Molecules

17 pages, 1969 KiB

Open AccessArticle

Analysis of Phenolic Composition of Byproducts (Seeds and Peels) of Avocado (Persea americana Mill.) Cultivated in Colombia

by Johanna C. Rosero, Silvia Cruz, Coralia Osorio and Nelson Hurtado

Molecules 2019, 24(17), 3209; https://doi.org/10.3390/molecules24173209 - 3 Sep 2019

Cited by 59 | Viewed by 9150

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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24 pages, 2912 KiB

Open AccessArticle

NMR-Based Metabolomics Profiling for Radical Scavenging and Anti-Aging Properties of Selected Herbs

by Mahanom Hussin, Azizah Abdul Hamid, Faridah Abas, Nurul Shazini Ramli, Ahmad Haniff Jaafar, Suri Roowi, Nordiana Abdul Majid and Mohd Sabri Pak Dek

Molecules 2019, 24(17), 3208; https://doi.org/10.3390/molecules24173208 - 3 Sep 2019

Cited by 19 | Viewed by 5191

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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16 pages, 1902 KiB

Open AccessArticle

Asymmetric and Reduced Xanthene Fluorophores: Synthesis, Photochemical Properties, and Application to Activatable Fluorescent Probes for Detection of Nitroreductase

by Kunal N. More, Tae-Hwan Lim, Julie Kang, Hwayoung Yun, Sung-Tae Yee and Dong-Jo Chang

Molecules 2019, 24(17), 3206; https://doi.org/10.3390/molecules24173206 - 3 Sep 2019

Cited by 16 | Viewed by 6801

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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13 pages, 2552 KiB

Open AccessArticle

Effect of Chlorogenic Acid on the Physicochemical and Functional Properties of Coregonus Peled Myofibrillar Protein through Hydroxyl Radical Oxidation

by Xin Guo, Hengheng Qiu, Xiaorong Deng, Xiaoying Mao, Xiaobing Guo, Chengjian Xu and Jian Zhang

Molecules 2019, 24(17), 3205; https://doi.org/10.3390/molecules24173205 - 3 Sep 2019

Cited by 50 | Viewed by 3928

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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18 pages, 4871 KiB

Open AccessArticle

A Reversible Phase Transition of 2D Coordination Layers by B–H∙∙∙Cu(II) Interactions in a Coordination Polymer

by Lei Gan, Pol G. Fonquernie, Mark E. Light, Gantulga Norjmaa, Gregori Ujaque, Duane Choquesillo-Lazarte, Julio Fraile, Francesc Teixidor, Clara Viñas and José G. Planas

Molecules 2019, 24(17), 3204; https://doi.org/10.3390/molecules24173204 - 3 Sep 2019

Cited by 11 | Viewed by 4487

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

(This article belongs to the Special Issue Boron Chemistry and Its Development in the 21st Century: In Memory of Professor Bohumil Štíbr (1940-2020))

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11 pages, 555 KiB

Open AccessCommunication

Chemical Composition and Antimicrobial Activity of Essential Oils from the Aerial Parts of Pinus eldarica Grown in Northwestern Iran

by Tayyebeh Ghaffari, Hossein Samadi Kafil, Solmaz Asnaashari, Safar Farajnia, Abbas Delazar, Su Cheol Baek, Hamed Hamishehkar and Ki Hyun Kim

Molecules 2019, 24(17), 3203; https://doi.org/10.3390/molecules24173203 - 3 Sep 2019

Cited by 51 | Viewed by 4323

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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14 pages, 1906 KiB

Open AccessArticle

Cordidepsine is A Potential New Anti-HIV Depsidone from Cordia millenii, Baker

by Rostanie Dongmo Zeukang, Xavier Siwe-Noundou, Maurice Tagatsing Fotsing, Turibio Tabopda Kuiate, Joseph Tanyi Mbafor, Rui W. M. Krause, Muhammad Iqbal Choudhary and Alex de Théodore Atchadé

Molecules 2019, 24(17), 3202; https://doi.org/10.3390/molecules24173202 - 3 Sep 2019

Cited by 8 | Viewed by 3614

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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13 pages, 1367 KiB

Open AccessArticle

High Performance Size Exclusion Chromatography-Inductively Coupled Plasma-Mass Spectrometry to Study the Copper and Cadmium Complexation with Humic Acids

by Marta Radaelli, Elisa Scalabrin, Giuseppa Toscano and Gabriele Capodaglio

Molecules 2019, 24(17), 3201; https://doi.org/10.3390/molecules24173201 - 3 Sep 2019

Cited by 13 | Viewed by 3752

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

(This article belongs to the Special Issue Determination of Trace Heavy Metals and Metalloids in Environmental Samples)

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16 pages, 3199 KiB

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

by Mengyang Hou, Wenzhong Hu, Zhilong Xiu, Aili Jiang, Lei Men, Kexin Hao, Xingsheng Sun and Duo Cao

Molecules 2019, 24(17), 3200; https://doi.org/10.3390/molecules24173200 - 3 Sep 2019

Cited by 33 | Viewed by 4810

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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10 pages, 2372 KiB

Open AccessArticle

Studying Proton Mobility in Zeolites by Varying Temperature Infrared Spectroscopy

by Pit Losch, Hrishikesh Joshi, Niklas Stegmann, Olena Vozniuk and Wolfgang Schmidt

Molecules 2019, 24(17), 3199; https://doi.org/10.3390/molecules24173199 - 3 Sep 2019

Cited by 4 | Viewed by 3185

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 E_act < 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 E_act ~ 50 and 120 kJ mol⁻¹, respectively. Full article

(This article belongs to the Special Issue Zeolites and Related Porous Materials: Design, Synthesis, and Applications)

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9 pages, 561 KiB

Open AccessArticle

Two New Flavonoids from the Leaves of Baccharis oblongifolia (Ruiz and Pav.) Pers. (Asteraceae)

by Paulo R. F. Zampieri, Cinthia I. Tamayose, Oriana A. Fávero, Paulete Romoff and Marcelo J. P. Ferreira

Molecules 2019, 24(17), 3198; https://doi.org/10.3390/molecules24173198 - 3 Sep 2019

Cited by 3 | Viewed by 3054

Abstract

In this work, two new flavonoids, oblongifolioside A (1) and oblongifolioside B (2), along with eight known compounds (3–10), 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 (3–10), 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 (1–10) 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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17 pages, 3788 KiB

Open AccessArticle

Alcohol-Supported Cu-Mediated ¹⁸F-Fluorination of Iodonium Salts under “Minimalist” Conditions

by Victoriya V. Orlovskaya, Daniel J. Modemann, Olga F. Kuznetsova, Olga S. Fedorova, Elizaveta A. Urusova, Niklas Kolks, Bernd Neumaier, Raisa N. Krasikova and Boris D. Zlatopolskiy

Molecules 2019, 24(17), 3197; https://doi.org/10.3390/molecules24173197 - 3 Sep 2019

Cited by 16 | Viewed by 3870

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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14 pages, 2039 KiB

Open AccessArticle

Sixteen New Prenylated Flavonoids from the Fruit of Sinopodophyllum hexandrum

by Yanjun Sun, Haojie Chen, Junmin Wang, Meiling Gao, Chen Zhao, Ruijie Han, Hui Chen, Meng Li, Guimin Xue and Weisheng Feng

Molecules 2019, 24(17), 3196; https://doi.org/10.3390/molecules24173196 - 3 Sep 2019

Cited by 17 | Viewed by 2816

Abstract

Sixteen new prenylated flavonoids, sinoflavonoids P–Z (1–11) and sinoflavonoids NA–NE (12–16), were isolated from the fruit of Sinopodophyllum hexandrum, along with eight known analogues (17–24). Their structures were elucidated on [...] Read more.

Sixteen new prenylated flavonoids, sinoflavonoids P–Z (1–11) and sinoflavonoids NA–NE (12–16), were isolated from the fruit of Sinopodophyllum hexandrum, along with eight known analogues (17–24). 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 1–18, 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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26 pages, 1290 KiB

Open AccessReview

Chemical Constituents and Biological Activity Profiles on Pleione (Orchidaceae)

by Xiao-Qian Wu, Wei Li, Jing-Xin Chen, Jun-Wen Zhai, Hui-You Xu, Lin Ni and Sha-Sha Wu

Molecules 2019, 24(17), 3195; https://doi.org/10.3390/molecules24173195 - 3 Sep 2019

Cited by 26 | Viewed by 3718

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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24 pages, 2589 KiB

Open AccessReview

Emergence and Applications of Base Metals (Fe, Co, and Ni) in Hydroboration and Hydrosilylation

by Sem Raj Tamang and Michael Findlater

Molecules 2019, 24(17), 3194; https://doi.org/10.3390/molecules24173194 - 3 Sep 2019

Cited by 81 | Viewed by 8206

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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10 pages, 1430 KiB

Open AccessFeature PaperArticle

Synthesis and Herbicidal Activity Against Buffelgrass (Cenchrus ciliaris) of (±)-3-deoxyradicinin

by Giulia Marsico, Maria Sabrina Ciccone, Marco Masi, Fabrizio Freda, Massimo Cristofaro, Antonio Evidente, Stefano Superchi and Patrizia Scafato

Molecules 2019, 24(17), 3193; https://doi.org/10.3390/molecules24173193 - 3 Sep 2019

Cited by 13 | Viewed by 3823

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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18 pages, 482 KiB

Open AccessArticle

Nutritional Potential and Toxicological Evaluation of Tetraselmis sp. CTP4 Microalgal Biomass Produced in Industrial Photobioreactors

by Hugo Pereira, Joana Silva, Tamára Santos, Katkam N. Gangadhar, Ana Raposo, Cláudia Nunes, Manuel A. Coimbra, Luísa Gouveia, Luísa Barreira and João Varela

Molecules 2019, 24(17), 3192; https://doi.org/10.3390/molecules24173192 - 3 Sep 2019

Cited by 60 | Viewed by 5645

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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22 pages, 10103 KiB

Open AccessReview

Recent Advances in Enantioselective Photochemical Reactions of Stabilized Diazo Compounds

by Ting-Bi Hua, Qing-Qing Yang and You-Quan Zou

Molecules 2019, 24(17), 3191; https://doi.org/10.3390/molecules24173191 - 2 Sep 2019

Cited by 37 | Viewed by 6617

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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15 pages, 2305 KiB

Open AccessArticle

Fungicide Tebuconazole Influences the Structure of Human Serum Albumin Molecule

by Katarína Želonková, Samuel Havadej, Valéria Verebová, Beáta Holečková, Jozef Uličný and Jana Staničová

Molecules 2019, 24(17), 3190; https://doi.org/10.3390/molecules24173190 - 2 Sep 2019

Cited by 15 | Viewed by 4120

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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11 pages, 500 KiB

Open AccessArticle

Proximate Composition and Nutritional Profile of Rainbow Trout (Oncorhynchus mykiss) Heads and Skipjack tuna (Katsuwonus Pelamis) Heads

by Weinan Li, Yu Liu, Wei Jiang and Xiaojun Yan

Molecules 2019, 24(17), 3189; https://doi.org/10.3390/molecules24173189 - 2 Sep 2019

Cited by 25 | Viewed by 4212

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

(This article belongs to the Special Issue Extraction of Bioactive Molecules from Food By-Products and Their Utilization as Functional Ingredients)

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16 pages, 3270 KiB

Open AccessArticle

Effect of Different Post-Harvest Processing Methods on the Chemical Constituents of Notopterygium franchetii by an UHPLC-QTOF-MS-MS Metabolomics Approach

by Xueyan Su, Youjiao Wu, Ying Li, Yanfei Huang, Yuan Liu, Pei Luo and Zhifeng Zhang

Molecules 2019, 24(17), 3188; https://doi.org/10.3390/molecules24173188 - 2 Sep 2019

Cited by 21 | Viewed by 3237

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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15 pages, 2106 KiB

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

by Alina Pyka-Pająk, Wioletta Parys and Małgorzata Dołowy

Molecules 2019, 24(17), 3187; https://doi.org/10.3390/molecules24173187 - 2 Sep 2019

Cited by 6 | Viewed by 3349

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., R_MWS and R_MWO) were compared with the theoretical ones (e.g., AlogPs, AClogP, milogP, AlogP, MlogP, XlogP2, XlogP3) and the experimental value of the partition coefficient (logP_exp). It was found that the R_MWS 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 R_MWO was more suitable for compounds with a medium lipophilicity (i.e., non-steroidal anti-inflammatory drugs). The chromatographic parameter φ_0(a) can be helpful for the prediction of partition coefficients, i.e., AClogP, XlogP3, as well as logP_exp of examined compounds. Full article

(This article belongs to the Section Medicinal Chemistry)

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14 pages, 2704 KiB

Open AccessArticle

Chiral C₂-Symmetric Diimines with 4,5-Diazafluorene Units

by Eugene S. Vasilyev, Sergey N. Bizyaev, Vladislav Yu. Komarov, Yury V. Gatilov and Alexey V. Tkachev

Molecules 2019, 24(17), 3186; https://doi.org/10.3390/molecules24173186 - 2 Sep 2019

Cited by 6 | Viewed by 3132

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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10 pages, 1683 KiB

Open AccessArticle

Effective Hydrogenation of 3-(2”-furyl)- and 3-(2”-thienyl)-1-(2’-hydroxyphenyl)-prop-2-en-1-one in Selected Yeast Cultures

by Mateusz Łużny, Martyna Krzywda, Ewa Kozłowska, Edyta Kostrzewa-Susłow and Tomasz Janeczko

Molecules 2019, 24(17), 3185; https://doi.org/10.3390/molecules24173185 - 2 Sep 2019

Cited by 12 | Viewed by 2892

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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18 pages, 2394 KiB

Open AccessArticle

Probing the Effects of Pyrimidine Functional Group Switches on Acyclic Fleximer Analogues for Antiviral Activity

by Mary K. Yates, Payel Chatterjee, Mike Flint, Yafet Arefeayne, Damjan Makuc, Janez Plavec, Christina F. Spiropoulou and Katherine L. Seley-Radtke

Molecules 2019, 24(17), 3184; https://doi.org/10.3390/molecules24173184 - 2 Sep 2019

Cited by 14 | Viewed by 5498

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

(This article belongs to the Special Issue Discovery, Design, Synthesis, and Application of Nucleoside/Nucleotides)

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15 pages, 1232 KiB

Open AccessArticle

Pharmacokinetics and Tissue Distribution of Alnustone in Rats after Intravenous Administration by Liquid Chromatography-Mass Spectrometry

by Yang Song, Yu Zhou, Xiao-Ting Yan, Jing-Bo Bi, Xin Qiu, Yu Bian, Ke-Fei Wang, Yuan Zhang and Xue-Song Feng

Molecules 2019, 24(17), 3183; https://doi.org/10.3390/molecules24173183 - 2 Sep 2019

Cited by 7 | Viewed by 3039

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 (C_max) value was 7066.36 ± 820.62 ng/mL, and the mean area under the concentration-time curve (AUC_0–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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22 pages, 3971 KiB

Open AccessArticle

Biomimetic Non-Heme Iron-Catalyzed Epoxidation of Challenging Terminal Alkenes Using Aqueous H₂O₂ as an Environmentally Friendly Oxidant

by Anja Fingerhut, Jorge Vargas-Caporali, Marco Antonio Leyva-Ramírez, Eusebio Juaristi and Svetlana B. Tsogoeva

Molecules 2019, 24(17), 3182; https://doi.org/10.3390/molecules24173182 - 1 Sep 2019

Cited by 1 | Viewed by 6338

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

(This article belongs to the Special Issue Organic Transformations Promoted by 3d Metal Complexes: Synthetic Applications and Mechanisms)

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10 pages, 3922 KiB

Open AccessArticle

Structure-Based Pharmacophore Design and Virtual Screening for Novel Tubulin Inhibitors with Potential Anticancer Activity

by Yunjiang Zhou, Bin Di and Miao-Miao Niu

Molecules 2019, 24(17), 3181; https://doi.org/10.3390/molecules24173181 - 1 Sep 2019

Cited by 18 | Viewed by 3718

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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14 pages, 3388 KiB

Open AccessArticle

Design, Synthesis and Molecular Docking Analysis of Flavonoid Derivatives as Potential Telomerase Inhibitors

by Zhan-Fang Fan, Sai-Tim Ho, Rui Wen, Ya Fu, Lei Zhang, Jian Wang, Chun Hu, Pang-Chui Shaw, Yang Liu and Mao-Sheng Cheng

Molecules 2019, 24(17), 3180; https://doi.org/10.3390/molecules24173180 - 1 Sep 2019

Cited by 11 | Viewed by 3770

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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10 pages, 1344 KiB

Open AccessArticle

Finding High-Quality Metal Ion-Centric Regions Across the Worldwide Protein Data Bank

by Sen Yao and Hunter N.B. Moseley

Molecules 2019, 24(17), 3179; https://doi.org/10.3390/molecules24173179 - 1 Sep 2019

Cited by 5 | Viewed by 3028

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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