Molecules

11 pages, 3591 KiB

Open AccessArticle

Enantioselective Protonation of Radical Anion Intermediates in Photoallylation and Photoreduction Reactions of 3,3-Diaryl-1,1-dicyano-2-methylprop-1-ene with Allyltrimethylsilane

by Hajime Maeda, Masayuki Iida, Daisuke Ogawa and Kazuhiko Mizuno

Molecules 2019, 24(14), 2677; https://doi.org/10.3390/molecules24142677 - 23 Jul 2019

Cited by 1 | Viewed by 3816

Abstract

Photoreactions of acetonitrile solutions of 3,3-diaryl-1,1-dicyano-2-methylprop-1-enes (1a–c) with allyltrimethylsilane (2) in the presence of phenanthrene as a photoredox catalyst and acetic acid as a proton source formed photoallylation (3) and photoreduction (4) products [...] Read more.

Photoreactions of acetonitrile solutions of 3,3-diaryl-1,1-dicyano-2-methylprop-1-enes (1a–c) with allyltrimethylsilane (2) in the presence of phenanthrene as a photoredox catalyst and acetic acid as a proton source formed photoallylation (3) and photoreduction (4) products via photoinduced electron transfer pathways. When (S)-mandelic acid was used as the proton source, the reactions proceeded with 3.4 and 4.8 %ee for formation of 3 and 4, respectively. The results of studies of the effect of aryl ring substituents and several chiral carboxylic acids suggested that the enantioselectivities of the reactions are governed by steric controlled proton transfer in intermediate complexes formed by π-π and OH-π interactions of anion radicals derived from 1a–c and chiral carboxylic acids. Full article

(This article belongs to the Special Issue New Insights in Photoredox Catalysis)

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17 pages, 3414 KiB

Open AccessArticle

The Role of Orientation of Surface Bound Dihydropyrrol-2-ones (DHP) on Biological Activity

by Aditi Taunk, Renxun Chen, George Iskander, Kitty K. K. Ho, Basmah Almohaywi, David StClair Black, Mark D. P. Willcox and Naresh Kumar

Molecules 2019, 24(14), 2676; https://doi.org/10.3390/molecules24142676 - 23 Jul 2019

Cited by 6 | Viewed by 3795

Abstract

Quorum sensing (QS) signaling system is important for bacterial growth, adhesion, and biofilm formation resulting in numerous infectious diseases. Dihydropyrrol-2-ones (DHPs) represent a novel class of antimicrobial agents that inhibit QS, and are less prone to develop bacterial resistance due to their non-growth [...] Read more.

Quorum sensing (QS) signaling system is important for bacterial growth, adhesion, and biofilm formation resulting in numerous infectious diseases. Dihydropyrrol-2-ones (DHPs) represent a novel class of antimicrobial agents that inhibit QS, and are less prone to develop bacterial resistance due to their non-growth inhibition mechanism of action which does not cause survival pressure on bacteria. DHPs can prevent bacterial colonization and quorum sensing when covalently bound to substrates. In this study, the role of orientation of DHP compounds was investigated after covalent attachment by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) coupling reaction to amine-functionalized glass surfaces via various positions of the DHP scaffold. The functionalized glass surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle measurements and tested for their in vitro biological activity against S. aureus and P. aeruginosa. DHPs attached via the N-1 position resulted in the highest antibacterial activities against S. aureus, while no difference was observed for DHPs attached either via the N-1 position or the C-4 phenyl ring against P. aeruginosa. Full article

(This article belongs to the Special Issue Recent Advances in Antimicrobial Biomaterials)

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17 pages, 3336 KiB

Open AccessArticle

New and Potent Quinuclidine-Based Antimicrobial Agents

by Andreja Radman Kastelic, Renata Odžak, Iskra Pezdirc, Karlo Sović, Tomica Hrenar, Ana Čipak Gašparović, Mirjana Skočibušić and Ines Primožič

Molecules 2019, 24(14), 2675; https://doi.org/10.3390/molecules24142675 - 23 Jul 2019

Cited by 16 | Viewed by 5115

Abstract

Developing new antibiotics is currently very important since antibiotic resistance is one of the biggest problems of global health today. In the search for a new class of potential antimicrobial agents, ten new compounds were designed and synthesized based on the quinuclidinium heterocyclic [...] Read more.

Developing new antibiotics is currently very important since antibiotic resistance is one of the biggest problems of global health today. In the search for a new class of potential antimicrobial agents, ten new compounds were designed and synthesized based on the quinuclidinium heterocyclic core and the oxime functional group. The antimicrobial activity was assessed against a panel of representative gram-positive and gram-negative bacteria. All compounds demonstrated potent activity against the tested microorganisms, with the minimum inhibitory concentration (MIC) values ranging from 0.25 to 256.00 μg/mL. Among the tested compounds, two quaternary compounds, para-N-chlorobenzyl and meta-N-bromobenzyl quinuclidinium oximes, displayed the most potent and broad-spectrum activity against both gram-positive and gram-negative bacterial strains (MIC values from 0.25 to 4.00 μg/mL), with the lowest value for the important multidrug resistant gram-negative pathogen Pseudomonas aeruginosa. In the case of Klebsiella pneumoniae, activity of those compounds are 256-fold and 16-fold better than gentamicin, respectively. MTT assays showed that compounds are nontoxic for human cell lines. Multi-way analysis was used to separately reduce dimensionality of quantum chemical data and biological activity data to obtain a regression model and the required parameters for the enhancement of biological activity. Full article

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12 pages, 2498 KiB

Open AccessArticle

Discrimination of Natural Mature Acacia Honey Based on Multi-Physicochemical Parameters Combined with Chemometric Analysis

by Tianchen Ma, Haoan Zhao, Caiyun Liu, Min Zhu, Hui Gao, Ni Cheng and Wei Cao

Molecules 2019, 24(14), 2674; https://doi.org/10.3390/molecules24142674 - 23 Jul 2019

Cited by 16 | Viewed by 4059

Abstract

Honey maturity is an important factor in evaluating the quality of honey. We established a method for the identification of natural mature acacia honey with eighteen physicochemical parameters combined with chemometric analysis. The analysis of variance showed significant differences between mature and immature [...] Read more.

Honey maturity is an important factor in evaluating the quality of honey. We established a method for the identification of natural mature acacia honey with eighteen physicochemical parameters combined with chemometric analysis. The analysis of variance showed significant differences between mature and immature acacia honey in physicochemical parameters. The principal component analysis explained 82.64% of the variance among samples, and indicated that total phenolic content, total protein content, and total sugar (glucose, fructose, sucrose) were the major variables. The cluster analysis and orthogonal partial least squares-discriminant analysis demonstrated that samples were grouped in relation to the maturity coinciding with the results of the principal component analysis. Meanwhile, the 35 test samples were classified with 100% accuracy with the method of multi-physicochemical parameters combined with chemometric analysis. All the results presented above proved the possibility of identifying mature acacia honey and immature acacia honey according to the chemometric analysis based on the multi-physicochemical parameters. Full article

(This article belongs to the Collection Advances in Food Analysis)

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20 pages, 8511 KiB

Open AccessArticle

Anti-Diabetic Effect of a Shihunine-Rich Extract of Dendrobium loddigesii on 3T3-L1 Cells and db/db Mice by Up-Regulating AMPK–GLUT4–PPARα

by Xue-Wen Li, Meixiang Huang, Kakei Lo, Wei-Li Chen, Ying-Yan He, Yongli Xu, Huizhen Zheng, Haiyan Hu and Jun Wang

Molecules 2019, 24(14), 2673; https://doi.org/10.3390/molecules24142673 - 23 Jul 2019

Cited by 16 | Viewed by 5227

Abstract

The stems of Dendrobium loddigesii, a Chinese herb, are often used to treat diabetes and its polar extract is rich in shihunine, a water-soluble Orchidaceae alkaloid, but little is known about the anti-diabetes effects and mechanism of shihunine. This study investigated the [...] Read more.

The stems of Dendrobium loddigesii, a Chinese herb, are often used to treat diabetes and its polar extract is rich in shihunine, a water-soluble Orchidaceae alkaloid, but little is known about the anti-diabetes effects and mechanism of shihunine. This study investigated the anti-diabetic effect of a shihunine-rich extract of D. loddigesii (DLS) based on 3T3-L1 cells and db/db mice. The underlying mechanisms were primarily explored using Western blot analysis and immunohistochemical staining. The 3T3-L1 cell experiments showed that DLS can reduce the intracellular accumulation of oil droplets as well as triglycerides (p < 0.001) and promote the 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2deoxyglucose (2-NBDG) uptake of 3T3-L1 cells (p < 0.001). The animal experiments confirmed that after 8 weeks of DLS treatment, the body weight, fasting blood sugar, and serum lipid levels of mice were significantly lowered, and the oral glucose tolerance test and serum insulin level were significantly improved compared to the no-treatment diabetes mellitus group. Further histomorphology observation led to the conclusion that the quantities of islet cells were significantly increased and the increase in adipose cell size was significantly suppressed. The immunohistochemical test of pancreatic tissue revealed that DLS inhibited the expression of cleaved cysteine aspartic acid-specific protease 3 (cleaved caspase-3). Western blot experiments showed that DLS had agonistic effects on adenosine monophosphate (AMP)-activated protein kinase phosphorylation (p-AMPK) and increased the expression levels of peroxisome proliferator-activated receptor α (PPARα) and glucose transporter 4 (GLUT4) in liver or adipose tissues. These data suggest that the shihunine-rich extract of D. loddigesii is an anti-diabetic fraction of D. loddigesii. Under our experimental condition, DLS at a dose of 50 mg/kg has good anti-diabetic efficacy. Full article

(This article belongs to the Special Issue Plant Bioactives in Preventing Chronic Diseases)

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15 pages, 3482 KiB

Open AccessArticle

Insight into the Synthesis and Characterization of Organophosphorus-Based Bridged Triazine Compounds

by Khalifah A. Salmeia, Antonia Neels, Dambarudhar Parida, Sandro Lehner, Daniel Rentsch and Sabyasachi Gaan

Molecules 2019, 24(14), 2672; https://doi.org/10.3390/molecules24142672 - 23 Jul 2019

Cited by 16 | Viewed by 5234

Abstract

In this article, we report the synthesis of 2,4,6-substituted s-triazine-based organophosphorus compounds via a two-step process, which enables their production in high yields, and with a high purity as solids. In the first step, a Michaelis–Arbuzov rearrangement of cyanuric chloride with triethyl [...] Read more.

In this article, we report the synthesis of 2,4,6-substituted s-triazine-based organophosphorus compounds via a two-step process, which enables their production in high yields, and with a high purity as solids. In the first step, a Michaelis–Arbuzov rearrangement of cyanuric chloride with triethyl phosphite afforded 2,4,6-trisdiethoxyphosphinyl-1,3,5-triazine (HEPT). Subsequently, the nucleophilic substitution reaction on the triazine carbon was achieved, owing to the electron-withdrawing ability of the phosphonate groups. This characteristic of HEPT facilitated its derivatization with bi-functional amines, producing novel P–C containing bridged triazine organophosphorus compounds. The molecular structures of all of the compounds were confirmed by NMR spectroscopy, CHN elemental analysis, and single crystal X-ray analysis. In the thermogravimetric analysis in an N₂ environment, >33% char formation was observed for the bridged compounds. The chemical composition analysis of the char obtained under the oxidative thermal decomposition of the bridged compounds confirmed the presence of phosphorus- and nitrogen-enriched species, which indicate their function in the condensed phase. Comparatively, the detection of HPO and H–C≡P in the gas phase during the pyrolysis of the bridged compounds can act as a source for PO^•, which is known for its gas phase flame inhibition reactions. The synergy of significant char formation and the generation of intermediates leading to PO^• during pyrolysis makes these molecules promising flame-retardant additives. Full article

(This article belongs to the Special Issue Recent Developments in the Synthesis and Utilization of Organophosphorus Compounds)

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10 pages, 1140 KiB

Open AccessArticle

Screening and Evaluation of Xanthine Oxidase Inhibitors from Gnetum parvifolium in China

by Xiaosheng Tang, Ping Tang, Lei Ma and Liangliang Liu

Molecules 2019, 24(14), 2671; https://doi.org/10.3390/molecules24142671 - 23 Jul 2019

Cited by 24 | Viewed by 4844

Abstract

As a traditional natural medicine for treating many kinds of diseases, Gnetum parvifolium showed apparent inhibition on xanthine oxidase (XO). In this study, ultrafiltration combined with liquid chromatography-mass spectrometry (LC-MS) is used for the screening of XO inhibitors from Gnetum parvifolium. Their [...] Read more.

As a traditional natural medicine for treating many kinds of diseases, Gnetum parvifolium showed apparent inhibition on xanthine oxidase (XO). In this study, ultrafiltration combined with liquid chromatography-mass spectrometry (LC-MS) is used for the screening of XO inhibitors from Gnetum parvifolium. Their antioxidation, XO inhibition, and enzymic kinetic parameters are also determined. Finally, piceatannol (1), rhaponiticin (2), resveratrol (3), and isorhapontigenin (4) are screened out and identified as XO inhibitors from the extract of Gnetum parvifolium. Four inhibitors show better inhibition than allopurinol and good radical scavenging abilities. However, the antioxidant activities are weaker than ascorbic acid. The kinetic parameters illustrate the inhibition mode of XO by piceatannol is competitive type, while the inhibition modes for rhaponiticin, resveratrol and isorhapontigenin are uncompetitive types. In order to evaluate the difference among samples obtained in China, the amounts of four inhibitors and related activities in 20 samples are assessed and analyzed by partial least squares analysis. The results indicate piceatannol contribute the highest coefficients in three kinds of activities. Based on these findings, more comprehensive research on pharmaceutical and biochemical activities of these four XO inhibitors could be conducted in future. Full article

(This article belongs to the Special Issue Phytochemicals in Medicine and Food)

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20 pages, 1401 KiB

Open AccessFeature PaperReview

Venoms of Iranian Scorpions (Arachnida, Scorpiones) and Their Potential for Drug Discovery

by Seyed Mahdi Kazemi and Jean-Marc Sabatier

Molecules 2019, 24(14), 2670; https://doi.org/10.3390/molecules24142670 - 23 Jul 2019

Cited by 20 | Viewed by 7755

Abstract

Scorpions, a characteristic group of arthropods, are among the earliest diverging arachnids, dating back almost 440 million years. One of the many interesting aspects of scorpions is that they have venom arsenals for capturing prey and defending against predators, which may play a [...] Read more.

Scorpions, a characteristic group of arthropods, are among the earliest diverging arachnids, dating back almost 440 million years. One of the many interesting aspects of scorpions is that they have venom arsenals for capturing prey and defending against predators, which may play a critical role in their evolutionary success. Unfortunately, however, scorpion envenomation represents a serious health problem in several countries, including Iran. Iran is acknowledged as an area with a high richness of scorpion species and families. The diversity of the scorpion fauna in Iran is the subject of this review, in which we report a total of 78 species and subspecies in 19 genera and four families. We also list some of the toxins or genes studied from five species, including Androctonus crassicauda, Hottentotta zagrosensis, Mesobuthus phillipsi, Odontobuthus doriae, and Hemiscorpius lepturus, in the Buthidae and Hemiscorpiidae families. Lastly, we review the diverse functions of typical toxins from the Iranian scorpion species, including their medical applications. Full article

(This article belongs to the Special Issue Natural Product Pharmacology and Medicinal Chemistry)

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15 pages, 8839 KiB

Open AccessReview

Porphyrin as Diagnostic and Therapeutic Agent

by Ncediwe Tsolekile, Simphiwe Nelana and Oluwatobi Samuel Oluwafemi

Molecules 2019, 24(14), 2669; https://doi.org/10.3390/molecules24142669 - 23 Jul 2019

Cited by 128 | Viewed by 9225

Abstract

The synthesis and application of porphyrins has seen a huge shift towards research in porphyrin bio-molecular based systems in the past decade. The preferential localization of porphyrins in tumors, as well as their ability to generate reactive singlet oxygen and low dark toxicities [...] Read more.

The synthesis and application of porphyrins has seen a huge shift towards research in porphyrin bio-molecular based systems in the past decade. The preferential localization of porphyrins in tumors, as well as their ability to generate reactive singlet oxygen and low dark toxicities has resulted in their use in therapeutic applications such as photodynamic therapy. However, their inherent lack of bio-distribution due to water insolubility has shifted research into porphyrin-nanomaterial conjugated systems to address this challenge. This has broadened their bio-applications, viz. bio-sensors, fluorescence tracking, in vivo magnetic resonance imaging (MRI), and positron emission tomography (PET)/CT imaging to photo-immuno-therapy just to highlight a few. This paper reviews the unique theranostic role of porphyrins in disease diagnosis and therapy. The review highlights porphyrin conjugated systems and their applications. The review ends by bringing current challenges and future perspectives of porphyrin based conjugated systems and their respective applications into light. Full article

(This article belongs to the Special Issue Porphyrins and Its Derivatives: Design, Synthesis and Applications)

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20 pages, 5680 KiB

Open AccessArticle

ON/OFF Photostimulation of Isatin Bipyridyl Hydrazones: Photochemical and Spectral Study

by Róbert Šandrik, Pavol Tisovský, Klaudia Csicsai, Jana Donovalová, Martin Gáplovský, Róbert Sokolík, Juraj Filo and Anton Gáplovský

Molecules 2019, 24(14), 2668; https://doi.org/10.3390/molecules24142668 - 23 Jul 2019

Cited by 10 | Viewed by 3333

Abstract

Four novel isatin hydrazones containing bipyridyl fragments were synthesized as potential ON/OFF switches. Hydrazone Z-isomers exhibit high thermal stability. The characteristic photochemical reaction for all studied hydrazones is the Z–E isomerization in CHCl₃. After irradiation of hydrazones 1 [...] Read more.

Four novel isatin hydrazones containing bipyridyl fragments were synthesized as potential ON/OFF switches. Hydrazone Z-isomers exhibit high thermal stability. The characteristic photochemical reaction for all studied hydrazones is the Z–E isomerization in CHCl₃. After irradiation of hydrazones 1 and 2 in dimethylformamide (DMF), the photoreaction products are tautomers. When using light with the appropriate wavelength, the photo-tautomerization reaction is reversible. In these conditions, studied hydrazones have ON/OFF switch properties. In the case of hydrazones 1 and 2, by alternating heat and light stimulation it is possible to control the isomerization process reversibly. In the presence of fluoride ions, NH hydrogen from the studied hydrazones is cleaved, and the corresponding anions are formed. The resulting anions of Z-isomers are changed to the corresponding E-isomer at room temperature. Full article

(This article belongs to the Section Photochemistry)

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9 pages, 2005 KiB

Open AccessArticle

Electronic Structure and Lithium Diffusion in LiAl₂(OH)₆Cl Studied by First Principle Calculations

by Yueping Zhang, Xiyue Cheng, Chen Wu, Jürgen Köhler and Shuiquan Deng

Molecules 2019, 24(14), 2667; https://doi.org/10.3390/molecules24142667 - 23 Jul 2019

Cited by 13 | Viewed by 3966

Abstract

First-principles calculations based on the density functional theory (DFT) were carried out to study the atomic structure and electronic structure of LiAl₂(OH)₆Cl, the only material in the layered double hydroxide family in which delithiation was found to occur. Ab [...] Read more.

First-principles calculations based on the density functional theory (DFT) were carried out to study the atomic structure and electronic structure of LiAl₂(OH)₆Cl, the only material in the layered double hydroxide family in which delithiation was found to occur. Ab initio molecular dynamics (AIMD) simulations were used to explore the evolution of the structure of LiAl₂(OH)₆Cl during a thermally induced delithiation process. The simulations show that this process occurs due to the drastic dynamics of Li⁺ at temperatures higher than ~450 K, in which the [Al₂(OH)₆] host layers remain stable up to 1100 K. The calculated large value of the Li⁺ diffusion coefficient D,

~ 3.13 \times 10^{- 5} c m^{2} / s

, at 500 K and the high stability of the [Al₂(OH)₆] framework suggest a potential technical application of the partially-delithiated Li_1-xAl₂(OH)₆Cl_1-x (0 < x < 1) as a superionic conductor at high temperatures. Full article

(This article belongs to the Special Issue Celebrating 150th Birthday of the Periodic Table – Foundation of Chemical Trends)

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15 pages, 463 KiB

Open AccessArticle

Solidago graminifolia L. Salisb. (Asteraceae) as a Valuable Source of Bioactive Polyphenols: HPLC Profile, In Vitro Antioxidant and Antimicrobial Potential

by Anca Toiu, Laurian Vlase, Dan Cristian Vodnar, Ana-Maria Gheldiu and Ilioara Oniga

Molecules 2019, 24(14), 2666; https://doi.org/10.3390/molecules24142666 - 23 Jul 2019

Cited by 40 | Viewed by 4947

Abstract

Solidago species are often used in traditional medicine as anti-inflammatory, diuretic, wound-healing and antimicrobial agents. Still, the bioactive compounds and biological activities of some species have not been studied. The present work aimed to investigate the polyphenolic profile and the biological properties of [...] Read more.

Solidago species are often used in traditional medicine as anti-inflammatory, diuretic, wound-healing and antimicrobial agents. Still, the bioactive compounds and biological activities of some species have not been studied. The present work aimed to investigate the polyphenolic profile and the biological properties of Solidago graminifolia L. Salisb., a poorly explored medicinal plant. The hydroalcoholic extracts from aerial parts were evaluated for total phenolic content (TPC), total flavonoid content (TFC) and the polyphenolic compounds were investigated by HPLC-MS. The antioxidant potential in vitro was determined using DPPH and FRAP assays. Antibacterial and antifungal effects were evaluated by dilution assays and MIC, MBC and MFC were calculated. The results showed that Solidago graminifolia aerial parts contain an important amount of total phenolics (192.69 mg GAE/g) and flavonoids (151.41 mg RE/g), with chlorogenic acid and quercitrin as major constituents. The hydroalcoholic extracts showed promising antioxidant and antimicrobial potential, with potent antibacterial activity against Staphylococcus aureus and important antifungal effect against Candida albicans and C. parapsilosis. The obtained results indicated that the aerial parts of Solidago graminifolia could be used as novel resource of phytochemicals in herbal preparations with antioxidant and antimicrobial activities. Full article

(This article belongs to the Collection Bioactive Compounds)

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14 pages, 3148 KiB

Open AccessArticle

Diallyl Disulfide Induces Apoptosis and Autophagy in Human Osteosarcoma MG-63 Cells through the PI3K/Akt/mTOR Pathway

by Ziqi Yue, Xin Guan, Rui Chao, Cancan Huang, Dongfang Li, Panpan Yang, Shanshan Liu, Tomoka Hasegawa, Jie Guo and Minqi Li

Molecules 2019, 24(14), 2665; https://doi.org/10.3390/molecules24142665 - 23 Jul 2019

Cited by 58 | Viewed by 7876

Abstract

Diallyl disulfide (DADs), a natural organic compound, is extracted from garlic and scallion and has anti-tumor effects against various tumors. This study investigated the anti-tumor activity of DADs in human osteosarcoma cells and the mechanisms. MG-63 cells were exposed to DADs (0, 20, [...] Read more.

Diallyl disulfide (DADs), a natural organic compound, is extracted from garlic and scallion and has anti-tumor effects against various tumors. This study investigated the anti-tumor activity of DADs in human osteosarcoma cells and the mechanisms. MG-63 cells were exposed to DADs (0, 20, 40, 60, 80, and 100 μM) for different lengths of time (24, 48, and 72 h). The CCK8 assay results showed that DADs inhibited osteosarcoma cell viability in a dose-and time-dependent manner. FITC-Annexin V/propidium iodide staining and flow cytometry demonstrated that the apoptotic ratio increased and the cell cycle was arrested at the G₂/M phase as the DADs concentration was increased. A Western blot analysis was employed to detect the levels of caspase-3, Bax, Bcl-2, LC3-II/LC3-I, and p62 as well as suppression of the mTOR pathway. High expression of LC3-II protein revealed that DADs induced formation of autophagosome. Furthermore, DADs-induced apoptosis was weakened after adding 3-methyladenine, demonstrating that the DADs treatment resulted in autophagy-mediated death of MG-63 cells. In addition, DADs depressed p-mTOR kinase activity, and the inhibited PI3K/Akt/mTOR pathway increased DADs-induced apoptosis and autophagy. In conclusion, our results reveal that DADs induced G₂/M arrest, apoptosis, and autophagic death of human osteosarcoma cells by inhibiting the PI3K/Akt/mTOR signaling pathway. Full article

(This article belongs to the Special Issue Antitumoral Properties of Natural Products)

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15 pages, 3308 KiB

Open AccessArticle

Separation and Enrichment of Three Coumarins from Angelicae Pubescentis Radix by Macroporous Resin with Preparative HPLC and Evaluation of Their Anti-Inflammatory Activity

by Yuqiao Yang, Ruichao Zhu, Jin Li, Xuejing Yang, Jun He, Hui Wang and Yanxu Chang

Molecules 2019, 24(14), 2664; https://doi.org/10.3390/molecules24142664 - 23 Jul 2019

Cited by 22 | Viewed by 4228

Abstract

In order to enrich and separate three coumarins (columbianetin acetate, osthole and columbianadin) from Angelicae Pubescentis Radix (APR), an efficient method was established by combining macroporous resins (MARs) with preparative high-performance liquid chromatography (PHPLC). Five different macroporous resins (D101, AB-8, DA-201, HP-20 and [...] Read more.

In order to enrich and separate three coumarins (columbianetin acetate, osthole and columbianadin) from Angelicae Pubescentis Radix (APR), an efficient method was established by combining macroporous resins (MARs) with preparative high-performance liquid chromatography (PHPLC). Five different macroporous resins (D101, AB-8, DA-201, HP-20 and GDX-201) were used to assess the adsorption and desorption characteristics of three coumarins. The result demonstrated that HP-20 resin possessed the best adsorption and desorption capacities for these three coumarins. Moreover, the adsorption dynamics profiles of three coumarins were well fitted to the pseudo second order equation (R² > 0.99) for the HP-20 resin. The adsorption process was described by the three isotherms models including Langmuir (R² > 0.98, 0.046 ≤ R_L ≤ 0.103), Freundlich (R² > 0.99, 0.2748 ≤ 1/n ≤ 0.3103) and Dubinin Radushkevich (R² > 0.97). The contents of columbianetin acetate, osthole and columbianadin in the product were increased 10.69-fold, 19.98-fold and 19.68-fold after enrichment, respectively. Three coumarins were further purified by PHPLC and the purities of them reached above 98%. Additionally, the anti-inflammatory effects of these three coumarins were assessed by Lipopolysaccharide (LPS)-induced RAW 264.7 cells. It was found that the production of NO and MCP-1 was obviously inhibited by three coumarins. Columbianetin acetate, osthole and columbianadin could be used as potentially natural anti-inflammatory ingredients in pharmaceutical products. It was concluded that the new method combining MARs with PHPLC was efficient and economical for enlarging scale separation and enrichment of columbianetin acetate, osthole and columbianadin with anti-inflammatory effect from the APR extract. Full article

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15 pages, 5582 KiB

Open AccessArticle

Magnetic Polyurea Nano-Capsules Synthesized via Interfacial Polymerization in Inverse Nano-Emulsion

by Suzana Natour, Anat Levi-Zada and Raed Abu-Reziq

Molecules 2019, 24(14), 2663; https://doi.org/10.3390/molecules24142663 - 23 Jul 2019

Cited by 14 | Viewed by 6423

Abstract

Polyurea (PU) nano-capsules have received voluminous interest in various fields due to their biocompatibility, high mechanical properties, and surface functionality. By incorporating magnetic nanoparticle (MNPs) into the polyurea system, the attributes of both PU and MNPs can be combined. In this work, we [...] Read more.

Polyurea (PU) nano-capsules have received voluminous interest in various fields due to their biocompatibility, high mechanical properties, and surface functionality. By incorporating magnetic nanoparticle (MNPs) into the polyurea system, the attributes of both PU and MNPs can be combined. In this work, we describe a facile and quick method for preparing magnetic polyurea nano-capsules. Encapsulation of ionic liquid-modified magnetite nanoparticles (MNPs), with polyurea nano-capsules (PU NCs) having an average size of 5–20 nm was carried out through interfacial polycondensation between amine and isocyanate monomers in inverse nano-emulsion (water-in-oil). The desired magnetic PU NCs were obtained utilizing toluene and triple-distilled water as continuous and dispersed phases respectively, polymeric non-ionic surfactant cetyl polyethyleneglycol/polypropyleneglycol-10/1 dimethicone (ABIL EM 90), diethylenetriamine, ethylenediamine diphenylmethane-4,4′-diisocyanate, and various percentages of the ionic liquid-modified MNPs. High loading of the ionic liquid-modified MNPs up to 11 wt% with respect to the dispersed aqueous phase was encapsulated. The magnetic PU NCs were probed using various analytical instruments including electron microscopy, infrared spectroscopy, X-ray diffraction, and nuclear magnetic spectroscopy. This unequivocally manifested the successful synthesis of core-shell polyurea nano-capsules even without utilizing osmotic pressure agents, and confirmed the presence of high loading of MNPs in the core. Full article

(This article belongs to the Special Issue Nanocomposites of Polymers and Inorganic Particles)

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17 pages, 9868 KiB

Open AccessArticle

Carbon Nanotube and Cellulose Nanocrystal Hybrid Films

by Mingzhe Jiang, Robert Seney, Paul Charles Bayliss and Christopher L. Kitchens

Molecules 2019, 24(14), 2662; https://doi.org/10.3390/molecules24142662 - 23 Jul 2019

Cited by 14 | Viewed by 4831

Abstract

The use of cellulose nanocrystals (CNC) in high performance coatings is attractive for micro-scale structures or device fabrication due to the anisotropic geometry, however CNC are insulating materials. Carbon nanotubes (CNT) are also rod-shaped nanomaterials that display high mechanical strength and electrical conductivity. [...] Read more.

The use of cellulose nanocrystals (CNC) in high performance coatings is attractive for micro-scale structures or device fabrication due to the anisotropic geometry, however CNC are insulating materials. Carbon nanotubes (CNT) are also rod-shaped nanomaterials that display high mechanical strength and electrical conductivity. The hydrophobic regions of surface-modified CNC can interact with hydrophobic CNT and aid in association between the two anisotropic nanomaterials. The long-range electrostatic repulsion of CNC plays a role in forming a stable CNT and CNC mixture dispersion in water, which is integral to forming a uniform hybrid film. At concentrations favorable for film formation, the multiwalled nanotubes + CNC mixture dispersion shows cellular network formation, indicating local phase separation, while the single-walled nanotube + CNC mixture dispersion shows schlieren texture, indicating liquid crystal mixture formation. Conductive CNT + CNC hybrid films (5–20 μm thick) were cast on glass microscope slides with and without shear by blade coating. The CNT + CNC hybrid films electrical conductivity increased with increasing CNT loadings and some anisotropy was observed with the sheared hybrid films, although to a lesser extent than what was anticipated. Percolation models were applied to model the hybrid film conductivity and correlate with the hybrid film microstructure. Full article

(This article belongs to the Special Issue Emerging Trends in Nanocelluloses)

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19 pages, 8994 KiB

Open AccessArticle

Photothermal-Induced Antibacterial Activity of Gold Nanorods Loaded into Polymeric Hydrogel against Pseudomonas aeruginosa Biofilm

by Amal G. Al-Bakri and Nouf N. Mahmoud

Molecules 2019, 24(14), 2661; https://doi.org/10.3390/molecules24142661 - 23 Jul 2019

Cited by 65 | Viewed by 5798

Abstract

In this study, the photothermal-induced bactericidal activity of phospholipid-decorated gold nanorods (DSPE-AuNR) suspension against Pseudomonas aeruginosa planktonic and biofilm cultures was investigated. We found that the treatment of planktonic culture of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.25–0.03 nM) followed by a continuous laser [...] Read more.

In this study, the photothermal-induced bactericidal activity of phospholipid-decorated gold nanorods (DSPE-AuNR) suspension against Pseudomonas aeruginosa planktonic and biofilm cultures was investigated. We found that the treatment of planktonic culture of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.25–0.03 nM) followed by a continuous laser beam exposure resulted in ~6 log cycle reduction of the bacterial viable count in comparison to the control. The percentage reduction of Pseudomonas aeruginosa biofilm viable count was ~2.5–6.0 log cycle upon laser excitation with different concentrations of DSPE-AuNR as compared to the control. The photothermal ablation activity of DSPE-AuNR (0.125 nM) loaded into poloxamer 407 hydrogel against Pseudomonas aeruginosa biofilm resulted in ~4.5–5 log cycle reduction in the biofilm viable count compared to the control. Moreover, transmission electron microscope (TEM) images of the photothermally-treated bacteria revealed a significant change in the bacterial shape and lysis of the bacterial cell membrane in comparison to the untreated bacteria. Furthermore, the results revealed that continuous and pulse laser beam modes effected a comparable photothermal-induced bactericidal activity. Therefore, it can be concluded that phospholipid-coated gold nanorods present a promising nanoplatform to eradicate Pseudomonas aeruginosa biofilm responsible for common skin diseases. Full article

(This article belongs to the Special Issue Photothermal Agents in Therapy)

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14 pages, 3488 KiB

Open AccessArticle

Dendrobium officinale Polysaccharides Inhibit 1-Methyl-2-Nitro-1-Nitrosoguanidine Induced Precancerous Lesions of Gastric Cancer in Rats through Regulating Wnt/β-Catenin Pathway and Altering Serum Endogenous Metabolites

by Yi Zhao, Bingtao Li, Gaoyu Wang, Shuchao Ge, Ximing Lan, Guoliang Xu and Hongning Liu

Molecules 2019, 24(14), 2660; https://doi.org/10.3390/molecules24142660 - 23 Jul 2019

Cited by 46 | Viewed by 4664

Abstract

Dendrobium officinale is a herb in traditional Chinese medicine where D. officinale polysaccharides (DOP) are the main active ingredient. This study aimed at evaluating DOP efficiency at inhibiting 1-Methyl-2-nitro-1-nitrosoguanidine (MNNG) induced precancerous lesions of gastric cancer (PLGC) in rats through the Wnt/b-catenin pathway [...] Read more.

Dendrobium officinale is a herb in traditional Chinese medicine where D. officinale polysaccharides (DOP) are the main active ingredient. This study aimed at evaluating DOP efficiency at inhibiting 1-Methyl-2-nitro-1-nitrosoguanidine (MNNG) induced precancerous lesions of gastric cancer (PLGC) in rats through the Wnt/b-catenin pathway and analyzing the variations of serum endogenous metabolites. PLGC was established in male Sprague-Dawley (SD) rats by administering 150 μg/mL MNNG in drinking water for 7 months and giving 0.1 mL of 10% NaCl once weekly during the initial 20 weeks. Treatment with DOP inhibited the progress of PLGC through decreasing the expression of β-catenin by immunohistochemical analysis. The futher study indicated DOP downregulated gene expression of Wnt2β, Gsk3β, PCNA, CyclinD1, and β-catenin, as well as protein expression of Wnt2β, PCNA, and β-catenin. On the other hand, there were nine endogenous metabolites identified after the DOP treatment. Among these, the most significant one is betaine because of its strong antioxidant activity, leading to an anti-tumor effect. DOP can inhibit MNNG-induced PLGC models via regulating Wnt/β-catenin pathway and by changing endogenous metabolites. Full article

(This article belongs to the Special Issue Natural Products for Cancer Chemoprevention)

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26 pages, 339 KiB

Open AccessReview

What are the Main Sensor Methods for Quantifying Pesticides in Agricultural Activities? A Review

by Roy Zamora-Sequeira, Ricardo Starbird-Pérez, Oscar Rojas-Carillo and Seiling Vargas-Villalobos

Molecules 2019, 24(14), 2659; https://doi.org/10.3390/molecules24142659 - 23 Jul 2019

Cited by 71 | Viewed by 6378

Abstract

In recent years, there has been an increase in pesticide use to improve crop production due to the growth of agricultural activities. Consequently, various pesticides have been present in the environment for an extended period of time. This review presents a general description [...] Read more.

In recent years, there has been an increase in pesticide use to improve crop production due to the growth of agricultural activities. Consequently, various pesticides have been present in the environment for an extended period of time. This review presents a general description of recent advances in the development of methods for the quantification of pesticides used in agricultural activities. Current advances focus on improving sensitivity and selectivity through the use of nanomaterials in both sensor assemblies and new biosensors. In this study, we summarize the electrochemical, optical, nano-colorimetric, piezoelectric, chemo-luminescent and fluorescent techniques related to the determination of agricultural pesticides. A brief description of each method and its applications, detection limit, purpose—which is to efficiently determine pesticides—cost and precision are considered. The main crops that are assessed in this study are bananas, although other fruits and vegetables contaminated with pesticides are also mentioned. While many studies have assessed biosensors for the determination of pesticides, the research in this area needs to be expanded to allow for a balance between agricultural activities and environmental protection. Full article

(This article belongs to the Special Issue Advanced Analysis of Contaminants of Emerging Concern )

26 pages, 2916 KiB

Open AccessArticle

Identification of Metabolites of Eupatorin in Vivo and in Vitro Based on UHPLC-Q-TOF-MS/MS

by Luya Li, Yuting Chen, Xue Feng, Jintuo Yin, Shenghao Li, Yupeng Sun and Lantong Zhang

Molecules 2019, 24(14), 2658; https://doi.org/10.3390/molecules24142658 - 23 Jul 2019

Cited by 16 | Viewed by 6456

Abstract

Eupatorin is the major bioactive component of Java tea (Orthosiphon stamineus), exhibiting strong anticancer and anti-inflammatory activities. However, no research on the metabolism of eupatorin has been reported to date. In the present study, ultra-high-performance liquid chromatography coupled with hybrid triple [...] Read more.

Eupatorin is the major bioactive component of Java tea (Orthosiphon stamineus), exhibiting strong anticancer and anti-inflammatory activities. However, no research on the metabolism of eupatorin has been reported to date. In the present study, ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) combined with an efficient online data acquisition and a multiple data processing method were developed for metabolite identification in vivo (rat plasma, bile, urine and feces) and in vitro (rat liver microsomes and intestinal flora). A total of 51 metabolites in vivo, 60 metabolites in vitro were structurally characterized. The loss of CH₂, CH₂O, O, CO, oxidation, methylation, glucuronidation, sulfate conjugation, N-acetylation, hydrogenation, ketone formation, glycine conjugation, glutamine conjugation and glucose conjugation were the main metabolic pathways of eupatorin. This was the first identification of metabolites of eupatorin in vivo and in vitro and it will provide reference and valuable evidence for further development of new pharmaceuticals and pharmacological mechanisms. Full article

(This article belongs to the Special Issue Advances in Chemical Analysis Procedures (Part II): Statistical and Chemometric Approaches)

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9 pages, 5396 KiB

Open AccessArticle

Chalcogen Bonding due to the Exo-Substitution of Icosahedral Dicarbaborane

by Jindřich Fanfrlík, Drahomír Hnyk and Pavel Hobza

Molecules 2019, 24(14), 2657; https://doi.org/10.3390/molecules24142657 - 23 Jul 2019

Cited by 6 | Viewed by 3014

Abstract

Chalcogen atoms are a class of substituents capable of generating inner and outer derivatives of boron clusters. It is well known that chalcogenated boron clusters can form strong σ-hole interactions when a chalcogen atom is a part of an icosahedron. This paper studies [...] Read more.

Chalcogen atoms are a class of substituents capable of generating inner and outer derivatives of boron clusters. It is well known that chalcogenated boron clusters can form strong σ-hole interactions when a chalcogen atom is a part of an icosahedron. This paper studies σ-hole interactions of dicarbaboranes with two exopolyhedral chalcogen atoms bonded to carbon vertices. Specifically, a computational investigation has been carried out on the co-crystal of (1,2-C₂B₁₀H₁₀)₂Se₄•toluene and a single crystal of (1,2-C₂B₁₀H₁₀)₂Te₄. Full article

(This article belongs to the Special Issue σ and π Holes: A New Class of Non-Covalent Interactions)

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13 pages, 1236 KiB

Open AccessArticle

Structural and Biological Investigations for a Series of N-5 Substituted Pyrrolo[3,2-d]pyrimidines as Potential Anti-Cancer Therapeutics

by Brian M. Cawrse, Nia’mani M. Robinson, Nina C. Lee, Gerald M. Wilson and Katherine L. Seley-Radtke

Molecules 2019, 24(14), 2656; https://doi.org/10.3390/molecules24142656 - 23 Jul 2019

Cited by 10 | Viewed by 3687

Abstract

Pyrrolo[3,2-d]pyrimidines have been studied for many years as potential lead compounds for the development of antiproliferative agents. Much of the focus has been on modifications to the pyrimidine ring, with enzymatic recognition often modulated by C2 and C4 substituents. In contrast, [...] Read more.

Pyrrolo[3,2-d]pyrimidines have been studied for many years as potential lead compounds for the development of antiproliferative agents. Much of the focus has been on modifications to the pyrimidine ring, with enzymatic recognition often modulated by C2 and C4 substituents. In contrast, this work focuses on the N5 of the pyrrole ring by means of a series of novel N5-substituted pyrrolo[3,2-d]pyrimidines. The compounds were screened against the NCI-60 Human Tumor Cell Line panel, and the results were analyzed using the COMPARE algorithm to elucidate potential mechanisms of action. COMPARE analysis returned strong correlation to known DNA alkylators and groove binders, corroborating the hypothesis that these pyrrolo[3,2-d]pyrimidines act as DNA or RNA alkylators. In addition, N5 substitution reduced the EC₅₀ against CCRF-CEM leukemia cells by up to 7-fold, indicating that this position is of interest in the development of antiproliferative lead compounds based on the pyrrolo[3,2-d]pyrimidine scaffold. Full article

(This article belongs to the Special Issue Bioactive Nucleosides and Nucleotides)

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8 pages, 1097 KiB

Open AccessArticle

Cytotoxic Polyketides from the Marine Sponge-Derived Fungus Pestalotiopsis heterocornis XWS03F09

by Hui Lei, Jing Lei, Xuefeng Zhou, Mei Hu, Hong Niu, Can Song, Siwei Chen, Yonghong Liu and Dan Zhang

Molecules 2019, 24(14), 2655; https://doi.org/10.3390/molecules24142655 - 22 Jul 2019

Cited by 14 | Viewed by 3326

Abstract

Four new compounds, including two new polyketides, heterocornols M and N (1, 2), and a pair of epimers, heterocornols O and P (3, 4), were isolated from the fermentation broth of the marine sponge-derived fungus Pestalotiopsis heterocornis [...] Read more.

Four new compounds, including two new polyketides, heterocornols M and N (1, 2), and a pair of epimers, heterocornols O and P (3, 4), were isolated from the fermentation broth of the marine sponge-derived fungus Pestalotiopsis heterocornis XWS03F09, together with three known compounds (5–7). The new chemical structures were established on the basis of a spectroscopic analysis, optical rotation, experimental and calculated electronic circular dichroism (ECD). All of the compounds (1–7) were evaluated for their cytotoxic activities, and heterocornols M-P (1–4) exhibited cytotoxicities against four human cancer cell lines with IC₅₀ values of 20.4–94.2 μM. Full article

(This article belongs to the Section Bioorganic Chemistry)

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15 pages, 1458 KiB

Open AccessArticle

Synthesis of the Core Framework of the Cornexistins by Intramolecular Nozaki-Hiyama-Kishi Coupling

by Anthony Aimon, Louis J. Farrugia and J. Stephen Clark

Molecules 2019, 24(14), 2654; https://doi.org/10.3390/molecules24142654 - 22 Jul 2019

Cited by 6 | Viewed by 4569

Abstract

A new and direct approach to the construction of the core framework of the herbicidal natural products cornexistin and hydroxycornexistin has been developed. Formation of the nine-membered carbocycle found in the natural products has been accomplished by an intramolecular Nozaki-Hiyama-Kishi reaction between a [...] Read more.

A new and direct approach to the construction of the core framework of the herbicidal natural products cornexistin and hydroxycornexistin has been developed. Formation of the nine-membered carbocycle found in the natural products has been accomplished by an intramolecular Nozaki-Hiyama-Kishi reaction between a vinylic iodide and an aldehyde. Good yields of carbocyclic products were obtained from the reaction, but diastereomeric mixtures of allylic alcohols were produced. The cyclisation reaction was successful irrespective of the relative configuration of the stereogenic centres in the cyclisation precursor. Full article

(This article belongs to the Special Issue Total Synthesis of Natural Products: A Themed Issue Dedicated to Professor Dr. Dieter Schinzer for His 65th Birthday)

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13 pages, 1506 KiB

Open AccessArticle

Topological Water Network Analysis Around Amino Acids

by Kwang-Eun Choi, Eunkyoung Chae, Anand Balupuri, Hye Ree Yoon and Nam Sook Kang

Molecules 2019, 24(14), 2653; https://doi.org/10.3390/molecules24142653 - 22 Jul 2019

Cited by 10 | Viewed by 4433

Abstract

Water molecules play a key role in protein stability, folding, function and ligand binding. Protein hydration has been studied using free energy perturbation algorithms. However, the study of protein hydration without free energy calculation is also an active field of research. Accordingly, topological [...] Read more.

Water molecules play a key role in protein stability, folding, function and ligand binding. Protein hydration has been studied using free energy perturbation algorithms. However, the study of protein hydration without free energy calculation is also an active field of research. Accordingly, topological water network (TWN) analysis has been carried out instead of free energy calculation in the present work to investigate hydration of proteins. Water networks around 20 amino acids in the aqueous solution were explored through molecular dynamics (MD) simulations. These simulation results were compared with experimental observations. Water molecules from the protein data bank structures showed TWN patterns similar to MD simulations. This work revealed that TWNs are effected by the surrounding environment. TWNs could provide valuable clues about the environment around amino acid residues in the proteins. The findings from this study could be exploited for TWN-based drug discovery and development. Full article

(This article belongs to the Section Computational and Theoretical Chemistry)

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16 pages, 2548 KiB

Open AccessArticle

Development and Validation of an HPLC-ESI/MS/MS Method for the Determination of Amoxicillin, Its Major Metabolites, and Ampicillin Residues in Chicken Tissues

by Lan Chen, Bo Wang, Zhixiang Diao, Min Zhao, Kaizhou Xie, Peiyang Zhang, Xutang Wang, Tao Zhang and Jinyu Wang

Molecules 2019, 24(14), 2652; https://doi.org/10.3390/molecules24142652 - 22 Jul 2019

Cited by 10 | Viewed by 6260

Abstract

A method for the simultaneous analysis of amoxicillin (AMO), amoxicillin metabolites, and ampicillin residues in edible chicken muscle, liver, and kidney samples via high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI/MS/MS) was developed and verified. The extraction and purification procedures involved the extraction [...] Read more.

A method for the simultaneous analysis of amoxicillin (AMO), amoxicillin metabolites, and ampicillin residues in edible chicken muscle, liver, and kidney samples via high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI/MS/MS) was developed and verified. The extraction and purification procedures involved the extraction of the sample using a liquid-liquid extraction method with acetonitrile to eliminate the proteins. The chicken tissue extract was then injected directly onto an HPLC column coupled to a mass spectrometer with an ESI(+) source. The HPLC-ESI/MS/MS method was validated according to specificity, sensitivity, linearity, matrix effects, precision, accuracy, decision limit, detection capability, and stability, as defined by the European Union and Food and Drug Administration. The linearity was desirable, and the determination coefficients (r² values) ranged from 0.9968 and 0.9999. The limits of detection and limits of quantification were 0.10–2.20 μg/kg and 0.30–8.50 μg/kg, respectively. The decision limits were 57.71–61.25 μg/kg, and the detection capabilities were 65.41–72.50 μg/kg, and the recoveries of the four target analytes exceeded 75% at the limits of quantification and exceeded 83% at 25, 50, and 100 μg/kg (n = 6 at each level), confirming the reliability of this method for determining these analytes and providing a new detection technology. For real sample analysis, this experiment tested 30 chicken tissue samples, only one chicken muscle, liver, and kidney sample were contaminated with 5.20, 17.45, and 7.33 μg/kg of AMO values, respectively, while other target compounds were not detected in the 30 tested chicken tissue samples. Full article

(This article belongs to the Special Issue Analysis of Residues in Food and Environment)

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22 pages, 5515 KiB

Open AccessReview

Metadevices with Potential Practical Applications

by Yafei Li, Jiangtao Lv, Qiongchan Gu, Sheng Hu, Zhigang Li, Xiaoxiao Jiang, Yu Ying and Guangyuan Si

Molecules 2019, 24(14), 2651; https://doi.org/10.3390/molecules24142651 - 22 Jul 2019

Cited by 3 | Viewed by 3331

Abstract

Metamaterials are “new materials” with different superior physical properties, which have generated great interest and become popular in scientific research. Various designs and functional devices using metamaterials have formed a new academic world. The application concept of metamaterial is based on designing diverse [...] Read more.

Metamaterials are “new materials” with different superior physical properties, which have generated great interest and become popular in scientific research. Various designs and functional devices using metamaterials have formed a new academic world. The application concept of metamaterial is based on designing diverse physical structures that can break through the limitations of traditional optical materials and composites to achieve extraordinary material functions. Therefore, metadevices have been widely studied by the academic community recently. Using the properties of metamaterials, many functional metadevices have been well investigated and further optimized. In this article, different metamaterial structures with varying functions are reviewed, and their working mechanisms and applications are summarized, which are near-field energy transfer devices, metamaterial mirrors, metamaterial biosensors, and quantum-cascade detectors. The development of metamaterials indicates that new materials will become an important breakthrough point and building blocks for new research domains, and therefore they will trigger more practical and wide applications in the future. Full article

(This article belongs to the Special Issue Researches on Photonics and Plasmonics)

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16 pages, 2914 KiB

Open AccessArticle

Rheology of Polyacrylonitrile/Lignin Blends in Ionic Liquids under Melt Spinning Conditions

by Jinxue Jiang, Keerthi Srinivas, Alper Kiziltas, Andrew Geda and Birgitte K. Ahring

Molecules 2019, 24(14), 2650; https://doi.org/10.3390/molecules24142650 - 22 Jul 2019

Cited by 8 | Viewed by 3536

Abstract

Lignin, while economically and environmentally beneficial, has had limited success in use in reinforcing carbon fibers due to harmful chemicals used in biomass pretreatment along with the limited physical interactions between lignin and polyacrylonitrile (PAN) during the spinning process. The focus of this [...] Read more.

Lignin, while economically and environmentally beneficial, has had limited success in use in reinforcing carbon fibers due to harmful chemicals used in biomass pretreatment along with the limited physical interactions between lignin and polyacrylonitrile (PAN) during the spinning process. The focus of this study is to use lignin obtained from chemical-free oxidative biomass pretreatment (WEx) for blending with PAN at melt spinning conditions to produce carbon fiber precursors. In this study, the dynamic rheology of blending PAN with biorefinery lignin obtained from the WEx process is investigated with the addition of 1-butyl-3-methylimidazolium chloride as a plasticizer to address the current barriers of developing PAN/lignin carbon fiber precursors in the melt-spinning process. Lignin was esterified using butyric anhydride to reduce its hydrophilicity and to enhance its interactions with PAN. The studies indicate that butyration of the lignin (BL) increased non-Newtonian behavior and decreased thermo-reversibility of blends. The slope of the Han plot was found to be around 1.47 for PAN at 150 °C and decreased with increasing lignin concentrations as well as temperature. However, these blends were found to have higher elasticity and solution yield stress (47.6 Pa at 20%wt BL and 190 °C) when compared to pure PAN (5.8 Pa at 190 °C). The results from this study are significant for understanding lignin–PAN interactions during melt spinning for lower-cost carbon fibers. Full article

(This article belongs to the Special Issue Lignin—Chemistry and Materials: Past, Present and Future)

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10 pages, 2131 KiB

Open AccessArticle

Comprehensive Characterization of Lignans from Forsythia viridissima by UHPLC-ESI-QTOF-MS, and Their NO Inhibitory Effects on RAW 264.7 Cells

by Jungmoo Huh, Chang-Min Lee, Seoyoung Lee, Soeun Kim, Namki Cho and Young-Chang Cho

Molecules 2019, 24(14), 2649; https://doi.org/10.3390/molecules24142649 - 22 Jul 2019

Cited by 3 | Viewed by 3352

Abstract

Lignans are known to be an important class of phenylpropanoid secondary metabolites. In the course of our studies on the chemodiversity of lignans, the necessity arose to develop a method for the fast detection and identification of bioactive lignan subclasses. In this study, [...] Read more.

Lignans are known to be an important class of phenylpropanoid secondary metabolites. In the course of our studies on the chemodiversity of lignans, the necessity arose to develop a method for the fast detection and identification of bioactive lignan subclasses. In this study, we detected 10 lignan derivatives of different extracts of F. viridissima by UHPLC-ESI-QTOF-MS. Lignan glycosides (1 and 2), lignans (3 and 4), and lignan dimers (5–10) were identified by analysis of their exact masses and MS^e spectra along with the characteristic mass fragmentation patterns and molecular formulas. We further investigated NO inhibitory effects of F. viridissima fractions and their major lignan derivatives to evaluate those anti-inflammatory effects. The methylene chloride fraction of F. viridissima as well as compounds 8 and 10 showed potent dose-dependent NO inhibitory effects on RAW 264.7 cells. Corresponding to the NO inhibition by compounds 8 and 10, lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) expression was notably reduced by both compounds. Our combined data with the bioactive results and the component analysis by UHPLC-ESI-QTOF-MS suggest that the methylene chloride fraction of F. viridissima roots could be potential anti-inflammatory agents and these are related to major lignans including dimeric dibenzylbutyrolactone lignans. Full article

(This article belongs to the Special Issue Biological Sample Analysis by Liquid Chromatography)

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15 pages, 4055 KiB

Open AccessArticle

Synthesis of Pyrrolo[3,4-b]pyridin-5-ones via Multicomponent Reactions and In Vitro–In Silico Studies Against SiHa, HeLa, and CaSki Human Cervical Carcinoma Cell Lines

by Daniel Segura-Olvera, Ailyn N. García-González, Ivette Morales-Salazar, Alejandro Islas-Jácome, Yareli Rojas-Aguirre, Ilich A. Ibarra, Erik Díaz-Cervantes, Sofía Lizeth Alcaraz-Estrada and Eduardo González-Zamora

Molecules 2019, 24(14), 2648; https://doi.org/10.3390/molecules24142648 - 22 Jul 2019

Cited by 10 | Viewed by 3829

Abstract

A series of 12 polysubstituted pyrrolo[3,4-b]pyridin-5-ones were synthesized via a one-pot cascade process (Ugi–3CR/aza Diels-Alder/N-acylation/decarboxylation/dehydration) and studied in vitro using human epithelial cervical carcinoma SiHa, HeLa, and CaSki cell line cultures. Three compounds of the series exhibited significative [...] Read more.

A series of 12 polysubstituted pyrrolo[3,4-b]pyridin-5-ones were synthesized via a one-pot cascade process (Ugi–3CR/aza Diels-Alder/N-acylation/decarboxylation/dehydration) and studied in vitro using human epithelial cervical carcinoma SiHa, HeLa, and CaSki cell line cultures. Three compounds of the series exhibited significative cytotoxicity against the three cell lines, with HeLa being the most sensitive one. Then, based on these results, in silico studies by docking techniques were performed using Paclitaxel as a reference and αβ-tubulin as the selected biological target. Worth highlighting is that strong hydrophobic interactions were observed between the three active molecules and the reference drug Paclitaxel, to the αβ-tubulin. In consequence, it was determined that hydrophobic–aromatic moieties of bioactive compounds and Paclitaxel play a key role in making stronger interactions to the ligand–target complex. A quantitative structure activity relationship (QSAR) study revealed that the six membered rings are the most significant molecular frameworks, being present in all proposed models for the in vitro-studied cell lines. Finally, also from the docking interpretation, a ligand-based pharmacophore model is proposed in order to find further potential polyheterocyclic candidates to bind stronger to the αβ-tubulin. Full article

(This article belongs to the Special Issue Application of Organic Synthesis to Bioactive Compounds)

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