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Molecules, Volume 24, Issue 24 (December-2 2019) – 209 articles

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Cover Story (view full-size image) The photocatalytic activity of a cordierite-honeycomb-supported TiO2 thin film was evaluated within [...] Read more.
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Open AccessArticle
Electrochemical Hydrogen Evolution over Hydrothermally Synthesized Re-Doped MoS2 Flower-Like Microspheres
Molecules 2019, 24(24), 4631; https://doi.org/10.3390/molecules24244631 - 17 Dec 2019
Viewed by 444
Abstract
In this research, we report a simple hydrothermal synthesis to prepare rhenium (Re)- doped MoS2 flower-like microspheres and the tuning of their structural, electronic, and electrocatalytic properties by modulating the insertion of Re. The obtained compounds were characterized by X-ray diffraction (XRD), [...] Read more.
In this research, we report a simple hydrothermal synthesis to prepare rhenium (Re)- doped MoS2 flower-like microspheres and the tuning of their structural, electronic, and electrocatalytic properties by modulating the insertion of Re. The obtained compounds were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Structural, morphological, and chemical analyses confirmed the synthesis of poorly crystalline Re-doped MoS2 flower-like microspheres composed of few stacked layers. They exhibit enhanced hydrogen evolution reaction (HER) performance with low overpotential of 210 mV at current density of 10 mA/cm2, with a small Tafel slope of 78 mV/dec. The enhanced catalytic HER performance can be ascribed to activation of MoS2 basal planes and by reduction in charge transfer resistance during HER upon doping. Full article
(This article belongs to the Special Issue Electrocatalytic Water Splitting)
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Open AccessReview
Heparinoid Complex-Based Heparin-Binding Cytokines and Cell Delivery Carriers
Molecules 2019, 24(24), 4630; https://doi.org/10.3390/molecules24244630 - 17 Dec 2019
Viewed by 361
Abstract
Heparinoid is the generic term that is used for heparin, heparan sulfate (HS), and heparin-like molecules of animal or plant origin and synthetic derivatives of sulfated polysaccharides. Various biological activities of heparin/HS are attributed to their specific interaction and regulation with various heparin-binding [...] Read more.
Heparinoid is the generic term that is used for heparin, heparan sulfate (HS), and heparin-like molecules of animal or plant origin and synthetic derivatives of sulfated polysaccharides. Various biological activities of heparin/HS are attributed to their specific interaction and regulation with various heparin-binding cytokines, antithrombin (AT), and extracellular matrix (ECM) biomolecules. Specific domains with distinct saccharide sequences in heparin/HS mediate these interactions are mediated and require different highly sulfated saccharide sequences with different combinations of sulfated groups. Multivalent and cluster effects of the specific sulfated sequences in heparinoids are also important factors that control their interactions and biological activities. This review provides an overview of heparinoid-based biomaterials that offer novel means of engineering of various heparin-binding cytokine-delivery systems for biomedical applications and it focuses on our original studies on non-anticoagulant heparin-carrying polystyrene (NAC-HCPS) and polyelectrolyte complex-nano/microparticles (N/MPs), in addition to heparin-coating devices. Full article
(This article belongs to the Special Issue Emerging Frontiers in Glycosaminoglycans and Mimetics)
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Open AccessArticle
Silica Coated Iron/Iron Oxide Nanoparticles as a Nano-Platform for T2 Weighted Magnetic Resonance Imaging
Molecules 2019, 24(24), 4629; https://doi.org/10.3390/molecules24244629 - 17 Dec 2019
Viewed by 356
Abstract
The growing concern over the toxicity of Gd-based contrast agents used in magnetic resonance imaging (MRI) motivates the search for less toxic and more effective alternatives. Among these alternatives, iron–iron oxide ([email protected]) core-shell architectures have been long recognized as promising MRI contrast agents [...] Read more.
The growing concern over the toxicity of Gd-based contrast agents used in magnetic resonance imaging (MRI) motivates the search for less toxic and more effective alternatives. Among these alternatives, iron–iron oxide ([email protected]) core-shell architectures have been long recognized as promising MRI contrast agents while limited information on their engineering is available. Here we report the synthesis of 10 nm large [email protected] nanoparticles, their coating with a 11 nm thick layer of dense silica and functionalization by 5 kDa PEG chains to improve their biocompatibility. The nanomaterials obtained have been characterized by a set of complementary techniques such as infra-red and nuclear magnetic resonance spectroscopies, transmission electron microscopy, dynamic light scattering and zetametry, and magnetometry. They display hydrodynamic diameters in the 100 nm range, zetapotential values around −30 mV, and magnetization values higher than the reference contrast agent RESOVIST®. They display no cytotoxicity against 1BR3G and HCT116 cell lines and no hemolytic activity against human red blood cells. Their nuclear magnetic relaxation dispersion (NMRD) profiles are typical for nanomaterials of this size and magnetization. They display high r2 relaxivity values and low r1 leading to enhanced r2/r1 ratios in comparison with RESOVIST®. All these data make them promising contrast agents to detect early stage tumors. Full article
(This article belongs to the Special Issue Nanomaterials for Cancer Diagnosis and Therapy)
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Open AccessCorrection
Correction: Zhao, L.S., et al. Protective Effect of the Total Flavonoids from Rosa laevigata Michx Fruit on Renal Ischemia–Reperfusion Injury through Suppression of Oxidative Stress and Inflammation. Molecules 2016, 21, 952.
Molecules 2019, 24(24), 4628; https://doi.org/10.3390/molecules24244628 - 17 Dec 2019
Cited by 1 | Viewed by 283
Abstract
During the course of a review of our publications, an error in the title paper [...] Full article
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Open AccessArticle
Increase in Protective Effect of Panax vietnamensis by Heat Processing on Cisplatin-Induced Kidney Cell Toxicity
Molecules 2019, 24(24), 4627; https://doi.org/10.3390/molecules24244627 - 17 Dec 2019
Viewed by 375
Abstract
Cisplatin is a platinum-based anticancer agent used for treating a wide range of solid cancers. One of the side effects of this drug is its severe nephrotoxicity, limiting the safe dose of cisplatin. Therefore, many natural products have been studied and applied to [...] Read more.
Cisplatin is a platinum-based anticancer agent used for treating a wide range of solid cancers. One of the side effects of this drug is its severe nephrotoxicity, limiting the safe dose of cisplatin. Therefore, many natural products have been studied and applied to attenuate the toxicity of this compound. In this study, we found that steamed Vietnamese ginseng (Panax vietnamensis) could significantly reduce the kidney damage of cisplatin in an in vitro model using porcine proximal tubular LLC-PK1 kidney cells. From processed ginseng under optimized conditions (120 °C, 12 h), we isolated seven compounds (20(R,S)-ginsenoside Rh2, 20(R,S)-ginsenoside Rg3, ginsenoside Rk1, ginsenoside-Rg5, and ocotillol genin) that showed kidney-protective potential against cisplatin toxicity. By comparing the 50% recovery concentration (RC50), the R form of ginsenoside, Rh2 and Rg3, had RC50 values of 6.67 ± 0.42 µM and 8.39 ± 0.3 µM, respectively, while the S forms of ginsenoside, Rh2 and Rg3, and Rk1, had weaker protective effects, with RC50 ranging from 46.15 to 88.4 µM. G-Rg5 and ocotillol, the typical saponin of Vietnamese ginseng, had the highest RC50 (180.83 ± 33.27; 226.19 ± 66.16, respectively). Our results suggest that processed Vietnamese gingseng (PVG), as well as those compounds, has the potential to improve kidney damage due to cisplatin toxicity. Full article
(This article belongs to the Special Issue Saponins)
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Open AccessReview
Endocannabinoid System in the Airways
Molecules 2019, 24(24), 4626; https://doi.org/10.3390/molecules24244626 - 17 Dec 2019
Viewed by 416
Abstract
Cannabinoids and the mammalian endocannabinoid system is an important research area of interest and attracted many researchers because of their widespread biological effects. The significant immune-modulatory role of cannabinoids has suggested their therapeutic use in several inflammatory conditions. Airways are prone to environmental [...] Read more.
Cannabinoids and the mammalian endocannabinoid system is an important research area of interest and attracted many researchers because of their widespread biological effects. The significant immune-modulatory role of cannabinoids has suggested their therapeutic use in several inflammatory conditions. Airways are prone to environmental irritants and stimulants, and increased inflammation is an important process in most of the respiratory diseases. Therefore, the main strategies for treating airway diseases are suppression of inflammation and producing bronchodilation. The ability of cannabinoids to induce bronchodilation and modify inflammation indicates their importance for airway physiology and pathologies. In this review, the contribution of cannabinoids and the endocannabinoid system in the airways are discussed, and the existing data for their therapeutic use in airway diseases are presented. Full article
(This article belongs to the Special Issue Research on the Cannabinoid Receptors Pharmacology)
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Open AccessArticle
Blotting Paper-Derived Activated Porous Carbon/Reduced Graphene Oxide Composite Electrodes for Supercapacitor Applications
Molecules 2019, 24(24), 4625; https://doi.org/10.3390/molecules24244625 - 17 Dec 2019
Viewed by 300
Abstract
A facile strategy, engineered for low-cost mass production, to synthesize biomass-derived activated carbon/reduced graphene oxide composite electrodes (GBPCs) by one-pot carbonization of blotting papers containing graphene oxide (GO) and zinc chloride (ZnCl2) was proposed. Benefitting from the water absorption characteristic of [...] Read more.
A facile strategy, engineered for low-cost mass production, to synthesize biomass-derived activated carbon/reduced graphene oxide composite electrodes (GBPCs) by one-pot carbonization of blotting papers containing graphene oxide (GO) and zinc chloride (ZnCl2) was proposed. Benefitting from the water absorption characteristic of blotting papers in which the voids between the celluloses can easily absorb the GO/ZnCl2 solution, the chemical activation and reduction of GO can synchronously achieve via one-step carbonization process. As a result, the GBPCs deliver a large specific surface area to accumulate charge. Simultaneously, it provides high conductivity for electron transfer. The symmetric supercapacitor assembled with the optimal GBPCs in 6 M KOH electrolyte exhibits an excellent specific capacitance of 204 F g−1 (0.2 A g−1), outstanding rate capability of 100 F g−1 (20 A g−1). Meanwhile, it still keeps 90% of the initial specific capacitance over 10,000 cycles. The readily available raw material, effective chemical activation, simple rGO additive, and resulting electrochemical properties hold out the promise of hope to achieve low-cost, green, and large-scale production of practical activated carbon composite materials for high-efficiency energy storage applications. Full article
(This article belongs to the Special Issue Porous Carbon Materials and Their Applications)
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Open AccessCommunication
Thermal Decomposition Study on Li2O2 for Li2NiO2 Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries
Molecules 2019, 24(24), 4624; https://doi.org/10.3390/molecules24244624 - 17 Dec 2019
Viewed by 284
Abstract
Herein, thermal decomposition experiments of lithium peroxide (Li2O2) were performed to prepare a precursor (Li2O) for sacrificing cathode material, Li2NiO2. The Li2O2 was prepared by a hydrometallurgical reaction between LiOH·H [...] Read more.
Herein, thermal decomposition experiments of lithium peroxide (Li2O2) were performed to prepare a precursor (Li2O) for sacrificing cathode material, Li2NiO2. The Li2O2 was prepared by a hydrometallurgical reaction between LiOH·H2O and H2O2. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H2O, (2) decomposition of Li2O2, and (3) pyrolysis of the remaining anhydrous LiOH. This stepwise reaction was elucidated by thermal gravimetric and quantitative X-ray diffraction analyses. Furthermore, over-lithiated lithium nickel oxide (Li2NiO2) using our lithium precursor was synthesized, which exhibited a larger yield of 90.9% and higher irreversible capacity of 261 to 265 mAh g−1 than the sample prepared by commercially purchased Li2O (45.6% and 177 to 185 mAh g−1, respectively) due to optimal powder preparation conditions. Full article
(This article belongs to the Special Issue Next Generation Electrode Material)
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Open AccessArticle
Conversion of D-fructose to 5-acetoxymethyl-2-furfural Using Immobilized Lipase and Cation Exchange Resin
Molecules 2019, 24(24), 4623; https://doi.org/10.3390/molecules24244623 - 17 Dec 2019
Viewed by 272
Abstract
5-Acetoxymethyl-2-furfural (AMF) was prepared from D-fructose via 1,6-diacetylfructose (DAF) through a simple two-step reaction pathway. Immobilized enzyme (Novozym 435) was found to be the best enzymatic catalyst for the trans-esterification step (yielding 94.6% DAF). In the dehydration step, while soluble H2SO [...] Read more.
5-Acetoxymethyl-2-furfural (AMF) was prepared from D-fructose via 1,6-diacetylfructose (DAF) through a simple two-step reaction pathway. Immobilized enzyme (Novozym 435) was found to be the best enzymatic catalyst for the trans-esterification step (yielding 94.6% DAF). In the dehydration step, while soluble H2SO4 was found to be the best acidic catalyst (yielding 86.6% AMF), we opted to utilize heterogeneous cation exchange resin (Amberlyst 15) together with recyclable industrial solvents (1,4-dioxane) for a more sustainable AMF synthesis procedure. Although the total yield of AMF was a little lower, both the enzyme and the solid acid catalyst could be recycled for five cycles without a significant loss of activity, which has a major contribution to the cost-efficient aspect of the entire process. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle
Intramolecular and Metal-to-Molecule Charge Transfer Electronic Resonances in the Surface-Enhanced Raman Scattering of 1,4-Bis((E)-2-(pyridin-4-yl)vinyl)naphthalene
Molecules 2019, 24(24), 4622; https://doi.org/10.3390/molecules24244622 - 17 Dec 2019
Viewed by 318
Abstract
Electrochemical surface-enhanced Raman scattering (SERS) of the cruciform system 1,4-bis((E)-2-(pyridin-4-yl)vinyl)naphthalene (bpyvn) was recorded on nanostructured silver surfaces at different electrode potentials by using excitation laser lines of 785 and 514.5 nm. SERS relative intensities were analyzed on the basis of the [...] Read more.
Electrochemical surface-enhanced Raman scattering (SERS) of the cruciform system 1,4-bis((E)-2-(pyridin-4-yl)vinyl)naphthalene (bpyvn) was recorded on nanostructured silver surfaces at different electrode potentials by using excitation laser lines of 785 and 514.5 nm. SERS relative intensities were analyzed on the basis of the resonance Raman vibronic theory with the help of DFT calculations. The comparison between the experimental and the computed resonance Raman spectra calculated for the first five electronic states of the Ag2-bpyvn surface complex model points out that the selective enhancement of the SERS band recorded at about 1600 cm−1, under 785 nm excitation, is due to a resonant Raman process involving a photoexcited metal-to-molecule charge transfer state of the complex, while the enhancement of the 1570 cm−1 band using 514.5 nm excitation is due to an intramolecular π→π* electronic transition localized in the naphthalenyl framework, resulting in a case of surface-enhanced resonance Raman spectrum (SERRS). Thus, the enhancement of the SERS bands of bpyvn is controlled by a general chemical enhancement mechanism in which different resonance processes of the overall electronic structure of the metal-molecule system are involved. Full article
(This article belongs to the Special Issue Computational Spectroscopy 2019)
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Open AccessArticle
Analytical Methodology for Trace Determination of Propoxur and Fenitrothion Pesticide Residues by Decanoic Acid Modified Magnetic Nanoparticles
Molecules 2019, 24(24), 4621; https://doi.org/10.3390/molecules24244621 - 17 Dec 2019
Viewed by 302
Abstract
A sensitive, rapid, reliable, and easily applicable method based on magnetic solid phase extraction (MSPE) combined with HPLC-PDA was developed for monitoring propoxur (PRO) and fenitrothion (FEN) pesticides in environmental water samples. The effect of major experimental variables on the extraction efficiency of [...] Read more.
A sensitive, rapid, reliable, and easily applicable method based on magnetic solid phase extraction (MSPE) combined with HPLC-PDA was developed for monitoring propoxur (PRO) and fenitrothion (FEN) pesticides in environmental water samples. The effect of major experimental variables on the extraction efficiency of both the pesticides was investigated and optimized systematically. For this purpose, a new magnetic material containing decanoic acid on the surface of particles was synthesized and characterized by XRD, FT-IR, SEM, EDX, and TGA analysis in detail. The simultaneous determination of pesticide molecules was carried out by using a Luna Omega C18 column, isocratic elution of acetonitrile (ACN): Water (70:30 v/v) with a flow rate of 1.2 mL min−1. After MSPE, the linear range for pesticide molecules (r2 > 0.9982) was obtained in the range of 5–800 and 10–800 ng mL−1, respectively. The limit of detections (LOD) are 1.43 and 4.71 ng mL−1 for PRO and FEN, respectively while RSDs % are below 3.5%. The applicability of the proposed method in four different environmental samples were also investigated using a standard addition-recovery procedure. Average recoveries at two spiking levels were over the range of 91.3–102.5% with RSD < 5.0% (n = 3). The obtained results show that decanoic acid grafted magnetic particles in MSPE combined with HPLC-PDA is a fast and simple method for the determination of PRO and FEN in environmental water samples. Full article
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Open AccessReview
Nucleic Acid Nanoparticles at a Crossroads of Vaccines and Immunotherapies
Molecules 2019, 24(24), 4620; https://doi.org/10.3390/molecules24244620 - 17 Dec 2019
Viewed by 511
Abstract
Vaccines and immunotherapies involve a variety of technologies and act through different mechanisms to achieve a common goal, which is to optimize the immune response against an antigen. The antigen could be a molecule expressed on a pathogen (e.g., a disease-causing bacterium, a [...] Read more.
Vaccines and immunotherapies involve a variety of technologies and act through different mechanisms to achieve a common goal, which is to optimize the immune response against an antigen. The antigen could be a molecule expressed on a pathogen (e.g., a disease-causing bacterium, a virus or another microorganism), abnormal or damaged host cells (e.g., cancer cells), environmental agent (e.g., nicotine from a tobacco smoke), or an allergen (e.g., pollen or food protein). Immunogenic vaccines and therapies optimize the immune response to improve the eradication of the pathogen or damaged cells. In contrast, tolerogenic vaccines and therapies retrain or blunt the immune response to antigens, which are recognized by the immune system as harmful to the host. To optimize the immune response to either improve the immunogenicity or induce tolerance, researchers employ different routes of administration, antigen-delivery systems, and adjuvants. Nanocarriers and adjuvants are of particular interest to the fields of vaccines and immunotherapy as they allow for targeted delivery of the antigens and direct the immune response against these antigens in desirable direction (i.e., to either enhance immunogenicity or induce tolerance). Recently, nanoparticles gained particular attention as antigen carriers and adjuvants. This review focuses on a particular subclass of nanoparticles, which are made of nucleic acids, so-called nucleic acid nanoparticles or NANPs. Immunological properties of these novel materials and considerations for their clinical translation are discussed. Full article
(This article belongs to the Special Issue Nucleic Acid Nanobiology for Drug Delivery and Immunotherapy)
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Open AccessEditorial
Editorial for Special Issue: Enzyme Immobilization and Its Applications
Molecules 2019, 24(24), 4619; https://doi.org/10.3390/molecules24244619 - 17 Dec 2019
Viewed by 237
Abstract
Modern chemistry demands cleaner processes, for which more efficient catalysts are required [...] Full article
(This article belongs to the Special Issue Enzyme Immobilization and Its Applications)
Open AccessArticle
Ultrasound-Assisted Solvent Extraction of a Porous Membrane Packed Sample for the Determination of Tobacco-Specific Nitrosamines in the Replacement Liquids for E-Cigarettes
Molecules 2019, 24(24), 4618; https://doi.org/10.3390/molecules24244618 - 17 Dec 2019
Viewed by 285
Abstract
The content of tobacco-specific nitrosamines (TSNAs) possessing carcinogenic properties has been an important area of research since replacement liquids were introduced for e-cigarettes. A method for determining N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosoanatabine (NAT), and N′-nitrosoanabasine (NAB) in replacement liquids for [...] Read more.
The content of tobacco-specific nitrosamines (TSNAs) possessing carcinogenic properties has been an important area of research since replacement liquids were introduced for e-cigarettes. A method for determining N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosoanatabine (NAT), and N′-nitrosoanabasine (NAB) in replacement liquids for electronic cigarettes was developed using liquid chromatography–tandem mass spectrometry with electrospray ionisation (HPLC-ESI-MS/MS) in the multiple reaction monitoring mode. The sample preparation of replacement liquids was accomplished via the ultrasound-assisted solvent extraction of a porous membrane packed sample. The sample preparation proved to be successful in extracting the analytes, with recoveries from 87% to 105%, with coefficients of variation < 4.9%. Moreover, the linearity and limits of detection and quantitation (LOD, LOQ), together with repeatability and accuracy, were determined for the developed method. The proposed sample preparation and developed chromatographic method were successfully applied to the determination of TSNAs in 9 replacement liquid samples. The NNK and NNN were found to be most frequently detected (89 and 67%, respectively), with concentration ranges from 1.2–54.3 ng/mL and 4.1–30.2 ng/mL, respectively, while NAT was detected with frequency of 22% with range 1.7–2.5 ng/mL and NAB were found to be below the LOD in all samples. Full article
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Open AccessReview
Advances in the Analysis of Veterinary Drug Residues in Food Matrices by Capillary Electrophoresis Techniques
Molecules 2019, 24(24), 4617; https://doi.org/10.3390/molecules24244617 - 17 Dec 2019
Viewed by 289
Abstract
In the last years, the European Commission has adopted restrictive directives on food quality and safety in order to protect animal and human health. Veterinary drugs represent an important risk and the need to have sensitive and fast analytical techniques to detect and [...] Read more.
In the last years, the European Commission has adopted restrictive directives on food quality and safety in order to protect animal and human health. Veterinary drugs represent an important risk and the need to have sensitive and fast analytical techniques to detect and quantify them has become mandatory. Over the years, the availability of different modes, interfaces, and formats has improved the versatility, sensitivity, and speed of capillary electrophoresis (CE) techniques. Thus, CE represents a powerful tool for the analysis of a large variety of food matrices and food-related molecules with important applications in food quality and safety. This review focuses the attention of CE applications over the last decade on the detection of different classes of drugs (used as additives in animal food or present as contaminants in food products) with a potential risk for animal and human health. In addition, considering that the different sample preparation procedures have strongly contributed to CE sensitivity and versatility, the most advanced sample pre-concentration techniques are discussed here. Full article
(This article belongs to the Special Issue Food and Drug Analysis)
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Open AccessArticle
Antibacterial Isoquinoline Alkaloids from the Fungus Penicillium Spathulatum Em19
Molecules 2019, 24(24), 4616; https://doi.org/10.3390/molecules24244616 - 17 Dec 2019
Viewed by 358
Abstract
In the search for new microbial antibacterial secondary metabolites, two new compounds (1 and 2) were isolated from culture broths of Penicillium spathulatum Em19. Structure determination by nuclear magnetic resonance and mass spectrometry identified the compounds as 6,7-dihydroxy-5,10-dihydropyrrolo[1,2-b]isoquinoline-3-carboxylic acid [...] Read more.
In the search for new microbial antibacterial secondary metabolites, two new compounds (1 and 2) were isolated from culture broths of Penicillium spathulatum Em19. Structure determination by nuclear magnetic resonance and mass spectrometry identified the compounds as 6,7-dihydroxy-5,10-dihydropyrrolo[1,2-b]isoquinoline-3-carboxylic acid (1, spathullin A) and 5,10-dihydropyrrolo[1,2-b]isoquinoline-6,7-diol (2, spathullin B). The two compounds displayed activity against both Gram-negative and -positive bacteria, including Escherichia coli, Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumonia, Pseudomonas aeruginosa, and Staphylococcus aureus. Compound 2 was more potent than 1 against all tested pathogens, with minimal inhibitory concentrations down to 1 µg/mL (5 µM) against S. aureus, but 2 was also more cytotoxic than 1 (50% inhibitory concentrations 112 and 11 µM for compounds 1 and 2, respectively, towards Huh7 cells). Based on stable isotope labelling experiments and a literature comparison, the biosynthesis of 1 was suggested to proceed from cysteine, tyrosine and methionine via a non-ribosomal peptides synthase like enzyme complex, whereas compound 2 was formed spontaneously from 1 by decarboxylation. Compound 1 was also easily oxidized to the 1,2-benzoquinone 3. Due to the instability of compound 1 and the toxicity of 2, the compounds are of low interest as possible future antibacterial drugs. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle
Vitamin B Complex Treatment Attenuates Local Inflammation after Peripheral Nerve Injury
Molecules 2019, 24(24), 4615; https://doi.org/10.3390/molecules24244615 - 17 Dec 2019
Viewed by 727
Abstract
Peripheral nerve injury (PNI) leads to a series of cellular and molecular events necessary for axon regeneration and reinnervation of target tissues, among which inflammation is crucial for the orchestration of all these processes. Macrophage activation underlies the pathogenesis of PNI and is [...] Read more.
Peripheral nerve injury (PNI) leads to a series of cellular and molecular events necessary for axon regeneration and reinnervation of target tissues, among which inflammation is crucial for the orchestration of all these processes. Macrophage activation underlies the pathogenesis of PNI and is characterized by morphological/phenotype transformation from proinflammatory (M1) to an anti-inflammatory (M2) type with different functions in the inflammatory and reparative process. The aim of this study was to evaluate influence of the vitamin B (B1, B2, B3, B5, B6, and B12) complex on the process of neuroinflammation that is in part regulated by l-type CaV1.2 calcium channels. A controlled transection of the motor branch of the femoral peripheral nerve was used as an experimental model. Animals were sacrificed after 1, 3, 7, and 14 injections of vitamin B complex. Isolated nerves were used for immunofluorescence analysis. Treatment with vitamin B complex decreased expression of proinflammatory and increased expression of anti-inflammatory cytokines, thus contributing to the resolution of neuroinflammation. In parallel, B vitamins decreased the number of M1 macrophages that expressed the CaV1.2 channel, and increased the number of M2 macrophages that expressed this channel, suggesting their role in M1/M2 transition after PNI. In conclusion, B vitamins had the potential for treatment of neuroinflammation and neuroregeneration and thereby might be an effective therapy for PNI in humans. Full article
(This article belongs to the Special Issue Natural Products for Neurodegenerative Diseases)
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Open AccessArticle
Polyphenol Extracts from Three Colombian Passifloras (Passion Fruits) Prevent Inflammation-Induced Barrier Dysfunction of Caco-2 Cells
Molecules 2019, 24(24), 4614; https://doi.org/10.3390/molecules24244614 - 17 Dec 2019
Viewed by 329
Abstract
Chronic intestinal inflammation is associated with pathophysiology of obesity and inflammatory bowel diseases. Gastrointestinal inflammation increases barrier dysfunction exacerbating the immune response and perpetuating chronic inflammation. Anti-inflammatory flavonoids may prevent this intestinal barrier dysfunction. The purpose of this study was to evaluate the [...] Read more.
Chronic intestinal inflammation is associated with pathophysiology of obesity and inflammatory bowel diseases. Gastrointestinal inflammation increases barrier dysfunction exacerbating the immune response and perpetuating chronic inflammation. Anti-inflammatory flavonoids may prevent this intestinal barrier dysfunction. The purpose of this study was to evaluate the polyphenol composition of Colombian Passiflora edulis var. Flavicarpa (Maracuyá), Passiflora edulis var. Sims (Gulupa), and Passiflora ligularis var. Juss (Granadilla) (passion fruits) and to evaluate their ability to inhibit disruption of intestinal barrier dysfunction of Caco-2 (colorectal adenocarcinoma) cells by an inflammatory cocktail (IC). Polyphenols (flavan-3-ols, phenolic acids, flavonols), xanthenes, and a terpene were identified in passion fruits. Cyanidin 3-rutinoside, (+)-catechin and ferulic acid were the most abundant phenolics in P. edulis var. Flavicarpa, P. edulis var. Sims, and P. ligularis var. Juss, respectively. Fruit extracts prevented loss of transepithelial electrical resistance in Caco-2 cells treated with the IC. Among the extracts, P. ligularis var. Juss was most effective at maintaining Caco-2 transepithelial electrical resistance (TEER) with ~73% relative to the IC-treated cells with about 43% of initial TEER values. This fruit had cyanidin-3-rutinoside, (+)-catechin, (−)-epicatechin, and ferulic acid in its phenolic profile. Results of this work support the hypothesis that consumption of passion fruit extracts could benefit intestinal health. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues II)
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Open AccessArticle
Valorization of Lignin as an Immobilizing Agent for Bioinoculant Production using Azospirillum brasilense as a Model Bacteria
Molecules 2019, 24(24), 4613; https://doi.org/10.3390/molecules24244613 - 17 Dec 2019
Viewed by 232
Abstract
Plant growth-promoting bacteria (PGPB) have been largely considered as beneficial in harsh and limiting environments given their effects on alleviating plant stress. For practical applications, most of the PGPB are prepared in immobilization matrices to improve the stability and benefits of bacteria. Despite [...] Read more.
Plant growth-promoting bacteria (PGPB) have been largely considered as beneficial in harsh and limiting environments given their effects on alleviating plant stress. For practical applications, most of the PGPB are prepared in immobilization matrices to improve the stability and benefits of bacteria. Despite the long list of immobilizing agents/carriers tested to date, a long list of desired requirements is yet to be achieved. Here, lignin stands as a scarcely tested immobilizer for bioinoculants with great potential for this purpose. The aim of this work was to demonstrate the feasibility of lignin as a carrier of the nitrogen-fixing Azospirillum brasilense. These bacteria were cultured in liquid media with recovered organosolv lignin added for bacterial immobilization. Then, lignin was recovered and the immobilized biomass was quantified gravimetrically by DNA extraction and serial dilution plating. Fluorescent microscopy as well as Congo red agar plating showed the immobilization of the bacterial cells in the lignin matrix and crystal violet dyeing showed the biofilms formation in lignin particles. A high number of cells were counted per gram of dried lignin. Lignin can be readily used as low-cost, health-safe bioinoculant carrier to be used in soil and agricultural applications. Full article
(This article belongs to the Special Issue Lignin—Chemistry and Materials: Past, Present and Future)
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Open AccessArticle
Synthesis and Structural Determination of New Brassinosteroid 24-Nor-5α-Cholane Type Analogs
Molecules 2019, 24(24), 4612; https://doi.org/10.3390/molecules24244612 - 17 Dec 2019
Viewed by 276
Abstract
Natural brassinosteroids possess a 22R, 23R configuration that appears essential for biological activity. It is, therefore, interesting to elucidate if the activity of brassinosteroids with a short side chain depends on the C22 configuration. Herein, we describe the synthesis of [...] Read more.
Natural brassinosteroids possess a 22R, 23R configuration that appears essential for biological activity. It is, therefore, interesting to elucidate if the activity of brassinosteroids with a short side chain depends on the C22 configuration. Herein, we describe the synthesis of new brassinosteroids analogs with 24-norcholane type of side chain and R configuration at C22. The initial reaction is the dihydroxylation of a terminal olefin that leads to S/R epimers. Three different methods were tested in order to evaluate the obtained S/R ratio and the reaction yields. The results indicate that Upjohn dihydroxylation is the most selective reaction giving a 1.0:0.24 S/R ratio, whereas a Sharpless reaction leads to a mixture of 1.0:0.90 S/R with 95% yield. Using the latter mixture and following a previous reported method, benzoylated derivatives and both S and R brassinosteroids analogs were synthesized. All synthesized compounds were completely characterized by NMR spectroscopy, and HRMS of new compounds are also given. In conclusion, a synthetic route for preparation of new analogs of brassinosteroids of 24-norcholane type and R configuration at C22 were described. It is expected that this will help to elucidate if a configuration at C22 is a structural requirement for hormonal growth activity in plants. Full article
(This article belongs to the Section Organic Chemistry)
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Open AccessArticle
Lignin-Only Polymeric Materials Based on Unmethylated Unfractionated Kraft and Ball-Milled Lignins Surpass Polyethylene and Polystyrene in Tensile Strength
Molecules 2019, 24(24), 4611; https://doi.org/10.3390/molecules24244611 - 17 Dec 2019
Viewed by 311
Abstract
Functional polymeric materials composed solely of lignin preparations appeared only very recently. A gradual paradigm shift spanning 56 years has revealed how lignin–lignin blends can upgrade the performance of 100 wt% lignin-based plastics. The view, first espoused in 1960, that lignin macromolecules are [...] Read more.
Functional polymeric materials composed solely of lignin preparations appeared only very recently. A gradual paradigm shift spanning 56 years has revealed how lignin–lignin blends can upgrade the performance of 100 wt% lignin-based plastics. The view, first espoused in 1960, that lignin macromolecules are crosslinked reduces the plausibility of creating functional polymeric materials that are composed only of lignin preparations. Lignin-based materials would be much weaker mechanically if interstices remain in significant numbers between adjoining macromolecular structures that consist of rigid crosslinked chains. In 1982, random-coil features in the hydrodynamic character of kraft lignin (KL) components were evident from ultracentrifugal sedimentation equilibrium studies of their SEC behavior. In 1997, it was recognized that the macromolecular species in plastics with 85 wt% levels of KL are associated complexes rather than individual components. Finally, in 2016, the first polymeric material composed entirely of ball-milled softwood lignin (BML) was found to support a tensile strength above polyethylene. Except in its molecular weight, the BML was similar in structure to the native biopolymer. It was composed of associated lignin complexes, each with aromatic rings arranged in two domains. The inner domain maintains structural integrity largely through noncovalent interactions between cofacially-offset aromatic rings; the peripheral domain contains a higher proportion of edge-on aromatic-ring arrangements. Interdigitation between peripheral domains in adjoining complexes creates material continuity during casting. By interacting at low concentrations with the peripheral domains, non-lignin blend components can improve the tensile strengths of BML-based plastics to values well beyond those seen in polystyrene. The KL-based plastics are weaker because the peripheral domains of adjoining complexes are less capable of interdigitation than those of BML. Blending with 5 wt% 1,8-dinitroanthraquinone results in a tensile strength above that of polyethylene. Analogous effects can be achieved with 10 wt% maple γ-valerolactone (GVL) lignin which, with a structure close to the native biopolymer, imparts some native character to the peripheral domains of the KL complexes. Comparable enhancements in the behavior of BML complexes upon blending with 10 wt% ball-milled corn-stover lignin (BMCSL) result in lignin-only polymeric materials with tensile strengths well beyond polystyrene. Full article
(This article belongs to the Special Issue Lignin—Chemistry and Materials: Past, Present and Future)
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Open AccessCorrection
Correction: Kumar, M.R., et al. Characterization of Polysulfides, Polysulfanes, and Other Unique Species in the Reaction between GSNO and H2S. Molecules 2019, 24, 3090
Molecules 2019, 24(24), 4610; https://doi.org/10.3390/molecules24244610 - 16 Dec 2019
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Abstract
The authors wish to make the following corrections to this paper [...] Full article
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Open AccessArticle
Quantitative Analysis of Cold Stress Inducing Lipidomic Changes in Shewanella putrefaciens Using UHPLC-ESI-MS/MS
Molecules 2019, 24(24), 4609; https://doi.org/10.3390/molecules24244609 - 16 Dec 2019
Viewed by 370
Abstract
Shewanella putrefaciens is a well-known specific spoilage organism (SSO) and cold-tolerant microorganism in refrigerated fresh marine fish. Cold-adapted mechanism includes increased fluidity of lipid membranes by the ability to finely adjust lipids composition. In the present study, the lipid profile of S. putrefaciens [...] Read more.
Shewanella putrefaciens is a well-known specific spoilage organism (SSO) and cold-tolerant microorganism in refrigerated fresh marine fish. Cold-adapted mechanism includes increased fluidity of lipid membranes by the ability to finely adjust lipids composition. In the present study, the lipid profile of S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C was explored using ultra-high-pressure liquid chromatography/electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) to discuss the effect of lipid composition on cold-adapted tolerance. Lipidomic analysis detected a total of 27 lipid classes and 606 lipid molecular species in S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C. S. putrefaciens cultivated at 30 °C (SP-30) had significantly higher content of glycerolipids, sphingolipids, saccharolipids, and fatty acids compared with that at 0 °C (SP-0); however, the lower content of phospholipids (13.97%) was also found in SP-30. PE (30:0), PE (15:0/15:0), PE (31:0), PA (33:1), PE (32:1), PE (33:1), PE (25:0), PC (22:0), PE (29:0), PE (34:1), dMePE (15:0/16:1), PE (31:1), dMePE (15:1/15:0), PG (34:2), and PC (11:0/11:0) were identified as the most abundant lipid molecular species in S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C. The increase of PG content contributes to the construction of membrane lipid bilayer and successfully maintains membrane integrity under cold stress. S. putrefaciens cultivated at low temperature significantly increased the total unsaturated liquid contents but decreased the content of saturated liquid contents. Full article
(This article belongs to the Special Issue Mass Spectrometry Based Lipidomics)
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Open AccessArticle
Extraction and Determination of Polar Bioactive Compounds from Alfalfa (Medicago sativa L.) Using Supercritical Techniques
Molecules 2019, 24(24), 4608; https://doi.org/10.3390/molecules24244608 - 16 Dec 2019
Viewed by 339
Abstract
The aim of this research was to select parameters for supercritical extraction with CO2 of Medicago sativa L., considered as functional food, in quarter-technical plant, providing the highest concentration of bioactive polar constituents and simultaneously maintaining the highest efficiency of the process. [...] Read more.
The aim of this research was to select parameters for supercritical extraction with CO2 of Medicago sativa L., considered as functional food, in quarter-technical plant, providing the highest concentration of bioactive polar constituents and simultaneously maintaining the highest efficiency of the process. For the purpose of optimization, mathematical statistics was used. Qualitative analysis of products was performed with supercritical fluid chromatography (SFC). The SFC analysis revealed a proper separation of flavonoids and phenolics acids for dedicated TFC and TPC optimal parameters. The obtained results have proved that it is a possibility to extract polar compounds with non-polar solvent under higher values of pressure and temperature and to enrich product with desired group of bioactive compounds with proper optimization. The proposed extraction technique allows to obtain on an industrial scale, using an environmentally friendly solvent, a preparation rich in biologically active nutrients that can be implemented in the cosmetics, pharmaceutical and food industries. Full article
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Open AccessArticle
Novel Synthetic Approaches for Bisnaphthalimidopropyl (BNIP) Derivatives as Potential Anti-Parasitic Agents for the Treatment of Leishmaniasis
Molecules 2019, 24(24), 4607; https://doi.org/10.3390/molecules24244607 - 16 Dec 2019
Viewed by 287
Abstract
Leishmaniasis is a neglected parasitic disease that is widely seen in more than 60 countries worldwide, including Turkey and its subcontinental region. There are several chemotherapy agents for the treatment of leishmaniasis, including pentavalent antimonials—i.e., sodium stibogluconate (Pentostan) and meglumine antimoniate (Glucantim), pentamidine, [...] Read more.
Leishmaniasis is a neglected parasitic disease that is widely seen in more than 60 countries worldwide, including Turkey and its subcontinental region. There are several chemotherapy agents for the treatment of leishmaniasis, including pentavalent antimonials—i.e., sodium stibogluconate (Pentostan) and meglumine antimoniate (Glucantim), pentamidine, conventional amphotericin B deoxycholate, miltefosine, paramomycin (aminosidine), and liposomal amphotericin B. However, these therapies are usually unsatisfactory due to dose-limiting toxicity issues and limited efficacy. Furthermore, resistance gained by parasites endangers future success of these therapies. Addressing these issues, the development of novel drugs with high efficacy has a vital importance. Latest studies have shown that bisnaphthalimidopropyl (BNIP) derivatives display high activity against Leishmaniasis parasites by selectively targeting parasitic sirtuin proteins and interacting with DNA. Despite the promising anti-parasitic activity, the low solubility and toxicity on human macrophages are the limitations to overcome. This study describes the new synthesis strategies for existing—i.e., BNIPDaoct and BNIPDanon—and novel BNIP derivatives differing in respect of their alkyl linker chain lengths. The new synthesis approach provides certain advantages compared to its existing alternatives reported in the literature. The proposed methodology does not only decrease the number of synthesis steps and production time of BNIPDaoct and BNIPDanon, but also provides higher yields, thereby making the synthesis highly cost-effective. Full article
(This article belongs to the Special Issue Application of Organic Synthesis to Bioactive Compounds)
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Open AccessArticle
Highly Efficient Aggregation-Induced Room-Temperature Phosphorescence with Extremely Large Stokes Shift Emitted from Trinuclear Gold(I) Complex Crystals
Molecules 2019, 24(24), 4606; https://doi.org/10.3390/molecules24244606 - 16 Dec 2019
Viewed by 258
Abstract
Highly efficient (≈75% quantum yield), aggregation-induced phosphorescence is reported. The phosphorescence is emitted at room temperature and in the presence of air from crystals of trinuclear Au(I) complexes, accompanied by an extremely large Stokes shift of 2.2 × 104 cm−1 (450 [...] Read more.
Highly efficient (≈75% quantum yield), aggregation-induced phosphorescence is reported. The phosphorescence is emitted at room temperature and in the presence of air from crystals of trinuclear Au(I) complexes, accompanied by an extremely large Stokes shift of 2.2 × 104 cm−1 (450 nm). The mechanism of the aggregation-induced room-temperature phosphorescence from the Au complex crystals was investigated in terms of the crystal packing structure and the primary structure of the molecules. It was found that two kinds of intermolecular interactions occurred in the crystals, and that these multiple dual-mode intermolecular interactions in the crystals play a crucial role in the in-air room-temperature phosphorescence of the trinuclear Au(I) complexes. Full article
(This article belongs to the Special Issue Aggregation-Induced Emission: Materials and Applications)
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Open AccessFeature PaperReview
Extraction of Metal Ions with Metal–Organic Frameworks
Molecules 2019, 24(24), 4605; https://doi.org/10.3390/molecules24244605 - 16 Dec 2019
Viewed by 354
Abstract
Metal–organic frameworks (MOFs) are crystalline porous materials composed of metal ions or clusters coordinated with organic linkers. Due to their extraordinary properties such as high porosity with homogeneous and tunable in size pores/cages, as well as high thermal and chemical stability, MOFs have [...] Read more.
Metal–organic frameworks (MOFs) are crystalline porous materials composed of metal ions or clusters coordinated with organic linkers. Due to their extraordinary properties such as high porosity with homogeneous and tunable in size pores/cages, as well as high thermal and chemical stability, MOFs have gained attention in diverse analytical applications. MOFs have been coupled with a wide variety of extraction techniques including solid-phase extraction (SPE), dispersive solid-phase extraction (d-SPE), and magnetic solid-phase extraction (MSPE) for the extraction and preconcentration of metal ions from complex matrices. The low concentration levels of metal ions in real samples including food samples, environmental samples, and biological samples, as well as the increased number of potentially interfering ions, make the determination of trace levels of metal ions still challenging. A wide variety of MOF materials have been employed for the extraction of metals from sample matrices prior to their determination with spectrometric techniques. Full article
(This article belongs to the Special Issue Metal Organic Frameworks: Synthesis and Application)
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Open AccessReview
Glycan Mimetics from Natural Products: New Therapeutic Opportunities for Neurodegenerative Disease
Molecules 2019, 24(24), 4604; https://doi.org/10.3390/molecules24244604 - 16 Dec 2019
Viewed by 442
Abstract
Neurodegenerative diseases (NDs) affect millions of people worldwide. Characterized by the functional loss and death of neurons, NDs lead to symptoms (dementia and seizures) that affect the daily lives of patients. In spite of extensive research into NDs, the number of approved drugs [...] Read more.
Neurodegenerative diseases (NDs) affect millions of people worldwide. Characterized by the functional loss and death of neurons, NDs lead to symptoms (dementia and seizures) that affect the daily lives of patients. In spite of extensive research into NDs, the number of approved drugs for their treatment remains limited. There is therefore an urgent need to develop new approaches for the prevention and treatment of NDs. Glycans (carbohydrate chains) are ubiquitous, abundant, and structural complex natural biopolymers. Glycans often covalently attach to proteins and lipids to regulate cellular recognition, adhesion, and signaling. The importance of glycans in both the developing and mature nervous system is well characterized. Moreover, glycan dysregulation has been observed in NDs such as Alzheimer’s disease (AD), Huntington’s disease (HD), Parkinson’s disease (PD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS). Therefore, glycans are promising but underexploited therapeutic targets. In this review, we summarize the current understanding of glycans in NDs. We also discuss a number of natural products that functionally mimic glycans to protect neurons, which therefore represent promising new therapeutic approaches for patients with NDs. Full article
(This article belongs to the Special Issue Natural Products for Neurodegenerative Diseases)
Open AccessArticle
Study of the Variation of Phenolic Acid and Flavonoid Content from Fresh Artemisiae argyi Folium to Moxa Wool
Molecules 2019, 24(24), 4603; https://doi.org/10.3390/molecules24244603 - 16 Dec 2019
Viewed by 283
Abstract
Artemisiae argyi Folium (AAF) is a popular herbal medicine that is always employed in moxa sticks and by oral dosage in clinical use. Less attention has been paid to nonvolatile compounds as active compounds, such as phenolic acids and flavonoids. In this study, [...] Read more.
Artemisiae argyi Folium (AAF) is a popular herbal medicine that is always employed in moxa sticks and by oral dosage in clinical use. Less attention has been paid to nonvolatile compounds as active compounds, such as phenolic acids and flavonoids. In this study, we focused on the variation rule of phenolic acids and flavonoids in the various transformations of Artemisiae argyi Folium. Using the established ultra-performance liquid chromatography (UPLC) method with an excellent methodology under “spider-web” mode, six phenolic acids and three flavonoids were simultaneously quantified in fresh and drying Artemisiae argyi Folium as well as in moxa wool and residue. Some interesting phenomena about the variation rule of phenolic acids and flavonoids were uncovered. First, a sharp increase was observed in the detected compounds’ content as the moisture gradually decreased, when fresh Artemisiae argyi Folium was exposed to sunlight and ambient or high temperature. Nevertheless, the increased phenolic acids were subjected to high temperature, leading to obvious degradation under oven-drying (60 °C and 80 °C). Second, a wide content distribution was revealed for the detected compounds in Artemisiae argyi Folium from different habitats, especially rutin, caffeic acid, chlorogenic acid, jaceosidin, eupatilin, and cryptochlorogenic acid. Third, accompanied by the elevated ratio of Artemisiae argyi Folium/moxa wool, the detected compounds conspicuously decreased in moxa wool and the correspondingly removed powder as residue. Importantly, a greater variation was found in moxa wool. Our findings contribute to the optimization of the drying process, the quality evaluation of the various transformations of Artemisiae argyi Folium, and the distinctive characterization of moxa wool produced at different ratios of Artemisiae argyi Folium/moxa wool. Full article
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Open AccessArticle
Preparative Separation of Alkaloids from Stem of Euchresta tubulosa Dunn. by High-Speed Counter-Current Chromatography Using Stepwise Elution
Molecules 2019, 24(24), 4602; https://doi.org/10.3390/molecules24244602 - 16 Dec 2019
Viewed by 285
Abstract
Euchresta tubulosa Dunn. is a Chinese herbal medicine with biological activity, but there are few studies on its components at present. Alkaloids in the stem of Euchresta tubulosa Dunn. were isolated and purified by high-speed counter-current chromatography (HSCCC) using stepwise elution. First of [...] Read more.
Euchresta tubulosa Dunn. is a Chinese herbal medicine with biological activity, but there are few studies on its components at present. Alkaloids in the stem of Euchresta tubulosa Dunn. were isolated and purified by high-speed counter-current chromatography (HSCCC) using stepwise elution. First of all, liquid-liquid extraction (methylene chloride-methanol-water, 5:1:4, v/v) was used for the preliminary enrichment. According to the partition coefficient (K) of a target compound in a series of different two-phase solvents, the final result was that carbon tetrachloride-methylene chloride-methanol-water (2:3:3:2, v/v) (1) and methylene chloride-methanol-water (5:3:2, v/v) (2) were suitable for the HSCCC using stepwise elution. As a result, the purity was all higher than 93% and matrine (1), oxymatrine (2), N-formyl cytisine (3), and N-acetyl cytisine (4) can be eluted at one time by this mode. Cytisine-type alkaloids were isolated for the first time in this plant. Finally, the applicability of the mode was verified. Full article
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