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1.
Pernille Hammelsoe 《Pigment cell & melanoma research》2009,22(6):701-701
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Sibling species groups are suitable models for the understanding of inter‐ and intraspecific processes in taxonomy and biogeography. We analysed 262 individuals from the Alps of the Coenonympha arcania/gardetta species complex by allozyme electrophoresis. These taxa showed high variance amongst populations (FST: 0.391) and strong intertaxon genetic differentiation (FCT: 0.376). Although morphologically similar, Coenonympha gardetta and Coenonympha arcania clearly differ in their genetic characteristics; the morphologically intermediate taxa Coenonympha darwiniana darwiniana and Coenonympha darwiniana macromma are genetically well distinguished from each other and the two other taxa. Coenonympha arcania and C. d. macromma most probably share a common ancestor and evolved by cladogenesis, whereas the taxonomic situation of C. d. darwiniana is still unresolved: This taxon might be the result of hybridization between C. arcania and C. gardetta or it might have a common ancestor together with C. gardetta. We suggest species rank for all four taxa. The distribution of genetic diversity of these populations and the differentiation amongst populations suggest rather different biogeographical scenarios: C. arcania most probably is of Mediterranean origin with postglacial range expansion northwards; C. gardetta survived the last ice age in peripheral refugia of the Alps and has spread all over this high mountain system in the postglacial; C. darwiniana and C. macromma survived the Würm in geographic proximity to their actual distribution areas and only have performed moderate uphill translocations during postglacial warming. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 890–904. 相似文献
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《化学与生物多样性》2018,15(1)
A variety of applications of 8‐alkynylated nucleosides has prompted the synthesis of new purine analogues. Bromination of unprotected 2‐amino‐2′‐deoxyadenosine with Br2/AcOH/AcONa gives 2‐amino‐8‐bromo‐2′‐deoxyadenosine (87%). The brominated derivative is converted to 8‐alkynylated 2‐amino‐2′‐deoxyadenosines by palladium‐catalyzed Sonogashira cross‐coupling reaction via microwave assistance (81 – 95%). The resulting compounds are further transformed to 8‐alkynylated 2′‐deoxyisoguanosines (52 – 70%). The physical properties of new compounds are investigated. 相似文献
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Christian Starkenmann Fabienne Mayenzet Robert Brauchli Myriam Troccaz 《化学与生物多样性》2013,10(12):2197-2208
5α‐Androst‐16‐en‐3α‐ol (α‐androstenol) is an important contributor to human axilla sweat odor. It is assumed that α‐andostenol is excreted from the apocrine glands via a H2O‐soluble conjugate, and this precursor was formally characterized in this study for the first time in human sweat. The possible H2O‐soluble precursors, sulfate and glucuronide derivatives, were synthesized as analytical standards, i.e., α‐androstenol, β‐androstenol sulfates, 5α‐androsta‐5,16‐dien‐3β‐ol (β‐androstadienol) sulfate, α‐androstenol β‐glucuronide, α‐androstenol α‐glucuronide, β‐androstadienol β‐glucuronide, and α‐androstenol β‐glucuronide furanose. The occurrence of α‐androstenol β‐glucuronide was established by ultra performance liquid chromatography (UPLC)/MS (heated electrospray ionization (HESI)) in negative‐ion mode in pooled human sweat, containing eccrine and apocrine secretions and collected from 25 female and 24 male underarms. Its concentration was of 79 ng/ml in female secretions and 241 ng/ml in male secretions. The release of α‐androstenol was observed after incubation of the sterile human sweat or α‐androstenol β‐glucuronide with a commercial glucuronidase enzyme, the urine‐isolated bacteria Streptococcus agalactiae, and the skin bacteria Staphylococcus warneri DSM 20316, Staphylococcus haemolyticus DSM 20263, and Propionibacterium acnes ATCC 6919, reported to have β‐glucuronidase activities. We demonstrated that if α‐ and β‐androstenols and androstadienol sulfates were present in human sweat, their concentrations would be too low to be considered as potential precursors of malodors; therefore, the H2O‐soluble precursor of α‐androstenol in apocrine secretion should be a β‐glucuronide. 相似文献
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Optically active 3,3′‐dimethyl‐2,2′‐diamino‐1,1′‐binaphthyl (DM‐DABN) and 3,3′‐dimethyl‐2‐amino‐2′‐hydroxybinaphthyl (DM‐NOBIN) derivatives were synthesized by Cu‐(?)‐sparteine complex‐catalyzed enantioselective homo‐ and hetero‐coupling of 2‐naphthylamine, respectively. The difference in enantioselectivity was observed by changing the concentration of oxygen. Chirality, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
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Ferenc Faigl Bernadett Vas‐Feldhoffer Veronika Kudar Mátyás Czugler Krisztina Pál Miklós Kubinyi 《Chirality》2009,21(10):905-910
Site selective mono‐ and dimetalation methods have been developed for the functionalization of 1‐[(1,1′‐biphenyl)‐2‐yl]‐1H‐pyrrole. Optical resolution of the prepared 1‐[(3‐carboxy‐1,1′‐biphenyl)‐2‐yl]pyrrole‐2‐carboxylic acid provided new atropisomeric 1‐arylpyrrole derivatives. The absolute configuration of the pure dicarboxylic acid enantiomers was determined by single crystal X‐ray diffraction and CD spectroscopy. Chirality 2009. © 2009 Wiley‐Liss, Inc. 相似文献
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Comparative CD studies have been carried out to characterize the properties of 2′–5′ and 3′–5′ oligoriboadenylates and oligoribouridylates from dimer to decamer. The CD band of the 3′–5′ oligoribonucleotides was larger than that of the 2′–5′ oligoribonucleotides and increased with the increase in chain length, while the CD band of the 2′–5′ oligoribonucleotides increased little beyond the dimer level. The CD analysis of the chain length dependency revealed that the 3′–5′ oligoribonucleotides adopt mainly the base-base stacking interaction, while the base-sugar interaction is predominant in the 2′–5′ oligoribonucleotides. The CD intensity of 3′–5′ oligoribonucleotides decreased to a larger extent at elevated temperatures or in the presence of ethanol compared to that of the 2′–5′ counterparts. Mg2+ or Mn2+ ion enhanced the magnitude of the CD of 3′–5′ octariboadenylate, while a small decrease in the CD was observed by the presence of Mg2+ or Mn2+ ion to the 2′–5′ octariboadenylate. The 3′–5′ oligoribonucleotide is likely conformationally flexible and can form helical ordered structure with strong base-base stacking depending on changes in the environment such as temperature, the presence of Mg2+ ion, or hydrophobicity of the solution. © 1996 John Wiley & Sons, Inc. 相似文献
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Fibrillation of β‐amyloid is recognized as a key process leading to the development of Alzheimer's disease. Small peptides called β‐sheet breakers were found to inhibit the process of β‐amyloid fibrillation and to dissolve amyloid fibrils in vitro, in vivo, and in cell culture studies [1,2]. The mechanism by which peptide inhibition takes place remains elusive and a detailed model needs to be established. Here, we present new insights into the possible role of consecutive Phe residues, present in the structure of β‐sheet breakers, supported by the results obtained by means of MD simulations. We performed a 30‐ns MD of two β‐sheet breakers: iAβ5 (LPFFD) and iAβ6 (LPFFFD) which have two and three consecutive Phe residues, respectively. We have found that Phe rings in these peptides tend to form stacked conformations. For one of the peptides – iAβ6 – the calculated electrostatic contribution to free energy of one of the conformers with three rings stacked (c2) is significantly lower than that corresponding to the unstacked one (c1), two rings stacked (c0) and second conformer with three rings stacked (c3). This may favor the interaction of the c2 conformer with the target on amyloid fibril. We hypothesize that the mechanism of inhibition of amyloidogenesis by β‐sheet breaker involves competition among π‐stacked Phe residues of the inhibitor and π‐stacking within the β‐amyloid fibril. iAβ6 may be a promising candidate for a lead compound of amyloidogenesis inhibitors. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
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The β‐amyloid peptides (Aβ), Aβ1–40 and Aβ1–42, have been implicated in Alzheimer's disease (AD) pathology. Although Aβ1–42 is generally considered to be the pathological peptide in AD, both Aβ1–40 and Aβ1–42 have been used in a variety of experimental models without discrimination. Here we show that monomeric or oligomeric forms of the two Aβ peptides, when interact with the neuronal cation channel, α7 nicotinic acetylcholine receptors (α7nAChR), would result in distinct physiologic responses as measured by acetylcholine release and calcium influx experiments. While Aβ1–42 effectively attenuated these α7nAChR‐dependent physiology to an extent that was apparently irreversible, Aβ1–40 showed a lower inhibitory activity that could be restored upon washings with physiologic buffers or treatment with α7nAChR antagonists. Our data suggest a clear pharmacological distinction between Aβ1–40 and Aβ1–42. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 25–30, 2003 相似文献
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Hidehisa Kawashima Nobuko Watanabe Hisako K. Ijuin Masakatsu Matsumoto 《Luminescence》2013,28(5):696-704
Bicyclic dioxetanes 2a–c bearing a 2′‐alkoxy‐2‐hydroxy‐1,1′‐binaphthyl‐7‐yl moiety were effectively synthesized and their base‐induced chemiluminescent decomposition was investigated by the use of alkaline metal (Na+ and K+) or Mg2+ alkoxide in MeOH. When 2a–c were treated with tetrabutylammonium fluoride (TBAF) in dimethyl sulfoxide (DMSO) as a reference system, they showed chemiluminescence as a flash of orange light (maximum wavelength λmaxCL = 573–577 nm) with efficiency ΦCL = 6–8 × 10–2. On the other hand, for an alkaline metal (Na+ or K+) alkoxide/MeOH system, 2a–c decomposed slowly to emit a glow of chemiluminescence, the spectra of which were shifted slightly toward red from the TBAF/DMSO system, and ΦCL (= 1.4–2.3 × 10–3) was considerably decreased. In addition, Mg(OMe)2 was found to play a characteristic role as a base for the chemiluminescent decomposition of 2a–c through coordination to the intermediary oxidoaryl‐substituted dioxetanes 13. Thus, Mg2+ increased ΦCL to more than twice those with Na+ or K+, while it shifted λmaxCL considerably toward blue (λmaxCL = 550–566 nm). Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Human α‐amino‐β‐carboxymuconate‐ε‐semialdehyde decarboxylase (ACMSD): A structural and mechanistic unveiling
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Human α‐amino‐β‐carboxymuconate‐ε‐semialdehyde decarboxylase determines the fate of tryptophan metabolites in the kynurenine pathway by controlling the quinolinate levels for de novo nicotinamide adenine dinucleotide biosynthesis. The unstable nature of its substrate has made gaining insight into its reaction mechanism difficult. Our electron paramagnetic resonance (EPR) spectroscopic study on the Cu‐substituted human enzyme suggests that the native substrate does not directly ligate to the metal ion. Substrate binding did not result in a change of either the hyperfine structure or the super‐hyperfine structure of the EPR spectrum. We also determined the crystal structure of the human enzyme in its native catalytically active state (at 1.99 Å resolution), a substrate analogue‐bound form (2.50 Å resolution), and a selected active site mutant form with one of the putative substrate binding residues altered (2.32 Å resolution). These structures illustrate that each asymmetric unit contains three pairs of dimers. Consistent with the EPR findings, the ligand‐bound complex structure shows that the substrate analogue does not directly coordinate to the metal ion but is bound to the active site by two arginine residues through noncovalent interactions. Proteins 2015; 83:178–187. © 2014 Wiley Periodicals, Inc. 相似文献
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The 2‐[2‐(2‐phenylethenyl)cyclopent‐3‐en‐1‐yl]‐1,3‐benzothiazoles were synthesized from the reactions of 7‐benzylidenebicyclo[3.2.0]hept‐2‐en‐6‐ones with 2‐aminobenzenethiol. The antiproliferative activities of 2‐[2‐(2‐phenylethenyl)cyclopent‐3‐en‐1‐yl]‐1,3‐benzothiazoles were determined against C6 (rat brain tumor) and HeLa (human cervical carcinoma cells) cell lines using BrdU cell proliferation ELISA assay. Cisplatin and 5‐fluorouracil (5‐FU) were used as standards. The most active compound was 2‐{(1S,2S)‐2‐[(E)‐2‐(4‐methylphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against C6 cell lines with IC50=5.89 μm value (cisplatin, IC50=14.46 μm and 5‐FU, IC50=76.74 μm ). Furthermore, the most active compound was 2‐{(1S,2S)‐2‐[(E)‐2‐(2‐methoxyphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against HeLa cell lines with IC50=3.98 μm (cisplatin, IC50=37.95 μm and 5‐FU, IC50=46.32 μm ). Additionally, computational studies of related molecules were performed by using B3LYP/6‐31G+(d,p) level in the gas phase. Experimental IR and NMR data were compared with the calculated results and were found to be compatible with each other. Molecular electrostatic potential (MEP) maps of the most active 2‐{(1S,2S)‐2‐[(E)‐2‐(2‐methoxyphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against HeLa and the most active 2‐{(1S,2S)‐2‐[(E)‐2‐(4‐methylphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole against C6 were investigated, aiming to determine the region that the molecule is biologically active. Biological activities of mentioned molecules were investigated with molecular docking analyses. The appropriate target protein (PDB codes: 1 M17 for the HeLa cells and 1JQH for the C6 cells) was used for 2‐{(1S,2S)‐2‐[(E)‐2‐(2‐methoxyphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole and 2‐{(1S,2S)‐2‐[(E)‐2‐(4‐methylphenyl)ethenyl]cyclopent‐3‐en‐1‐yl}‐1,3‐benzothiazole molecules exhibiting the highest biological activity against HeLa and C6 cells in the docking studies. As a result, it was determined that these molecules are the best candidates for the anticancer drug. 相似文献
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Spectral‐converting study of Ba9–3(m+n)/2ErmYbnY2Si6O24 (m = 0.005 – 0.2, n = 0 – 0.3) orthosilicate phosphors
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Optical materials composed of Ba9–3(m+n)/2ErmYbnY2Si6O24 (m = 0.005–0.2, n = 0–0.3) were prepared using a solid‐state reaction. The X‐ray diffraction patterns of the obtained phosphors were examined to index the peak positions. The photoluminescence (PL) excitation and emission spectra of the Er3+‐activated phosphors and the critical emission quenching as a function of Er3+ content in the Ba9–3m/2ErmY2Si6O24 structure were monitored. The spectral conversion properties of Er3+ and Er3+–Yb3+ ions doped in Ba9Y2Si6O24 phosphors were elucidated under diode‐laser irradiation at 980 nm. Up‐conversion emission spectra and the dependence of the emission intensity on pump power for the Ba8.55Er0.1Yb0.2Y2Si6O24 phosphor were investigated. The desired up‐conversion of the emitted light, which passed through the green, yellow, orange and red regions of the spectrum, was achieved through the use of appropriate Er3+ and/or Yb3+ concentrations in the host structure and 980 nm excitation light. The up‐conversion mechanism in the phosphors is described by an energy‐level schematic. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Synthesis and Antioxidant Activity of 3‐(Pyridin‐2‐ylmethyl)‐1,3‐thiazinan(thiazolidin)‐4‐ones
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Juliano Bosenbecker Valéria D.O. Bareño Roberta Difabio Flávia A. Vasconcellos Filipe S.P. Dutra Pathise S. Oliveira Alethéa G. Barschak Francieli M. Stefanello Wilson Cunico 《Journal of biochemical and molecular toxicology》2014,28(9):425-432
The antioxidant properties of two series of thiazolidinones and thiazinanones were reported. The novel six‐membered thiazinanones were synthesized from the efficient multicomponent reaction of 2‐picolylamine (2‐aminomethylpyridine), arenaldehydes, and the 3‐mercaptopropionic acid in moderate to excellent yields. These novel compounds were fully identified and characterized by NMR and GC‐MS techniques. In vitro antioxidant activities of all compounds were evaluated by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azinobis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) tests. The antioxidant assays of thiobarbituric acid reactive species and total thiol content levels in the cerebral cortex and liver of rats were also performed. Thiazinanone 5a showed the best radical scavenging activity in DPPH and ABTS tests, as well as reduced lipid peroxidation and increased total thiol group in biological systems. Altogether, the results may be considered a good starting point for the discovery of a new radical scavenger. 相似文献
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Christian Wiese Eva Große Maestrup Dirk Schepmann Stefan Grimme Hans‐Ulrich Humpf Peter Brust Bernhard Wünsch 《Chirality》2011,23(2):148-154
It was shown that racemic (±)‐ 2 [1′‐benzyl‐3‐(3‐fluoropropyl)‐3H‐spiro[[2]benzofuran‐1,4′‐piperidine], WMS‐1813 ] represents a promising positron emission tomography (PET) tracer for the investigation of centrally located σ1 receptors. To study the pharmacological activity of the enantiomers of 2 , a preparative HPLC separation of (R)‐2 and (S)‐2 was performed. The absolute configuration of the enantiomers was determined by CD‐spectroscopy together with theoretical calculations of the CD‐spectrum of a model compound. In receptor binding studies with the radioligand [3H]‐(+)‐pentazocine, (S)‐2 was thrice more potent than its (R)‐configured enantiomer (R)‐2 . The metabolic degradation of the more potent (S)‐enantiomer was considerably slower than the metabolism of (R)‐2 . The structures of the main metabolites of both enantiomers were elucidated by determination of the exact mass using an Orbitrap‐LC‐MS system. These experiments showed a stereoselective biotransformation of the enantiomers of 2 . Chirality, 2011. © 2010 Wiley‐Liss, Inc. 相似文献