studied. The aim of this study is to investigate the molecular weight (MW) distribution of humic acids (HAs) isolated from soils of central Yakutia. Native, fallow and agricultural soils in the vicinity of Yakutsk city were studied. MW distributions of HA preparations were obtained on an AKTAbasic 10 UPS chromatographic system (Amersam Biosciences,Uppsala, Sweden) using a SuperdexTM 200 10/300 GL column (with cross-linked dextran gel, fractionation range for globular proteins 10–600 kDa). The data on the molecular-mass distribution of HAs of fallow and agricultural soils of Central Yakutia were obtained for the first time. According to the obtained data, it was found that the highest carbon content in the structure of HAs was observed in agricultural soils (52.56%), and is associated with soil cultivation and fertilizer application. Among the HAs of fallow soils, we note that those soils that are in the process of self-vegetation have a relatively high carbon content in the HAs (45.84%), but the highest content was observed in fallow soils used as hayfields (49.98%), indicating that the reinvolvement of agriculture in fallow soils leads to an increase in the carbon content of HAs. According to the data of the MW distribution of HAs, it was found that the highest content of a high MW fraction of HAs was recorded in native soil (18.8%); this is due to the early stages of humification and the low maturity of organic matter. The highest content of a low MW fraction of HAs was recorded in agricultural soil (73.3%); this is due to the formation of molecular complexes of a “secondary” nature, which are more stable in the environment than the primary transformation products of humification precursors. The molecular composition of the HAs of fallow soils in the process of self-overgrowing is characterized by values closer to the HAs of native soils, which indicates their transformation towards HAs of native soils. The obtained results indicate that the reinvolvement of fallow soils leads to the transformation of the molecular composition of HAs towards HAs of agricultural soils, and to an increase in the resistance of SOM to biodegradation. Full article

(This article belongs to the Special Issue Environmental Analytical Chemistry II)

17 pages, 1270 KiB

Open AccessArticle

Sorption of Iodine on Biochar Derived from the Processing of Urban Sludge and Garden Waste at Different Pyrolysis Temperatures

by Bing Bai, Qingyang Liu, He Li, Dan Liu, Haichao Wang, Chengliang Zhang, Zheng Yang and Jingjing Yao

Molecules 2024, 29(13), 3007; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133007 (registering DOI) - 25 Jun 2024

Viewed by 85

Abstract

The United Nations proposed the Sustainable Development Goals with the aim to make human settlements in cities resilient and sustainable. The excessive discharge of urban waste including sludge and garden waste can pollute groundwater and lead to the emission of greenhouse gases (e.g., [...] Read more.

The United Nations proposed the Sustainable Development Goals with the aim to make human settlements in cities resilient and sustainable. The excessive discharge of urban waste including sludge and garden waste can pollute groundwater and lead to the emission of greenhouse gases (e.g., CH₄). The proper recycling of urban waste is essential for responsible consumption and production, reducing environmental pollution and addressing climate change issues. This study aimed to prepare biochar with high adsorption amounts of iodine using urban sludge and peach wood from garden waste. The study was conducted to examine the variations in the mass ratio between urban sludge and peach wood (2/1, 1/1, and 1/2) as well as pyrolysis temperatures (300 °C, 500 °C, and 700 °C) on the carbon yield and adsorption capacities of biochar. Scanning electron microscopy, Brunauer–Emmett–Teller analysis, Fourier transform infrared spectrometry, powder X-ray diffraction, and elemental analysis were used to characterize the biochar produced at different pyrolysis temperatures and mass ratios. The results indicate that the carbon yield of biochar was found to be the highest (>60%) at a pyrolysis temperature of 300 °C across different pyrolysis temperatures. The absorbed amounts of iodine in the aqueous solution ranged from 86 to 223 mg g⁻¹ at a mass ratio of 1:1 between urban sludge and peach wood, which were comparably higher than those observed in other mass ratios. This study advances water treatment by offering a cost-effective method by using biochar derived from the processing of urban sludge and garden waste. Full article

(This article belongs to the Section Green Chemistry)

17 pages, 465 KiB

Open AccessArticle

A Recyclable Polypropylene Multilayer Film Maintaining the Quality and the Aroma of Coffee Pods during Their Shelf Life

by Martina Calabrese, Lucia De Luca, Giulia Basile, Gianfranco Lambiase, Raffaele Romano and Fabiana Pizzolongo

Molecules 2024, 29(13), 3006; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133006 (registering DOI) - 25 Jun 2024

Viewed by 84

Abstract

Films for coffee-pod packaging usually contain aluminium as an impermeable foil that is not recyclable and has to be discharged as waste. In this study, a recyclable polypropylene multilayer film is proposed as an alternative. The performance on the chemical composition of coffee [...] Read more.

Films for coffee-pod packaging usually contain aluminium as an impermeable foil that is not recyclable and has to be discharged as waste. In this study, a recyclable polypropylene multilayer film is proposed as an alternative. The performance on the chemical composition of coffee was evaluated and compared to that of film containing aluminium (standard). The oxygen in the headspace, moisture, lipidic oxidation, and volatile organic compounds were studied in coffee pods during storage for 12 months at 25 and 40 °C. In addition, the acidity and acceptability of extracted coffee were evaluated. In the polypropylene-packaged pods, the percentage of oxygen during storage at 25 °C was lower than that in the standard. Moisture was not affected by the type of packaging materials. No differences were found between the peroxide values, except in pods stored for 3, 10, and 11 months at 25 °C, where they were even lower than the standard. Furans and pyrazines were the main volatile organic compounds detected. No differences were found in the pH and titratable acidity of the coffee brew either. All samples were well accepted by consumers without any perceived difference related to the packaging film. The polypropylene multilayer film is a sustainable recyclable material with high performance, in particular, against oxygen permeation. Full article

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

18 pages, 1028 KiB

Open AccessArticle

Synthesis of 2-Ethylhexyl 5-Bromothiophene-2-Carboxylates; Antibacterial Activities against Salmonella Typhi, Validation via Docking Studies, Pharmacokinetics, and Structural Features Determination through DFT

by Waseem Nazeer, Muhammad Usman Qamar, Nasir Rasool, Mohamed Taibi and Ahmad Mohammad Salamatullah

Molecules 2024, 29(13), 3005; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133005 (registering DOI) - 25 Jun 2024

Viewed by 118

Abstract

A new class of thiophene-based molecules of 5-bromothiophene-2-carboxylic acid (1) have been synthesized in current research work. All analogs 4A–4G were synthesized with optimized conditions by coupling reactions of 2-ethylhexyl 5-bromothiophene-2-carboxylate (3) with various arylboronic acids. The results indicated [...] Read more.

A new class of thiophene-based molecules of 5-bromothiophene-2-carboxylic acid (1) have been synthesized in current research work. All analogs 4A–4G were synthesized with optimized conditions by coupling reactions of 2-ethylhexyl 5-bromothiophene-2-carboxylate (3) with various arylboronic acids. The results indicated that the majority of compounds showed promising effective in vitro antibacterial activity. Herein, 2-ethylhexyl-5-(p-tolyl)thiophene-2-carboxylate (4F), in particular among the synthesized analogs, showed outstanding antibacterial action (MIC value 3.125 mg/mL) against XDR Salmonella Typhi compared to ciprofloxacin and ceftriaxone. The intermolecular interaction was investigated by using a molecular docking study of thiophene derivatives 4A–4G against XDR S. Typhi. The values of the binding affinity of functionalized thiophene molecules and ciprofloxacin were compared against bacterial enzyme PDB ID: 5ztj. Therefore, 4F appears to be a promising antibacterial agent and showed the highest potential value. Density functional theory (DFT) calculations were executed to examine the electronic, structural, and spectroscopic features of the newly synthesized molecules 4A–4G. Full article

(This article belongs to the Special Issue Heterocyclic Compounds: Synthesis and Medicinal Chemistry Applications)

28 pages, 1161 KiB

Open AccessReview

The Chromenopyridine Scaffold: A Privileged Platform in Drug Design

by Fábio Pedroso de Lima, Marta Costa, Ana Sousa and Maria Fernanda Proença

Molecules 2024, 29(13), 3004; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133004 (registering DOI) - 25 Jun 2024

Viewed by 125

Abstract

The chromenopyridine scaffold represents an important class of heterocyclic compounds exhibiting a broad spectrum of biological properties. This review describes novel and efficient procedures for the synthesis of this scaffold. Herein, several methods were detailed and grouped according to their starting material (e.g., [...] Read more.

The chromenopyridine scaffold represents an important class of heterocyclic compounds exhibiting a broad spectrum of biological properties. This review describes novel and efficient procedures for the synthesis of this scaffold. Herein, several methods were detailed and grouped according to their starting material (e.g., salicylaldehydes, chromones, chromanones and coumarins) and respective biological activity, when reported. This review highlights the potential of the reported synthetic strategies for preparing chromenopyridine derivatives with promising biological activity, paving the way for further developments in drug discovery. Full article

(This article belongs to the Special Issue Heterocyclic Compounds for Drug Design and Drug Discovery)

20 pages, 13254 KiB

Open AccessArticle

Theoretical Analysis of Coordination Geometries in Transition Metal–Histidine Complexes Using Quantum Chemical Calculations

by Dapeng Zhang and Naoki Kishimoto

Molecules 2024, 29(13), 3003; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133003 (registering DOI) - 25 Jun 2024

Viewed by 108

Abstract

A theoretical investigation utilizing density functional theory (DFT) calculations was conducted to explore the coordination complexes formed between histidine (His) ligands and various divalent transition metal ions (Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and [...] Read more.

A theoretical investigation utilizing density functional theory (DFT) calculations was conducted to explore the coordination complexes formed between histidine (His) ligands and various divalent transition metal ions (Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺). Conformational exploration of the His ligand was initially performed to assess its stability upon coordination. Both 1:1 and 1:2 of metal-to-ligand complexes were scrutinized to elucidate their structural features and the relative stability of the complexes. This study examined the ability of His to act as a bidentate or tridentate coordinating ligand, along with the differences in coordination geometry when solvent effects were incorporated. The reduced density gradient (RDG) analysis and local electron attachment energy (LEAE) analysis were employed to elucidate the interaction planes and the nucleophilic and electrophilic properties. The electronic properties were analyzed through electrostatic potential (ESP) maps and natural population analysis (NPA) of atomic charge distributions. This computational study provides valuable insights into the diverse coordination modes of His and its interactions with divalent transition metal ions, contributing to a better understanding of the role of this amino acid ligand in the formation of transition metal complexes. The findings can aid in the design and construction of self-assembled structures involving His-metal coordination. Full article

(This article belongs to the Special Issue Exclusive Feature Papers on Molecular Structure)

22 pages, 1185 KiB

Open AccessReview

Phage Display Technology in Biomarker Identification with Emphasis on Non-Cancerous Diseases

by Mohammad Sadraeian, Reza Maleki, Mahta Moraghebi and Abasalt Bahrami

Molecules 2024, 29(13), 3002; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133002 (registering DOI) - 25 Jun 2024

Viewed by 115

Abstract

In recent years, phage display technology has become vital in clinical research. It helps create antibodies that can specifically bind to complex antigens, which is crucial for identifying biomarkers and improving diagnostics and treatments. However, existing reviews often overlook its importance in areas [...] Read more.

In recent years, phage display technology has become vital in clinical research. It helps create antibodies that can specifically bind to complex antigens, which is crucial for identifying biomarkers and improving diagnostics and treatments. However, existing reviews often overlook its importance in areas outside cancer research. This review aims to fill that gap by explaining the basics of phage display and its applications in detecting and treating various non-cancerous diseases. We focus especially on its role in degenerative diseases, inflammatory and autoimmune diseases, and chronic non-communicable diseases, showing how it is changing the way we diagnose and treat illnesses. By highlighting important discoveries and future possibilities, we hope to emphasize the significance of phage display in modern healthcare. Full article

16 pages, 3432 KiB

Open AccessArticle

Revisiting and Updating the Interaction between Human Serum Albumin and the Non-Steroidal Anti-Inflammatory Drugs Ketoprofen and Ketorolac

by Rita S. Cunha, Pedro F. Cruz, Telma Costa, Zaida L. Almeida, Marco Edilson Freire de Lima, Carlos Serpa and Otávio A. Chaves

Molecules 2024, 29(13), 3001; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133001 - 24 Jun 2024

Viewed by 327

Abstract

Ketoprofen (KTF) and ketorolac (KTL) are among the most primarily used non-steroidal anti-inflammatory drugs (NSAIDs) in humans to alleviate moderate pain and to treat inflammation. Their binding affinity with albumin (the main globular protein responsible for the biodistribution of drugs in the bloodstream) [...] Read more.

Ketoprofen (KTF) and ketorolac (KTL) are among the most primarily used non-steroidal anti-inflammatory drugs (NSAIDs) in humans to alleviate moderate pain and to treat inflammation. Their binding affinity with albumin (the main globular protein responsible for the biodistribution of drugs in the bloodstream) was previously determined by spectroscopy without considering some conventional pitfalls. Thus, the present work updates the biophysical characterization of the interactions of HSA:KTF and HSA:KTL by ¹H saturation-transfer difference nuclear magnetic resonance (¹H STD-NMR), ultraviolet (UV) absorption, circular dichroism (CD), steady-state, and time-resolved fluorescence spectroscopies combined with in silico calculations. The binding of HSA:NSAIDs is spontaneous, endothermic, and entropically driven, leading to a conformational rearrangement of HSA with a slight decrease in the α-helix content (7.1% to 7.6%). The predominance of the static quenching mechanism (ground-state association) was identified. Thus, both Stern–Volmer quenching constant (K_SV) and binding constant (K_b) values enabled the determination of the binding affinity. In this sense, the K_SV and K_b values were found in the order of 10⁴ M⁻¹ at human body temperature, indicating moderate binding affinity with differences in the range of 0.7- and 3.4-fold between KTF and KTL, which agree with the previously reported experimental pharmacokinetic profile. According to ¹H STD-NMR data combined with in silico calculations, the aromatic groups in relation to the aliphatic moiety of the drugs interact preferentially with HSA into subdomain IIIA (site II) and are stabilized by interactions via hydrogen bonding and hydrophobic forces. In general, the data obtained in this study have been revised and updated in comparison to those previously reported by other authors who did not account for inner filter corrections, spectral backgrounds, or the identification of the primary mathematical approach for determining the binding affinity of HSA:KTF and HSA:KTL. Full article

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12 pages, 494 KiB

Open AccessArticle

Colorimetric Immunoassays with Boronic Acid-Decorated, Peroxidase-Like Metal-Organic Frameworks as the Carriers of Antibodies and Enzymes

by Ting Sun, Xinyao Yi, Lin Liu and Feng Zhao

Molecules 2024, 29(13), 3000; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29133000 - 24 Jun 2024

Viewed by 189

Abstract

The sensitivity of immunoassays is generally limited by the low signal reporter/recognition element ratio. Nanomaterials serving as the carriers can enhance the loading number of signal reporters, thus improving the detection sensitivity. However, the general immobilization strategies, including direct physical adsorption and covalent [...] Read more.

The sensitivity of immunoassays is generally limited by the low signal reporter/recognition element ratio. Nanomaterials serving as the carriers can enhance the loading number of signal reporters, thus improving the detection sensitivity. However, the general immobilization strategies, including direct physical adsorption and covalent coupling, may cause the random orientation and conformational change in proteins, partially or completely suppressing the enzymatic activity and the molecular recognition ability. In this work, we proposed a strategy to load recognition elements of antibodies and enzyme labels using boronic acid-modified metal-organic frameworks (MOFs) as the nanocarriers for signal amplification. The conjugation strategy was proposed based on the boronate ester interactions between the carbohydrate moieties in antibodies and enzymes and the boronic acid moieties on MOFs. Both enzymes and MOFs could catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H₂O₂, therefore achieving dual signal amplification. To indicate the feasibility and sensitivity of the strategy, colorimetric immunoassays of prostate specific antigen (PSA) were performed with boronic acid-modified Cu-MOFs as peroxidase mimics to catalyze TMB oxidation and nanocarriers to load antibody and enzyme (horseradish peroxidase, HRP). According to the change in the absorbance intensity of the oxidized TMB (_oxTMB), PSA at the concentration range of 1~250 pg/mL could be readily determined. In addition, this work presented a site-specific and oriented conjugation strategy for the modification of nanolabels with recognition elements and signal reporters, which should be valuable for the design of novel biosensors with high sensitivity and selectivity. Full article

(This article belongs to the Special Issue Advanced Nano-Based Chemsensors and Biosensors for Detective Application)

15 pages, 783 KiB

Open AccessArticle

Comprehensive Assessment of Collagen/Sodium Alginate-Based Sponges as Hemostatic Dressings

by Leilei Sun, Yanyan Shen, Mingbo Li, Qiuting Wang, Ruimin Li and Shunmin Gong

Molecules 2024, 29(13), 2999; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132999 - 24 Jun 2024

Viewed by 163

Abstract

In our search for a biocompatible composite hemostatic dressing, we focused on the design of a novel biomaterial composed of two natural biological components, collagen and sodium alginate (SA), cross-linked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) and oxidized sodium alginate (OSA). We conducted a series [...] Read more.

In our search for a biocompatible composite hemostatic dressing, we focused on the design of a novel biomaterial composed of two natural biological components, collagen and sodium alginate (SA), cross-linked using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) and oxidized sodium alginate (OSA). We conducted a series of tests to evaluate the physicochemical properties, acute systemic toxicity, skin irritation, intradermal reaction, sensitization, cytotoxicity, and in vivo femoral artery hemorrhage model. The results demonstrated the excellent biocompatibility of the collagen/sodium alginate (C/SA)-based dressings before and after crosslinking. Specifically, the femoral artery hemorrhage model revealed a significantly shortened hemostasis time of 132.5 ± 12.82 s for the EDC/NHS cross-linked dressings compared to the gauze in the blank group (hemostasis time of 251.43 ± 10.69 s). These findings indicated that C/SA-based dressings exhibited both good biocompatibility and a significant hemostatic effect, making them suitable for biomedical applications. Full article

(This article belongs to the Special Issue Synthesis and Applications of Natural Polymers and Their Derivatives)

19 pages, 1303 KiB

Open AccessArticle

Factors, Mechanisms, and Kinetics of Spontaneous Emulsification for Heavy Oil-in-Water Emulsions

by Jinhe Liu, Yao Li, Zengmin Lun, Yuhui Zhang, Pujiang Yang, Xinyu Tang and Qingxuan Zhang

Molecules 2024, 29(13), 2998; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132998 - 24 Jun 2024

Viewed by 164

Abstract

In challenging reservoirs where thermal recovery falls short, cold or chemical oil recovery methods are crucial. Spontaneous emulsification (SE), triggered by gentle disturbance, significantly enhances oil recovery. In elucidating SE mechanisms and kinetics, SE processes via direct contact between oil and aqueous phases [...] Read more.

In challenging reservoirs where thermal recovery falls short, cold or chemical oil recovery methods are crucial. Spontaneous emulsification (SE), triggered by gentle disturbance, significantly enhances oil recovery. In elucidating SE mechanisms and kinetics, SE processes via direct contact between oil and aqueous phases without stirring were conducted. The effects of temperature, emulsifier concentration, pH, NaCl concentration, and the oil-to-water ratio on SE were investigated through droplet size analysis and turbidity measurements. Furthermore, the emulsification mechanism and derived emulsification kinetics based on turbidity data were obtained. The results underscore the feasibility of SE for oil–water systems, reducing viscous and capillary resistances without agitation. The emulsified oil mass increased with the temperature, pH, and aqueous-to-oil phase volume ratio while decreasing with the NaCl concentration. In this study, for GD-2 crude oil, the optimal emulsified oil amount occurred at a betaine surfactant (BetS-2) emulsifier concentration of 0.45%. Microscopic photo analysis indicated narrow particle size distributions and small droplets, which remained stable over time under various experimental conditions. A combined SE mechanism involving ultralow interfacial tension, interfacial turbulence due to Marangoni effects, and “diffusion and stranding” due to in situ emulsifier hydrophilicity, was speculated. Additionally, an analogous second-order kinetic equation for SE was proposed, indicating exceptional correlation with calculated and experimentally measured values. This study offers theoretical insight for enhancing oil recovery in chemical and cold production of heavy oil in oilfields. Full article

(This article belongs to the Special Issue Surfactants at Liquid Interfaces: Applications in Enhanced Oil Recovery)

21 pages, 884 KiB

Open AccessArticle

Design, Synthesis, Antitumor, and Antiplasmodial Evaluation of New 7-Chloroquinoline–Benzimidazole Hybrids

by Luka Krstulović, Vesna Rastija, Lais Pessanha de Carvalho, Jana Held, Zrinka Rajić, Zorislava Živković, Miroslav Bajić and Ljubica Glavaš-Obrovac

Molecules 2024, 29(13), 2997; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132997 - 24 Jun 2024

Viewed by 191

Abstract

Newly synthesized 7-chloro-4-aminoquinoline–benzimidazole hybrids were characterized by NMR and elemental analysis. Compounds were tested for their effects on the growth of the non-tumor cell line MRC-5 (human fetal lung fibroblasts) and carcinoma (HeLa and CaCo-2), leukemia, and lymphoma (Hut78, THP-1, and HL-60) cell [...] Read more.

Newly synthesized 7-chloro-4-aminoquinoline–benzimidazole hybrids were characterized by NMR and elemental analysis. Compounds were tested for their effects on the growth of the non-tumor cell line MRC-5 (human fetal lung fibroblasts) and carcinoma (HeLa and CaCo-2), leukemia, and lymphoma (Hut78, THP-1, and HL-60) cell lines. The obtained results, expressed as the concentration at which 50% inhibition of cell growth is achieved (IC₅₀ value), show that the tested compounds affect cell growth differently depending on the cell line and the applied dose (IC₅₀ ranged from 0.2 to >100 µM). Also, the antiplasmodial activity of these hybrids was evaluated against two P. falciparum strains (Pf3D7 and PfDd2). The tested compounds showed potent antiplasmodial activity, against both strains, at nanomolar concentrations. Quantitative structure–activity relationship (QSAR) analysis resulted in predictive models for antiplasmodial activity against the 3D7 strain (R² = 0.886; R_ext² = 0.937; F = 41.589) and Dd2 strain (R² = 0.859; R_ext² = 0.878; F = 32.525) of P. falciparum. QSAR models identified the structural features of these favorable effects on antiplasmodial activities. Full article

(This article belongs to the Special Issue Design, Synthesis and Structure-Activity Relationship of Biologically Active Inhibitors)

11 pages, 3394 KiB

Open AccessArticle

KF-Containing Interphase Formation Enables Better Potassium Ion Storage Capability

by Tianyi Zhang, Ning Yuan, Zijie Li, Kun Chao, Zhonghua Zhang and Guicun Li

Molecules 2024, 29(13), 2996; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132996 - 24 Jun 2024

Viewed by 262

Abstract

Rechargeable potassium ion batteries have long been regarded as one alternative to conventional lithium ion batteries because of their resource sustainability and cost advantages. However, the compatibility between anodes and electrolytes remains to be resolved, impeding their commercial adoption. In this work, the [...] Read more.

Rechargeable potassium ion batteries have long been regarded as one alternative to conventional lithium ion batteries because of their resource sustainability and cost advantages. However, the compatibility between anodes and electrolytes remains to be resolved, impeding their commercial adoption. In this work, the K-ion storage properties of Bi nanoparticles encapsulated in N-doped carbon nanocomposites have been examined in two typical electrolyte solutions, which show a significant effect on potassium insertion/removal processes. In a KFSI-based electrolyte, the N-C@Bi nanocomposites exhibit a high specific capacity of 255.2 mAh g⁻¹ at 0.5 A g⁻¹, which remains at 245.6 mAh g⁻¹ after 50 cycles, corresponding to a high capacity retention rate of 96.24%. In a KPF₆-based electrolyte, the N-C@Bi nanocomposites show a specific capacity of 209.0 mAh g⁻¹, which remains at 71.5 mAh g⁻¹ after 50 cycles, corresponding to an inferior capacity retention rate of only 34.21%. Post-investigations reveal the formation of a KF interphase derived from salt decomposition and an intact rod-like morphology after cycling in K2 electrolytes, which are responsible for better K-ion storage properties. Full article

(This article belongs to the Special Issue Electrochemical Energy Conversion and Potential Strategies in Electrochemical Energy Storage)

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16 pages, 4697 KiB

Open AccessArticle

Ionic Liquid-Based Immunization Patch for the Transdermal Delivery of Antigens

by Rashedul Islam, Fahmida Habib Nabila, Rie Wakabayashi, Yoshirou Kawaguchi, Noriho Kamiya, Muhammad Moniruzzaman and Masahiro Goto

Molecules 2024, 29(13), 2995; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132995 - 24 Jun 2024

Viewed by 250

Abstract

Herein, we report a transdermal patch prepared using an ionic liquid-based solid in oil (IL-S/O) nanodispersion and a pressure-sensitive adhesive (PSA) to deliver the macromolecular antigenic protein, ovalbumin (OVA). The IL-S/O nanodispersion and a PSA were first mixed at an equal weight ratio, [...] Read more.

Herein, we report a transdermal patch prepared using an ionic liquid-based solid in oil (IL-S/O) nanodispersion and a pressure-sensitive adhesive (PSA) to deliver the macromolecular antigenic protein, ovalbumin (OVA). The IL-S/O nanodispersion and a PSA were first mixed at an equal weight ratio, then coated onto a release liner, and covered with a support film. To evaluate the effect of the PSA, three types of PSAs, DURO-TAK 87-4098, DURO-TAK 87-4287, and DURO-TAK 87-235A, were used to obtain the corresponding IL-S/O patches SP-4098, SP-4287, and SP-235A, respectively. The prepared IL-S/O patches were characterized for surface morphology, viscoelasticity, and moisture content. In vitro skin penetration and in vivo immunization studies of the IL-S/O patches were performed using Yucatan micropig skin and the C57BL/6NJc1 mice model, respectively. The SP-4098 and SP-4287 delivered 5.49-fold and 5.47-fold higher amounts of drug compared with the aqueous formulation. Although both patches delivered a similar amount of drug, SP-4287 was not detached fully from the release liner after 30 days, indicating low stability. Mice immunized with the OVA-containing SP-4098 produced a 10-fold increase in anti-OVA IgG compared with those treated with an aqueous formulation. These findings suggested that the IL-S/O patch may be a good platform for the transdermal delivery of antigen molecules. Full article

(This article belongs to the Section Molecular Liquids)

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14 pages, 1007 KiB

Open AccessArticle

Differential Effects of In Vitro Simulated Digestion on Antioxidant Activity and Bioaccessibility of Phenolic Compounds in Purple Rice Bran Extracts

by Pitchaporn Wanyo, Tossaporn Chamsai, Nitchara Toontom, Le Ke Nghiep and Kukiat Tudpor

Molecules 2024, 29(13), 2994; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132994 - 24 Jun 2024

Viewed by 264

Abstract

Pigmented rice varieties are abundant in phenolic compounds. Antioxidant activity and bioaccessibility of phenolic compounds are modified in the gastrointestinal tract. After in vitro simulated digestion, changes in antioxidant activity and bioaccessibility of phenolic compounds (phenolic acids, flavonoids, and anthocyanins) in purple rice [...] Read more.

Pigmented rice varieties are abundant in phenolic compounds. Antioxidant activity and bioaccessibility of phenolic compounds are modified in the gastrointestinal tract. After in vitro simulated digestion, changes in antioxidant activity and bioaccessibility of phenolic compounds (phenolic acids, flavonoids, and anthocyanins) in purple rice brans (Hom Nil and Riceberry) were compared with undigested crude extracts. The digestion method was conducted following the INFOGEST protocol. Antioxidant activity was determined using the ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assays. The bioaccessibility index (BI) was calculated from the ratio of digested to undigested soluble phenolic content. Overall results showed that the in vitro simulated digested rice brans had lower antioxidant activity and lower total phenolic, flavonoid, and anthocyanin contents. However, the concentration of sinapic acid was stable, while other phenolic acids (gallic, protocatechuic, vanillic, ρ-coumaric, and ferulic acids) degraded after the oral, gastric, and intestinal phases. The BI of sinapic, gallic, vanillic, and ferulic acids remained stable, and the BI of quercetin was resistant to digestion. Conversely, anthocyanins degraded during the intestinal phase. In conclusion, selective phenolic compounds are lost along the gastrointestinal tract, suggesting that controlled food delivery is of further interest. Full article

(This article belongs to the Special Issue Bioactive Compounds in Food: Characterization and Role in Human Health)

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14 pages, 4997 KiB

Open AccessArticle

Targeted Stimulation of Micropores by CS₂ Extraction on Molecular of Coal

by Zhen Zhang, Gaofeng Liu, Xiaoming Wang, Jia Lin, George Barakos and Ping Chang

Molecules 2024, 29(13), 2993; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132993 - 23 Jun 2024

Viewed by 372

Abstract

The targeted stimulation of micropores based on the transformation of coal’s molecular structure is proposed due to the chemical properties and difficult-to-transform properties of micropores. Carbon disulfide (CS₂) extraction is used as a targeted stimulation to reveal the internal evolution mechanism [...] Read more.

The targeted stimulation of micropores based on the transformation of coal’s molecular structure is proposed due to the chemical properties and difficult-to-transform properties of micropores. Carbon disulfide (CS₂) extraction is used as a targeted stimulation to reveal the internal evolution mechanism of micropore transformation. The variations of microcrystalline structures and micropores of bituminous coal and anthracite extracted by CS₂ were analyzed with X-ray diffraction (XRD), low-temperature carbon dioxide (CO₂) adsorption, and molecular simulation. The results show that CS₂ extraction, with the broken chain effect, swelling effect, and aromatic ring rearrangement effect, can promote micropore generation of bituminous coal by transforming the microcrystalline structure. Furthermore, CS₂ extraction on bituminous coal can decrease the average micropore size and increase the micropore volume and area. The aromatic layer fragmentation effect of CS₂ extraction on anthracite, compared to the micropore generation effect of the broken chain effect and swelling effect, can enlarge micropores more remarkably, as it induces an enhancement in the average micropore size and a decline in the micropore volume and area. The research is expected to provide a theoretical basis for establishing reservoir stimulation technology based on CS₂ extraction. Full article

(This article belongs to the Section Molecular Structure)

13 pages, 3402 KiB

Open AccessArticle

Insights into Actin Isoform-Specific Interactions with Myosin via Computational Analysis

by Chan Jong Yu, Yoon Ho Park, Mi Young An, Bumhan Ryu and Hyun Suk Jung

Molecules 2024, 29(13), 2992; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132992 - 23 Jun 2024

Viewed by 393

Abstract

Actin, which plays a crucial role in cellular structure and function, interacts with various binding proteins, notably myosin. In mammals, actin is composed of six isoforms that exhibit high levels of sequence conservation and structural similarity overall. As a result, the selection of [...] Read more.

Actin, which plays a crucial role in cellular structure and function, interacts with various binding proteins, notably myosin. In mammals, actin is composed of six isoforms that exhibit high levels of sequence conservation and structural similarity overall. As a result, the selection of actin isoforms was considered unimportant in structural studies of their binding with myosin. However, recent high-resolution structural research discovered subtle structural differences in the N-terminus of actin isoforms, suggesting the possibility that each actin isoform may engage in specific interactions with myosin isoforms. In this study, we aimed to explore this possibility, particularly by understanding the influence of different actin isoforms on the interaction with myosin 7A. First, we compared the reported actomyosin structures utilizing the same type of actin isoforms as the high-resolution filamentous skeletal α-actin (3.5 Å) structure elucidated using cryo-EM. Through this comparison, we confirmed that the diversity of myosin isoforms leads to differences in interaction with the actin N-terminus, and that loop 2 of the myosin actin-binding sites directly interacts with the actin N-terminus. Subsequently, with the aid of multiple sequence alignment, we observed significant variations in the length of loop 2 across different myosin isoforms. We predicted that these length differences in loop 2 would likely result in structural variations that would affect the interaction with the actin N-terminus. For myosin 7A, loop 2 was found to be very short, and protein complex predictions using skeletal α-actin confirmed an interaction between loop 2 and the actin N-terminus. The prediction indicated that the positively charged residues present in loop 2 electrostatically interact with the acidic patch residues D24 and D25 of actin subdomain 1, whereas interaction with the actin N-terminus beyond this was not observed. Additionally, analyses of the actomyosin-7A prediction models generated using various actin isoforms consistently yielded the same results regardless of the type of actin isoform employed. The results of this study suggest that the subtle structural differences in the N-terminus of actin isoforms are unlikely to influence the binding structure with short loop 2 myosin 7A. Our findings are expected to provide a deeper understanding for future high-resolution structural binding studies of actin and myosin. Full article

(This article belongs to the Special Issue Recent Progress for Structure and Function Prediction of Protein and RNA)

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11 pages, 3896 KiB

Open AccessArticle

Ca-Doping Cobalt-Free Double Perovskite Oxide as a Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cell

by Liangmei Xue, Songbo Li, Shengli An, Qiming Guo, Mengxin Li and Ning Li

Molecules 2024, 29(13), 2991; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132991 - 23 Jun 2024

Viewed by 404

Abstract

Mixed oxygen ion and electron-conducting materials are viable cathodes for solid oxide fuel cells due to their excellent oxygen transport kinetics and mixed electrical conductivity, which ensure highly efficient operation at low and medium temperatures. However, iron-based double perovskite oxides usually exhibit poor [...] Read more.

Mixed oxygen ion and electron-conducting materials are viable cathodes for solid oxide fuel cells due to their excellent oxygen transport kinetics and mixed electrical conductivity, which ensure highly efficient operation at low and medium temperatures. However, iron-based double perovskite oxides usually exhibit poor electrocatalytic activity due to low electron and oxygen ion conductivity. In this paper, Ca is doped in PrBaFe₂O_5+δ A-site to improve the electrochemical performance of PrBaFe₂O_5+δ. Results show that replacing Pr with Ca does not change the crystal structure, and the Ca doping effectively increases the adsorbed oxygen content and accelerates the migration and diffusion rate of O²⁻ to the electrolyte|cathode interface. The polarization resistance of the symmetric cell PC_0.15BF|CGO|PC_0.15BF is 0.033 Ω·cm² at 800 °C, which is about 56% lower than that of PBF, confirming the enhancement of the mixed conduction of oxygen ions and electrons. In addition, the anode-supported single cell has a peak power density of 512 mW·cm⁻² at 800 °C. Full article

(This article belongs to the Collection Green Energy and Environmental Materials)

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13 pages, 1165 KiB

Open AccessArticle

A Comparison of Phenolic, Flavonoid, and Amino Acid Compositions and In Vitro Antioxidant and Neuroprotective Activities in Thai Plant Protein Extracts

by Pontapan Polyiam and Wipawee Thukhammee

Molecules 2024, 29(13), 2990; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132990 - 23 Jun 2024

Viewed by 449

Abstract

The leaves of mulberry, Azolla spp., sunflower sprouts, cashew nut, and mung bean are considered rich sources of plant protein with high levels of branched-chain amino acids. Furthermore, they contain beneficial phytochemicals such as antioxidants and anti-inflammatory agents. Additionally, there are reports suggesting [...] Read more.

The leaves of mulberry, Azolla spp., sunflower sprouts, cashew nut, and mung bean are considered rich sources of plant protein with high levels of branched-chain amino acids. Furthermore, they contain beneficial phytochemicals such as antioxidants and anti-inflammatory agents. Additionally, there are reports suggesting that an adequate consumption of amino acids can reduce nerve cell damage, delay the onset of memory impairment, and improve sleep quality. In this study, protein isolates were prepared from the leaves of mulberry, Azolla spp., sunflower sprouts, cashew nut, and mung bean. The amino acid profile, dietary fiber content, phenolic content, and flavonoid content were evaluated. Pharmacological properties, such as antioxidant, anticholinesterase, monoamine oxidase, and γ-aminobutyric acid transaminase (GABA-T) activities, were also assessed. This study found that concentrated protein from mung beans has a higher quantity of essential amino acids (52,161 mg/100 g protein) compared to concentrated protein from sunflower sprouts (47,386 mg/100 g protein), Azolla spp. (42,097 mg/100 g protein), cashew nut (26,710 mg/100 g protein), and mulberry leaves (8931 mg/100 g protein). The dietary fiber content ranged from 0.90% to 3.24%, while the phenolic content and flavonoid content ranged from 0.25 to 2.29 mg/g and 0.01 to 2.01 mg/g of sample, respectively. Sunflower sprout protein isolates exhibited the highest levels of dietary fiber (3.24%), phenolic content (2.292 ± 0.082 mg of GAE/g), and flavonoids (2.014 mg quercetin/g of sample). The biological efficacy evaluation found that concentrated protein extract from sunflower sprouts has the highest antioxidant activity; the percentages of inhibition of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical were 20.503 ± 0.288% and 18.496 ± 0.105%, respectively. Five plant-based proteins exhibited a potent inhibition of acetylcholinesterase (AChE) enzyme activity, monoamine oxidase (MAO) inhibition, and GABA-T ranging from 3.42% to 24.62%, 6.14% to 20.16%, and 2.03% to 21.99%, respectively. These findings suggest that these plant protein extracts can be used as natural resources for developing food supplements with neuroprotective activity. Full article

(This article belongs to the Special Issue Functional Proteins in Food: Chemistry, Applications, and Health Benefits)

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22 pages, 2827 KiB

Open AccessReview

Host–guest Metal–Organic Frameworks-Based Long-Afterglow Luminescence Materials

by Zhi-Chen Zhang, Zhi-Gang Gu and Jian Zhang

Molecules 2024, 29(13), 2989; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132989 - 23 Jun 2024

Viewed by 317

Abstract

Long-afterglow materials have a broad of applications in optoelectronic devices, sensors, medicine and other fields due to their excellent luminescent properties. The host-guest long-afterglow MOFs material combines the advantages of multi-component characteristics and the stability of MOFs, which improves its luminous performance and [...] Read more.

Long-afterglow materials have a broad of applications in optoelectronic devices, sensors, medicine and other fields due to their excellent luminescent properties. The host-guest long-afterglow MOFs material combines the advantages of multi-component characteristics and the stability of MOFs, which improves its luminous performance and expands its other properties. This review introduces the classification, synthesis and application of host-guest MOFs materials with long afterglow. Due to their rigid frames and multi-channel characteristics, MOFs can load common guest materials including rare earth metals, organic dyes, carbon dots, etc. The synthesis methods of loading guest materials into MOFs include solvothermal synthesis, post-encapsulation, post-modification, etc. Those long-afterglow host-guest MOFs have a wide range of applications in the fields of sensors, information security and biological imaging. Full article

(This article belongs to the Special Issue Featured Reviews in Organometallic Chemistry, 2nd Edition)

26 pages, 5196 KiB

Open AccessArticle

Development of FluoAHRL: A Novel Synthetic Fluorescent Compound That Activates AHR and Potentiates Anti-Inflammatory T Regulatory Cells

by Natalija Jonić, Ivan Koprivica, Christos M. Chatzigiannis, Antonis D. Tsiailanis, Stavroula G. Kyrkou, Eleftherios Paraskevas Tzakos, Aleksandar Pavić, Mirjana Dimitrijević, Andjelina Jovanović, Milan B. Jovanović, Sérgio Marinho, Inês Castro-Almeida, Vesna Otašević, Pedro Moura-Alves, Andreas G. Tzakos and Ivana Stojanović

Molecules 2024, 29(13), 2988; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132988 - 23 Jun 2024

Viewed by 328

Abstract

Aryl Hydrocarbon Receptor (AHR) ligands, upon binding, induce distinct gene expression profiles orchestrated by the AHR, leading to a spectrum of pro- or anti-inflammatory effects. In this study, we designed, synthesized and evaluated three indole-containing potential AHR ligands (FluoAHRL: AGT-4, AGT-5 and AGT-6). [...] Read more.

Aryl Hydrocarbon Receptor (AHR) ligands, upon binding, induce distinct gene expression profiles orchestrated by the AHR, leading to a spectrum of pro- or anti-inflammatory effects. In this study, we designed, synthesized and evaluated three indole-containing potential AHR ligands (FluoAHRL: AGT-4, AGT-5 and AGT-6). All synthesized compounds were shown to emit fluorescence in the near-infrared. Their AHR agonist activity was first predicted using in silico docking studies, and then confirmed using AHR luciferase reporter cell lines. FluoAHRLs were tested in vitro using mouse peritoneal macrophages and T lymphocytes to assess their immunomodulatory properties. We then focused on AGT-5, as it illustrated the predominant anti-inflammatory effects. Notably, AGT-5 demonstrated the ability to foster anti-inflammatory regulatory T cells (Treg) while suppressing pro-inflammatory T helper (Th)17 cells in vitro. AGT-5 actively induced Treg differentiation from naïve CD4⁺ cells, and promoted Treg proliferation, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) expression and interleukin-10 (IL-10) production. The increase in IL-10 correlated with an upregulation of Signal Transducer and Activator of Transcription 3 (STAT3) expression. Importantly, the Treg-inducing effect of AGT-5 was also observed in human tonsil cells in vitro. AGT-5 showed no toxicity when applied to zebrafish embryos and was therefore considered safe for animal studies. Following oral administration to C57BL/6 mice, AGT-5 significantly upregulated Treg while downregulating pro-inflammatory Th1 cells in the mesenteric lymph nodes. Due to its fluorescent properties, AGT-5 could be visualized both in vitro (during uptake by macrophages) and ex vivo (within the lamina propria of the small intestine). These findings make AGT-5 a promising candidate for further exploration in the treatment of inflammatory and autoimmune diseases. Full article

(This article belongs to the Section Applied Chemistry)

15 pages, 3658 KiB

Open AccessArticle

Atomic Layer Deposition of CeO₂ Film with a Novel Heteroleptic Ce(III) Complex

by Wenyong Zhao, Hong Zhou, Jiahao Li, Yuchen Lu and Yuqiang Ding

Molecules 2024, 29(13), 2987; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules29132987 - 23 Jun 2024

Viewed by 367

Abstract

In this paper, four heteroleptic Ce(III) complexes, including Ce(thd)₃-phen (thd = 2,2,6,6-tetramethyl-3,5-heptanedione, phen = 1, 10—phenanthroline (1), Ce(thd)₃-MEDA (MEDA = N—Methylethylenediamine (2), Ce(thd)₃-MOMA (MOMA = N-(2-Methoxyethyl)methylamine (3), and Ce(thd)₃-DMDE [...] Read more.

In this paper, four heteroleptic Ce(III) complexes, including Ce(thd)₃-phen (thd = 2,2,6,6-tetramethyl-3,5-heptanedione, phen = 1, 10—phenanthroline (1), Ce(thd)₃-MEDA (MEDA = N—Methylethylenediamine (2), Ce(thd)₃-MOMA (MOMA = N-(2-Methoxyethyl)methylamine (3), and Ce(thd)₃-DMDE (DMDE = N,N″-dimethyl ethanol amine (4), were synthesized and characterized with ¹H-NMR, elemental analysis, and X-ray single-crystal diffraction. The thermogravimetric analysis and vapor pressure results indicated that the complexing ability of a nitrogen-containing bidentate ligand with a cerium ion was stronger than that of a mixed oxygen-nitrogen-containing bidentate ligand. Complex 2 was selected as an ALD precursor to deposit a CeO₂ film on a SiO₂/Si (100) wafer. The self-limited deposition results demonstrated that complex 2 was a potential ALD precursor. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Coordination Complexes)

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Molecules, Volume 29, Issue 13 (July-1 2024) – 69 articles

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