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Molecules, Volume 17, Issue 11 (November 2012), Pages 12469-13703

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Open AccessArticle On the Catalytic Effect of Water in the Intramolecular Diels–Alder Reaction of Quinone Systems: A Theoretical Study
Molecules 2012, 17(11), 13687-13703; https://doi.org/10.3390/molecules171113687
Received: 18 September 2012 / Revised: 8 November 2012 / Accepted: 12 November 2012 / Published: 20 November 2012
Cited by 11 | PDF Full-text (454 KB) | Supplementary Files
Abstract
The mechanism of the intramolecular Diels–Alder (IMDA) reaction of benzoquinone 1, in the absence and in the presence of three water molecules, 1w, has been studied by means of density functional theory (DFT) methods, using the M05-2X and B3LYP functionals for exploration of
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The mechanism of the intramolecular Diels–Alder (IMDA) reaction of benzoquinone 1, in the absence and in the presence of three water molecules, 1w, has been studied by means of density functional theory (DFT) methods, using the M05-2X and B3LYP functionals for exploration of the potential energy surface (PES). The energy and geometrical results obtained are complemented with a population analysis using the NBO method, and an analysis based on the global, local and group electrophilicity and nucleophilicity indices. Both implicit and explicit solvation emphasize the increase of the polarity of the reaction and the reduction of activation free energies associated with the transition states (TSs) of this IMDA process. These results are reinforced by the analysis of the reactivity indices derived from the conceptual DFT, which show that the increase of the electrophilicity of the quinone framework by the hydrogen-bond formation correctly explains the high polar character of this intramolecular process. Large polarization at the TSs promoted by hydrogen-bonds and implicit solvation by water together with a high electrophilicity-nucleophilicity difference consistently explains the catalytic effects of water molecules. Full article
(This article belongs to the Special Issue Diels-Alder Reaction)
Open AccessArticle Chemical Constituents from Stem Bark and Roots of Clausena anisata
Molecules 2012, 17(11), 13673-13686; https://doi.org/10.3390/molecules171113673
Received: 11 October 2012 / Revised: 14 November 2012 / Accepted: 15 November 2012 / Published: 20 November 2012
Cited by 18 | PDF Full-text (233 KB)
Abstract
Phytochemical investigations on the stem bark and roots of the tropical shrub Clausena anisata led to the isolation and characterization three carbazole alkaloids: girinimbine, murrayamine-A and ekeberginine; two peptide derivatives: aurantiamide acetate and N-benzoyl-l-phenylalaninyl-N-benzoyl-l-phenylalaninate; and a mixture of two phytosterols:
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Phytochemical investigations on the stem bark and roots of the tropical shrub Clausena anisata led to the isolation and characterization three carbazole alkaloids: girinimbine, murrayamine-A and ekeberginine; two peptide derivatives: aurantiamide acetate and N-benzoyl-l-phenylalaninyl-N-benzoyl-l-phenylalaninate; and a mixture of two phytosterols: sitosterol and stigmasterol. The structures of these compounds were established by nuclear magnetic resonance (1H-NMR, 13C-NMR, COSY, HSQC, HMQC, HMBC and NOESY) spectroscopy and electrospray ionization mass spectrometry (MS). Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle Beckmann Rearrangement of Ketoximes Induced by Phenyl Dichlorophosphate at Ambient Temperature
Molecules 2012, 17(11), 13662-13672; https://doi.org/10.3390/molecules171113662
Received: 21 September 2012 / Revised: 12 November 2012 / Accepted: 14 November 2012 / Published: 20 November 2012
Cited by 6 | PDF Full-text (232 KB)
Abstract
Upon treatment with phenyl dichlorophosphate (PhOP=OCl2) in acetonitrile at ambient temperature, a variety of ketoximes underwent a Beckmann rearrangement in an effective manner to afford the corresponding amides in moderate to high yields. Full article
(This article belongs to the Section Organic Chemistry)
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Open AccessArticle Clerodendranoic Acid, a New Phenolic Acid from Clerodendranthus spicatus
Molecules 2012, 17(11), 13656-13661; https://doi.org/10.3390/molecules171113656
Received: 1 November 2012 / Revised: 13 November 2012 / Accepted: 14 November 2012 / Published: 19 November 2012
Cited by 7 | PDF Full-text (216 KB)
Abstract
Phenolic acid derivatives are typical constituents of Clerodendranthus spicatus which were considered to the active principles of this medicinal plant. These chemical constituents with their interesting frameworks and biological significance attracted our attention. As part of our ongoing chemical investigation of C. spicatus
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Phenolic acid derivatives are typical constituents of Clerodendranthus spicatus which were considered to the active principles of this medicinal plant. These chemical constituents with their interesting frameworks and biological significance attracted our attention. As part of our ongoing chemical investigation of C. spicatus using various column chromatography techniques, a new phenolic compound, named clerodendranoic acid (1), was isolated from the aerial parts of C. spicatus together with five known ones, including rosmarinic acid (2), methyl rosmarinate (3), caffeic acid (4), methyl caffeate (5), ethyl caffeate (6). Their structures, including stereochemical configurations, were completely established by extensive spectroscopic methods, mainly inclvolving 1D, 2D NMR, as well as HRESIMS. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle Synthesis and Antimicrobial Activity of Some New Pyrimidinone and Oxazinone Derivatives Fused with Thiophene Rings Using 2-Chloro-6-ethoxy-4-acetylpyridine as Starting Material
Molecules 2012, 17(11), 13642-13655; https://doi.org/10.3390/molecules171113642
Received: 19 September 2012 / Revised: 9 November 2012 / Accepted: 12 November 2012 / Published: 19 November 2012
Cited by 21 | PDF Full-text (218 KB)
Abstract
A series of pyridines, pyrimidinones, oxazinones and their derivatives were synthesized as antimicrobial agents using citrazinic acid (2,6-dihydroxyisonicotinic acid) as a starting material. α,β-Unsaturated ketones 3ac were condensed with cyanothio-acetamide in the presence of ammonium acetate to give 2-cyanopyridinethiones 4a
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A series of pyridines, pyrimidinones, oxazinones and their derivatives were synthesized as antimicrobial agents using citrazinic acid (2,6-dihydroxyisonicotinic acid) as a starting material. α,β-Unsaturated ketones 3ac were condensed with cyanothio-acetamide in the presence of ammonium acetate to give 2-cyanopyridinethiones 4ac, which were reacted with ethyl chloroacetate to yield the corresponding cyano esters 5ac. The esters 5ac were cyclized by action of sodium methoxide to aminoesters 6ac, which were aminolyzed with ammonia to corresponding aminoamide derivatives 7a-c. Also, the esters 6ac were hydrolyzed with NaOH to the corresponding sodium salt 8ac, which were treated with acetic anhydride to afford 2-methyloxazinones 9ac. The latter compounds were treated with ammonium acetate to afford 2-methylpyrimidinones 10ac, followed by methylation with methyl iodide to yield 2,3-dimethyl-pyrimidinones 11ac. The antimicrobial screening showed that many of these compounds have good antibacterial and antifungal activities comparable to streptomycin and fusidic acid used as reference drugs. Full article
Open AccessArticle Monoterpenoid Indole Alkaloids from Alstonia yunnanensis and Their Cytotoxic and Anti-inflammatory Activities
Molecules 2012, 17(11), 13631-13641; https://doi.org/10.3390/molecules171113631
Received: 12 October 2012 / Revised: 8 November 2012 / Accepted: 12 November 2012 / Published: 16 November 2012
Cited by 11 | PDF Full-text (235 KB)
Abstract
The 80% ethanol extract of Alstonia yunnanensis afforded five new monoterpenoid indole alkaloids: 11-hydroxy-6,7-epoxy-8-oxo-vincadifformine (1), 14-chloro-15-hydroxy- vincadifformine (2), perakine N4-oxide (3), raucaffrinoline N4-oxide (4), and vinorine N1,
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The 80% ethanol extract of Alstonia yunnanensis afforded five new monoterpenoid indole alkaloids: 11-hydroxy-6,7-epoxy-8-oxo-vincadifformine (1), 14-chloro-15-hydroxy- vincadifformine (2), perakine N4-oxide (3), raucaffrinoline N4-oxide (4), and vinorine N1,N4-dioxide (5), together with three known compounds: 11-methoxy-6,7-epoxy-8-oxo- vincadifformine (6), vinorine N4-oxide (7) and vinorine (8). The structures of the isolated compounds were established based on 1D and 2D (1H-1H-COSY, HMQC, HMBC, and ROESY) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated compounds were tested in vitro for cytotoxic potential against seven tumor cell lines and anti-inflammatory activities. Compounds 3, 4 and 7 exhibited weak cytotoxicity against the tested cell lines and selective inhibition of Cox-2 (>85%). Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessArticle Amelioration of Dextran Sodium Sulfate-Induced Colitis in Mice by Rhodobacter sphaeroides Extract
Molecules 2012, 17(11), 13622-13630; https://doi.org/10.3390/molecules171113622
Received: 24 October 2012 / Revised: 13 November 2012 / Accepted: 14 November 2012 / Published: 16 November 2012
Cited by 15 | PDF Full-text (1184 KB)
Abstract
Bacteria can produce some compounds in response to their environment. These compounds are widely used in cosmetic and pharmaceutical applications. Some probiotics have immunomodulatory activities and modulate the symptoms of several diseases. Autoimmune diseases represent a complex group of conditions that are thought
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Bacteria can produce some compounds in response to their environment. These compounds are widely used in cosmetic and pharmaceutical applications. Some probiotics have immunomodulatory activities and modulate the symptoms of several diseases. Autoimmune diseases represent a complex group of conditions that are thought to be mediated through the development of autoreactive immunoresponses. Inflammatory bowel disease (IBD) is common autoimmune disease that affects many individuals worldwide. Previously, we found that the extracts of Rhodobacter sphaeroides (Lycogen) inhibited nitric oxide production and inducible nitric-oxide synthase expression in activated macrophages. In this study, the effect of Lycogen™, a potent anti-inflammatory agent, was evaluated in mice with dextran sodium sulfate (DSS)-induced colitis. Oral administration of Lycogen™ reduced the expressions of proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β) in female BABL/c mice. In addition, the increased number of bacterial flora in the colon induced by DSS was amelirated by Lycogen™. The histological score of intestinal inflammation in 5% DSS-treated mice after oral administration of Lycogen™ was lower than that of control mice. Meanwhile, Lycogen™ dramatically prolonged the survival of mice with severe colitis. These findings identified that Lycogen™ is an anti-inflammatory agent with the capacity to ameliorate DSS-induced colitis. Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessReview Organophosphorus Chemistry for the Synthesis of Dendrimers
Molecules 2012, 17(11), 13605-13621; https://doi.org/10.3390/molecules171113605
Received: 31 October 2012 / Revised: 9 November 2012 / Accepted: 12 November 2012 / Published: 16 November 2012
Cited by 15 | PDF Full-text (1190 KB)
Abstract
Dendrimers are multifunctional, hyperbranched and perfectly defined macromolecules, synthesized layer after layer in an iterative manner. Besides the nature of the terminal groups responsible for most of the properties, the nature of the internal structure, and more precisely of the branching points, is
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Dendrimers are multifunctional, hyperbranched and perfectly defined macromolecules, synthesized layer after layer in an iterative manner. Besides the nature of the terminal groups responsible for most of the properties, the nature of the internal structure, and more precisely of the branching points, is also of crucial importance. For more than 15 years, we have demonstrated that the presence of phosphorus atom(s) at each branching point of the dendrimeric structure is particularly important and highly valuable for three main reasons: (i) the versatility of phosphorus chemistry that allows diversified organochemistry for the synthesis of dendrimers; (ii) the use of 31P-NMR, which is a highly valuable tool for the characterization of dendrimers; (iii) some properties (in the fields of catalysis, materials, and especially biology), that are directly connected to the nature of the internal structure and of the branching points. This review will give an overview of the methods of synthesis of phosphorus-containing dendrimers, as well on the ways to graft phosphorus derivatives as terminal groups, with emphasis on the various roles played by the chemistry of phosphorus. Full article
(This article belongs to the Special Issue Organophosphorus Chemistry)
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Open AccessReview Ivabradine: An Intelligent Drug for the Treatment of Ischemic Heart Disease
Molecules 2012, 17(11), 13592-13604; https://doi.org/10.3390/molecules171113592
Received: 10 October 2012 / Revised: 30 October 2012 / Accepted: 30 October 2012 / Published: 16 November 2012
Cited by 14 | PDF Full-text (189 KB)
Abstract
Heart rate (HR) is a precisely regulated variable, which plays a critical role in health and disease. Elevated resting HR is a significant predictor of all-cause and cardiovascular mortality in the general population and patients with cardiovascular disease (CVD). β-blocking drugs exert negative
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Heart rate (HR) is a precisely regulated variable, which plays a critical role in health and disease. Elevated resting HR is a significant predictor of all-cause and cardiovascular mortality in the general population and patients with cardiovascular disease (CVD). β-blocking drugs exert negative effects on regional myocardial blood flow and function when HR reduction is eliminated by atrial pacing; calcium channel antagonists (CCAs) functionally antagonize coronary vasoconstriction mediated through α-adreno-receptors and are thus devoid of this undesired effect, but the compounds are nevertheless negative inotropes. From these observations derives the necessity to find alternative, more selective drugs to reduce HR through inhibition of specific electrical current (If). Ivabradine (IVA) is a novel specific HR-lowering agent that acts in sinus atrial node (SAN) cells by selectively inhibiting the pacemaker If current in a dose-dependent manner by slowing the diastolic depolarization slope of SAN cells, and by reducing HR at rest during exercise in humans. Coronary artery diseases (CAD) represent the most common cause of death in middle–aged and older adults in European Countries. Most ischemic episodes are triggered by an increase in HR, that induces an imbalance between myocardial oxygen delivery and consumption. IVA, a selective and specific inhibitor of the If current which reduced HR without adverse hemodynamic effects, has clearly and unequivocally demonstrated its efficacy in the treatment of chronic stable angina pectoris (CSAP) and myocardial ischemia with optimal tolerability profile due to selective interaction with If channels. The aim of this review is to point out the usefulness of IVA in the treatment of ischemic heart disease. Full article
(This article belongs to the Special Issue Ivabradine)
Open AccessReview Nucleoside Triphosphates — Building Blocks for the Modification of Nucleic Acids
Molecules 2012, 17(11), 13569-13591; https://doi.org/10.3390/molecules171113569
Received: 21 September 2012 / Revised: 7 November 2012 / Accepted: 9 November 2012 / Published: 15 November 2012
Cited by 87 | PDF Full-text (442 KB)
Abstract
Nucleoside triphosphates are moldable entities that can easily be functionalized at various locations. The enzymatic polymerization of these modified triphosphate analogues represents a versatile platform for the facile and mild generation of (highly) functionalized nucleic acids. Numerous modified triphosphates have been utilized in
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Nucleoside triphosphates are moldable entities that can easily be functionalized at various locations. The enzymatic polymerization of these modified triphosphate analogues represents a versatile platform for the facile and mild generation of (highly) functionalized nucleic acids. Numerous modified triphosphates have been utilized in a broad palette of applications spanning from DNA-tagging and -labeling to the generation of catalytic nucleic acids. This review will focus on the recent progress made in the synthesis of modified nucleoside triphosphates as well as on the understanding of the mechanisms underlying their polymerase acceptance. In addition, the usefulness of chemically altered dNTPs in SELEX and related methods of in vitro selection will be highlighted, with a particular emphasis on the generation of modified DNA enzymes (DNAzymes) and DNA-based aptamers. Full article
(This article belongs to the Special Issue DNA-Directed Chemistry)
Open AccessReview Synthesis and Modifications of Phosphinic Dipeptide Analogues
Molecules 2012, 17(11), 13530-13568; https://doi.org/10.3390/molecules171113530
Received: 17 October 2012 / Revised: 9 November 2012 / Accepted: 12 November 2012 / Published: 15 November 2012
Cited by 24 | PDF Full-text (904 KB)
Abstract
Pseudopeptides containing the phosphinate moiety (-P(O)(OH)CH2-) have been studied extensively, mainly as transition state analogue inhibitors of metalloproteases. The key synthetic aspect of their chemistry is construction of phosphinic dipeptide derivatives bearing appropriate side-chain substituents. Typically, this synthesis involves a multistep
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Pseudopeptides containing the phosphinate moiety (-P(O)(OH)CH2-) have been studied extensively, mainly as transition state analogue inhibitors of metalloproteases. The key synthetic aspect of their chemistry is construction of phosphinic dipeptide derivatives bearing appropriate side-chain substituents. Typically, this synthesis involves a multistep preparation of two individual building blocks, which are combined in the final step. As this methodology does not allow simple variation of the side-chain structure, many efforts have been dedicated to the development of alternative approaches. Recent achievements in this field are summarized in this review. Improved methods for the formation of the phosphinic peptide backbone, including stereoselective and multicomponent reactions, are presented. Parallel modifications leading to the structurally diversified substituents are also described. Finally, selected examples of the biomedical applications of the title compounds are given. Full article
(This article belongs to the Special Issue Organophosphorus Chemistry)
Open AccessReview Therapeutic Applications of Nucleic Acids and Their Analogues in Toll-like Receptor Signaling
Molecules 2012, 17(11), 13503-13529; https://doi.org/10.3390/molecules171113503
Received: 21 September 2012 / Revised: 7 November 2012 / Accepted: 9 November 2012 / Published: 14 November 2012
Cited by 34 | PDF Full-text (346 KB)
Abstract
Toll-like receptors (TLRs) belong to a family of innate immune receptors that detect and clear invading microbial pathogens. Specifically intracellular TLRs such as TLR3, TLR7, TLR8 and TLR9 recognize nucleic acids such as double-stranded RNA, single-stranded RNA and CpG DNA respectively derived from
[...] Read more.
Toll-like receptors (TLRs) belong to a family of innate immune receptors that detect and clear invading microbial pathogens. Specifically intracellular TLRs such as TLR3, TLR7, TLR8 and TLR9 recognize nucleic acids such as double-stranded RNA, single-stranded RNA and CpG DNA respectively derived from microbial components. Upon infection, nucleic acid sensing TLRs signal within endosomal compartment triggering the induction of essential proinflammatory cytokines and type I interferons to initiate innate immune responses thereby leading to a critical role in the development of adaptive immune responses. Thus, stimulation of TLRs by nucleic acids is a promising area of research for the development of novel therapeutic strategies against pathogenic infection, allergies, malignant neoplasms and autoimmunity. This review summarizes the therapeutic applications of nucleic acids or nucleic acid analogues through the modulation of TLR signaling pathways. Full article
(This article belongs to the Special Issue Nucleic Acid Analogs)
Open AccessArticle Investigation of the Biological Properties of (Hetero)Aromatic Thiosemicarbazones
Molecules 2012, 17(11), 13483-13502; https://doi.org/10.3390/molecules171113483
Received: 8 October 2012 / Revised: 7 November 2012 / Accepted: 8 November 2012 / Published: 14 November 2012
Cited by 17 | PDF Full-text (263 KB) | Supplementary Files
Abstract
Two series of thiosemicarbazone-based iron chelators (twenty-seven compounds) were designed and synthesized using a microwave-assisted approach. Quinoline and halogenated phenyl were selected as parent scaffolds on the basis of a similarity search. The lipophilicity of the synthesized compounds was measured using HPLC and
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Two series of thiosemicarbazone-based iron chelators (twenty-seven compounds) were designed and synthesized using a microwave-assisted approach. Quinoline and halogenated phenyl were selected as parent scaffolds on the basis of a similarity search. The lipophilicity of the synthesized compounds was measured using HPLC and then calculated. Primary in vitro screening of the synthesized compounds was performed against eight pathogenic fungal strains. Only a few compounds showed moderate activity against fungi, and (E)-2-(quinolin-2-ylvinyl)-N,N-dimethylhydrazine-carbothioamide appeared to be more effective than fluconazole against most of the fungal strains tested. Antiproliferative activity was measured using a human colon cancer cell line (HCT-116). Several of the tested compounds showed submicromolar antiproliferative activity. Compounds were also tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. The structure-activity relationships are discussed for all of the compounds. Full article
(This article belongs to the Special Issue Advances in Medicinal Chemistry of Antifungals)
Open AccessArticle Wild Argentinian Amaryllidaceae, a New Renewable Source of the Acetylcholinesterase Inhibitor Galanthamine and Other Alkaloids
Molecules 2012, 17(11), 13473-13482; https://doi.org/10.3390/molecules171113473
Received: 8 October 2012 / Revised: 2 November 2012 / Accepted: 9 November 2012 / Published: 13 November 2012
Cited by 18 | PDF Full-text (307 KB)
Abstract
The Amaryllidaceae family is well known for its pharmacologically active alkaloids. An important approach to treat Alzheimer’s disease involves the inhibition of the enzyme acetylcholinesterase (AChE). Galanthamine, an Amaryllidaceae alkaloid, is an effective, selective, reversible, and competitive AchE inhibitor. This work was aimed
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The Amaryllidaceae family is well known for its pharmacologically active alkaloids. An important approach to treat Alzheimer’s disease involves the inhibition of the enzyme acetylcholinesterase (AChE). Galanthamine, an Amaryllidaceae alkaloid, is an effective, selective, reversible, and competitive AchE inhibitor. This work was aimed at studying the alkaloid composition of four wild Argentinian Amarillydaceae species for the first time, as well as analyzing their inhibitory activity on acetylcholinesterase. Alkaloid content was characterized by means of GC-MS analysis. Chloroform basic extracts from Habranthus jamesonii, Phycella herbertiana, Rhodophiala mendocina and Zephyranthes filifolia collected in the Argentinian Andean region all contained galanthamine, and showed a strong AChE inhibitory activity (IC50 between 1.2 and 2 µg/mL). To our knowledge, no previous reports on alkaloid profiles and AChEIs activity of wild Argentinian Amarillydaceae species have been publisihed. The demand for renewable sources of industrial products like galanthamine and the need to protect plant biodiversity creates an opportunity for Argentinian farmers to produce such crops. Full article
(This article belongs to the Section Natural Products Chemistry)
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Open AccessArticle Antioxidant Ability and Mechanism of Rhizoma Atractylodes macrocephala
Molecules 2012, 17(11), 13457-13472; https://doi.org/10.3390/molecules171113457
Received: 18 October 2012 / Revised: 7 November 2012 / Accepted: 8 November 2012 / Published: 13 November 2012
Cited by 39 | PDF Full-text (1148 KB) | Supplementary Files
Abstract
Rhizoma Atractylodes macrocephala (AM) has been used in Traditional Chinese Medicine (TCM) for about 2,000 years. In the study, we firstly determined the antioxidant levels of five AM extracts by •OH-scavenging, •O2-scavenging, Fe2+-chelating, Cu2+-chelating, DPPH·-scavenging, and
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Rhizoma Atractylodes macrocephala (AM) has been used in Traditional Chinese Medicine (TCM) for about 2,000 years. In the study, we firstly determined the antioxidant levels of five AM extracts by •OH-scavenging, •O2-scavenging, Fe2+-chelating, Cu2+-chelating, DPPH·-scavenging, and ABTS+·-scavenging assays. After measurement of the chemical contents in five AM extracts, we quantitatively analyzed the correlations between antioxidant levels and chemical contents. It was observed that total phenolics and total flavonoids had significant positive correlations with antioxidant levels (R = 0.685 and 0.479, respectively). In contrast, total sugars and total saponins presented lower correlations with antioxidant levels (R = −0.272 and 0.244, respectively). It means that antioxidant activity of AM should be attributed to total phenolics (including phenolic acids and flavonoids), and not total sugars and total saponins. Further analysis indicated that phenolic acids exhibited higher R values with radical-scavenging assays (R = 0.32–1.00), while flavonoids showed higher R values with metal-chelating assays (R= 0.86 and 0.90). In conclusion, AM exerts its antioxidant effect through metal-chelating, and radical-scavenging which is via donating hydrogen atom and donating electron. Its metal-chelating may result from flavonoids, while its radical-scavenging can be attributed to phenolic acids, especially caffeic acid, ferulic acid, and protocatechuic acid. Full article
(This article belongs to the Section Medicinal Chemistry)
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Open AccessArticle New Triterpenes from Maytenus robusta: Structural Elucidation Based on NMR Experimental Data and Theoretical Calculations
Molecules 2012, 17(11), 13439-13456; https://doi.org/10.3390/molecules171113439
Received: 12 September 2012 / Revised: 5 November 2012 / Accepted: 7 November 2012 / Published: 12 November 2012
Cited by 36 | PDF Full-text (238 KB) | Supplementary Files
Abstract
Leaves of Maytenus robusta (Celastraceae) were subjected to phytochemical investigation mainly directed at the isolation of pentacyclic triterpenes. The compounds friedelin (1), β-friedelinol (2), 3-oxo-21β-H-hop-22(29)-ene (7), 3,4-seco-friedelan-3,11β-olide (
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Leaves of Maytenus robusta (Celastraceae) were subjected to phytochemical investigation mainly directed at the isolation of pentacyclic triterpenes. The compounds friedelin (1), β-friedelinol (2), 3-oxo-21β-H-hop-22(29)-ene (7), 3,4-seco-friedelan-3,11β-olide (8), 3β-hydroxy-21β-H-hop-22(29)-ene (9), 3,4-seco-21β-H-hop-22(29)-en-3-oic acid (10), 3,4-seco-friedelan-3-oic acid (11), and sitosterol were identified in the hexane extract of M. robusta leaves. Compounds 8 and 9 are described herein for the first time. The structure and stereochemistry of both compounds were experimentally established by IR, HRLC-MS, and 1D (1H, 13C, and DEPT 135) and 2D (HSQC, HMBC and COSY) NMR data and supported by correlations with carbon chemical shifts calculated using the DFT method (BLYP/6-31G* level). Compounds 7 and 10 are also described for the first time, and their chemical structures were established by comparison with NMR data of similar structures described in the literature and correlations with BLYP/6-31G* calculated carbon chemical shifts. Compound 9, a mixture of 11 and sitosterol, and 3β,11β-dihydroxyfriedelane (4) were evaluated by the Ellman’s method and all these compounds showed acethylcholinesterase inhibitory properties. Full article
(This article belongs to the Special Issue Triterpenes and Triterpenoids 2013)
Open AccessArticle NADPH Oxidase-Derived Reactive Oxygen Species Are Involved in the HL-60 Cell Monocytic Differentiation Induced by Isoliquiritigenin
Molecules 2012, 17(11), 13424-13438; https://doi.org/10.3390/molecules171113424
Received: 24 September 2012 / Revised: 24 October 2012 / Accepted: 7 November 2012 / Published: 12 November 2012
Cited by 19 | PDF Full-text (407 KB)
Abstract
The present study was undertaken to test the hypothesis that NADPH oxidase-derived reactive oxygen species (ROS) are involved in isoliquiritigenin (ISL)-induced monocytic differentiation in human acute promyelocytic leukemia HL-60 cells. Morphological changes, cell surface markers CD11b/CD14 and NBT-reducing ability were used to determine
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The present study was undertaken to test the hypothesis that NADPH oxidase-derived reactive oxygen species (ROS) are involved in isoliquiritigenin (ISL)-induced monocytic differentiation in human acute promyelocytic leukemia HL-60 cells. Morphological changes, cell surface markers CD11b/CD14 and NBT-reducing ability were used to determine the differentiation of HL-60 cells, and 2,7-dichlorofluorescein (DCFH-DA) was used to detect the level of intracellular ROS. ISL-induced HL-60 cell differentiation was accompanied by an increase in the intracellular ROS levels. l-Buthionine-(S,R)-sulfoximine (BSO), N-acetyl-l-cysteine (NAC), superoxide dismutase (SOD) and 4-hydroxy-2,2,6,6-tetramethylpiperidinoxyl (Tempol) were used to interfere with ROS production. NADPH oxidase inhibitors, apocynin (APO) and diphenyleneiodonium (DPI) were used to study the role of NADPH oxidase in ISL-induced HL-60 cell differentiation. The ISL-induced HL-60 cell differentiation and intracellular ROS generation were enhanced by the oxidant BSO and inhibited by the antioxidants NAC, SOD, and tempol, and were also inhibited by the NADPH oxidase inhibitors APO and DPI. The protein and mRNA expression of the NADPH oxidase subunits gp91phox and p47phox were determined by Western blotting and RT-PCR, respectively. The levels of translation and transcription of the NADPH oxidase subunits gp91phox and p47phox increased markedly in a concentration-dependent manner. These findings suggest that NADPH oxidase plays a critical role in HL-60 cell differentiation induced by ISL and that NADPH oxidase-derived ROS is involved in the differentiation mechanism. Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessArticle By Improving Regional Cortical Blood Flow, Attenuating Mitochondrial Dysfunction and Sequential Apoptosis Galangin Acts as a Potential Neuroprotective Agent after Acute Ischemic Stroke
Molecules 2012, 17(11), 13403-13423; https://doi.org/10.3390/molecules171113403
Received: 19 October 2012 / Revised: 31 October 2012 / Accepted: 6 November 2012 / Published: 9 November 2012
Cited by 20 | PDF Full-text (830 KB)
Abstract
Ischemic stroke is a devastating disease with a complex pathophysiology. Galangin is a natural flavonoid isolated from the rhizome of Alpina officinarum Hance, which has been widely used as an antioxidant agent. However, its effects against ischemic stroke have not been reported and
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Ischemic stroke is a devastating disease with a complex pathophysiology. Galangin is a natural flavonoid isolated from the rhizome of Alpina officinarum Hance, which has been widely used as an antioxidant agent. However, its effects against ischemic stroke have not been reported and its related neuroprotective mechanism has not really been explored. In this study, neurological behavior, cerebral infarct volumes and the improvement of the regional cortical blood flow (rCBF) were used to evaluate the therapeutic effect of galangin in rats impaired by middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia. Furthermore, the determination of mitochondrial function and Western blot of apoptosis-related proteins were performed to interpret the neuroprotective mechanism of galangin. The results showed that galangin alleviated the neurologic impairments, reduced cerebral infarct at 24 h after MCAO and exerted a protective effect on the mitochondria with decreased production of mitochondrial reactive oxygen species (ROS). These effects were consistent with improvements in the membrane potential level (Dym), membrane fluidity, and degree of mitochondrial swelling in a dose-dependent manner. Moreover, galangin significantly improved the reduced rCBF after MCAO. Western blot analysis revealed that galangin also inhibited apoptosis in a dose-dependent manner concomitant with the up-regulation of Bcl-2 expression, down-regulation of Bax expression and the Bax/Bcl-2 ratio, a reduction in cytochrome c release from the mitochondria to the cytosol, the reduced expression of activated caspase-3 and the cleavage of poly(ADP-ribose) polymerase (PARP). All these data in this study demonstrated that galangin might have therapeutic potential for ischemic stroke and play its protective role through the improvement in rCBF, mitochondrial protection and inhibiting caspase-dependent mitochondrial cell death pathway for the first time. Full article
Open AccessArticle Spatial Control of DNA Reaction Networks by DNA Sequence
Molecules 2012, 17(11), 13390-13402; https://doi.org/10.3390/molecules171113390
Received: 25 September 2012 / Revised: 5 November 2012 / Accepted: 5 November 2012 / Published: 9 November 2012
Cited by 10 | PDF Full-text (578 KB)
Abstract
We have developed a set of DNA circuits that execute during gel electrophoresis to yield immobile, fluorescent features in the gel. The parallel execution of orthogonal circuits led to the simultaneous production of different fluorescent lines at different positions in the gel. The
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We have developed a set of DNA circuits that execute during gel electrophoresis to yield immobile, fluorescent features in the gel. The parallel execution of orthogonal circuits led to the simultaneous production of different fluorescent lines at different positions in the gel. The positions of the lines could be rationally manipulated by changing the mobilities of the reactants. The ability to program at the nanoscale so as to produce patterns at the macroscale is a step towards programmable, synthetic chemical systems for generating defined spatiotemporal patterns. Full article
(This article belongs to the Special Issue DNA-Directed Chemistry)
Open AccessArticle Endo-S-c-di-GMP Analogues-Polymorphism and Binding Studies with Class I Riboswitch
Molecules 2012, 17(11), 13376-13389; https://doi.org/10.3390/molecules171113376
Received: 21 September 2012 / Revised: 30 October 2012 / Accepted: 1 November 2012 / Published: 9 November 2012
Cited by 10 | PDF Full-text (520 KB)
Abstract
C-di-GMP, a cyclic guanine dinucleotide, has been shown to regulate biofilm formation as well as virulence gene expression in a variety of bacteria. Analogues of c-di-GMP have the potential to be used as chemical probes to study c-di-GMP signaling and could even become
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C-di-GMP, a cyclic guanine dinucleotide, has been shown to regulate biofilm formation as well as virulence gene expression in a variety of bacteria. Analogues of c-di-GMP have the potential to be used as chemical probes to study c-di-GMP signaling and could even become drug leads for the development of anti-biofilm compounds. Herein we report the synthesis and biophysical studies of a series of c-di-GMP analogues, which have both phosphate and sugar moieties simultaneously modified (called endo-S-c-di-GMP analogues). We used computational methods to predict the relative orientation of the guanine nucleobases in c-di-GMP and analogues. DOSY NMR of the endo-S-c-di-GMP series showed that the polymorphism of c-di-GMP can be tuned with conservative modifications to the phosphate and sugar moieties (conformational steering). Binding studies with Vc2 RNA (a class I c-di-GMP riboswitch) revealed that conservative modifications to the phosphate and 2'-positions of c-di-GMP dramatically affected binding to class I riboswitch. Full article
(This article belongs to the Special Issue Nucleic Acid Analogs)
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Open AccessArticle One-Pot Synthesis of 2-Phenylimidazo[1,2-α]pyridines from Acetophenone, [Bmim]Br3 and 2-Aminopyridine under Solvent-Free Conditions
Molecules 2012, 17(11), 13368-13375; https://doi.org/10.3390/molecules171113368
Received: 24 September 2012 / Revised: 24 October 2012 / Accepted: 26 October 2012 / Published: 9 November 2012
Cited by 13 | PDF Full-text (186 KB)
Abstract
One-pot synthesis of 2-phenylimidazo[1,2-α]pyridines from acetophenone, [Bmim]Br3 and 2-aminopyridine under solvent-free conditions in the presence of Na2CO3, gave the corresponding 2-phenylimidazo[1,2-α]pyridines in excellent yields ranging from 72% to 89%. Full article
(This article belongs to the Section Organic Chemistry)
Open AccessArticle α-Lipoic Acid Reduces Hypertension and Increases Baroreflex Sensitivity in Renovascular Hypertensive Rats
Molecules 2012, 17(11), 13357-13367; https://doi.org/10.3390/molecules171113357
Received: 13 September 2012 / Revised: 26 October 2012 / Accepted: 31 October 2012 / Published: 9 November 2012
Cited by 15 | PDF Full-text (266 KB)
Abstract
Renovascular hypertension has robust effects on control of blood pressure, including an impairment in baroreflex mechanisms, which involves oxidative stress. Although α-lipoic acid (LA) has been described as a potent antioxidant, its effect on renovascular hypertension and baroreflex sensitivity (BRS) has not been
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Renovascular hypertension has robust effects on control of blood pressure, including an impairment in baroreflex mechanisms, which involves oxidative stress. Although α-lipoic acid (LA) has been described as a potent antioxidant, its effect on renovascular hypertension and baroreflex sensitivity (BRS) has not been investigated. In the present study we analyzed the effects caused by chronic treatment with LA on blood pressure, heart rate and baroreflex sensitivity (sympathetic and parasympathetic components) in renovascular hypertensive rats. Male Wistar rats underwent 2-Kidney-1-Clip (2K1C) or sham surgery and were maintained untouched for four weeks to develop hypertension. Four weeks post-surgery, rats were treated with LA (60 mg/kg) or saline for 14 days orally. On the 15th day mean arterial pressure (MAP) and heart rate (HR) were recorded. In addition, baroreflex sensitivity test using phenylephrine (8 µg/kg, i.v.) and sodium nitroprusside (25 µg/kg, i.v.) was performed. Chronic treatment with LA decreased blood pressure in hypertensive animals; however, no significant changes in baseline HR were observed. Regarding baroreflex, LA treatment increased the sensitivity of both the sympathetic and parasympathetic components. All parameters studied were not affected by treatment with LA in normotensive animals. Our data suggest that chronic treatment with LA promotes antihypertensive effect and improves baroreflex sensitivity in rats with renovascular hypertension. Full article
(This article belongs to the Special Issue Antioxidants 2012)
Open AccessArticle Variation of Medicinal Components in a Unique Geographical Accession of Horny Goat Weed Epimedium sagittatum Maxim. (Berberidaceae)
Molecules 2012, 17(11), 13345-13356; https://doi.org/10.3390/molecules171113345
Received: 11 September 2012 / Revised: 2 November 2012 / Accepted: 5 November 2012 / Published: 8 November 2012
Cited by 13 | PDF Full-text (347 KB)
Abstract
Herbal Epimedium species have been widely in Traditional Chinese Medicine for sexual enhancement, immunity improvement, anticancer and anti-aging treatment, with flavonoids and polysaccharides being the major active components. However, exhaustive depletion of wild sources warrants germplasm evaluation and quality resource exploration. A preliminarily
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Herbal Epimedium species have been widely in Traditional Chinese Medicine for sexual enhancement, immunity improvement, anticancer and anti-aging treatment, with flavonoids and polysaccharides being the major active components. However, exhaustive depletion of wild sources warrants germplasm evaluation and quality resource exploration. A preliminarily analysis had previously indicated that a specific local geographic accession of Epimedium sagittatum found in Luotian (LT) county of Hubei Province (China) had a much higher content of total flavonoids and polysaccharides. In this study, we further investigated the medicinal component variation in the LT type under different light intensities and in different regions by the common-garden experiment. The results indicated a light intensity range of 40–160 μmol/m2/s was the most suitable for the synthesis and accumulation of total flavonoids, while polysaccharide accumulation was negatively correlated with the light intensity. Icariin was the component displaying the highest content among flavonoids, and the content of major flavonoid bioactive components was relatively stable in the third year after cultivation. There was significant correlation between the major flavonol glycoside constituents and the geographic location, and Central China followed by Northern China were the highly suitable regions for cultivation of LT type E. sagittatum. The results revealed that there was a functional balance between flavonoids and polysaccharides at different developmental stages, and the best harvesting stage should consider the primary contents of interest. This study provides important information on the exploration of quality resources, further breeding approaches and cultivation practices of E. sagittatum, and thus the important insights to enhance our understanding of quality control of traditional medicinal plants. Full article
(This article belongs to the Section Natural Products Chemistry)
Open AccessArticle Asymmetric Construction of All-Carbon Quaternary Stereocenters by Chiral-Auxiliary-Mediated Claisen Rearrangement and Total Synthesis of (+)-Bakuchiol
Molecules 2012, 17(11), 13330-13344; https://doi.org/10.3390/molecules171113330
Received: 9 October 2012 / Revised: 23 October 2012 / Accepted: 2 November 2012 / Published: 8 November 2012
Cited by 10 | PDF Full-text (417 KB)
Abstract
An asymmetric Claisen rearrangement using Oppolzer’s camphorsultam was developed. Under thermal conditions, a geraniol-derived substrate underwent the rearrangement with good stereoselectivity. The absolute configuration of the newly formed all-carbon quaternary stereocenter was confirmed by the total synthesis of (+)-bakuchiol from the rearrangement product.
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An asymmetric Claisen rearrangement using Oppolzer’s camphorsultam was developed. Under thermal conditions, a geraniol-derived substrate underwent the rearrangement with good stereoselectivity. The absolute configuration of the newly formed all-carbon quaternary stereocenter was confirmed by the total synthesis of (+)-bakuchiol from the rearrangement product. Full article
(This article belongs to the Special Issue Claisen Rearrangement)
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Open AccessArticle Investigating Silver Coordination to Mixed Chalcogen Ligands
Molecules 2012, 17(11), 13307-13329; https://doi.org/10.3390/molecules171113307
Received: 28 September 2012 / Revised: 31 October 2012 / Accepted: 5 November 2012 / Published: 8 November 2012
Cited by 6 | PDF Full-text (598 KB) | Supplementary Files
Abstract
Six silver(I) coordination complexes have been prepared and structurally characterised. Mixed chalcogen-donor acenaphthene ligands L1L3 [Acenap(EPh)(E'Ph)] (Acenap = acenaphthene-5,6-diyl; E/E' = S, Se, Te) were independently treated with silver(I) salts (AgBF4/AgOTf). In order to keep the number of variables
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Six silver(I) coordination complexes have been prepared and structurally characterised. Mixed chalcogen-donor acenaphthene ligands L1L3 [Acenap(EPh)(E'Ph)] (Acenap = acenaphthene-5,6-diyl; E/E' = S, Se, Te) were independently treated with silver(I) salts (AgBF4/AgOTf). In order to keep the number of variables to a minimum, all reactions were carried out using a 1:1 ratio of Ag/L and run in dichloromethane. The nature of the donor atoms, the coordinating ability of the respective counter-anion and the type of solvent used in recrystallisation, all affect the structural architecture of the final silver(I) complex, generating monomeric, silver(I) complexes {[AgBF4(L)2] (1 L = L1; 2 L = L2; 3 L = L3), [AgOTf(L)3] (4 L = L1; 5 L = L3), [AgBF4(L)3] (2a L = L1; 3a L = L3)} and a 1D polymeric chain {[AgOTf(L3)]n 6}. The organic acenaphthene ligands L1-L3 adopt a number of ligation modes (bis-monodentate μ22-bridging, quasi-chelating combining monodentate and η6-E(phenyl)-Ag(I) and classical monodentate coordination) with the central silver atom at the centre of a tetrahedral or trigonal planar coordination geometry in each case. The importance of weak interactions in the formation of metal-organic structures is also highlighted by the number of short non-covalent contacts present within each complex. Full article
(This article belongs to the Special Issue Disulfide and Diselenide Chemistry)
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Open AccessArticle Synthesis, Cyclopolymerization and Cyclo-Copolymerization of 9-(2-Diallylaminoethyl)adenine and Its Hydrochloride Salt
Molecules 2012, 17(11), 13290-13306; https://doi.org/10.3390/molecules171113290
Received: 11 September 2012 / Revised: 26 September 2012 / Accepted: 2 November 2012 / Published: 8 November 2012
Cited by 4 | PDF Full-text (747 KB)
Abstract
We report herein the synthesis and characterization of 9-(2-diallylaminoethyl) adenine. We evaluated two different synthetic routes starting with adenine where the optimal route was achieved through coupling of 9-(2-chloroethyl)adenine with diallylamine. The cyclopolymerization and cyclo-copolymerization of 9-(2-diallylaminoethyl)adenine hydrochloride salt resulted in low molecular
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We report herein the synthesis and characterization of 9-(2-diallylaminoethyl) adenine. We evaluated two different synthetic routes starting with adenine where the optimal route was achieved through coupling of 9-(2-chloroethyl)adenine with diallylamine. The cyclopolymerization and cyclo-copolymerization of 9-(2-diallylaminoethyl)adenine hydrochloride salt resulted in low molecular weight oligomers in low yields. In contrast, 9-(2-diallylaminoethyl)adenine failed to cyclopolymerize, however, it formed a copolymer with SO2 in relatively good yields. The molecular weights of the cyclopolymers were around 1,700–6,000 g/mol, as estimated by SEC. The cyclo-copolymer was stable up to 226 °C. To the best of our knowledge, this is the first example of a free-radical cyclo-copolymerization of a neutral alkyldiallylamine derivative with SO2. These polymers represent a novel class of carbocyclic polynucleotides. Full article
(This article belongs to the Section Organic Chemistry)
Open AccessArticle Synthesis, Antioxidant and Antimicrobial Activity of a New Phloridzin Derivative for Dermo-Cosmetic Applications
Molecules 2012, 17(11), 13275-13289; https://doi.org/10.3390/molecules171113275
Received: 7 September 2012 / Revised: 25 October 2012 / Accepted: 29 October 2012 / Published: 7 November 2012
Cited by 16 | PDF Full-text (299 KB)
Abstract
The phenolic compound phloridzin (phloretin 2′-O-glucoside, variously named phlorizin, phlorrhizin, phlorhizin or phlorizoside) is a prominent member of the chemical class of dihydrochalcones, which are phenylpropanoids. Phloridzin is specifically found in apple and apple juice and known for its biological properties.
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The phenolic compound phloridzin (phloretin 2′-O-glucoside, variously named phlorizin, phlorrhizin, phlorhizin or phlorizoside) is a prominent member of the chemical class of dihydrochalcones, which are phenylpropanoids. Phloridzin is specifically found in apple and apple juice and known for its biological properties. In particular we were attracted by potential dermo-cosmetic applications. Here we report the synthesis, stability studies and antimicrobial activity of compound F2, a new semi-synthetic derivative of phloridzin. The new derivative was also included in finished formulations to evaluate its stability with a view to a potential topical use. Stability studies were performed by HPLC; PCL assay and ORAC tests were used to determine the antioxidant activity. F2 presented an antioxidant activity very close to that of the parent phloridzin, but, unlike the latter, was more stable in formulations. To further explore potential health claims, antifungal activity of phloridzin and its derivative F2 were determined; the results, however, were rather low; the highest value was 31,6% of inhibition reached by F2 on Microsporum canis at the highest dose. Full article
Open AccessCommunication Radioiodination of Aryl-Alkyl Cyclic Sulfates
Molecules 2012, 17(11), 13266-13274; https://doi.org/10.3390/molecules171113266
Received: 7 September 2012 / Revised: 24 September 2012 / Accepted: 23 October 2012 / Published: 7 November 2012
Cited by 1 | PDF Full-text (217 KB) | Supplementary Files
Abstract
Among the currently available positron emitters suitable for Positron Emission Tomography (PET), 124I has the longest physical half-life (4.2 days). The long half-life and well-investigated behavior of iodine in vivo makes 124I very attractive for pharmacological studies. In this communication, we
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Among the currently available positron emitters suitable for Positron Emission Tomography (PET), 124I has the longest physical half-life (4.2 days). The long half-life and well-investigated behavior of iodine in vivo makes 124I very attractive for pharmacological studies. In this communication, we describe a simple yet effective method for the synthesis of novel 124I labeled compounds intended for PET imaging of arylsulfatase activity in vivo. Arylsulfatases have important biological functions, and genetic deficiencies of such functions require pharmacological replacement, the efficacy of which must be properly and non-invasively evaluated. These enzymes, even though their natural substrates are mostly of aliphatic nature, hydrolyze phenolic sulfates to phenol and sulfuric acid. The availability of [124I]iodinated substrates is expected to provide a PET-based method for measuring their activity in vivo. The currently available methods of synthesis of iodinated arylsulfates usually require either introducing of a protected sulfate ester early in the synthesis or introduction of sulfate group at the end of synthesis in a separate step. The described method gives the desired product in one step from an aryl-alkyl cyclic sulfate. When treated with iodide, the source cyclic sulfate opens with substitution of iodide at the alkyl center and gives the desired arylsulfate monoester. Full article
(This article belongs to the Special Issue Organic Iodine Chemistry 2012)
Open AccessArticle Effects of Taraxacum officinale on Fatigue and Immunological Parameters in Mice
Molecules 2012, 17(11), 13253-13265; https://doi.org/10.3390/molecules171113253
Received: 2 July 2012 / Revised: 18 July 2012 / Accepted: 31 October 2012 / Published: 7 November 2012
Cited by 13 | PDF Full-text (586 KB)
Abstract
In Korean herbal medicine dandelion (Taraxacum officinale, TO) has been used to improve energy levels and health. However, the effects of TO in experimental models remain unclear. We examined the anti-fatigue and immune-enhancing effects of TO in mice by performing a
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In Korean herbal medicine dandelion (Taraxacum officinale, TO) has been used to improve energy levels and health. However, the effects of TO in experimental models remain unclear. We examined the anti-fatigue and immune-enhancing effects of TO in mice by performing a forced swimming test (FST) and in vitro by using peritoneal macrophages, respectively. After daily oral administration of TO, blood biochemical parameters related to fatigue were measured after the FST. FST immobility time was significantly decreased in the TO-treated group (100 mg/kg) on the tenth day. TO (10 and 100 mg/kg) treatment significantly increased glucose levels, acting as an energy source. The level of lactic dehydrogenase, which is an accurate indicator of muscle damage, tended to decline after TO administration (10 and 100 mg/kg). When TO (100 mg/kg) was orally administered to mice, blood urea nitrogen levels decreased significantly. We also examined the effect of TO on the production of cytokines and nitric oxide (NO) in mouse peritoneal macrophages. When TO was used in combination with recombinant interferon-gamma (rIFN-γ), a noticeable cooperative induction of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-12p70, and IL-10 production was observed. Furthermore, in peritoneal macrophages, rIFN-γ plus TO treatment significantly increased the production of NO through inducible nitric oxide synthase (iNOS) induction. Taken together, these results suggest that TO improves fatigue-related indicators and immunological parameters in mice. Full article
Open AccessReview Azide-Alkyne Huisgen [3+2] Cycloaddition Using CuO Nanoparticles
Molecules 2012, 17(11), 13235-13252; https://doi.org/10.3390/molecules171113235
Received: 19 September 2012 / Revised: 29 October 2012 / Accepted: 1 November 2012 / Published: 6 November 2012
Cited by 27 | PDF Full-text (1366 KB)
Abstract
Recent developments in the synthesis of CuO nanoparticles (NPs) and their application to the [3+2] cycloaddition of azides with terminal alkynes are reviewed. With respect to the importance of click chemistry, CuO hollow NPs, CuO hollow NPs on acetylene black, water-soluble double-hydrophilic block
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Recent developments in the synthesis of CuO nanoparticles (NPs) and their application to the [3+2] cycloaddition of azides with terminal alkynes are reviewed. With respect to the importance of click chemistry, CuO hollow NPs, CuO hollow NPs on acetylene black, water-soluble double-hydrophilic block copolymer (DHBC) nanoreactors and ZnO–CuO hybrid NPs were synthesized. Non-conventional energy sources such as microwaves and ultrasound were also applied to these click reactions, and good catalytic activity with high regioselectivity was observed. CuO hollow NPs on acetylene black can be recycled nine times without any loss of activity, and water-soluble DHBC nanoreactors have been developed for an environmentally friendly process. Full article
(This article belongs to the Special Issue Transition Metals Catalysis)
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