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Molecules, Volume 24, Issue 17 (September-1 2019)

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Cover Story (view full-size image) Aflatoxins (AFs) contamination of cereal commodities may occur due to fungal infections of crops in [...] Read more.
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Open AccessArticle
Analysis of Phenolic Composition of Byproducts (Seeds and Peels) of Avocado (Persea americana Mill.) Cultivated in Colombia
Molecules 2019, 24(17), 3209; https://doi.org/10.3390/molecules24173209 - 03 Sep 2019
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Abstract
The byproducts (seeds and peels) of an avocado cultivated in the south of Colombia were extracted with aqueous acetone and their antioxidant properties were measured with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays, and total polyphenol content was determined by Folin–Ciocalteu method. A [...] Read more.
The byproducts (seeds and peels) of an avocado cultivated in the south of Colombia were extracted with aqueous acetone and their antioxidant properties were measured with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays, and total polyphenol content was determined by Folin–Ciocalteu method. A bioguided fractionation was performed, first by SPE (solid phase extraction) on Amberlite XAD-7, and then by size exclusion chromatography on Sephadex LH-20. The polyphenolic-rich extracts and their fractions were analyzed by ultra-performance liquid chromatography–electrospray ionization–mass spectrometry (UPLC-ESI-MS/MS), finding the presence of organic acids, hydroxycinnamic acids, catechins, free and glycosylated flavonoids, and dimeric and trimeric procyanidins. Catechin, epicatechin, six quercetin derivatives, four dimeric procyanidins (three type B and one type A), and three trimeric procyanidins (two type B and one type A) were detected in the most active fractions of avocado peel and seeds. The most antioxidant fractions contain the higher molecular weight phenolic compounds (condensed tannins). Full article
(This article belongs to the Special Issue Bioactives and Functional Ingredients in Foods and Beverages)
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Open AccessArticle
NMR-Based Metabolomics Profiling for Radical Scavenging and Anti-Aging Properties of Selected Herbs
Molecules 2019, 24(17), 3208; https://doi.org/10.3390/molecules24173208 - 03 Sep 2019
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Abstract
Herbs that are usually recognized as medicinal plants are well known for their therapeutic effects and are traditionally used to treat numerous diseases, including aging. This study aimed to evaluate the metabolite variations among six selected herbs namely Curcurma longa, Oenanthe javanica [...] Read more.
Herbs that are usually recognized as medicinal plants are well known for their therapeutic effects and are traditionally used to treat numerous diseases, including aging. This study aimed to evaluate the metabolite variations among six selected herbs namely Curcurma longa, Oenanthe javanica, Vitex negundo, Pluchea indica, Cosmos caudatus and Persicaria minus using proton nuclear magnetic resonance (1H-NMR) coupled with multivariate data analysis (MVDA). The free radical scavenging activity of the extract was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and oxygen radical absorbance capacity (ORAC) assay. The anti-aging property was characterized by anti-elastase and anti-collagenase inhibitory activities. The results revealed that P. minus showed the highest radical scavenging activities and anti-aging properties. The partial least squares (PLS) biplot indicated the presence of potent metabolites in P. minus such as quercetin, quercetin-3-O-rhamnoside (quercitrin), myricetin derivatives, catechin, isorhamnetin, astragalin and apigenin. It can be concluded that P. minus can be considered as a potential source for an anti-aging ingredient and also a good free radical eradicator. Therefore, P. minus could be used in future development in anti-aging researches and medicinal ingredient preparations. Full article
(This article belongs to the Section Chemical Biology)
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Open AccessArticle
Asymmetric and Reduced Xanthene Fluorophores: Synthesis, Photochemical Properties, and Application to Activatable Fluorescent Probes for Detection of Nitroreductase
Molecules 2019, 24(17), 3206; https://doi.org/10.3390/molecules24173206 - 03 Sep 2019
Viewed by 321
Abstract
Xanthene fluorophores, including fluorescein, rhodol, and rhodamines, are representative classes of fluorescent probes that have been applied in the detection and visualization of biomolecules. “Turn on” activatable fluorescent probes, that can be turned on in response to enzymatic reactions, have been developed and [...] Read more.
Xanthene fluorophores, including fluorescein, rhodol, and rhodamines, are representative classes of fluorescent probes that have been applied in the detection and visualization of biomolecules. “Turn on” activatable fluorescent probes, that can be turned on in response to enzymatic reactions, have been developed and prepared to reduce the high background signal of “always-on” fluorescent probes. However, the development of activity-based fluorescent probes for biological applications, using simple xanthene dyes, is hampered by their inefficient synthetic methods and the difficulty of chemical modifications. We have, thus, developed a highly efficient, versatile synthetic route to developing chemically more stable reduced xanthene fluorophores, based on fluorescein, rhodol, and rhodamine via continuous Pd-catalyzed cross-coupling. Their fluorescent nature was evaluated by monitoring fluorescence with variation in the concentration, pH, and solvent. As an application to activatable fluorescent probe, nitroreductase (NTR)-responsive fluorescent probes were also developed using the reduced xanthene fluorophores, and their fluorogenic properties were evaluated. Full article
(This article belongs to the Special Issue Application of Organic Synthesis to Bioactive Compounds)
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Open AccessArticle
Effect of Chlorogenic Acid on the Physicochemical and Functional Properties of Coregonus Peled Myofibrillar Protein through Hydroxyl Radical Oxidation
Molecules 2019, 24(17), 3205; https://doi.org/10.3390/molecules24173205 - 03 Sep 2019
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Abstract
The effects of chlorogenic acid (CA) (6, 30, and 150 μM/g protein) on the physicochemical and functional properties of Coregonus peled myofibrillar protein (MP) through oxidation using a hydroxyl radical oxidation system (0.01 mM FeCl3, 0.01 mM Asc, and 1 mM [...] Read more.
The effects of chlorogenic acid (CA) (6, 30, and 150 μM/g protein) on the physicochemical and functional properties of Coregonus peled myofibrillar protein (MP) through oxidation using a hydroxyl radical oxidation system (0.01 mM FeCl3, 0.01 mM Asc, and 1 mM H2O2) were investigated. The result showed that CA inhibited the increase in protein carbonyl content but did not prevent losses in sulfhydryl and free amine contents caused by oxidation. The presence of CA also increased conformational changes in the secondary and tertiary structures of oxidized MP. Oxidized MP containing 6 μM/g CA had superior functional properties (solubility, emulsifying, foaming, and gel properties), while oxidized MP containing 150 μM/g CA aggregated, resulting in insolubility and a poor gel network. Full article
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Open AccessArticle
A Reversible Phase Transition of 2D Coordination Layers by B–H∙∙∙Cu(II) Interactions in a Coordination Polymer
Molecules 2019, 24(17), 3204; https://doi.org/10.3390/molecules24173204 - 03 Sep 2019
Viewed by 330
Abstract
Materials that combine flexibility and open metal sites are crucial for myriad applications. In this article, we report a 2D coordination polymer (CP) assembled from CuII ions and a flexible meta-carborane-based linker [Cu2(L1)2(Solv)2]•xSolv (1-DMA, 1-DMF, and [...] Read more.
Materials that combine flexibility and open metal sites are crucial for myriad applications. In this article, we report a 2D coordination polymer (CP) assembled from CuII ions and a flexible meta-carborane-based linker [Cu2(L1)2(Solv)2]•xSolv (1-DMA, 1-DMF, and 1-MeOH; L1: 1,7-di(4-carboxyphenyl)-1,7-dicarba-closo-dodecaborane). 1-DMF undergoes an unusual example of reversible phase transition on solvent treatment (i.e., MeOH and CH2Cl2). Solvent exchange, followed by thermal activation provided a new porous phase that exhibits an estimated Brunauer-Emmett-Teller (BET) surface area of 301 m2 g−1 and is capable of a CO2 uptake of 41 cm3 g−1. The transformation is reversible and 1-DMF is reformed on addition of DMF to the porous phase. We provide evidence for the reversible process being the result of the formation/cleavage of weak but attractive B–H∙∙∙Cu interactions by a combination of single-crystal (SCXRD), powder (PXRD) X-ray diffraction, Raman spectroscopy, and DFT calculations. Full article
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Open AccessCommunication
Chemical Composition and Antimicrobial Activity of Essential Oils from the Aerial Parts of Pinus eldarica Grown in Northwestern Iran
Molecules 2019, 24(17), 3203; https://doi.org/10.3390/molecules24173203 - 03 Sep 2019
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Abstract
Pinus eldarica (Pinaceae), an evergreen plant, is distributed across the warm and dry climates of western Asia, including Asia Minor, the Middle East, and land surrounding the Caspian Sea. Essential oils (EOs) from different aerial parts of this tree have been used in [...] Read more.
Pinus eldarica (Pinaceae), an evergreen plant, is distributed across the warm and dry climates of western Asia, including Asia Minor, the Middle East, and land surrounding the Caspian Sea. Essential oils (EOs) from different aerial parts of this tree have been used in traditional medicine. We aimed to investigate the chemical profile and antimicrobial activity of the EO from P. eldarica grown in northwestern Iran. EO from the needles, bark, and pollen were extracted with boiling water using a Clevenger apparatus at yield of 0.7–1.2 cm3/100 g of dry plant material. The main chemical components of the EO from the needles were D-germacrene (18.17%), caryophyllene (15.42%), γ-terpinene (12.96%), and β-pinene (10.62%); those from the bark were limonene (16.99%), caryophyllene oxide (13.22%), and drimenol (13.2%); and those from the pollen were α-pinene (25.64%) and limonene (19.94%). In total, 83 constituents were characterized in the EOs, using gas chromatography mass spectrometry analysis; mainly, sesquiterpene hydrocarbons in needle EO and monoterpene hydrocarbons in pollen and bark EOs. β-Pinene, β-myrcene, limonene, and caryophyllene were identified in the EOs from all three plant parts. The antibacterial and antifungal properties of the EOs were examined: pollen EO exhibited antibacterial activity against Escherichia coli; bark EO inhibited the growth of Candida albicans and Staphylococcus aureus; and the needle EO inhibited the growth of S. aureus. Thus, the EOs from aerial parts of P. eldarica can benefit the EO industry and antibiotic development. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle
Cordidepsine is A Potential New Anti-HIV Depsidone from Cordia millenii, Baker
Molecules 2019, 24(17), 3202; https://doi.org/10.3390/molecules24173202 - 03 Sep 2019
Viewed by 370
Abstract
Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid ( [...] Read more.
Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle
High Performance Size Exclusion Chromatography-Inductively Coupled Plasma-Mass Spectrometry to Study the Copper and Cadmium Complexation with Humic Acids
Molecules 2019, 24(17), 3201; https://doi.org/10.3390/molecules24173201 - 03 Sep 2019
Viewed by 245
Abstract
Dissolved organic matter (DOM) plays an important role in the environment by influencing the transport and distribution of organic and inorganic components through different processes: the retention, mobilization, and bio-availability of potentially toxic elements (PTEs). The aim of the present study is to [...] Read more.
Dissolved organic matter (DOM) plays an important role in the environment by influencing the transport and distribution of organic and inorganic components through different processes: the retention, mobilization, and bio-availability of potentially toxic elements (PTEs). The aim of the present study is to examine the dimensional characterization of humic acids (HA) extracted from soil matrix, as well as to analyze the metal distribution among different ligand classes. The molecular size distribution of the HA extract from soil showed three dimensional classes: 52 KDa, 4.5 KDa, and 900 Da. HPSEC-ICP-MS measurements demonstrated that the dimensional classes, relative to first two fractions, bind the largest part of metals. The complexing capacity of HA was evaluated to assess the pollutants mobility in the environmental system. In particular, cadmium (Cd) and copper (Cu) complexation was investigated due to the great concern regarding their bio-availability and toxicity in natural waters. The complexing capacity of HA solution (20 mg/L) was measured by titration using a high-performance size exclusion chromatography (HP-SEC) coupled to an inductively coupled mass spectrometry (ICP-MS). Results obtained by this technique are compared with those obtained by anodic stripping voltammetry (ASV) to investigate the effects of kinetic lability of complexes on measurements carried by HPSEC-ICP-MS. In this study, results of ligand concentrations and stability constants obtained via the two techniques are assessed considering the detection window associated to the applied analytical methodology. Results obtained using the two analytical techniques showed that Cd is complexed by two classes of ligands. However, the ligand concentration values obtained using the two techniques are different, because the detection window associated to the two methodologies; the complexing capacity, which was obtained as sum of the two classes of ligands, were 33 nmol/L and 9 nmol/L for ASV and HPSEC-ICP-MS, respectively. The copper complexing capacities determined by the two methodologies are comparable: 166 and 139 nmol/L for ASV and HPSEC-ICP-MS, respectively. However, the results of Cu titration differ for the two techniques, highlighting only one class of ligands when ASV was used, and two classes when HPSEC-ICP-MS was employed. Differences on results obtained by the two techniques are explained considering the kinetic lability of complexes; the results show that, differently from previous studies, also Cu complexes can be kinetically labile, if one technique with high reaction time is used, as well some cadmium complexes are sufficient stable to be determined by HPSEC-ICP-MS. Full article
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Open AccessArticle
Preparative Purification of Total Flavonoids from Sophora tonkinensis Gagnep. by Macroporous Resin Column Chromatography and Comparative Analysis of Flavonoid Profiles by HPLC-PAD
Molecules 2019, 24(17), 3200; https://doi.org/10.3390/molecules24173200 - 03 Sep 2019
Viewed by 212
Abstract
For the full development and utilization of Sophora tonkinensis Gagnep., this study was primarily intended to established a simple and efficient approach for the preparative purification of total flavonoids from S. tonkinensis by macroporous resin column chromatography (MRCC). The adsorption and desorption characteristics [...] Read more.
For the full development and utilization of Sophora tonkinensis Gagnep., this study was primarily intended to established a simple and efficient approach for the preparative purification of total flavonoids from S. tonkinensis by macroporous resin column chromatography (MRCC). The adsorption and desorption characteristics of the total flavonoids on ten macroporous resins were first studied, and AB-8 resin was chosen as the most suitable, and the adsorption data were best fitted to the pseudo-second-order kinetics model and Langmuir isotherm model. Furthermore, the technological parameters for the purification of the total flavonoids were optimized using column chromatography. After a sample one-step purification procedure, the content of the total flavonoids increased by about 4.76-fold from 12.14% to 57.82%, with a recovery yield of 84.93%. In addition, the comparative analysis of the flavonoid extracts before and after purification was performed by high-performance liquid chromatography coupled with photodiode-array detection (HPLC-PAD). The results showed that the contents of six major flavonoids in the purified product were all higher than before the purification. Therefore, the AB-8 MRCC established in this work was a promising method for the industrial-scale purification of the total flavonoids from S. tonkinensis. Full article
(This article belongs to the Special Issue Chromatographic Science of Natural Products)
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Open AccessArticle
Studying Proton Mobility in Zeolites by Varying Temperature Infrared Spectroscopy
Molecules 2019, 24(17), 3199; https://doi.org/10.3390/molecules24173199 - 03 Sep 2019
Viewed by 204
Abstract
We report a varying temperature infrared spectroscopic (VTIR) study with partial deuterium isotopic exchange as a method for characterizing proton mobility in acidic materials. This VTIR technique permits the estimation of activation energies for proton diffusion. Different acidic materials comprising classical proton-conducting materials, [...] Read more.
We report a varying temperature infrared spectroscopic (VTIR) study with partial deuterium isotopic exchange as a method for characterizing proton mobility in acidic materials. This VTIR technique permits the estimation of activation energies for proton diffusion. Different acidic materials comprising classical proton-conducting materials, such as transition metal phosphates and sulfonated solids, as well as different zeolites, are tested with this new method. The applicability of the method is thus extended to a vast library of materials. Its underlying principles and assumptions are clearly presented herein. Depending on the temperature ranges, different activation energies for proton transfer are observed irrespective of the different materials. In addition to the well-studied transition metal phosphates, Si-rich zeolites appear to be promising proton-transfer materials (with Eact < 40 kJ mol−1) for application in high-temperature (>150 °C) PEM fuel cells. They significantly outperform Nafion and sulfonated silica, which exhibit higher activation energies with Eact ~ 50 and 120 kJ mol−1, respectively. Full article
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Open AccessArticle
Two New Flavonoids from the Leaves of Baccharis oblongifolia (Ruiz and Pav.) Pers. (Asteraceae)
Molecules 2019, 24(17), 3198; https://doi.org/10.3390/molecules24173198 - 03 Sep 2019
Viewed by 200
Abstract
In this work, two new flavonoids, oblongifolioside A (1) and oblongifolioside B (2), along with eight known compounds (310), are isolated from the leaves of Baccharis oblongifolia (Asteraceae). The new structures are established through spectroscopic [...] Read more.
In this work, two new flavonoids, oblongifolioside A (1) and oblongifolioside B (2), along with eight known compounds (310), are isolated from the leaves of Baccharis oblongifolia (Asteraceae). The new structures are established through spectroscopic data and the known compounds are identified by comparison with data reported in the literature. The compounds (110) are evaluated in relation to their antiradical properties. Compounds 1 and 2 are found to exhibit high antiradical activity compared to their respective non-acylated flavonoids. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle
Alcohol-Supported Cu-Mediated 18F-Fluorination of Iodonium Salts under “Minimalist” Conditions
Molecules 2019, 24(17), 3197; https://doi.org/10.3390/molecules24173197 - 03 Sep 2019
Viewed by 257
Abstract
In the era of personalized precision medicine, positron emission tomography (PET) and related hybrid methods like PET/CT and PET/MRI gain recognition as indispensable tools of clinical diagnostics. A broader implementation of these imaging modalities in clinical routine is closely dependent on the increased [...] Read more.
In the era of personalized precision medicine, positron emission tomography (PET) and related hybrid methods like PET/CT and PET/MRI gain recognition as indispensable tools of clinical diagnostics. A broader implementation of these imaging modalities in clinical routine is closely dependent on the increased availability of established and emerging PET-tracers, which in turn could be accessible by the development of simple, reliable, and efficient radiolabeling procedures. A further requirement is a cGMP production of imaging probes in automated synthesis modules. Herein, a novel protocol for the efficient preparation of 18F-labeled aromatics via Cu-mediated radiofluorination of (aryl)(mesityl)iodonium salts without the need of evaporation steps is described. Labeled aromatics were prepared in high radiochemical yields simply by heating of iodonium [18F]fluorides with the Cu-mediator in methanolic DMF. The iodonium [18F]fluorides were prepared by direct elution of 18F from an anion exchange resin with solutions of the corresponding precursors in MeOH/DMF. The practicality of the novel method was confirmed by the racemization-free production of radiolabeled fluorophenylalanines, including hitherto unknown 3-[18F]FPhe, in 22–69% isolated radiochemical yields as well as its direct implementation into a remote-controlled synthesis unit. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle
Sixteen New Prenylated Flavonoids from the Fruit of Sinopodophyllum hexandrum
Molecules 2019, 24(17), 3196; https://doi.org/10.3390/molecules24173196 - 03 Sep 2019
Viewed by 188
Abstract
Sixteen new prenylated flavonoids, sinoflavonoids P–Z (111) and sinoflavonoids NA–NE (1216), were isolated from the fruit of Sinopodophyllum hexandrum, along with eight known analogues (1724). Their structures were elucidated on [...] Read more.
Sixteen new prenylated flavonoids, sinoflavonoids P–Z (111) and sinoflavonoids NA–NE (1216), were isolated from the fruit of Sinopodophyllum hexandrum, along with eight known analogues (1724). Their structures were elucidated on the basis of extensive spectroscopic data (HR-ESI-MS, 1H-NMR, 13C-NMR, HSQC, HMBC). The cytotoxic activities of compounds 118, 20, and 22 were evaluated by MTT assay. Compound 6 showed the most potent cytotoxicity in MCF-7, and HepG2 cell lines, with IC50 values of 6.25 and 3.83 μM, respectively. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessReview
Chemical Constituents and Biological Activity Profiles on Pleione (Orchidaceae)
Molecules 2019, 24(17), 3195; https://doi.org/10.3390/molecules24173195 - 03 Sep 2019
Viewed by 261
Abstract
Pleione (Orchidaceae) is not only famous for the ornamental value in Europe because of its special color, but also endemic in Southern Asia for its use in traditional medicine. A great deal of research about its secondary metabolites and biological activities has been [...] Read more.
Pleione (Orchidaceae) is not only famous for the ornamental value in Europe because of its special color, but also endemic in Southern Asia for its use in traditional medicine. A great deal of research about its secondary metabolites and biological activities has been done on only three of 30 species of Pleione. Up to now, 183 chemical compounds, such as phenanthrenes, bibenzyls, glucosyloxybenzyl succinate derivatives, flavonoids, lignans, terpenoids, etc., have been obtained from Pleione. These compounds have been demonstrated to play a significant role in anti-tumor, anti-neurodegenerative and anti-inflammatory biological activities and improve immunity. In order to further develop the drugs and utilize the plants, the chemical structural analysis and biological activities of Pleione are summarized in this review. Full article
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Open AccessReview
Emergence and Applications of Base Metals (Fe, Co, and Ni) in Hydroboration and Hydrosilylation
Molecules 2019, 24(17), 3194; https://doi.org/10.3390/molecules24173194 - 03 Sep 2019
Viewed by 348
Abstract
Base metal catalysis offers an alternative to reactions, which were once dominated by precious metals in hydrofunctionalization reactions. This review article details the development of some base metals (Fe, Co, and Ni) in the hydroboration and hydrosilylation reactions concomitant with a brief overview [...] Read more.
Base metal catalysis offers an alternative to reactions, which were once dominated by precious metals in hydrofunctionalization reactions. This review article details the development of some base metals (Fe, Co, and Ni) in the hydroboration and hydrosilylation reactions concomitant with a brief overview of recent advances in the field. Applications of both commercially available metal salts and well-defined metal complexes in catalysis and opportunities to further advance the field is discussed as well. Full article
(This article belongs to the Special Issue Sustainable Catalysis)
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Open AccessFeature PaperArticle
Synthesis and Herbicidal Activity Against Buffelgrass (Cenchrus ciliaris) of (±)-3-deoxyradicinin
Molecules 2019, 24(17), 3193; https://doi.org/10.3390/molecules24173193 - 03 Sep 2019
Viewed by 194
Abstract
A novel synthetic strategy for obtainment of (±)-3-deoxyradicinin (2) is reported. This synthetic methodology is more efficient than those previously reported in the literature and also shows higher versatility towards the introduction of different side-chains at both C-7 and C-2. The [...] Read more.
A novel synthetic strategy for obtainment of (±)-3-deoxyradicinin (2) is reported. This synthetic methodology is more efficient than those previously reported in the literature and also shows higher versatility towards the introduction of different side-chains at both C-7 and C-2. The obtained compound (±)-2 shows phytotoxicity against the grass-weed buffelgrass comparable to that of the natural phytotoxin radicinin (1). Therefore, (±)-2 can constitute a more practical synthetic alternative to 1 as bioherbicide for buffelgrass control. Full article
(This article belongs to the Special Issue Natural Compound to Biocontrol Agrarian Pests)
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Open AccessArticle
Nutritional Potential and Toxicological Evaluation of Tetraselmis sp. CTP4 Microalgal Biomass Produced in Industrial Photobioreactors
Molecules 2019, 24(17), 3192; https://doi.org/10.3390/molecules24173192 - 03 Sep 2019
Viewed by 385
Abstract
Commercial production of microalgal biomass for food and feed is a recent worldwide trend. Although it is common to publish nutritional data for microalgae grown at the lab-scale, data about industrial strains cultivated in an industrial setting are scarce in the literature. Thus, [...] Read more.
Commercial production of microalgal biomass for food and feed is a recent worldwide trend. Although it is common to publish nutritional data for microalgae grown at the lab-scale, data about industrial strains cultivated in an industrial setting are scarce in the literature. Thus, here we present the nutritional composition and a microbiological and toxicological evaluation of Tetraselmis sp. CTP4 biomass, cultivated in 100-m3 photobioreactors at an industrial production facility (AlgaFarm). This microalga contained high amounts of protein (31.2 g/100 g), dietary fibres (24.6 g/100 g), digestible carbohydrates (18.1 g/100 g) and ashes (15.2 g/100 g), but low lipid content (7.04 g/100 g). The biomass displayed a balanced amount of essential amino acids, n-3 polyunsaturated fatty acids, and starch-like polysaccharides. Significant levels of chlorophyll (3.5 g/100 g), carotenoids (0.61 g/100 g), and vitamins (e.g., 79.2 mg ascorbic acid /100 g) were also found in the biomass. Conversely, pathogenic bacteria, heavy metals, cyanotoxins, mycotoxins, polycyclic aromatic hydrocarbons, and pesticides were absent. The biomass showed moderate antioxidant activity in several in vitro assays. Taken together, as the biomass produced has a balanced biochemical composition of macronutrients and (pro-)vitamins, lacking any toxic contaminants, these results suggest that this strain can be used for nutritional applications. Full article
(This article belongs to the Special Issue Microalgae for Production of Bioproducts and Biofuels)
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Open AccessReview
Recent Advances in Enantioselective Photochemical Reactions of Stabilized Diazo Compounds
Molecules 2019, 24(17), 3191; https://doi.org/10.3390/molecules24173191 - 02 Sep 2019
Viewed by 306
Abstract
Diazo compounds have proven to be a useful class of carbenes or metal carbenoids sources under thermal, photochemical, or metal-catalyzed conditions, which can subsequently undergo a wide range of synthetically important transformations. Recently, asymmetric photocatalysis has provoked increasing research interests, and great advances [...] Read more.
Diazo compounds have proven to be a useful class of carbenes or metal carbenoids sources under thermal, photochemical, or metal-catalyzed conditions, which can subsequently undergo a wide range of synthetically important transformations. Recently, asymmetric photocatalysis has provoked increasing research interests, and great advances have been made in this discipline towards the synthesis of optically enriched compounds. In this context, the past two decades have been the most productive period in the developments of enantioselective photochemical reactions of diazo compounds due to a better understanding of the reactivities of diazo compounds and the emergence of new catalytic modes, as well as easier access to and treatment of stabilized diazo compounds. This review highlights these impressive achievements according to the reaction type, and the general mechanisms and stereochemical inductions are briefly discussed as well. Full article
(This article belongs to the Special Issue New Insights in Photoredox Catalysis)
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Open AccessArticle
Fungicide Tebuconazole Influences the Structure of Human Serum Albumin Molecule
Molecules 2019, 24(17), 3190; https://doi.org/10.3390/molecules24173190 - 02 Sep 2019
Viewed by 293
Abstract
Studies of interactions between pesticides and target mammalian proteins are important steps toward understanding the pesticide′s toxicity. Using calorimetric and spectroscopic methods, the interaction between triazole fungicide tebuconazole and human serum albumin has been investigated. The spectroscopic techniques showed that fluorescence quenching of [...] Read more.
Studies of interactions between pesticides and target mammalian proteins are important steps toward understanding the pesticide′s toxicity. Using calorimetric and spectroscopic methods, the interaction between triazole fungicide tebuconazole and human serum albumin has been investigated. The spectroscopic techniques showed that fluorescence quenching of human serum albumin by tebuconazole was the result of the formation of tebuconazole/human serum albumin complex with the static type as the dominant mechanism. The association constant was found to be 8.51 × 103 L/mol. The thermodynamic parameters were obtained as ΔH = −56.964 kJ/mol, ΔS = −115.98 J/mol·K. The main active interactions forming the tebuconazole/human serum albumin complex were identified as the interplay between hydrogen bonds and/or van der Waals forces, based on thermodynamic experiments. These binding modes were corroborated well by the predictions of molecular modeling. Hydrogen bonding of tebuconazole with Arg222, Ala215 and Ala291 of human serum albumin played a relevant role in binding. The conformation changes in secondary structure were characterized by circular dichroism and 3D fluorescence spectra. Full article
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Open AccessArticle
Proximate Composition and Nutritional Profile of Rainbow Trout (Oncorhynchus mykiss) Heads and Skipjack tuna (Katsuwonus Pelamis) Heads
Molecules 2019, 24(17), 3189; https://doi.org/10.3390/molecules24173189 - 02 Sep 2019
Viewed by 273
Abstract
In order to evaluate the application potential of rainbow trout (Oncorhynchus mykiss) heads and skipjack tuna (Katsuwonus pelamis) heads; proximate composition, amino acids, fatty acids, carnosine, and anserine contents were analyzed in this study. Rainbow trout heads showed significantly [...] Read more.
In order to evaluate the application potential of rainbow trout (Oncorhynchus mykiss) heads and skipjack tuna (Katsuwonus pelamis) heads; proximate composition, amino acids, fatty acids, carnosine, and anserine contents were analyzed in this study. Rainbow trout heads showed significantly higher protein (29.31 g/100 g FW, FW is abbreviation of fresh weight) and lipid (6.03 g/100 g FW) contents than skipjack tuna heads (18.47 g/100 g FW protein and 4.83 g/100 g FW lipid) (p < 0.05). Rainbow trout heads and skipjack tuna heads exhibited similar amino acid composition. Essential amino acids constituted more than 40% of total amino acids in both rainbow trout head and skipjack tuna head. The fatty acid profile was different between rainbow trout heads and skipjack tuna heads. Rainbow trout heads mainly contained 38.64% polyunsaturated fatty acids (PUFAs) and 38.57% monounsaturated fatty acids (MUFAs), whereas skipjack tuna heads mainly contained 54.46% saturated fatty acids (SFAs). Skipjack tuna heads contained 4563 mg/kg FW anserine and 1761 mg/kg FW carnosine, which were both significantly higher than those of rainbow trout heads (p < 0.05). These results demonstrate that both rainbow trout heads and skipjack tuna heads may be used as materials for recycling high-quality protein. Meanwhile, rainbow trout heads can be used to extract oil with high contents of unsaturated fatty acids, while skipjack tuna heads may be a source for obtaining carnosine and anserine. Full article
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Open AccessArticle
Effect of Different Post-Harvest Processing Methods on the Chemical Constituents of Notopterygium franchetii by an UHPLC-QTOF-MS-MS Metabolomics Approach
Molecules 2019, 24(17), 3188; https://doi.org/10.3390/molecules24173188 - 02 Sep 2019
Viewed by 266
Abstract
Notopterygium franchetii is a herb used in traditional Chinese medicine, where it is known as qianghuo. Its bioactive qualities are influenced by the post-harvest processing methods used (such as drying). However, changes in chemical components according to the drying method are unknown. [...] Read more.
Notopterygium franchetii is a herb used in traditional Chinese medicine, where it is known as qianghuo. Its bioactive qualities are influenced by the post-harvest processing methods used (such as drying). However, changes in chemical components according to the drying method are unknown. Fresh roots and rhizomes of N. franchetii were subjected to seven drying methods. Chromatography-mass spectrometry combined with targeted and untargeted analyses were used to investigate relationships between drying methods and chemical concentrations. According to targeted evaluations of the six main bioactive constituents, their total contents decreased significantly in all drying methods. Hierarchical clustering analysis of the drying methods and total metabolome detected 30 chemical constituents, for which heap maps were obtained. Hot air drying was the best processing method, producing the least chemical changes at the lowest cost, while shade drying caused the greatest chemical changes. In conclusion, the wide range of chemical changes in N. franchetii caused by drying was investigated. Such changes potentially affect the quality of herbal medicines. Full article
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Open AccessArticle
Comparison of the Utility of RP-TLC Technique and Different Computational Methods to Assess the Lipophilicity of Selected Antiparasitic, Antihypertensive, and Anti-inflammatory Drugs
Molecules 2019, 24(17), 3187; https://doi.org/10.3390/molecules24173187 - 02 Sep 2019
Viewed by 219
Abstract
The aim of this study was to assess the lipophilicity of selected antiparasitic, antihypertensive and non-steroidal anti-inflammatory drugs (NSAIDs) by means of reversed phase–thin layer chromatography (RP-TLC) as well by using Soczewiński–Wachtmeister’s and J. Ościk’s equations. The lipophilicity parameters of all examined compounds [...] Read more.
The aim of this study was to assess the lipophilicity of selected antiparasitic, antihypertensive and non-steroidal anti-inflammatory drugs (NSAIDs) by means of reversed phase–thin layer chromatography (RP-TLC) as well by using Soczewiński–Wachtmeister’s and J. Ościk’s equations. The lipophilicity parameters of all examined compounds obtained under various chromatographic systems (i.e., methanol-water and acetone-water, respectively) and those determined on the basis of Soczewiński-Wachtmeister’s and Ościk’s equations (i.e., RMWS and RMWO) were compared with the theoretical ones (e.g., AlogPs, AClogP, milogP, AlogP, MlogP, XlogP2, XlogP3) and the experimental value of the partition coefficient (logPexp). It was found that the RMWS parameter may be a good alternative tool in describing the lipophilic nature of biologically active compounds with a high and low lipophilicity (i.e., antihypertensive and antiparasitic drugs). Meanwhile, the RMWO was more suitable for compounds with a medium lipophilicity (i.e., non-steroidal anti-inflammatory drugs). The chromatographic parameter φ0(a) can be helpful for the prediction of partition coefficients, i.e., AClogP, XlogP3, as well as logPexp of examined compounds. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle
Chiral C2-Symmetric Diimines with 4,5-Diazafluorene Units
Molecules 2019, 24(17), 3186; https://doi.org/10.3390/molecules24173186 - 02 Sep 2019
Viewed by 227
Abstract
A synthetic approach to a new group of stable chiral C2-symmetric diimines with the 4,5-diazafluorene core has been developed based on condensation of dipinodiazafluorene with aromatic diamines. The chemical structures of new compounds were proven by spectroscopic methods and X-ray crystallography. [...] Read more.
A synthetic approach to a new group of stable chiral C2-symmetric diimines with the 4,5-diazafluorene core has been developed based on condensation of dipinodiazafluorene with aromatic diamines. The chemical structures of new compounds were proven by spectroscopic methods and X-ray crystallography. All the compounds form solvates with organic solvents (chloroform, benzene, 1,4-dioxane) and water. Specific spectral data of the new compounds are explained using calculated data (DFT). Diimines of the pinodiazafluorene series give colored reactions with transition metal ions and can be regarded as prospective polydentate ligands with interesting luminescent and chiroptical properties. Full article
(This article belongs to the Section Organic Chemistry)
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Open AccessArticle
Effective Hydrogenation of 3-(2”-furyl)- and 3-(2”-thienyl)-1-(2’-hydroxyphenyl)-prop-2-en-1-one in Selected Yeast Cultures
Molecules 2019, 24(17), 3185; https://doi.org/10.3390/molecules24173185 - 02 Sep 2019
Viewed by 223
Abstract
Biotransformations were performed on eight selected yeast strains, all of which were able to selectively hydrogenate the chalcone derivatives 3-(2”-furyl)- (1) and 3-(2”-thienyl)-1-(2’-hydroxyphenyl)-prop-2-en-1-one (3) into 3-(2”-furyl)- (2) and 3-(2”-thienyl)-1-(2’-hydroxyphenyl)-propan-1-one (4) respectively. The highest efficiency of [...] Read more.
Biotransformations were performed on eight selected yeast strains, all of which were able to selectively hydrogenate the chalcone derivatives 3-(2”-furyl)- (1) and 3-(2”-thienyl)-1-(2’-hydroxyphenyl)-prop-2-en-1-one (3) into 3-(2”-furyl)- (2) and 3-(2”-thienyl)-1-(2’-hydroxyphenyl)-propan-1-one (4) respectively. The highest efficiency of hydrogenation of the double bond in the substrate 1 was observed in the cultures of Saccharomyces cerevisiae KCh 464 and Yarrowia lipolytica KCh 71 strains. The substrate was converted into the product with > 99% conversion just in six hours after biotransformation started. The compound containing the sulfur atom in its structure was most effectively transformed by the Yarrowia lipolytica KCh 71 culture strain (conversion > 99%, obtained after three hours of substrate incubation). Also, we observed that, different strains of tested yeasts are able to carry out the bioreduction of the used substrate with different yields, depending on the presence of induced and constitutive ene reductases in their cells. The biggest advantage of this process is the efficient production of one product, practically without the formation of side products. Full article
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Open AccessArticle
Probing the Effects of Pyrimidine Functional Group Switches on Acyclic Fleximer Analogues for Antiviral Activity
Molecules 2019, 24(17), 3184; https://doi.org/10.3390/molecules24173184 - 02 Sep 2019
Viewed by 366
Abstract
Due to their ability to inhibit viral DNA or RNA replication, nucleoside analogues have been used for decades as potent antiviral therapeutics. However, one of the major limitations of nucleoside analogues is the development of antiviral resistance. In that regard, flexible nucleoside analogues [...] Read more.
Due to their ability to inhibit viral DNA or RNA replication, nucleoside analogues have been used for decades as potent antiviral therapeutics. However, one of the major limitations of nucleoside analogues is the development of antiviral resistance. In that regard, flexible nucleoside analogues known as “fleximers” have garnered attention over the years due to their ability to survey different amino acids in enzyme binding sites, thus overcoming the potential development of antiviral resistance. Acyclic fleximers have previously demonstrated antiviral activity against numerous viruses including Middle East Respiratory Syndrome coronavirus (MERS-CoV), Ebola virus (EBOV), and, most recently, flaviviruses such as Dengue (DENV) and Yellow Fever Virus (YFV). Due to these interesting results, a Structure Activity Relationship (SAR) study was pursued in order to analyze the effect of the pyrimidine functional group and acyl protecting group on antiviral activity, cytotoxicity, and conformation. The results of those studies are presented herein. Full article
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Open AccessArticle
Pharmacokinetics and Tissue Distribution of Alnustone in Rats after Intravenous Administration by Liquid Chromatography-Mass Spectrometry
Molecules 2019, 24(17), 3183; https://doi.org/10.3390/molecules24173183 - 02 Sep 2019
Viewed by 280
Abstract
Alnustone, a nonphenolic diarylheptanoid, first isolated from Alnus pendula (Betulaceae), has recently received a great deal of attention due to its various beneficial pharmacological effects. However, its pharmacokinetic profile in vivo remains unclear. The purpose of this study is to establish a fast [...] Read more.
Alnustone, a nonphenolic diarylheptanoid, first isolated from Alnus pendula (Betulaceae), has recently received a great deal of attention due to its various beneficial pharmacological effects. However, its pharmacokinetic profile in vivo remains unclear. The purpose of this study is to establish a fast and sensitive quantification method of alnustone using liquid chromatography tandem mass spectrometry (LC-MS/MS) and evaluate the pharmacokinetic and tissue distribution profiles of alnustone in rats. The sample was precipitated with acetonitrile with 0.5% formic acid and separated on BEH C18 Column. The mobile phase was composed of 0.1% formic acid in water and methanol at a flow rate of 0.3 mL/min. Alnustone and the internal standard (caffeine) were quantitatively monitored with precursor-to-product ion transitions of m/z 262.9→105.2 and m/z 195.2→138.0, respectively. The calibration curve for alnustone was linear from 1 to 2000 ng/mL. The intra- and inter-day assay precision (RSD) ranged from 1.1–9.0 % to 3.3–8.6%, respectively and the intra- and inter-day assay accuracy (RE) was between −8.2–9.7% and −10.3–9.9%, respectively. The validated method was successfully applied to the pharmacokinetic studies of alnustone in rats. After single-dose intravenous administration of alnustone (5 mg/kg), the mean peak plasma concentration (Cmax) value was 7066.36 ± 820.62 ng/mL, and the mean area under the concentration-time curve (AUC0–t) value was 6009.79 ± 567.30 ng/mL∙h. Our results demonstrated that the residence time of alnustone in vivo was not long and it eliminated quickly from the rat plasma. Meanwhile, the drug is mainly distributed in tissues with large blood flow, and the lung and liver might be the target organs for alnustone efficacy. The study will provide information for further application of alnustone. Full article
(This article belongs to the Special Issue Recent Trends in Pharmaceutical Analytical Chemistry)
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Open AccessArticle
Biomimetic Non-Heme Iron-Catalyzed Epoxidation of Challenging Terminal Alkenes Using Aqueous H2O2 as an Environmentally Friendly Oxidant
Molecules 2019, 24(17), 3182; https://doi.org/10.3390/molecules24173182 - 01 Sep 2019
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Abstract
Catalysis mediated by iron complexes is emerging as an eco-friendly and inexpensive option in comparison to traditional metal catalysis. The epoxidation of alkenes constitutes an attractive application of iron(III) catalysis, in which terminal olefins are challenging substrates. Herein, we describe our study on [...] Read more.
Catalysis mediated by iron complexes is emerging as an eco-friendly and inexpensive option in comparison to traditional metal catalysis. The epoxidation of alkenes constitutes an attractive application of iron(III) catalysis, in which terminal olefins are challenging substrates. Herein, we describe our study on the design of biomimetic non-heme ligands for the in situ generation of iron(III) complexes and their evaluation as potential catalysts in epoxidation of terminal olefins. Since it is well-known that active sites of oxidases might involve imidazole fragment of histidine, various simple imidazole derivatives (seven compounds) were initially evaluated in order to find the best reaction conditions and to develop, subsequently, more elaborated amino acid-derived peptide-like chiral ligands (10 derivatives) for enantioselective epoxidations. Full article
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Open AccessArticle
Structure-Based Pharmacophore Design and Virtual Screening for Novel Tubulin Inhibitors with Potential Anticancer Activity
Molecules 2019, 24(17), 3181; https://doi.org/10.3390/molecules24173181 - 01 Sep 2019
Viewed by 325
Abstract
Tubulin inhibitors have been considered as potential drugs for cancer therapy. However, their drug resistance and serious side-effects are the main reasons for clinical treatment failure. Therefore, there is still an urgent need to develop effective therapeutic drugs. Herein, a structure-based pharmacophore model [...] Read more.
Tubulin inhibitors have been considered as potential drugs for cancer therapy. However, their drug resistance and serious side-effects are the main reasons for clinical treatment failure. Therefore, there is still an urgent need to develop effective therapeutic drugs. Herein, a structure-based pharmacophore model was developed based on the co-crystallized structures of the tubulin with a high resolution. The model including one hydrogen-bond acceptor feature, two aromatic features, and one hydrophobic feature was further validated using the Gunner–Henry score method. Virtual screening was performed by an integrated protocol that combines drug-likeness analysis, pharmacophore mapping, and molecular docking approaches. Finally, five hits were selected for biological evaluation. The results indicated that all these hits at the concentration of 40 μM showed an inhibition of more than 50% against five human tumor cells (MCF-7, U87MG, HCT-116, MDA-MB-231, and HepG2). Particularly, hit 1 effectively inhibited the proliferation of these tumor cells, with inhibition rates of more than 80%. The results of tubulin polymerization and colchicine-site competition assays suggested that hit 1 significantly inhibited tubulin polymerization by binding to the colchicine site. Thus, hit 1 could be used as a potential chemotherapeutic agent for cancer treatment. This work also demonstrated the potential of our screening protocol to identify biologically active compounds. Full article
(This article belongs to the Section Computational and Theoretical Chemistry)
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Open AccessArticle
Design, Synthesis and Molecular Docking Analysis of Flavonoid Derivatives as Potential Telomerase Inhibitors
Molecules 2019, 24(17), 3180; https://doi.org/10.3390/molecules24173180 - 01 Sep 2019
Viewed by 330
Abstract
Based on the structural scaffolds of natural products, two series of flavonoid derivatives, for a total of twelve compounds, were designed and synthesized as potential human telomerase inhibitors. Using a modified TRAP-PCR assay, compound 5c exhibited the most potent inhibitory activity against human [...] Read more.
Based on the structural scaffolds of natural products, two series of flavonoid derivatives, for a total of twelve compounds, were designed and synthesized as potential human telomerase inhibitors. Using a modified TRAP-PCR assay, compound 5c exhibited the most potent inhibitory activity against human telomerase with an IC50 value of less than 50 μM. In vitro, the results demonstrated that compound 5c had potent anticancer activity against five classes of tumor cell lines. The molecular docking and molecular dynamics analyses binding to the human telomerase holoenzyme were performed to elucidate the binding mode of active compound 5c. This finding helps the rational design of more potent telomerase inhibitors based on the structural scaffolds of natural products. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle
Finding High-Quality Metal Ion-Centric Regions Across the Worldwide Protein Data Bank
Molecules 2019, 24(17), 3179; https://doi.org/10.3390/molecules24173179 - 01 Sep 2019
Viewed by 246
Abstract
As the number of macromolecular structures in the worldwide Protein Data Bank (wwPDB) continues to grow rapidly, more attention is being paid to the quality of its data, especially for use in aggregated structural and dynamics analyses. In this study, we systematically analyzed [...] Read more.
As the number of macromolecular structures in the worldwide Protein Data Bank (wwPDB) continues to grow rapidly, more attention is being paid to the quality of its data, especially for use in aggregated structural and dynamics analyses. In this study, we systematically analyzed 3.5 Å regions around all metal ions across all PDB entries with supporting electron density maps available from the PDB in Europe. All resulting metal ion-centric regions were evaluated with respect to four quality-control criteria involving electron density resolution, atom occupancy, symmetry atom exclusion, and regional electron density discrepancy. The resulting list of metal binding sites passing all four criteria possess high regional structural quality and should be beneficial to a wide variety of downstream analyses. This study demonstrates an approach for the pan-PDB evaluation of metal binding site structural quality with respect to underlying X-ray crystallographic experimental data represented in the available electron density maps of proteins. For non-crystallographers in particular, we hope to change the focus and discussion of structural quality from a global evaluation to a regional evaluation, since all structural entries in the wwPDB appear to have both regions of high and low structural quality. Full article
(This article belongs to the Special Issue Metalloproteins)
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