Novel quinazolinones and enniatins from Fusarium lateritium Nees

1993 ◽  
Vol 71 (9) ◽  
pp. 1362-1367 ◽  
Author(s):  
Youla S. Tsantrizos ◽  
Xiao-Jin Xu ◽  
Françoise Sauriol ◽  
Rosemary C. Hynes
Keyword(s):  
Antifungal Activity ◽  
Spectroscopic Analysis ◽  
Bioactive Metabolites ◽  
The Novel ◽  
Nmr Analysis ◽  
Biological Phenomenon ◽  
X Ray ◽  
X Ray Crystallography ◽  
Fusarium Lateritium ◽  
Absolute Stereochemistry

Fusarium lateritium Nees is a natural antagonist of the plant pathogen Eutypa armeniacae. In an effort to show that this biological phenomenon is chemically mediated, the bioactive metabolites of F. lateritium were investigated. The cytotoxic alkaloids 2-(1-hydroxyethyl)-4(3H)quinazolinone (1) and 2-acetyl-4(3H)quinazolinone (2), and the three cyclohexadepsipeptides, enniatins B (3), B1 (4), and A1 (5), were isolated and characterized. Metabolites 3, 4, and 5 were found to exhibit strong antifungal activity against E. armeniacae. The structures of the novel metabolites 1 and 2 were elucidated by spectroscopic analysis and that of 2 was confirmed by X-ray crystallography. The absolute stereochemistry of 1 was investigated by 1H and I9F NMR analysis of its Mosher ester derivative.

Preparation and structural analysis of (±)-threo-ritalinic acid

2013 ◽  
Vol 69 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Sara Wyss ◽  
Irmgard A. Werner ◽  
W. Bernd Schweizer ◽  
Simon M. Ametamey ◽  
Selena Milicevic Sephton
Keyword(s):  
Methyl Ester ◽  
Free Acid ◽  
Nmr Analysis ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ph Values ◽  
Ritalinic Acid ◽  
Methyl Phenidate ◽  
Hydrolysis Of

Hydrolysis of the methyl ester (±)-threo-methyl phenidate afforded the free acid in 40% yield,viz.(±)-threo-ritalinic acid, C13H17NO2. Hydrolysis and subsequent crystallization were accomplished at pH values between 5 and 7 to yield colourless prisms which were analysed by X-ray crystallography. Crystals of (±)-threo-ritalinic acid belong to theP21/nspace group and form intermolecular hydrogen bonds. An antiperiplanar disposition of the H atoms of the (HOOC—)CH—CHpygroup (py is pyridine) was found in both the solid (diffraction analysis) and solution state (NMR analysis). It was also determined that (±)-threo-ritalinic acid conforms to the minimization of negativegauche+–gauche−interactions.

scholarly journals CAAC Boranes. Synthesis and characterization of cyclic (alkyl) (amino) carbene borane complexes from BF3 and BH3

2010 ◽  
Vol 6 ◽  
pp. 709-712 ◽  
Author(s):  
Julien Monot ◽  
Louis Fensterbank ◽  
Max Malacria ◽  
Emmanuel Lacôte ◽  
Steven J Geib ◽  
...  
Keyword(s):  
Silica Gel ◽  
Synthesis And Characterization ◽  
Gel Chromatography ◽  
Nmr Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
In Situ Formation ◽  
Silica Gel Chromatography

In situ formation of two cyclic (alkyl) (amino) carbenes (CAACs) followed by addition of BF3•Et2O provided the first two examples of CAAC–BF3 complexes: 1-(2,6-diisopropylphenyl)-3,5,5-trimethyl-3-phenylpyrrolidin-2-ylidene trifluoroborane, and 2-(2,6-diisopropylphenyl)-3,3-dimethyl-2-azaspiro[4.5]decan-1-ylidene trifluoroborane. These CAAC–BF3 complexes are robust compounds that are stable to ambient laboratory conditions and silica gel chromatography. They were characterized by spectroscopy and X-ray crystallography. In contrast, a CAAC complex with borane (BH3) was readily formed in situ according to 1H and 11B NMR analysis, but did not survive the workup conditions. These results set the stage for further studies of the chemistry of CAAC boranes.

scholarly journals Übergangsmetall-Carben-Komplexe, CXXXIV [1]. Synthese neuer Mono- und Biscarben-Komplexe der VI. Nebengruppe; Röntgenstruktur des ersten Bis[amino(alkoxy)carben]-Komplexes / Transition Metal Carbene Complexes, CXXXIV [1]. Synthesis of New Mono- and Bis-Carbene Complexes of Group VIb Elements; Structure of the First Bis[amino(alkoxy)carbene]-Complex

1984 ◽  
Vol 39 (5) ◽  
pp. 668-674 ◽  
Author(s):  
Ernst Otto Fischer ◽  
Rudolf Reitmeier ◽  
Klaus Ackermann
Keyword(s):  
Molecular Structure ◽  
Transition Metal ◽  
Spectroscopic Data ◽  
The Novel ◽  
Nucleophilic Agent ◽  
Reaction Conditions ◽  
Carbene Complexes ◽  
X Ray ◽  
X Ray Crystallography ◽  
New Compounds

The hexacarbonyl compounds of chromium, molybdenum and tungsten react with the highly nucleophilic agent Li NiPr2 and in a subsequent alkylation with (Et3O)BF4 to give the carbene complexes (CO)5M[C(N′Pr2)OEt] (1, 3, 4). In case of W(CO)6 and Mo(CO)6 the novel biscarbene complexes cis(CO)4M[C(NiPr2)OEt]2 (2, 5) are additionally obtained. Reaction conditions, properties and spectroscopic data of the new compounds are reported. The molecular structure of cis(CO)4W[C(NiPr2)OEt]2 (4) was determined by X-ray crystallography

1,4,8,11-Tetra[2-aryl-1-diazenyl]-1,4,8,11-tetraazacyclotetradecanes — Synthesis, characterization, and X-ray crystallography of the first tetrakistriazenes to be reported

2006 ◽  
Vol 84 (10) ◽  
pp. 1280-1289 ◽  
Author(s):  
Jeffery D Clarke ◽  
Keith Vaughan ◽  
Valerio Bertolasi
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Electrospray Mass Spectrometry ◽  
Diazonium Salt ◽  
Diazonium Salts ◽  
The Novel ◽  
Analogous Reaction ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Mean

The reactions of a series of arene diazonium salts with 1,4,8,11-tetraazacyclotetradecane (cyclam) afford the novel compounds, the 1,4,8,11-tetra[2-aryl-1-diazenyl]-1,4,8,11-tetraazacyclotetradecanes (1a–1f), which are the first examples of tetrakistriazenes to be reported. The tetrakistriazenes were characterized by IR spectroscopy, proton and carbon NMR, elemental analysis, high resolution electrospray mass spectrometry, and X-ray crystallography. The analogous reaction of a diazonium salt with 1,4,7-triazacyclononane or 1,5,9-triazacyclododecane yields the tristriazenes 2, 3a, and 3b. The structures of compounds 1c and 1e were solved by X-ray crystallography at low temperature (150 K). Both molecules display a conformation where the four phenyltriazenyl groups point alternately upwards and downwards with respect to the mean macrocyclic plane.Key words: triazene, tetrakistriazene, cyclam, tetraazacyclotetradecane, X-ray, NMR, cyclic polyamines.

Synthesis and Characterization of Ammonium Decavanadate (V)

2005 ◽  
Vol 494 ◽  
pp. 351-356 ◽  
Author(s):  
M.R. Todorović ◽  
U.B. Mioč ◽  
I. Holclajtner-Antunović ◽  
D. Šegan
Keyword(s):  
Hydrogen Bonds ◽  
Spectroscopic Analysis ◽  
Synthesis And Characterization ◽  
The Novel ◽  
Biochemical Activity ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Conductive Properties ◽  
Ir And Raman

It is known that various polyoxovanadates interact specifically with enzymes, which is the main way of their biochemical activity. Therefore we have synthesized ammonium decavanadate, (NH4)6V10O28·6H2O. The novel compound was characterized by elemental and thermal analysis, X-ray powder and single crystal diffraction and IR and Raman spectroscopy. Its conductive properties have been studied, too. The spectroscopic analysis has shown the presence of hydrogen bonds of different strengths. In order to improve the biochemical activity of this compound and having in mind the presence of strong hydrogen bonds, we essayed the synthesis of complex of polyoxovanadate with alanine. The obtained product was characterized by the mentioned methods.

PLP undergoes conformational changes during the course of an enzymatic reaction

2014 ◽  
Vol 70 (2) ◽  
pp. 596-606 ◽  
Author(s):  
Ho-Phuong-Thuy Ngo ◽  
Nuno M. F. S. A. Cerqueira ◽  
Jin-Kwang Kim ◽  
Myoung-Ki Hong ◽  
Pedro Alexandrino Fernandes ◽  
...  
Keyword(s):  
Conformational Change ◽  
Conformational Changes ◽  
Catalytic Mechanism ◽  
Enzymatic Reaction ◽  
Nucleophilic Attack ◽  
The Novel ◽  
X Ray ◽  
X Ray Crystallography ◽  
Starting Point ◽  
High Level

Numerous enzymes, such as the pyridoxal 5′-phosphate (PLP)-dependent enzymes, require cofactors for their activities. Using X-ray crystallography, structural snapshots of the L-serine dehydratase catalytic reaction of a bacterial PLP-dependent enzyme were determined. In the structures, the dihedral angle between the pyridine ring and the Schiff-base linkage of PLP varied from 18° to 52°. It is proposed that the organic cofactor PLP directly catalyzes reactions by active conformational changes, and the novel catalytic mechanism involving the PLP cofactor was confirmed by high-level quantum-mechanical calculations. The conformational change was essential for nucleophilic attack of the substrate on PLP, for concerted proton transfer from the substrate to the protein and for directing carbanion formation of the substrate. Over the whole catalytic cycle, the organic cofactor catalyzes a series of reactions, like the enzyme. The conformational change of the PLP cofactor in catalysis serves as a starting point for identifying the previously unknown catalytic roles of organic cofactors.

scholarly journals Synthesis, crystal structure and EPR spectroscopic analysis of novel copper complexes formed from N-pyridyl-4-nitro-1,8-naphthalimide ligands

2014 ◽  
Vol 43 (17) ◽  
pp. 6468-6479 ◽  
Author(s):  
Jonathan A. Kitchen ◽  
Paulo N. Martinho ◽  
Grace G. Morgan ◽  
Thorfinnur Gunnlaugsson
Keyword(s):  
Crystal Structure ◽  
Copper Complexes ◽  
Spectroscopic Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cu Complexes

The synthesis of two new monodentate pyridyl based 4-nitro-1,8-naphthalimide ligands and their corresponding Cu-complexes (using various salts) is described. Of these, complexes 1–3 and 5, all gave rise to structures that were characterised by X-ray crystallography and EPR.

scholarly journals Crassifolins Q−W: Clerodane Diterpenoids From Croton crassifolius With Anti-Inflammatory and Anti-Angiogenesis Activities

2021 ◽  
Vol 9 ◽  
Author(s):  
Canjie Li ◽  
Xin Sun ◽  
Wenjing Yin ◽  
Zhaochun Zhan ◽  
Qing Tang ◽  
...  
Keyword(s):  
Spectroscopic Analysis ◽  
Umbilical Vein ◽  
Raw 264.7 ◽  
Significant Activity ◽  
Raw 264.7 Macrophages ◽  
X Ray ◽  
X Ray Crystallography ◽  
Clerodane Diterpenoids ◽  
Umbilical Vein Endothelial Cells

Seven new clerodane diterpenoids, crassifolins Q−W (1–7), along with five known analogues (8–12), were isolated from the roots of Croton crassifolius. Their structures were identified by comprehensive spectroscopic analysis (UV, IR, NMR, and HR-ESI-MS), and their absolute configurations were determined by ECD spectra and X-ray crystallography. The activities of compounds 1–5 against inflammatory cytokines IL-6 and TNF-α levels on LPS-induced RAW 264.7 macrophages were assessed, and compound 5 showed the most significant activity with the secretion levels of IL-6 and TNF-α at 32.78 and 12.53%, respectively. Moreover, compounds 1–5 were screened for their anti-angiogenesis using a human umbilical vein endothelial cells in vitro mode; the results showed all of them exhibited obvious anti-angiogenesis activities, in particular, compound 5 showed the strongest anti-angiogenesis effect in the range of 6.25–50 μM.

scholarly journals Synthesis, crystal structure and antifungal activity of dihydroisoquinoline Oxaziridines Substitued in Position 1

2014 ◽  
Vol 10 (4) ◽  
pp. 2551-2557 ◽  
Author(s):  
Mouna Bouzid ◽  
Raed Abdennabi ◽  
Chakib Hrizi ◽  
Neji Gharsallah ◽  
Majed Kammoun
Keyword(s):  
Crystal Structure ◽  
Antifungal Activity ◽  
Nitro Group ◽  
Oxidizing Agent ◽  
X Ray ◽  
X Ray Crystallography

We report here the synthesis and the X-ray crystallography of dihydroisoquinoline oxaziridines with methyl substitute in position 1 and with nitro group in position 7 (compound 3b). We also synthesized the compound 3a without nitro. These compounds have been prepared by the peracidic oxidation of imines with m-chloroperbenzoic (m-CPBA) like oxidizing agent. This two compounds exhibit higher antifungal activity.

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