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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 17 | 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 10 | 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 83 | 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 33 | 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
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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 16 | 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 38 | 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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