Molecules

14 pages, 2314 KiB

Open AccessArticle

Fused 1,2-Diboraoxazoles Based on closo-Decaborate Anion–Novel Members of Diboroheterocycle Class

by Vera V. Voinova, Nikita A. Selivanov, Ivan V. Plyushchenko, Mikhail F. Vokuev, Alexander Yu. Bykov, Ilya N. Klyukin, Alexander S. Novikov, Andrey P. Zhdanov, Mikhail S. Grigoriev, Igor A. Rodin, Konstantin Yu. Zhizhin and Nikolay T. Kuznetsov

Molecules 2021, 26(1), 248; https://doi.org/10.3390/molecules26010248 - 05 Jan 2021

Cited by 20 | Viewed by 5023

Abstract

The novel members of the 1,2-diboraoxazoles family have been obtained. In the present work, we have carried out the intramolecular ring-closure reaction of borylated iminols of general type [B₁₀H₉N=C(OH)R]⁻ (R = Me, Et, ⁿPr, ⁱPr, ^t [...] Read more.

The novel members of the 1,2-diboraoxazoles family have been obtained. In the present work, we have carried out the intramolecular ring-closure reaction of borylated iminols of general type [B₁₀H₉N=C(OH)R]⁻ (R = Me, Et, ⁿPr, ⁱPr, ^tBu, Ph, 4-Cl-Ph). This process is conducted in mild conditions with 83–87% yields. The solid-state structures of two salts of 1,2-diboraoxazoles were additionally investigated by X-ray crystallography. In addition, the phenomena of bonding interactions in the 1,2-diboraoxazole cycles have been theoretically studied by the Quantum Theory of Atoms in Molecules analysis. Several local and integral topological properties of the electron density involved in these interactions have been computed. Full article

(This article belongs to the Section Inorganic Chemistry)

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30 pages, 8409 KiB

Open AccessReview

Cyanobacteria as Natural Therapeutics and Pharmaceutical Potential: Role in Antitumor Activity and as Nanovectors

by Hina Qamar, Kashif Hussain, Aishwarya Soni, Anish Khan, Touseef Hussain and Benoît Chénais

Molecules 2021, 26(1), 247; https://doi.org/10.3390/molecules26010247 - 05 Jan 2021

Cited by 31 | Viewed by 6321

Abstract

Cyanobacteria (blue-green microalgae) are ubiquitous, Gram-negative photoautotrophic prokaryotes. They are considered as one of the most efficient sources of bioactive secondary metabolites. More than 50% of cyanobacteria are cultivated on commercial platforms to extract bioactive compounds, which have bene shown to possess anticancer [...] Read more.

Cyanobacteria (blue-green microalgae) are ubiquitous, Gram-negative photoautotrophic prokaryotes. They are considered as one of the most efficient sources of bioactive secondary metabolites. More than 50% of cyanobacteria are cultivated on commercial platforms to extract bioactive compounds, which have bene shown to possess anticancer activity. The chemically diverse natural compounds or their analogues induce cytotoxicity and potentially kill a variety of cancer cells via the induction of apoptosis, or altering the activation of cell signaling, involving especially the protein kinase-C family members, cell cycle arrest, mitochondrial dysfunctions and oxidative damage. These therapeutic properties enable their use in the pharma and healthcare sectors for the betterment of future generations. This review provides a baseline overview of the anti-cancerous cyanobacterial bioactive compounds, along with recently introduced nanomaterials that could be used for the development of new anticancer drugs to build a healthy future for mankind. Full article

(This article belongs to the Special Issue Algae and Microalgae and Their Bioactive Molecules for Human Health 2021)

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27 pages, 5136 KiB

Open AccessArticle

Optimization of Vacuum-Microwave-Assisted Extraction of Natural Polyphenols and Flavonoids from Raw Solid Waste of the Orange Juice Producing Industry at Industrial Scale

by Konstantinos Petrotos, Ioannis Giavasis, Konstantinos Gerasopoulos, Chrysanthi Mitsagga, Chryssoula Papaioannou and Paschalis Gkoutsidis

Molecules 2021, 26(1), 246; https://doi.org/10.3390/molecules26010246 - 05 Jan 2021

Cited by 20 | Viewed by 4149

Abstract

Orange pomace (OP) is a solid waste produced in bulk as a byproduct of the orange juice industry and accounts for approximately 50% of the quantity of the fruits processed into juice. In numerous literature references there is information about diverse uses of [...] Read more.

Orange pomace (OP) is a solid waste produced in bulk as a byproduct of the orange juice industry and accounts for approximately 50% of the quantity of the fruits processed into juice. In numerous literature references there is information about diverse uses of orange pomace for the production of high-added-value products including production of natural antioxidant and antimicrobial extracts rich in polyphenols and flavonoids which can substitute the hazardous chemical antioxidants/antimicrobials used in agro-food and cosmetics sectors. In this work and for the first time, according to our knowledge, the eco-friendly aqueous vacuum microwave assisted extraction of orange pomace was investigated and optimized at real industrial scale in order to produce aqueous antioxidant/antimicrobial extracts. A Response Surface Optimization methodology with a multipoint historical data experimental design was employed to obtain the optimal values of the process parameters in order to achieve the maximum rates of extraction of OP total polyphenols and/or total flavonoids for economically optimum production at industrial scale. The three factors used for the optimization were: (a) microwave power (b) water to raw pomace ratio and (c) extraction time. Moreover, the effectiveness and statistical soundness of the derived cubic polynomial predictive models were verified by ANOVA. Full article

(This article belongs to the Special Issue Advanced Production, Analysis and Applications of Natural Antimicrobials and Antioxidants)

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17 pages, 5498 KiB

Open AccessArticle

Antibacterial Activity and Mechanism of Linalool against Shewanella putrefaciens

by Fengyu Guo, Qiong Liang, Ming Zhang, Wenxue Chen, Haiming Chen, Yonghuan Yun, Qiuping Zhong and Weijun Chen

Molecules 2021, 26(1), 245; https://doi.org/10.3390/molecules26010245 - 05 Jan 2021

Cited by 62 | Viewed by 4867

Abstract

The demand for reduced chemical preservative usage is currently growing, and natural preservatives are being developed to protect seafood. With its excellent antibacterial properties, linalool has been utilized widely in industries. However, its antibacterial mechanisms remain poorly studied. Here, untargeted metabolomics was applied [...] Read more.

The demand for reduced chemical preservative usage is currently growing, and natural preservatives are being developed to protect seafood. With its excellent antibacterial properties, linalool has been utilized widely in industries. However, its antibacterial mechanisms remain poorly studied. Here, untargeted metabolomics was applied to explore the mechanism of Shewanella putrefaciens cells treated with linalool. Results showed that linalool exhibited remarkable antibacterial activity against S. putrefaciens, with 1.5 µL/mL minimum inhibitory concentration (MIC). The growth of S. putrefaciens was suppressed completely at 1/2 MIC and 1 MIC levels. Linalool treatment reduced the membrane potential (MP); caused the leakage of alkaline phosphatase (AKP); and released the DNA, RNA, and proteins of S. putrefaciens, thus destroying the cell structure and expelling the cytoplasmic content. A total of 170 differential metabolites (DMs) were screened using metabolomics analysis, among which 81 species were upregulated and 89 species were downregulated after linalool treatment. These DMs are closely related to the tricarboxylic acid (TCA) cycle, glycolysis, amino acid metabolism, pantothenate and CoA biosynthesis, aminoacyl-tRNA biosynthesis, and glycerophospholipid metabolism. In addition, linalool substantially affected the activity of key enzymes, such as succinate dehydrogenase (SDH), pyruvate kinase (PK), ATPase, and respiratory chain dehydrogenase. The results provided some insights into the antibacterial mechanism of linalool against S. putrefaciens and are important for the development and application of linalool in seafood preservation. Full article

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22 pages, 4365 KiB

Open AccessArticle

Oligosilanylated Silocanes

by Mohammad Aghazadeh Meshgi, Alexander Pöcheim, Judith Baumgartner, Viatcheslav V. Jouikov and Christoph Marschner

Molecules 2021, 26(1), 244; https://doi.org/10.3390/molecules26010244 - 05 Jan 2021

Cited by 4 | Viewed by 2463

Abstract

A number of mono- and dioligosilanylated silocanes were prepared. Compounds included silocanes with 1-methyl-1-tris(trimethylsilyl)silyl, 1,1-bis[tris(trimethylsilyl)silyl], and 1,1-bis[tris(trimethylsilyl)germyl] substitution pattern as well as two examples where the silocane silicon atom is part of a cyclosilane or oxacyclosilane ring. The mono-tris(trimethylsilyl)silylated compound could be converted [...] Read more.

A number of mono- and dioligosilanylated silocanes were prepared. Compounds included silocanes with 1-methyl-1-tris(trimethylsilyl)silyl, 1,1-bis[tris(trimethylsilyl)silyl], and 1,1-bis[tris(trimethylsilyl)germyl] substitution pattern as well as two examples where the silocane silicon atom is part of a cyclosilane or oxacyclosilane ring. The mono-tris(trimethylsilyl)silylated compound could be converted to the respective silocanylbis(trimethylsilyl)silanides by reaction with KO^tBu and in similar reactions the cyclosilanes were transformed to oligosilane-1,3-diides. However, the reaction of the 1,1-bis[tris(trimethylsilyl)silylated] silocane with two equivalents of KO^tBu leads to the replacement of one tris(trimethylsilyl)silyl unit with a tert-butoxy substituent followed by silanide formation via KO^tBu attack at one of the SiMe₃ units of remaining tris(trimethylsilyl)silyl group. For none of the silylated silocanes, signs of hypercoordinative interaction between the nitrogen and silicon silocane atoms were detected either in the solid state. by single crystal XRD analysis, nor in solution by ²⁹Si-NMR spectroscopy. This was further confirmed by cyclic voltammetry and a DFT study, which demonstrated that the N-Si distance in silocanes is not only dependent on the energy of a potential N-Si interaction, but also on steric factors and through-space interactions of the neighboring groups at Si and N, imposing the orientation of the p_z(N) orbital relative to the N-Si-X axis. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Organic Synthesis)

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12 pages, 19502 KiB

Open AccessReview

Interrogating Plant-Microbe Interactions with Chemical Tools: Click Chemistry Reagents for Metabolic Labeling and Activity-Based Probes

by Vivian S. Lin

Molecules 2021, 26(1), 243; https://doi.org/10.3390/molecules26010243 - 05 Jan 2021

Cited by 5 | Viewed by 4314

Abstract

Continued expansion of the chemical biology toolbox presents many new and diverse opportunities to interrogate the fundamental molecular mechanisms driving complex plant–microbe interactions. This review will examine metabolic labeling with click chemistry reagents and activity-based probes for investigating the impacts of plant-associated microbes [...] Read more.

Continued expansion of the chemical biology toolbox presents many new and diverse opportunities to interrogate the fundamental molecular mechanisms driving complex plant–microbe interactions. This review will examine metabolic labeling with click chemistry reagents and activity-based probes for investigating the impacts of plant-associated microbes on plant growth, metabolism, and immune responses. While the majority of the studies reviewed here used chemical biology approaches to examine the effects of pathogens on plants, chemical biology will also be invaluable in future efforts to investigate mutualistic associations between beneficial microbes and their plant hosts. Full article

(This article belongs to the Special Issue 25th Anniversary of Molecules—Recent Advances in Chemical Biology)

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22 pages, 4496 KiB

Open AccessArticle

Oleocanthal Quantification Using ¹H NMR Spectroscopy and Polyphenols HPLC Analysis of Olive Oil from the Bianchera/Belica Cultivar

by Martina Starec, Antonella Calabretti, Federico Berti and Cristina Forzato

Molecules 2021, 26(1), 242; https://doi.org/10.3390/molecules26010242 - 05 Jan 2021

Cited by 13 | Viewed by 3793

Abstract

The cultivar Bianchera is an autochthonous variety from the eastern part of northern Italy, but it is also cultivated in the Slovenian and Croatian peninsula of Istria where it is named Belica (Slovenia) and Bjelica (Croatia). The properties of oleocanthal, a natural anti-inflammatory [...] Read more.

The cultivar Bianchera is an autochthonous variety from the eastern part of northern Italy, but it is also cultivated in the Slovenian and Croatian peninsula of Istria where it is named Belica (Slovenia) and Bjelica (Croatia). The properties of oleocanthal, a natural anti-inflammatory ibuprofen-like compound found in commercial monocultivar extra virgin olive oils, were determined by means of both quantitative ¹H NMR (qNMR) and HPLC analyses, where qNMR was identified as a rapid and reliable method for determining the oleocanthal content. The total phenolic content (TPC) was determined by means of the Folin–Ciocalteau method and the major phenols present in the olive oils were also quantified by means of HPLC analyses. All these analyses confirmed that the cultivar Bianchera was very rich in polyphenols and satisfied the health claim provided by the EU Commission Regulation on the polyphenols content of olive oils and their beneficial effects on human health. Full article

(This article belongs to the Special Issue Plant Natural Products: Isolation, Identification and Biological Activity)

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45 pages, 6252 KiB

Open AccessReview

A Review of Composite Phase Change Materials Based on Porous Silica Nanomaterials for Latent Heat Storage Applications

by Raul-Augustin Mitran, Simona Ioniţǎ, Daniel Lincu, Daniela Berger and Cristian Matei

Molecules 2021, 26(1), 241; https://doi.org/10.3390/molecules26010241 - 05 Jan 2021

Cited by 53 | Viewed by 5784

Abstract

Phase change materials (PCMs) can store thermal energy as latent heat through phase transitions. PCMs using the solid-liquid phase transition offer high 100–300 J g⁻¹ enthalpy at constant temperature. However, pure compounds suffer from leakage, incongruent melting and crystallization, phase separation, and [...] Read more.

Phase change materials (PCMs) can store thermal energy as latent heat through phase transitions. PCMs using the solid-liquid phase transition offer high 100–300 J g⁻¹ enthalpy at constant temperature. However, pure compounds suffer from leakage, incongruent melting and crystallization, phase separation, and supercooling, which limit their heat storage capacity and reliability during multiple heating-cooling cycles. An appropriate approach to mitigating these drawbacks is the construction of composites as shape-stabilized phase change materials which retain their macroscopic solid shape even at temperatures above the melting point of the active heat storage compound. Shape-stabilized materials can be obtained by PCMs impregnation into porous matrices. Porous silica nanomaterials are promising matrices due to their high porosity and adsorption capacity, chemical and thermal stability and possibility of changing their structure through chemical synthesis. This review offers a first in-depth look at the various methods for obtaining composite PCMs using porous silica nanomaterials, their properties, and applications. The synthesis and properties of porous silica composites are presented based on the main classes of compounds which can act as heat storage materials (paraffins, fatty acids, polymers, small organic molecules, hydrated salts, molten salts and metals). The physico-chemical phenomena arising from the nanoconfinement of phase change materials into the silica pores are discussed from both theoretical and practical standpoints. The lessons learned so far in designing efficient composite PCMs using porous silica matrices are presented, as well as the future perspectives on improving the heat storage materials. Full article

(This article belongs to the Special Issue Porous Silica Nanomaterials for Energy Storage Applications)

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19 pages, 5405 KiB

Open AccessArticle

Improvement of Impact Strength of Polylactide Blends with a Thermoplastic Elastomer Compatibilized with Biobased Maleinized Linseed Oil for Applications in Rigid Packaging

by Ramon Tejada-Oliveros, Rafael Balart, Juan Ivorra-Martinez, Jaume Gomez-Caturla, Nestor Montanes and Luis Quiles-Carrillo

Molecules 2021, 26(1), 240; https://doi.org/10.3390/molecules26010240 - 05 Jan 2021

Cited by 18 | Viewed by 3156

Abstract

This research work reports the potential of maleinized linseed oil (MLO) as biobased compatibilizer in polylactide (PLA) and a thermoplastic elastomer, namely, polystyrene-b-(ethylene-ran-butylene)-b-styrene (SEBS) blends (PLA/SEBS), with improved impact strength for the packaging industry. The effects of [...] Read more.

This research work reports the potential of maleinized linseed oil (MLO) as biobased compatibilizer in polylactide (PLA) and a thermoplastic elastomer, namely, polystyrene-b-(ethylene-ran-butylene)-b-styrene (SEBS) blends (PLA/SEBS), with improved impact strength for the packaging industry. The effects of MLO are compared with a conventional polystyrene-b-poly(ethylene-ran-butylene)-b-polystyrene-graft-maleic anhydride terpolymer (SEBS-g-MA) since it is widely used in these blends. Uncompatibilized and compatibilized PLA/SEBS blends can be manufactured by extrusion and then shaped into standard samples for further characterization by mechanical, thermal, morphological, dynamical-mechanical, wetting and colour standard tests. The obtained results indicate that the uncompatibilized PLA/SEBS blend containing 20 wt.% SEBS gives improved toughness (4.8 kJ/m²) compared to neat PLA (1.3 kJ/m²). Nevertheless, the same blend compatibilized with MLO leads to an increase in impact strength up to 6.1 kJ/m², thus giving evidence of the potential of MLO to compete with other petroleum-derived compatibilizers to obtain tough PLA formulations. MLO also provides increased ductile properties, since neat PLA is a brittle polymer with an elongation at break of 7.4%, while its blend with 20 wt.% SEBS and MLO as compatibilizer offers an elongation at break of 50.2%, much higher than that provided by typical SEBS-g-MA compatibilizer (10.1%). MLO provides a slight decrease (about 3 °C lower) in the glass transition temperature (T_g) of the PLA-rich phase, thus showing some plasticization effects. Although MLO addition leads to some yellowing due to its intrinsic yellow colour, this can contribute to serving as a UV light barrier with interesting applications in the packaging industry. Therefore, MLO represents a cost-effective and sustainable solution to the use of conventional petroleum-derived compatibilizers. Full article

(This article belongs to the Special Issue PLA for Packaging Applications)

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12 pages, 2976 KiB

Open AccessArticle

Does Antibody Stabilize the Ligand Binding in GP120 of HIV-1 Envelope Protein? Evidence from MD Simulation

by Shalini Yadav, Vishnudatt Pandey, Rakesh Kumar Tiwari, Rajendra Prasad Ojha and Kshatresh Dutta Dubey

Molecules 2021, 26(1), 239; https://doi.org/10.3390/molecules26010239 - 05 Jan 2021

Cited by 1 | Viewed by 2473

Abstract

CD4-mimetic HIV-1 entry inhibitors are small sized molecules which imitate similar conformational flexibility, in gp120, to the CD4 receptor. However, the mechanism of the conformational flexibility instigated by these small sized inhibitors is little known. Likewise, the effect of the antibody on the [...] Read more.

CD4-mimetic HIV-1 entry inhibitors are small sized molecules which imitate similar conformational flexibility, in gp120, to the CD4 receptor. However, the mechanism of the conformational flexibility instigated by these small sized inhibitors is little known. Likewise, the effect of the antibody on the function of these inhibitors is also less studied. In this study, we present a thorough inspection of the mechanism of the conformational flexibility induced by a CD4-mimetic inhibitor, NBD-557, using Molecular Dynamics Simulations and free energy calculations. Our result shows the functional importance of Asn425 in substrate induced conformational dynamics in gp120. The MD simulations of Asn425Gly mutant provide a less dynamic gp120 in the presence of NBD-557 without incapacitating the binding enthalpy of NBD-557. The MD simulations of complexes with the antibody clearly show the enhanced affinity of NBD-557 due to the presence of the antibody, which is in good agreement with experimental Isothermal Titration Calorimetry results (Biochemistry2006, 45, 10973–10980). Full article

(This article belongs to the Special Issue Computational Answers to Biomolecular Recognition Problems)

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18 pages, 384 KiB

Open AccessReview

Thermal Stability of Amorphous Solid Dispersions

by Dijana Jelić

Molecules 2021, 26(1), 238; https://doi.org/10.3390/molecules26010238 - 05 Jan 2021

Cited by 22 | Viewed by 5480

Abstract

Amorphous solid dispersion drug delivery systems (ASD DDS) were proved to be efficient for the enhancement of solubility and bioavailability of poorly water-soluble drugs. One of the major keys for successful preparation of ASD is the selection of appropriate excipients, mostly polymers, which [...] Read more.

Amorphous solid dispersion drug delivery systems (ASD DDS) were proved to be efficient for the enhancement of solubility and bioavailability of poorly water-soluble drugs. One of the major keys for successful preparation of ASD is the selection of appropriate excipients, mostly polymers, which have a crucial role in improving drug solubility and its physical stability. Even though, excipients should be chemically inert, there is some evidence that polymers can affect the thermal stability of active pharmaceutical ingredients (API). The thermal stability of a drug is closely related to the shelf-life of pharmaceutical products and therefore it is a matter of high pharmaceutical relevance. An overview of thermal stability of amorphous solids is provided in this paper. Evaluation of thermal stability of amorphous solid dispersion is perceived from the physicochemical perspective, from a kinetic (motions) and thermodynamic (energy) point of view, focusing on activation energy and fragility, as well all other relevant parameters for ASD design, with a glance on computational kinetic analysis of solid-state decomposition. Full article

(This article belongs to the Special Issue Solid-State of Organic Pharmaceutical Compounds)

17 pages, 1377 KiB

Open AccessArticle

Insights into the Intraspecific Variability of the above and Belowground Emissions of Volatile Organic Compounds in Tomato

by Nafissa Dehimeche, Bruno Buatois, Nadia Bertin and Michael Staudt

Molecules 2021, 26(1), 237; https://doi.org/10.3390/molecules26010237 - 05 Jan 2021

Cited by 10 | Viewed by 3822

Abstract

The in-vivo monitoring of volatile organic compound (VOC) emissions is a potential non-invasive tool in plant protection, especially in greenhouse cultivation. We studied VOC production from above and belowground organs of the eight parents of the Multi-Parent Advanced Generation Intercross population (MAGIC) tomato [...] Read more.

The in-vivo monitoring of volatile organic compound (VOC) emissions is a potential non-invasive tool in plant protection, especially in greenhouse cultivation. We studied VOC production from above and belowground organs of the eight parents of the Multi-Parent Advanced Generation Intercross population (MAGIC) tomato population, which exhibits a high genetic variability, in order to obtain more insight into the variability of constitutive VOC emissions from tomato plants under stress-free conditions. Foliage emissions were composed of terpenes, the majority of which were also stored in the leaves. Foliage emissions were very low, partly light-dependent, and differed significantly among genotypes, both in quantity and quality. Soil with roots emitted VOCs at similar, though more variable, rates than foliage. Soil emissions were characterized by terpenes, oxygenated alkanes, and alkenes and phenolic compounds, only a few of which were found in root extracts at low concentrations. Correlation analyses revealed that several VOCs emitted from foliage or soil are jointly regulated and that above and belowground sources are partially interconnected. With respect to VOC monitoring in tomato crops, our results underline that genetic variability, light-dependent de-novo synthesis, and belowground sources are factors to be considered for successful use in crop monitoring. Full article

(This article belongs to the Special Issue Recent Discoveries and New Approaches to the Study of Plant Volatiles)

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12 pages, 3945 KiB

Open AccessArticle

Human Nails Permeation of an Antifungal Candidate Hydroalcoholic Extract from the Plant Sapindus saponaria L. Rich in Saponins

by Vanessa Mendes, Flávia Franco Veiga, Lidiane Vizioli de Castro-Hoshino, Francielle Sato, Mauro Luciano Baesso, Beatriz Vesco, Elton Cruz, Izabel Cristina Piloto Ferreira, Melyssa Negri and Terezinha Inez Estivalet Svidzinski

Molecules 2021, 26(1), 236; https://doi.org/10.3390/molecules26010236 - 05 Jan 2021

Cited by 3 | Viewed by 2518

Abstract

We evaluated a hydroalcoholic extract of Sapindus saponaria L. pericarps (ETHOSS), as a candidate to a topical antifungal medicine for onychomycosis. ETHOSS was produced by extracting the crushed fruits in ethanol. The saponin contents were identified and characterized by electrospray ionization mass spectrometry. [...] Read more.

We evaluated a hydroalcoholic extract of Sapindus saponaria L. pericarps (ETHOSS), as a candidate to a topical antifungal medicine for onychomycosis. ETHOSS was produced by extracting the crushed fruits in ethanol. The saponin contents were identified and characterized by electrospray ionization mass spectrometry. We measured the in vitro antifungal activity against three dermatophyte fungi, isolated from onychomycosis: Trichophyton rubrum, T. mentagrophytes, and T. interdigitale, using broth microdilution tests. The minimum fungicide concentration of ETHOSS ranged from 195.31 to 781.25 μg/mL. The cytotoxicity of the crude extract was tested on the HeLa cell line, and its ability to permeate into healthy human nails by photoacoustic spectroscopy and Fourier transformation infrared spectrometer (FTIR) spectroscopy by attenuated total reflection. Besides its strong antifungal activity, ETHOSS showed low cytotoxicity in human cells. It was able to permeate and reach the full thickness of the nail in one hour, without the aid of facilitating vehicles, and remained there for at least 24 h. These results suggest that ETHOSS has great potential for treating onychomycosis. Full article

(This article belongs to the Special Issue Biological Activity of Plant Compounds and Extracts)

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15 pages, 4013 KiB

Open AccessFeature PaperArticle

Classification of Congeneric and QSAR of Homologous Antileukemic S–Alkylcysteine Ketones

by Gloria Castellano, Adela León and Francisco Torrens

Molecules 2021, 26(1), 235; https://doi.org/10.3390/molecules26010235 - 05 Jan 2021

Viewed by 2026

Abstract

Based on a set of six vector properties, the partial correlation diagram is calculated for a set of 28 S-alkylcysteine diazomethyl- and chloromethyl-ketone derivatives. Those with the greatest antileukemic activity in the same class correspond to high partial correlations. A periodic classification [...] Read more.

Based on a set of six vector properties, the partial correlation diagram is calculated for a set of 28 S-alkylcysteine diazomethyl- and chloromethyl-ketone derivatives. Those with the greatest antileukemic activity in the same class correspond to high partial correlations. A periodic classification is performed based on information entropy. The first four characteristics denote the group, and the last two indicate the period. Compounds in the same period and, especially, group present similar properties. The most active substances are situated at the bottom right. Nine classes are distinguished. The principal component analysis of the homologous compounds shows five subclasses included in the periodic classification. Linear fits of both antileukemic activities and stability are good. They are in agreement with the principal component analysis. The variables that appear in the models are those that show positive loading in the principal component analysis. The most important properties to explain the antileukemic activities (50% inhibitory concentration Molt-3 T-lineage acute lymphoblastic leukemia minus the logarithm of 50% inhibitory concentration Nalm-6 B-lineage acute lymphoblastic leukemia and stability k) are ACD logD, surface tension and number of violations of Lipinski’s rule of five. After leave-m-out cross-validation, the most predictive model for cysteine diazomethyl- and chloromethyl-ketone derivatives is provided. Full article

(This article belongs to the Special Issue QSAR and QSPR: Recent Developments and Applications II)

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20 pages, 4244 KiB

Open AccessFeature PaperArticle

Evaluation of Changes in Protein Quality of High-Pressure Treated Aqueous Aquafaba

by Fatemah B. Alsalman and Hosahalli S. Ramaswamy

Molecules 2021, 26(1), 234; https://doi.org/10.3390/molecules26010234 - 05 Jan 2021

Cited by 19 | Viewed by 3679

Abstract

Chickpea cooking water (CCW), known as aquafaba, has potential as a replacement for egg whites due to its emulsion and foaming properties which come from the proteins and starch that leach out from chickpeas into the cooking water. High pressure (HP) processing has [...] Read more.

Chickpea cooking water (CCW), known as aquafaba, has potential as a replacement for egg whites due to its emulsion and foaming properties which come from the proteins and starch that leach out from chickpeas into the cooking water. High pressure (HP) processing has the ability to modify the functional characteristics of proteins. It is hypothesized that HP processing could favorably affect the functional properties of CCW proteins by influencing their structure. The objective of this study to evaluate the effect of HP treatment on the associated secondary structure, emulsion properties and thermal characteristics of CCW proteins. A central composite rotatable design is used with pressure level (227–573 MPa) and treatment time (6–24 min) as HP variables, and concentration of freeze dried CCW aquafaba powder (11–29%) as product variable, and compared to untreated CCW powder. HP improves aquafaba emulsion properties compared to control sample. HP reduces protein aggregates by 33.3%, while β-sheets decreases by 4.2–87.6% in which both correlated to increasing protein digestibility. α-helices drops by 50%. It affects the intensity of some HP treated samples, but not the trend of bands in most of them. HP treatment decreases T_d and enthalpy because of increasing the degree of denaturation. Full article

(This article belongs to the Special Issue Advances in High Pressure Processing on Foods)

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9 pages, 856 KiB

Open AccessArticle

Strawberry Decreases Intraluminal and Intestinal Wall Hydrolysis of Testosterone Undecanoate

by Atheer Zgair, Yousaf Dawood, Suhaib M. Ibrahem, Jong Bong Lee, Wanshan Feng, Peter M. Fischer and Pavel Gershkovich

Molecules 2021, 26(1), 233; https://doi.org/10.3390/molecules26010233 - 05 Jan 2021

Cited by 1 | Viewed by 2758

Abstract

Male hypogonadism is often treated by testosterone (T) replacement therapy such as oral administration of the ester prodrug, testosterone undecanoate (TU). However, the systemic exposure to T following oral TU is very low due to esterase-mediated metabolism, particularly in the small intestine. The [...] Read more.

Male hypogonadism is often treated by testosterone (T) replacement therapy such as oral administration of the ester prodrug, testosterone undecanoate (TU). However, the systemic exposure to T following oral TU is very low due to esterase-mediated metabolism, particularly in the small intestine. The aim of this work was to examine the esterase-inhibitory effect of natural fruit extract of strawberry (STW) on the intestinal degradation of TU as a potential approach to increasing the oral bioavailability of T. Herein, the hydrolysis of TU was assessed in fasted state simulated intestinal fluid with added esterase activity (FaSSIF/ES) and Caco-2 cell homogenates in the presence of STW extract. It is noteworthy that STW substantially inhibited the degradation of TU in FaSSIF/ES and Caco-2 cell homogenates at concentrations that could be achieved following oral consumption of less than one serving of STW fruit. This can significantly increase the fraction of unhydrolyzed TU in the intestinal lumen as well as in enterocytes. In addition, it was demonstrated that TU has high intestinal lymphatic transport potential as the association of TU with plasma-derived human chylomicrons was in the range of 84%. Therefore, oral co-administration of TU with STW could potentially increase the intestinal stability of TU and consequently the contribution of lymphatically delivered TU to the systemic exposure of T in vivo. Full article

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17 pages, 1065 KiB

Open AccessArticle

Evaluation of the Storage Conditions and Type of Cork Stopper on the Quality of Bottled White Wines

by María Consuelo Díaz-Maroto, Manuel López Viñas, Lourdes Marchante, María Elena Alañón, Ignacio Javier Díaz-Maroto and María Soledad Pérez-Coello

Molecules 2021, 26(1), 232; https://doi.org/10.3390/molecules26010232 - 05 Jan 2021

Cited by 9 | Viewed by 2734

Abstract

The effects of different storage conditions, light exposure, temperature and different commercially available cork stoppers on the phenolic, volatile and sensorial profile of Verdejo wines were studied. Two natural corks of different visual quality and a microgranulated cork stopper were investigated over one [...] Read more.

The effects of different storage conditions, light exposure, temperature and different commercially available cork stoppers on the phenolic, volatile and sensorial profile of Verdejo wines were studied. Two natural corks of different visual quality and a microgranulated cork stopper were investigated over one year at two different storage conditions. One simulating light exposure and temperature in retail outlets and the other simulating optimal cellar conditions (darkness and 12 °C). The wines stored under commercial conditions showed greater losses of total and free SO₂ and higher levels of brown-yellowish tones, related to the oxidation of flavan-3-ols. Although these wines underwent a decrease in the total content of stilbenes, a significant increase in trans-piceid was observed. In addition, these wines suffered important changes in their volatile and sensory profile. Volatile compounds with fruity and floral aromas decreased significantly, while volatile compounds related to aged-type characters, as linalool oxides, vitispirane, TDN or furan derivatives increased. Wines stored in darkness at 12 °C underwent minor changes and their sensory profiles were similar to wine before bottling. The high-quality natural corks and microgranulated corks better preserved the quality of the white wines from a sensory point of view. These results showed that temperature and light exposure conditions (diffuse white LEDs and 24 ± 2 °C) in retail outlets considerably decrease the quality of bottled white wines and, consequently, their shelf life, due to the premature development of aged-type characters. Full article

(This article belongs to the Special Issue Alcoholic Beverages Aging Technologies)

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14 pages, 2603 KiB

Open AccessCommunication

When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D₃

by Mengchen Liao, Yang Chen and Michael A. Brook

Molecules 2021, 26(1), 231; https://doi.org/10.3390/molecules26010231 - 05 Jan 2021

Cited by 3 | Viewed by 2185

Abstract

A simple, mild and efficient method to prepare HSi- or HOSi-telechelic, high-molecular-weight polydimethylsiloxane polymers (to 41,600 g·mol⁻¹) using the one-shot hydrolysis of M^HM^H is reported; titration of the water allowed for higher molecular weights (to 153,900 g·mol⁻¹ [...] Read more.

A simple, mild and efficient method to prepare HSi- or HOSi-telechelic, high-molecular-weight polydimethylsiloxane polymers (to 41,600 g·mol⁻¹) using the one-shot hydrolysis of M^HM^H is reported; titration of the water allowed for higher molecular weights (to 153,900 g·mol⁻¹). The “living” character of the chain extension processes was demonstrated by adding a small portion of M^HM^H and B(C₆F₅)₃ (BCF) to a first formed polymer, which led to a ~2-fold, second growth in molecular weight. The heterogeneous reaction reached completion in less than 30 min, much less in some cases, regardless of whether it was performed neat or 50 wt% in dry toluene; homogeneous reactions in toluene were much slower. The process does not involve traditional redistribution, as judged by the low quantities (<3%) of D₄ produced. However, it is not possible to avoid Chojnowski metathesis from M^HDDM^H giving D₃, which occurs competitively with chain extension. Full article

(This article belongs to the Special Issue Various Aspects of Silicon Polymer Chemistry: A Themed Issue in Honor of Professor Julian Chojnowski on the Occasion of His 85th Birthday)

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13 pages, 1316 KiB

Open AccessArticle

Application of HPLC-DAD for In Vitro Investigation of Acetylcholinesterase Inhibition Activity of Selected Isoquinoline Alkaloids from Sanguinaria canadensis Extracts

by Tomasz Tuzimski and Anna Petruczynik

Molecules 2021, 26(1), 230; https://doi.org/10.3390/molecules26010230 - 05 Jan 2021

Cited by 8 | Viewed by 3040

Abstract

Isoquinoline alkaloids may have a wide range of pharmacological activities. Some of them have acetylcholinesterase activity inhibition. Nowadays, neurodegenerative disorders such as Alzheimer’s disease have become a serious public health problem. Searching for new effective compounds with inhibited acetylcholinesterase activity is one of [...] Read more.

Isoquinoline alkaloids may have a wide range of pharmacological activities. Some of them have acetylcholinesterase activity inhibition. Nowadays, neurodegenerative disorders such as Alzheimer’s disease have become a serious public health problem. Searching for new effective compounds with inhibited acetylcholinesterase activity is one of the most significant challenges of modern scientific research. The aim of this study was the in vitro investigation of acetylcholinesterase activity inhibition of extracts obtained from Sanguinaria canadensis collected before, during and after flowering. The acetylcholinesterase activity inhibition of these extracts has not been previously tested. The aim was also to quantify selected alkaloids in the investigated extracts by high performance liquid chromatography (HPLC). The analyses of alkaloid content were performed using HPLC in reversed phase (RP) mode using Polar RP column and mobile phase containing acetonitrile, water and ionic liquid (IL). The acetylcholinesterase activity inhibition of the tested plant extracts and respective alkaloid standards were examined using high performance liquid chromatography with diode-array detector (HPLC-DAD) for the quantification of 5-thio-2-nitro-benzoic acid, which is the product of the reaction between the thiocholine (product of the hydrolysis of acetylthiocholine reaction) with Ellman reagent. The application of the HPLC method allowed for elimination of absorption of interfering components, for example, alkaloids such as sanguinarine and berberine. It is revealed that the HPLC method can be successfully used for the evaluation of the acetylcholinesterase inhibitory activity in samples such as plant extracts, especially those containing colored components adsorbing at wavelength in the range 405–412 nm. The acetylcholinesterase inhibition activity synergy of pairs of alkaloid standards and mixture of all investigated alkaloids was also determined. Most investigated alkaloids and all Sanguinaria canadensis extracts exhibited very high acetylcholinesterase activity inhibition. IC₅₀ values obtained for alkaloid standards were from 0.36 for berberine to 23.13 µg/mL for protopine and from 61.24 to 89.14 µg/mL for Sanguinaria canadensis extracts. Our investigations demonstrated that these plant extracts can be recommended for further in vivo experiments to confirm their acetylcholinesterase activity inhibition. Full article

(This article belongs to the Special Issue Theme Issue Honoring Professor Dr. Bogusław Buszewski on His 70th Birthday:"Separation Sciences & Related Techniques")

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15 pages, 1609 KiB

Open AccessReview

Anti-Inflammatory Action and Mechanisms of Resveratrol

by Tiantian Meng, Dingfu Xiao, Arowolo Muhammed, Juying Deng, Liang Chen and Jianhua He

Molecules 2021, 26(1), 229; https://doi.org/10.3390/molecules26010229 - 05 Jan 2021

Cited by 245 | Viewed by 15142

Abstract

Resveratrol (3,4′,5-trihy- droxystilbene), a natural phytoalexin polyphenol, exhibits anti-oxidant, anti-inflammatory, and anti-carcinogenic properties. This phytoalexin is well-absorbed and rapidly and extensively metabolized in the body. Inflammation is an adaptive response, which could be triggered by various danger signals, such as invasion by microorganisms [...] Read more.

Resveratrol (3,4′,5-trihy- droxystilbene), a natural phytoalexin polyphenol, exhibits anti-oxidant, anti-inflammatory, and anti-carcinogenic properties. This phytoalexin is well-absorbed and rapidly and extensively metabolized in the body. Inflammation is an adaptive response, which could be triggered by various danger signals, such as invasion by microorganisms or tissue injury. In this review, the anti-inflammatory activity and the mechanism of resveratrol modulates the inflammatory response are examined. Multiple experimental studies that illustrate regulatory mechanisms and the immunomodulatory function of resveratrol both in vivo and in vitro. The data acquired from those studies are discussed. Full article

(This article belongs to the Special Issue Nutraceuticals in Immune Function)

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21 pages, 6265 KiB

Open AccessArticle

Evaluation of Wound-Healing and Antioxidant Effects of Marantodes pumilum (Blume) Kuntze in an Excision Wound Model

by Shihab Uddin Ahmad, Nor-Ashila Binti Aladdin, Jamia Azdina Jamal, Ahmad Nazrun Shuid and Isa Naina Mohamed

Molecules 2021, 26(1), 228; https://doi.org/10.3390/molecules26010228 - 05 Jan 2021

Cited by 20 | Viewed by 4505

Abstract

Marantodes pumilum (MP) is a great source of herbal medicine used traditionally by both men and women for various purposes. MP may have potential wound-healing effects due to its diverse biological properties. An extensive study was conducted in a normal male rat model [...] Read more.

Marantodes pumilum (MP) is a great source of herbal medicine used traditionally by both men and women for various purposes. MP may have potential wound-healing effects due to its diverse biological properties. An extensive study was conducted in a normal male rat model for determining the effects of MP var. pumila (MPvp) and var. alata (MPva) on the wound healing process. Here, 126 male Sprague-Dawley rats were divided randomly into seven groups as follows: sham-operated (SH), vehicle dressing (VD), flavine dressing (FD), MPvp leaves (PL), MPvp roots (PR), MPva leaves (AL), and MPva roots (AR). The parameters studied were the percentage of wound contraction, histomorphology study by hematoxylin and eosin (H&E), Masson–Goldner trichrome (MGT), and immunohistochemistry (IHC) staining. In addition, the levels of enzymatic antioxidants and malondialdehyde were also measured in the wound tissue homogenates. Wounds treated with extracts (PL, PR, AL, and AR) showed significantly faster healing (p < 0.05) compared to untreated and control groups (SH, VD, and FD). Histological analysis among MP-treated groups revealed better re-epithelialization, higher collagen deposition, enhanced fibronectin content and fibroblast cells, and higher fiber transformation from collagen-III to collagen-I, accompanied with a significant surge in enzymatic antioxidant activities and a decline in lipid peroxidation. MP has antioxidant effects that may enhance wound healing in the rat model. Full article

(This article belongs to the Special Issue Natural Products and Skin Diseases)

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11 pages, 1231 KiB

Open AccessArticle

Calcium-Dependent Translocation of S100B Is Facilitated by Neurocalcin Delta

by Jingyi Zhang, Anuradha Krishnan, Hao Wu and Venkat Venkataraman

Molecules 2021, 26(1), 227; https://doi.org/10.3390/molecules26010227 - 05 Jan 2021

Cited by 1 | Viewed by 2434

Abstract

S100B is a calcium-binding protein that governs calcium-mediated responses in a variety of cells—especially neuronal and glial cells. It is also extensively investigated as a potential biomarker for several disease conditions, especially neurodegenerative ones. In order to establish S100B as a viable pharmaceutical [...] Read more.

S100B is a calcium-binding protein that governs calcium-mediated responses in a variety of cells—especially neuronal and glial cells. It is also extensively investigated as a potential biomarker for several disease conditions, especially neurodegenerative ones. In order to establish S100B as a viable pharmaceutical target, it is critical to understand its mechanistic role in signaling pathways and its interacting partners. In this report, we provide evidence to support a calcium-regulated interaction between S100B and the neuronal calcium sensor protein, neurocalcin delta both in vitro and in living cells. Membrane overlay assays were used to test the interaction between purified proteins in vitro and bimolecular fluorescence complementation assays, for interactions in living cells. Added calcium is essential for interaction in vitro; however, in living cells, calcium elevation causes translocation of the NCALD-S100B complex to the membrane-rich, perinuclear trans-Golgi network in COS7 cells, suggesting that the response is independent of specialized structures/molecules found in neuronal/glial cells. Similar results are also observed with hippocalcin, a closely related paralog; however, the interaction appears less robust in vitro. The N-terminal region of NCALD and HPCA appear to be critical for interaction with S100B based on in vitro experiments. The possible physiological significance of this interaction is discussed. Full article

(This article belongs to the Special Issue Implication of S100 Proteins in Inflammation and Cancer: S100 Proteins as Potential Pharmacological Targets)

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10 pages, 2081 KiB

Open AccessArticle

Different Reactivity of Raw Starch from Diverse Potato Genotypes

by Vadim Khlestkin and Ilia Eltsov

Molecules 2021, 26(1), 226; https://doi.org/10.3390/molecules26010226 - 05 Jan 2021

Cited by 5 | Viewed by 2258

Abstract

Potato starch is one of the most important renewable sources for industrial manufacturing of organic compounds. Currently, it is produced from mixed potato varieties that often are harvested from different fields. Meanwhile, tuber starches of various potato breeds differ in their crystallinity, granule [...] Read more.

Potato starch is one of the most important renewable sources for industrial manufacturing of organic compounds. Currently, it is produced from mixed potato varieties that often are harvested from different fields. Meanwhile, tuber starches of various potato breeds differ in their crystallinity, granule morphology, and other physical and chemical parameters. We studied the reactions of raw potato starches of different origins to chemical and biochemical reactions typically used for industrial starch modification. The results clearly demonstrate that there is a significant difference in the reactivity of the starches of different potato genotypes. While the main products of the transformations are the same, their preparative yields differ significantly. Thus, tuber starch of certain potato varieties may be more suitable for specific industrial purposes. Starch reactivity may potentially be a phenotypical trait for potato breeding to obtain potato starches for various industrial applications. Full article

(This article belongs to the Special Issue Modification of Starch – from Structure, through Functionalization to Special Applications)

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15 pages, 3669 KiB

Open AccessArticle

A Combined Experimental and Computational Study of Chrysanthemin as a Pigment for Dye-Sensitized Solar Cells

by Atoumane Ndiaye, Alle Dioum, Corneliu I. Oprea, Anca Dumbrava, Jeanina Lungu, Adrian Georgescu, Florin Moscalu, Mihai A. Gîrţu, Aboubaker Chedikh Beye and Issakha Youm

Molecules 2021, 26(1), 225; https://doi.org/10.3390/molecules26010225 - 04 Jan 2021

Cited by 6 | Viewed by 3147

Abstract

The theoretical study of chrysanthemin (cyanidin 3-glucoside) as a pigment for TiO₂-based dye-sensitized solar cells (DSSCs) was performed with the GAUSSSIAN 09 simulation. The electronic spectra of neutral and anionic chrysanthemin molecules were calculated by density functional theory with B3LYP functional [...] Read more.

The theoretical study of chrysanthemin (cyanidin 3-glucoside) as a pigment for TiO₂-based dye-sensitized solar cells (DSSCs) was performed with the GAUSSSIAN 09 simulation. The electronic spectra of neutral and anionic chrysanthemin molecules were calculated by density functional theory with B3LYP functional and DGDZVP basis set. A better energy level alignment was found for partially deprotonated molecules of chrysanthemin, with the excited photoelectron having enough energy in order to be transferred to the conduction band of TiO₂ semiconductor in DSSCs. In addition, we used the raw aqueous extracts of roselle (Hibiscus sabdariffa) calyces as the source of chrysanthemin and the extracts with various pH values were tested in DSSCs. The extracts and photosensitized semiconductor layers were characterized by UV-Vis spectroscopy, and DSSCs based on raw extracts were characterized by current density-voltage measurements. Full article

(This article belongs to the Special Issue Recent Advances in Dye-Sensitized Solar Cells)

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21 pages, 1997 KiB

Open AccessArticle

Efficient Separation of Phytochemicals from Muehlenbeckia volcanica (Benth.) Endl. by Polarity-Stepwise Elution Counter-Current Chromatography and Their Antioxidant, Antiglycation, and Aldose Reductase Inhibition Potentials

by Guang-Lei Zuo, Hyun Yong Kim, Yanymee N. Guillen Quispe, Zhi-Qiang Wang, Seung Hwan Hwang, Kyong-Oh Shin and Soon Sung Lim

Molecules 2021, 26(1), 224; https://doi.org/10.3390/molecules26010224 - 04 Jan 2021

Cited by 7 | Viewed by 3417

Abstract

Muehlenbeckia volcanica (Benth.) Endl. (M. volcanica), native to South America, is a traditional Peruvian medicinal plant that has multi-therapeutic properties; however, no phytochemicals have been identified from it yet. In this study, a five-step polarity-stepwise elution counter-current chromatography (CCC) was developed [...] Read more.

Muehlenbeckia volcanica (Benth.) Endl. (M. volcanica), native to South America, is a traditional Peruvian medicinal plant that has multi-therapeutic properties; however, no phytochemicals have been identified from it yet. In this study, a five-step polarity-stepwise elution counter-current chromatography (CCC) was developed using methanol/water (1:5, v/v) as the stationary phase and different ratios of n-hexane, ethyl acetate, and n-butanol as mobile phases to separate the compounds from the 70% methanol extract of M. volcanica, by which six compounds with a wide range of polarities were separated in a single run of CCC and were identified as gallic acid, protocatechuic acid, 4,4′-dihydroxy-3,3′-imino-di-benzoic acid, rutin, quercitrin, and quercetin. Then, two compounds from the fractions of stepwise elution CCC were separated using conventional high-speed CCC, pH-zone-refining CCC, and preparative high-performance liquid chromatography, and identified as shikimic acid and miquelianin. These compounds are reported from M. volcanica for the first time. Notably, except for shikimic acid, all other compounds showed anti-diabetic potentials via antioxidant, antiglycation, and aldose reductase inhibition. The results suggest that the polarity-stepwise elution CCC can be used to efficiently separate or fractionate compounds with a wide range of polarities from natural products. Moreover, M. volcanica and its bioactive compounds are potent anti-diabetic agents. Full article

(This article belongs to the Section Natural Products Chemistry)

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14 pages, 3426 KiB

Open AccessArticle

The Maillard Reaction as Source of Meat Flavor Compounds in Dry Cured Meat Model Systems under Mild Temperature Conditions

by Lei Li, Carmela Belloch and Mónica Flores

Molecules 2021, 26(1), 223; https://doi.org/10.3390/molecules26010223 - 04 Jan 2021

Cited by 18 | Viewed by 4502

Abstract

Flavor is amongst the major personal satisfaction indicators for meat products. The aroma of dry cured meat products is generated under specific conditions such as long ripening periods and mild temperatures. In these conditions, the contribution of Maillard reactions to the generation of [...] Read more.

Flavor is amongst the major personal satisfaction indicators for meat products. The aroma of dry cured meat products is generated under specific conditions such as long ripening periods and mild temperatures. In these conditions, the contribution of Maillard reactions to the generation of the dry cured flavor is unknown. The main purpose of this study was to examine mild curing conditions such as temperature, pH and a_w for the generation of volatile compounds responsible for the cured meat aroma in model systems simulating dry fermented sausages. The different conditions were tested in model systems resembling dry fermented sausages at different stages of production. Three conditions of model system, labeled initial (I), 1st drying (1D) and 2nd drying (2D) and containing different concentrations of amino acid and curing additives, as well as different pH and a_w values, were incubated at different temperatures. Changes in the profile of the volatile compounds were investigated by solid phase microextraction and gas chromatography mass spectrometry (SPME-GS-MS) as well as the amino acid content. Seventeen volatile compounds were identified and quantified in the model systems. A significant production of branched chain volatile compounds, sulfur, furans, pyrazines and heterocyclic volatile compounds were detected in the model systems. At the drying stages, temperature was the main factor affecting volatile production, followed by amino acid concentration and a_w. This research demonstrates that at the mild curing conditions used to produce dry cured meat product volatile compounds are generated via the Maillard reaction from free amino acids. Moreover, in these conditions a_w plays an important role promoting formation of flavor compounds. Full article

(This article belongs to the Special Issue Maillard Reaction: Formation of Flavour Compounds)

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11 pages, 1762 KiB

Open AccessCommunication

Synthesis, Structural Characterization, and Optical Properties of Benzene-Fused Tetracyclic and Pentacyclic Stiboles

by Mio Matsumura, Yuki Matsuhashi, Masato Kawakubo, Tadashi Hyodo, Yuki Murata, Masatoshi Kawahata, Kentaro Yamaguchi and Shuji Yasuike

Molecules 2021, 26(1), 222; https://doi.org/10.3390/molecules26010222 - 04 Jan 2021

Cited by 9 | Viewed by 3147

Abstract

The expectation that antimony (Sb) compounds should display phosphorescence emissions based on the “heavy element effect” prompted our interest in the introduction of antimony to a biaryl as the bridging atom in a fused heterole system. Herein, the synthesis, molecular structures, and optical [...] Read more.

The expectation that antimony (Sb) compounds should display phosphorescence emissions based on the “heavy element effect” prompted our interest in the introduction of antimony to a biaryl as the bridging atom in a fused heterole system. Herein, the synthesis, molecular structures, and optical properties of novel benzene-fused heteroacenes containing antimony or arsenic atoms are described. The stiboles and arsole were prepared by the condensation of dibromo(phenyl)stibane or dichloro(phenyl)arsine with dilithium intermediates derived from the corresponding dibromo compounds. Nuclear magnetic resonance (NMR) spectroscopy and X-ray crystal analysis revealed that the linear pentacyclic stibole was highly symmetric in both the solution and crystal states. In contrast, the curved pentacyclic stibole adopted a helical structure in solution, and surprisingly, only M helical molecules were crystallized from the racemate. All synthesized compounds produced very weak or no emissions at room temperature or in the solid state. In contrast, the linear penta- and tetracyclic stiboles exhibited clear phosphorescence emissions in the CHCl₃ frozen matrix at 77 K under aerobic conditions. Full article

(This article belongs to the Special Issue Modern Trends in Heterocyclic Chemistry)

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17 pages, 3692 KiB

Open AccessArticle

Enantioseparation of 5,5′-Dibromo-2,2′-dichloro-3-selanyl-4,4′-bipyridines on Polysaccharide-Based Chiral Stationary Phases: Exploring Chalcogen Bonds in Liquid-Phase Chromatography

by Paola Peluso, Alessandro Dessì, Roberto Dallocchio, Barbara Sechi, Carlo Gatti, Bezhan Chankvetadze, Victor Mamane, Robin Weiss, Patrick Pale, Emmanuel Aubert and Sergio Cossu

Molecules 2021, 26(1), 221; https://doi.org/10.3390/molecules26010221 - 04 Jan 2021

Cited by 16 | Viewed by 2603

Abstract

The chalcogen bond (ChB) is a noncovalent interaction based on electrophilic features of regions of electron charge density depletion (σ-holes) located on bound atoms of group VI. The σ-holes of sulfur and heavy chalcogen atoms (Se, Te) (donors) can interact through their positive [...] Read more.

The chalcogen bond (ChB) is a noncovalent interaction based on electrophilic features of regions of electron charge density depletion (σ-holes) located on bound atoms of group VI. The σ-holes of sulfur and heavy chalcogen atoms (Se, Te) (donors) can interact through their positive electrostatic potential (V) with nucleophilic partners such as lone pairs, π-clouds, and anions (acceptors). In the last few years, promising applications of ChBs in catalysis, crystal engineering, molecular biology, and supramolecular chemistry have been reported. Recently, we explored the high-performance liquid chromatography (HPLC) enantioseparation of fluorinated 3-arylthio-4,4′-bipyridines containing sulfur atoms as ChB donors. Following this study, herein we describe the comparative enantioseparation of three 5,5′-dibromo-2,2′-dichloro-3-selanyl-4,4′-bipyridines on polysaccharide-based chiral stationary phases (CSPs) aiming to understand function and potentialities of selenium σ-holes in the enantiodiscrimination process. The impact of the chalcogen substituent on enantioseparation was explored by using sulfur and non-chalcogen derivatives as reference substances for comparison. Our investigation also focused on the function of the perfluorinated aromatic ring as a π-hole donor recognition site. Thermodynamic quantities associated with the enantioseparation were derived from van’t Hoff plots and local electron charge density of specific molecular regions of the interacting partners were inspected in terms of calculated V. On this basis, by correlating theoretical data and experimental results, the participation of ChBs and π-hole bonds in the enantiodiscrimination process was reasonably confirmed. Full article

(This article belongs to the Special Issue Chiral Stationary Phases for Enantioseparations: Fundamentals, Preparation, Methods, Applications and Chiral Recognition Mechanisms)

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13 pages, 3326 KiB

Open AccessArticle

Kinetic Study on Alpha-Form Crystallization of Mixed-Acid Triacylglycerols POP, PPO, and Their Mixture

by Ken Taguchi, Akihiko Toda, Hironori Hondoh, Satoru Ueno and Kiyotaka Sato

Molecules 2021, 26(1), 220; https://doi.org/10.3390/molecules26010220 - 04 Jan 2021

Cited by 6 | Viewed by 2587

Abstract

The crystallization behavior of the metastable

α

form of triacylglycerols (TAGs) plays a critical role as a precursor for the crystallization of more stable

β^{'}

and

β

forms for various applications in food and pharmaceutical products. However, precise analysis of the crystallization [...] Read more.

The crystallization behavior of the metastable

α

form of triacylglycerols (TAGs) plays a critical role as a precursor for the crystallization of more stable

β^{'}

and

β

forms for various applications in food and pharmaceutical products. However, precise analysis of the crystallization kinetics of

α

has not been performed, likely due to its rapid and complex behavior. This paper presents the observation results of the initial stages of the isothermal crystallization kinetics of

α

forms of 1,3-dipalmitoyl-2-oleoyl-glycerol (POP), 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (rac-PPO), and molecular compound (MC) crystals of a POP/rac-PPO (1/1) mixture (MC

_{POP / PPO}

) using synchrotron radiation time-resolved X-ray diffraction and polarized optical microscopy. In all the TAGs,

α

crystals with a worm-like morphology started to grow rapidly in the first stage. Then, the

α

crystals slowly transformed into more stable forms in different manners for different TAG samples. In POP, the conversion was simple, as the

α

-2 form transformed into

γ

-3, whereas in rac-PPO, the lamellar distance values of the

α

-2 form continuously decreased with time and changed into the

α

-3 form. In the MC

_{POP / PPO}

crystals, in contrast, separate crystallization of

α

-2 of a rac-PPO fraction initially occurred, followed by the crystallization of

α

-2 of POP, and the two

α

forms merged into

α

-2 of MC

_{POP / PPO}

. This separate crystallization was caused by large differences in the crystallization kinetics of the

α

forms of POP and rac-PPO. Full article

(This article belongs to the Special Issue Crystallization of Lipids: From Fundamentals to Applications)

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15 pages, 3292 KiB

Open AccessArticle

Concept Design, Development and Preliminary Physical and Chemical Characterization of Tamoxifen-Guided-Mesoporous Silica Nanoparticles

by Candace M. Day, Martin J. Sweetman, Shane M. Hickey, Yunmei Song, Yongjun Liu, Na Zhang, Sally E. Plush and Sanjay Garg

Molecules 2021, 26(1), 219; https://doi.org/10.3390/molecules26010219 - 04 Jan 2021

Cited by 9 | Viewed by 2649

Abstract

Conventional chemotherapies used for breast cancer (BC) treatment are non-selective, attacking both healthy and cancerous cells. Therefore, new technologies that enhance drug efficacy and ameliorate the off-target toxic effects exhibited by currently used anticancer drugs are urgently needed. Here we report the design [...] Read more.

Conventional chemotherapies used for breast cancer (BC) treatment are non-selective, attacking both healthy and cancerous cells. Therefore, new technologies that enhance drug efficacy and ameliorate the off-target toxic effects exhibited by currently used anticancer drugs are urgently needed. Here we report the design and synthesis of novel mesoporous silica nanoparticles (MSNs) equipped with the hormonal drug tamoxifen (TAM) to facilitate guidance towards estrogen receptors (ERs) which are upregulated in breast tumours. TAM is linked to the MSNs using a poly-ʟ-histidine (PLH) polymer as a pH-sensitive gatekeeper, to ensure efficient delivery of encapsulated materials within the pores. XRD, HR-TEM, DLS, SEM, FT-IR and BET techniques were used to confirm the successful fabrication of MSNs. The MSNs have a high surface area (>1000 m²/g); and a mean particle size of 150 nm, which is an appropriate size to allow the penetration of premature blood vessels surrounding breast tumours. Successful surface functionalization was supported by FT-IR, XPS and TGA techniques, with a grafting ratio of approximately 29%. The outcomes of this preliminary work could be used as practical building blocks towards future formulations. Full article

(This article belongs to the Special Issue Design, Characterization and Applications of Functional Nanomaterials)

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