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Molecules in 2023

A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 34207

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Groupe de Recherche en Eco-Extraction de Produits Naturel, Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement, Université d´Avignon et des Pays du Vaucluse, 84029 Avignon, France
Interests: green extraction; alternative solvents; innovative technologies; original procedures; microwave; ultrasound; intensification
* It is with great sadness that we announce the passing of Professor Farid Chemat.
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Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, 87036 Rende, Italy
Interests: nanomaterials; biomaterials; carbon nanostructures; composite and hybrid materials; biomedical applications of functional materials; therapeutic devices; surface chemistry
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Laboratory of Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Biomedicine (IBUB), University of Barcelona, Avenue Joan XXIII, 27-31, E-08028 Barcelona, Spain
Interests: multitarget anti-Alzheimer agents; hybrid compounds; cholinesterase inhibitors; amyloid anti-aggregating compounds; BACE-1 inhibitors; antiprotozoan compounds
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Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
Interests: organic, organometallic, and medicinal chemistry; organic synthesis; nucleosides; heterocycles; alkynes; fluorine and fluorous; cycloisomerizations; cyclizations
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Special Issue Information

Dear Colleagues,

Thanks to our readers, innumerable authors, anonymous peer reviewers, editors, and all others contributing in some way to the journal, Molecules has achieved an IF which currently stands at 4.927. In 2023, the 28th volume of our journal is due to be being published.

To start and highlight another consecutive year of excellence on a high note, a Special Issue entitled “Molecules in 2023” is being launched.  This purpose of this Special Issue is to collect high-quality original research and review articles in all areas of interest covered by Molecules. The Special Issue aims to collect papers of our Editors-in-Chief, Editorial Board members, Guest Editors, affiliated societies members, authors, and reviewers from Molecules. The submission deadline will be 31 March 2023. We kindly encourage all research groups to contribute up-to-date results from the latest developments in your laboratory.

Prof. Dr. Farid Chemat
Dr. Giuseppe Cirillo
Prof. Dr. Diego Muñoz-Torrero
Prof. Dr. Roman Dembinski
Guest Editors

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Keywords

  • organic chemistry
  • medicinal chemistry
  • natural products
  • inorganic chemistry
  • physical chemistry
  • materials science
  • nanoscience
  • catalysis
  • chemical biology
  • analytical chemistry
  • supramolecular chemistry
  • theoretical chemistry
  • green chemistry
  • photochemistry

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Published Papers (15 papers)

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16 pages, 2868 KiB  
Article
Novel Cytotoxic Sesquiterpene Coumarin Ethers and Sulfur-Containing Compounds from the Roots of Ferula turcica
by Fatma Memnune Eruçar, Sarath P. D. Senadeera, Jennifer A. Wilson, Ekaterina Goncharova, John A. Beutler and Mahmut Miski
Molecules 2023, 28(15), 5733; https://doi.org/10.3390/molecules28155733 - 28 Jul 2023
Cited by 3 | Viewed by 1521
Abstract
Six new sesquiterpene coumarin ethers, namely turcicanol A (1), turcicanol A acetate (2), turcicanol B (3), turcica ketone (4), 11′-dehydrokaratavicinol (5), and galbanaldehyde (6), and one new sulfur-containing compound, namely turcicasulphide [...] Read more.
Six new sesquiterpene coumarin ethers, namely turcicanol A (1), turcicanol A acetate (2), turcicanol B (3), turcica ketone (4), 11′-dehydrokaratavicinol (5), and galbanaldehyde (6), and one new sulfur-containing compound, namely turcicasulphide (7), along with thirty-two known secondary metabolites were isolated from the root of the endemic species Ferula turcica Akalın, Miski, & Tuncay through a bioassay-guided isolation approach. The structures of the new compounds were elucidated by spectroscopic analysis and comparison with the literature. Cell growth inhibition of colon cancer cell lines (COLO205 and HCT116) and kidney cancer cell lines (UO31 and A498) was used to guide isolation. Seventeen of the compounds showed significant activity against the cell lines. Full article
(This article belongs to the Special Issue Molecules in 2023)
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21 pages, 3010 KiB  
Article
Morin Hydrate Encapsulation and Release from Mesoporous Silica Nanoparticles for Melanoma Therapy
by Catarina Cunha, Diogo Marinheiro, Bárbara J. M. L. Ferreira, Helena Oliveira and Ana L. Daniel-da-Silva
Molecules 2023, 28(12), 4776; https://doi.org/10.3390/molecules28124776 - 15 Jun 2023
Cited by 7 | Viewed by 2356
Abstract
Melanoma incidence, a type of skin cancer, has been increasing worldwide. There is a strong need to develop new therapeutic strategies to improve melanoma treatment. Morin is a bioflavonoid with the potential for use in the treatment of cancer, including melanoma. However, therapeutic [...] Read more.
Melanoma incidence, a type of skin cancer, has been increasing worldwide. There is a strong need to develop new therapeutic strategies to improve melanoma treatment. Morin is a bioflavonoid with the potential for use in the treatment of cancer, including melanoma. However, therapeutic applications of morin are restrained owing to its low aqueous solubility and limited bioavailability. This work investigates morin hydrate (MH) encapsulation in mesoporous silica nanoparticles (MSNs) to enhance morin bioavailability and consequently increase the antitumor effects in melanoma cells. Spheroidal MSNs with a mean size of 56.3 ± 6.5 nm and a specific surface area of 816 m2/g were synthesized. MH was successfully loaded (MH-MSN) using the evaporation method, with a loading capacity of 28.3% and loading efficiency of 99.1%. In vitro release studies showed that morin release from MH-MSNs was enhanced at pH 5.2, indicating increased flavonoid solubility. The in vitro cytotoxicity of MH and MH-MSNs on human A375, MNT-1 and SK-MEL-28 melanoma cell lines was investigated. Exposure to MSNs did not affect the cell viability of any of the cell lines tested, suggesting that the nanoparticles are biocompatible. The effect of MH and MH-MSNs on reducing cell viability was time- and concentration-dependent in all melanoma cell lines. The A375 and SK-MEL-28 cell lines were slightly more sensitive than MNT-1 cells in both the MH and MH-MSN treatments. Our findings suggest that MH-MSNs are a promising delivery system for the treatment of melanoma. Full article
(This article belongs to the Special Issue Molecules in 2023)
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23 pages, 3061 KiB  
Article
Ligand−Structure Effects on N−Heterocyclic Carbene Rhenium Photo− and Electrocatalysts of CO2 Reduction
by Lauren Kearney, Michael P. Brandon, Andrew Coleman, Ann M. Chippindale, František Hartl, Ralte Lalrempuia, Martin Pižl and Mary T. Pryce
Molecules 2023, 28(10), 4149; https://doi.org/10.3390/molecules28104149 - 17 May 2023
Cited by 1 | Viewed by 2394
Abstract
Three novel rhenium N−heterocyclic carbene complexes, [Re]−NHC−1−3 ([Re] = fac−Re(CO)3Br), were synthesized and characterized using a range of spectroscopic techniques. Photophysical, electrochemical and spectroelectrochemical studies were carried out to probe the properties of these organometallic compounds. Re−NHC−1 and Re−NHC−2 [...] Read more.
Three novel rhenium N−heterocyclic carbene complexes, [Re]−NHC−1−3 ([Re] = fac−Re(CO)3Br), were synthesized and characterized using a range of spectroscopic techniques. Photophysical, electrochemical and spectroelectrochemical studies were carried out to probe the properties of these organometallic compounds. Re−NHC−1 and Re−NHC−2 bear a phenanthrene backbone on an imidazole (NHC) ring, coordinating to Re by both the carbene C and a pyridyl group attached to one of the imidazole nitrogen atoms. Re−NHC−2 differs from Re−NHC−1 by replacing N−H with an N−benzyl group as the second substituent on imidazole. The replacement of the phenanthrene backbone in Re−NHC−2 with the larger pyrene gives Re−NHC−3. The two−electron electrochemical reductions of Re−NHC−2 and Re−NHC−3 result in the formation of the five−coordinate anions that are capable of electrocatalytic CO2 reduction. These catalysts are formed first at the initial cathodic wave R1, and then, ultimately, via the reduction of Re−Re bound dimer intermediates at the second cathodic wave R2. All three Re−NHC−1−3 complexes are active photocatalysts for the transformation of CO2 to CO, with the most photostable complex, Re−NHC−3, being the most effective for this conversion. Re−NHC−1 and Re−NHC−2 afforded modest CO turnover numbers (TONs), following irradiation at 355 nm, but were inactive at the longer irradiation wavelength of 470 nm. In contrast, Re−NHC−3, when photoexcited at 470 nm, yielded the highest TON in this study, but remained inactive at 355 nm. The luminescence spectrum of Re−NHC−3 is red−shifted compared to those of Re−NHC−1 and Re−NHC−2, and previously reported similar [Re]−NHC complexes. This observation, together with TD−DFT calculations, suggests that the nature of the lowest−energy optical excitation for Re−NHC−3 has π→π*(NHC−pyrene) and dπ(Re)→π*(pyridine) (IL/MLCT) character. The stability and superior photocatalytic performance of Re−NHC−3 are attributed to the extended conjugation of the π−electron system, leading to the beneficial modulation of the strongly electron−donating tendency of the NHC group. Full article
(This article belongs to the Special Issue Molecules in 2023)
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14 pages, 1705 KiB  
Article
Wheat Oxylipins in Response to Aphids, CO2 and Nitrogen Regimes
by Mari Merce Cascant-Vilaplana, Eduardo Viteritti, Víctor Sadras, Sonia Medina, María Puerto Sánchez-Iglesias, Camille Oger, Jean-Marie Galano, Thierry Durand, José Antonio Gabaldón, Julian Taylor, Federico Ferreres, Manuel Sergi and Angel Gil-Izquierdo
Molecules 2023, 28(10), 4133; https://doi.org/10.3390/molecules28104133 - 16 May 2023
Viewed by 1603
Abstract
Wheat is critical for food security, and is challenged by biotic stresses, chiefly aphids and the viruses they transmit. The objective of this study was to determine whether aphids feeding on wheat could trigger a defensive plant reaction to oxidative stress that involved [...] Read more.
Wheat is critical for food security, and is challenged by biotic stresses, chiefly aphids and the viruses they transmit. The objective of this study was to determine whether aphids feeding on wheat could trigger a defensive plant reaction to oxidative stress that involved plant oxylipins. Plants were grown in chambers with a factorial combination of two nitrogen rates (100% N vs. 20% N in Hoagland solution), and two concentrations of CO2 (400 vs. 700 ppm). The seedlings were challenged with Rhopalosiphum padi or Sitobion avenae for 8 h. Wheat leaves produced phytoprostanes (PhytoPs) of the F1 series, and three types of phytofurans (PhytoFs): ent-16(RS)-13-epi-ST-Δ14-9-PhytoF, ent-16(RS)-9-epi-ST-Δ14-10-PhytoF and ent-9(RS)-12-epi-ST-Δ10-13-PhytoF. The oxylipin levels varied with aphids, but not with other experimental sources of variation. Both Rhopalosiphum padi and Sitobion avenae reduced the concentrations of ent-16(RS)-13-epi-ST-Δ14-9-PhytoF and ent-16(RS)-9-epi-ST-Δ14-10-PhytoF in relation to controls, but had little or no effect on PhytoPs. Our results are consistent with aphids affecting the levels of PUFAs (oxylipin precursors), which decreased the levels of PhytoFs in wheat leaves. Therefore, PhytoFs could be postulated as an early indicator of aphid hosting for this plant species. This is the first report on the quantification of non-enzymatic PhytoFs and PhytoPs in wheat leaves in response to aphids. Full article
(This article belongs to the Special Issue Molecules in 2023)
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17 pages, 3443 KiB  
Article
Microwave-Assisted Synthesis and Spectral Properties of Pyrrolidine-Fused Chlorin Derivatives
by José Almeida, Augusto C. Tomé, Maria Rangel and Ana M. G. Silva
Molecules 2023, 28(9), 3833; https://doi.org/10.3390/molecules28093833 - 30 Apr 2023
Cited by 2 | Viewed by 1775
Abstract
In this work we pursued research involving the microwave-assisted N-alkylation of a NH pyrrolidine-fused chlorin with methyl 4-(bromomethyl) benzoate and subsequent ester hydrolysis as a straightforward strategy to obtain carboxylic acid functionality in the pyrrolidine-fused chlorin, as a single reaction product. We [...] Read more.
In this work we pursued research involving the microwave-assisted N-alkylation of a NH pyrrolidine-fused chlorin with methyl 4-(bromomethyl) benzoate and subsequent ester hydrolysis as a straightforward strategy to obtain carboxylic acid functionality in the pyrrolidine-fused chlorin, as a single reaction product. We studied the reaction’s scope by extending the N-alkylation of the free-base chlorin and its corresponding Zn(II) complex to other alkyl halides, including 1,4-diiodobutane, N-(2-bromoethyl)phthalimide, and 2-bromoethanaminium bromide. In addition, two new chlorin–dansyl dyads were synthesized by reacting dansyl chloride with the 2-aminoethyl pyrrolidine-fused chlorin (dyad 6) and NH pyrrolidine-fused chlorin (dyad 7). According to spectral studies, the linker length between the two fluorophores influences the response of the dyads to the solvent polarity. Because of the simplicity of these approaches, we believe it will enable access to a vast library of custom-tailored N-functionalized chlorins while preserving their important absorption and emission spectra as photosensitizers in photodynamic therapy (PDT) of cancer and photodynamic inactivation (PDI) of microorganisms. Full article
(This article belongs to the Special Issue Molecules in 2023)
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16 pages, 2498 KiB  
Article
A Sulfonic Acid Polyvinyl Pyridinium Ionic Liquid Catalyzes the Multi-Component Synthesis of Spiro-indoline-3,5′-pyrano[2,3-d]-pyrimidines and -Pyrazines
by Mehdi Khalaj, Mahboubeh Taherkhani, Leo Payen and Axel Klein
Molecules 2023, 28(9), 3663; https://doi.org/10.3390/molecules28093663 - 23 Apr 2023
Cited by 5 | Viewed by 2009
Abstract
A sulfonated poly-4-vinyl pyridinium (PVPy-IL-B-SO3H) containing an acidic pyridinium/HSO3 ionic liquid moiety was prepared and used as a catalyst for the three-component reaction of malononitrile with 1-alkylindoline-2,3-diones and 1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione or methyl 5-hydroxy-1H [...] Read more.
A sulfonated poly-4-vinyl pyridinium (PVPy-IL-B-SO3H) containing an acidic pyridinium/HSO3 ionic liquid moiety was prepared and used as a catalyst for the three-component reaction of malononitrile with 1-alkylindoline-2,3-diones and 1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione or methyl 5-hydroxy-1H-pyrazole-3-carboxylate, leading to methyl 6′-amino-5′-cyano-2-oxo-2′H-spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylates or -3,4′-pyrano[2,3-d]pyrimidine]-6′-carbonitrile derivatives under ultrasonic irradiation conditions. The solid catalyst allows easy separation, is cheap, produces high yields under mild conditions, and does not require column chromatography for product isolation and purification. Full article
(This article belongs to the Special Issue Molecules in 2023)
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11 pages, 1433 KiB  
Article
Chiral Separation of Apremilast by Capillary Electrophoresis Using Succinyl-β-Cyclodextrin—Reversal of Enantiomer Elution Order by Cationic Capillary Coating
by Zoltán-István Szabó, Beáta-Mária Benkő, Ágnes Bartalis-Fábián, Róbert Iványi, Erzsébet Varga, Levente Szőcs and Gergő Tóth
Molecules 2023, 28(8), 3310; https://doi.org/10.3390/molecules28083310 - 8 Apr 2023
Cited by 4 | Viewed by 2198
Abstract
A stereospecific capillary electrophoresis method was developed for the separation of the novel, antipsoriatic agent, apremilast (APR). Six anionic cyclodextrin (CD) derivatives were screened for their ability to discriminate between the uncharged enantiomers. Only succinyl-β-CD (Succ-β-CD) presented chiral interactions; however, the enantiomer migration [...] Read more.
A stereospecific capillary electrophoresis method was developed for the separation of the novel, antipsoriatic agent, apremilast (APR). Six anionic cyclodextrin (CD) derivatives were screened for their ability to discriminate between the uncharged enantiomers. Only succinyl-β-CD (Succ-β-CD) presented chiral interactions; however, the enantiomer migration order (EMO) was unfavorable, and the eutomer, S-APR, migrated faster. Despite the optimization of all possible parameters (pH, cyclodextrin concentration, temperature, and degree of substitution of CD), the method was unsuccessful for purity control due to the low resolution and the unfavorable enantiomer migration order. Changing the direction of electroosmotic flow (EOF) by the dynamic coating of the inner surface of the capillary with poly(diallyldimethylammonium) chloride or polybrene resulted in EMO reversal, and the developed method could be applied for the determination of R-APR as the enantiomeric purity. Thus, the application of the dynamic capillary coating offers a general opportunity for enantiomeric migration order reversal in particular cases when the chiral selector is a weak acid. Full article
(This article belongs to the Special Issue Molecules in 2023)
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14 pages, 3286 KiB  
Article
Synthesis and Elimination Pathways of 1-Methanesulfonyl-1,2-dihydroquinoline Sulfonamides
by Ebenezer Ametsetor, Kwabena Fobi and Richard A. Bunce
Molecules 2023, 28(7), 3256; https://doi.org/10.3390/molecules28073256 - 5 Apr 2023
Cited by 1 | Viewed by 1846
Abstract
A series of new Morita–Baylis–Hillman acetates were prepared and reacted with methanesulfonamide (K2CO3, DMF, 23 °C) to produce tertiary dihydroquinoline sulfonamides in high yields. Subsequent efforts to eliminate the methylsulfonyl group from these derivatives (K2CO3, [...] Read more.
A series of new Morita–Baylis–Hillman acetates were prepared and reacted with methanesulfonamide (K2CO3, DMF, 23 °C) to produce tertiary dihydroquinoline sulfonamides in high yields. Subsequent efforts to eliminate the methylsulfonyl group from these derivatives (K2CO3, DMF, 90 °C) as a route to quinolines were met with mixed results. Although dihydroquinoline sulfonamides prepared from ethyl acrylate and acrylonitrile generally underwent elimination to give excellent yields of quinolines, those generated from 3-buten-2-one failed to undergo elimination and instead decomposed. The failure of these ketone substrates to aromatize presumably derives from the enolizable methyl ketone at C-3. Finally, the attempted aromatization of the acrylate-derived 6,7-difluoro-1,2-dihydroquinoline sulfonamide demonstrated that other interesting processes could occur in preference to the desired elimination. Full article
(This article belongs to the Special Issue Molecules in 2023)
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16 pages, 3394 KiB  
Article
A Density Functional Study on Ethylene Trimerization and Tetramerization Using Real Sasol Cr-PNP Catalysts
by Minserk Cheong and Ajeet Singh
Molecules 2023, 28(7), 3101; https://doi.org/10.3390/molecules28073101 - 30 Mar 2023
Cited by 1 | Viewed by 2050
Abstract
To gain molecular-level insight into the intricate features of the catalytic behavior of chromium–diphosphine complexes regarding ethylene tri- and tetramerizations, we performed density functional theory (DFT) calculations. The selective formation of 1-hexene and 1-octene by the tri- and tetramerizations of ethylene are generally [...] Read more.
To gain molecular-level insight into the intricate features of the catalytic behavior of chromium–diphosphine complexes regarding ethylene tri- and tetramerizations, we performed density functional theory (DFT) calculations. The selective formation of 1-hexene and 1-octene by the tri- and tetramerizations of ethylene are generally accepted to follow the metallacycle mechanism. To explore the mechanism of ethylene tri- and tetramerizations, we used a real Sasol chromium complex with a nitrogen-bridged diphosphine ligand with ortho- and para-methoxyaryl substituents. We explore the trimerization mechanism for ethylene first and, later on for comparison, we extend the potential energy surfaces (PES) for the tetramerization of ethylene with both catalysts. The calculated results reveal that the formation of 1-hexene and 1-octene with the ortho-methoxyaryl and para-methoxyaryl Cr-PNP catalysts have nearly similar potential energy surfaces (PES). From the calculated results important insights are gained into the tri- and tetramerizations. The tetramerization of ethylene with the para-methoxyaryl Cr-PNP catalyst lowers the barrier height by ~2.6 kcal/mol compared to that of ethylene with the ortho-methoxyaryl Cr-PNP catalyst. The selectivity toward trimerization or tetramerization comes from whether the energy barrier for ethylene insertion to metallacycloheptane is higher than β-hydride transfer to make 1-hexene. The metallacycle mechanism with Cr (I)–Cr (III) intermediates is found to be the most favored, with the oxidative coupling of the two coordinated ethylenes to form chromacyclopentane being the rate-determining step. Full article
(This article belongs to the Special Issue Molecules in 2023)
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14 pages, 4363 KiB  
Article
Structural Insights into the Ligand–LsrK Kinase Binding Mode: A Step Forward in the Discovery of Novel Antimicrobial Agents
by Roberta Listro, Giorgio Milli, Angelica Pellegrini, Chiara Motta, Valeria Cavalloro, Emanuela Martino, Johannes Kirchmair, Giampiero Pietrocola, Daniela Rossi, Pasquale Linciano and Simona Collina
Molecules 2023, 28(6), 2542; https://doi.org/10.3390/molecules28062542 - 10 Mar 2023
Cited by 3 | Viewed by 2144
Abstract
LsrK is a bacterial kinase that triggers the quorum sensing, and it represents a druggable target for the identification of new agents for fighting antimicrobial resistance. Herein, we exploited tryptophan fluorescence spectroscopy (TFS) as a suitable technique for the identification of potential LsrK [...] Read more.
LsrK is a bacterial kinase that triggers the quorum sensing, and it represents a druggable target for the identification of new agents for fighting antimicrobial resistance. Herein, we exploited tryptophan fluorescence spectroscopy (TFS) as a suitable technique for the identification of potential LsrK ligands from an in-house library of chemicals comprising synthetic compounds as well as secondary metabolites. Three secondary metabolites (Hib-ester, Hib-carbaldehyde and (R)-ASME) showed effective binding to LsrK, with KD values in the sub-micromolar range. The conformational changes were confirmed via circular dichroism and molecular docking results further validated the findings and displayed the specific mode of interaction. The activity of the identified compounds on the biofilm formation by some Staphylococcus spp. was investigated. Hib-carbaldehyde and (R)-ASME were able to reduce the production of biofilm, with (R)-ASME resulting in the most effective compound with an EC50 of 14 mg/well. The successful application of TFS highlights its usefulness in searching for promising LsrK inhibitor candidates with inhibitor efficacy against biofilm formation. Full article
(This article belongs to the Special Issue Molecules in 2023)
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21 pages, 2386 KiB  
Article
Subcritical Water Extraction of Onosma mutabilis: Process Optimization and Chemical Profile of the Extracts
by Selda Doğan Çalhan, Bahar Meryemoğlu, Pelin Eroğlu, Barış Saçlı and Dimitrios Kalderis
Molecules 2023, 28(5), 2314; https://doi.org/10.3390/molecules28052314 - 2 Mar 2023
Cited by 7 | Viewed by 1974
Abstract
The aboveground and root parts of Onosma mutabilis were extracted using subcritical water and the process was optimized with response surface methodology. The composition of the extracts was determined by chromatographic methods and compared to that of conventional maceration of the plant. The [...] Read more.
The aboveground and root parts of Onosma mutabilis were extracted using subcritical water and the process was optimized with response surface methodology. The composition of the extracts was determined by chromatographic methods and compared to that of conventional maceration of the plant. The optimum total phenolic contents for the aboveground part and the roots were 193.9 and 174.4 μg/g, respectively. These results were achieved at a subcritical water temperature of 150 °C, an extraction time of 180 min, and a water/plant ratio of 0.1, for both parts of the plant. Principal component analysis revealed that the roots contained mainly phenols, ketones, and diols, with the aboveground part mostly alkenes and pyrazines, whereas the extract from maceration contained mainly terpenes, esters, furans, and organic acids. The quantification of selected phenolic substances showed that subcritical water extraction compared favorably to maceration, especially with respect to pyrocatechol (1062 as compared to 10.2 μg/g) and epicatechin (1109 as compared to 23.4 μg/g). Furthermore, the roots of the plant contained twice as much of these two phenolics compared to the aboveground part. Subcritical water extraction of O. mutabilis is an environmentally friendly method that can extract selected phenolics at higher concentrations compared to maceration. Full article
(This article belongs to the Special Issue Molecules in 2023)
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28 pages, 5898 KiB  
Article
Exploration of Pyrido[3,4-d]pyrimidines as Antagonists of the Human Chemokine Receptor CXCR2
by Max Van Hoof, Sandra Claes, Katrijn Boon, Tom Van Loy, Dominique Schols, Wim Dehaen and Steven De Jonghe
Molecules 2023, 28(5), 2099; https://doi.org/10.3390/molecules28052099 - 23 Feb 2023
Cited by 1 | Viewed by 2158
Abstract
Upregulated CXCR2 signalling is found in numerous inflammatory, autoimmune and neurodegenerative diseases, as well as in cancer. Consequently, CXCR2 antagonism is a promising therapeutic strategy for treatment of these disorders. We previously identified, via scaffold hopping, a pyrido[3,4-d]pyrimidine analogue as a [...] Read more.
Upregulated CXCR2 signalling is found in numerous inflammatory, autoimmune and neurodegenerative diseases, as well as in cancer. Consequently, CXCR2 antagonism is a promising therapeutic strategy for treatment of these disorders. We previously identified, via scaffold hopping, a pyrido[3,4-d]pyrimidine analogue as a promising CXCR2 antagonist with an IC50 value of 0.11 µM in a kinetic fluorescence-based calcium mobilization assay. This study aims at exploring the structure–activity relationship (SAR) and improving the CXCR2 antagonistic potency of this pyrido[3,4-d]pyrimidine via systematic structural modifications of the substitution pattern. Almost all new analogues completely lacked the CXCR2 antagonism, the exception being a 6-furanyl-pyrido[3,4-d]pyrimidine analogue (compound 17b) that is endowed with similar antagonistic potency as the original hit. Full article
(This article belongs to the Special Issue Molecules in 2023)
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12 pages, 1892 KiB  
Communication
Low-Coordinate Mixed Ligand NacNac Complexes of Rare Earth Metals
by Svetlana V. Klementyeva, Taisiya S. Sukhikh, Pavel A. Abramov and Andrey I. Poddel’sky
Molecules 2023, 28(4), 1994; https://doi.org/10.3390/molecules28041994 - 20 Feb 2023
Cited by 2 | Viewed by 2405
Abstract
We report the synthesis and characterization of two types of new mixed-ligand rare earth complexes: tetracoordinate (NacNacMes)Ln(BIANdipp) (Ln = Dy (1), Er (2) and Y (3)) and pentacoordinate (NacNacMes)Ln(APdipp)(THF) [...] Read more.
We report the synthesis and characterization of two types of new mixed-ligand rare earth complexes: tetracoordinate (NacNacMes)Ln(BIANdipp) (Ln = Dy (1), Er (2) and Y (3)) and pentacoordinate (NacNacMes)Ln(APdipp)(THF) (Ln = Dy (4), Er (5) and Y (6)). The first three compounds were prepared by the reaction of [(BIANDipp)LnI] with potassium β-diketiminate. The salt metathesis of β-diketiminato-supported rare earth dichlorides (NacNacMes)LnCl2(THF)2 with sodium o-amidophenolate results in compounds 46. The crystal structures of complexes 16 were determined by single-crystal analysis. The combination of bulky monoanionic N-mesityl-substituted β-diketiminates with sterically hindered redox-active ligands led to the very low coordination numbers of rare earths and strong distortion of the chelate ligands. Full article
(This article belongs to the Special Issue Molecules in 2023)
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14 pages, 2744 KiB  
Article
Preparation and Evaluation of Thermosensitive Liposomes Encapsulating I-125-Labeled Doxorubicin Derivatives for Auger Electron Therapy
by Mohamed Elsaid Nasr Elghobary, Masayuki Munekane, Kenji Mishiro, Takeshi Fuchigami and Kazuma Ogawa
Molecules 2023, 28(4), 1864; https://doi.org/10.3390/molecules28041864 - 16 Feb 2023
Viewed by 1907
Abstract
Auger electrons (AEs) are very low-energy electrons emitted by radionuclides such as I-125 (125I). This energy is deposited across a small distance (<0.5 μm), resulting in high linear energy transfer that is potent for causing lethal damage to cancer cells. Thus, [...] Read more.
Auger electrons (AEs) are very low-energy electrons emitted by radionuclides such as I-125 (125I). This energy is deposited across a small distance (<0.5 μm), resulting in high linear energy transfer that is potent for causing lethal damage to cancer cells. Thus, AE-emitting radiotherapeutic agents have great potential for cancer treatment. In this study, thermosensitive liposomes (TSLs) encapsulating 125I-labeled doxorubicin (DOX) derivatives were developed for Auger electron therapy, targeting the DNA of cancer cells. A radioiodinated DOX derivative [125I]5 highly accumulated in the nuclei of cancer cells and showed potent cytotoxicity against Colon 26 cancer cells by AEs. Subsequently, [125I]5 was loaded into the TSLs with high encapsulation efficiency. Potent release of [125I]5 from TSLs was achieved with heating, whereas a decreased release was observed without heating. Furthermore, TSLs encapsulating [125I]5 showed a high uptake in the nuclei at 42 °C for 1 h. We supposed that [125I]5 was released by heating at 42 °C and accumulated in the nuclei in the cells. These results suggest that the combination of TSLs encapsulating [125I]5 and hyperthermia is an effective cancer therapy. Full article
(This article belongs to the Special Issue Molecules in 2023)
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Review

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19 pages, 5295 KiB  
Review
Application of Cyclodextrin for Cancer Immunotherapy
by Xiaojie Wei, Cui-Yun Yu and Hua Wei
Molecules 2023, 28(14), 5610; https://doi.org/10.3390/molecules28145610 - 24 Jul 2023
Cited by 7 | Viewed by 2199
Abstract
Tumor immunotherapy, compared with other treatment strategies, has the notable advantage of a long-term therapeutic effect for preventing metastasis and the recurrence of tumors, thus holding great potential for the future of advanced tumor therapy. However, due to the poor water solubility of [...] Read more.
Tumor immunotherapy, compared with other treatment strategies, has the notable advantage of a long-term therapeutic effect for preventing metastasis and the recurrence of tumors, thus holding great potential for the future of advanced tumor therapy. However, due to the poor water solubility of immune modulators and immune escape properties of tumor cells, the treatment efficiency of immunotherapy is usually significantly reduced. Cyclodextrin (CD) has been repeatedly highlighted to be probably one of the most investigated building units for cancer therapy due to its elegant integration of an internal hydrophobic hollow cavity and an external hydrophilic outer surface. The application of CD for immunotherapy provides new opportunities for overcoming the aforementioned obstacles. However, there are few published reviews, to our knowledge, summarizing the use of CD for cancer immunotherapy. For this purpose, this paper provides a comprehensive summary on the application of CD for immunotherapy with an emphasis on the role, function, and reported strategies of CD in mediating immunotherapy. This review summarizes the research progress made in using CD for tumor immunotherapy, which will facilitate the generation of various CD-based immunotherapeutic delivery systems with superior anticancer efficacy. Full article
(This article belongs to the Special Issue Molecules in 2023)
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