Search results for "Pyran"
showing 10 items of 224 documents
KA-672 inhibits rat brain acetylcholinesterase in vitro but not in vivo.
1999
Abstract KA-672, a lipophilic benzopyranone derivative which is currently under development as a cognitive enhancer and antidementia drug, has previously been shown to have facilitatory effects on learning and memory in rats at doses of 0.1–1 mg/kg. We now report that KA-672 inhibited the activity of acetylcholinesterase (AChE), measured in vitro in rat brain cortical homogenate, with an IC 50 value of 0.36 μ M indicating that KA-672 may improve cognitive functions as a consequence of AChE inhibition. However, when we employed the microdialysis procedure to monitor acetylcholine (ACh) release from rat hippocampus, no effect of KA-672 (0.1–10 mg/kg) was found, indicating a lack of inhibition…
Crystal structures of O-acetylated 2-acylamino-2-deoxy-d-galactose derivatives
2003
The X-ray structures of 1,3,4,6-tetra-O-acetyl-2-deoxy-alpha-D-galactopyranoside derivatives with four different 2-(acylamino) substituents have been determined with Mo K(alpha) radiation at 123 K. The structure of the 2-acetylamino derivative and of its acyl-homologs with a 2-(propanoylamino)-, 2-(butanoylamino)-, and 2-(2-methyl-propanoylamino)-group crystallized in the monoclinic space group C2. The pyranose unit of all compounds has the usual 4C(1) shape. The different orientations of the 6-O-acetyl-groups are discussed. Conformations of the acylamino-group are compared to those found in the crystal structure of N-acetyl-alpha-D-galactosamine.
Investigation of new 2-aryl substituted Benzothiopyrano[4,3-d[pyrimidines as kinase inhibitors targeting vascular endothelial growth factor receptor 2
2015
Vascular Endothelial Growth Factor (VEGF) pathway has emerged as one of the most important positive modulators of Angiogenesis, a central process implicated in tumour growth and metastatic dissemination. This led to the design and development of anti-VEGF monoclonal antibodies and small-molecule ATP-competitive VEGFR-inhibitors. In this study, we describe the synthesis and the biological evaluation of novel 2-aryl substituted benzothiopyrano-fused pyrimidines 1a-i, 2a-i and 3a-i. The ability of the compounds to target the VEGF pathway was determined in vitro exploiting the compounds' antiproliferative efficacy against HUVEC cells. The VEGFR-2 inhibition was confirmed by enzymatic assays on …
Density Functional Theory Study of the Trans-Trans-Cis (TTC)→Trans-Trans-Trans (TTT) Isomerization of a Photochromic Spiropyran Merocyanine
2008
Density Functional Theory (DFT) calculations have been performed on the TTC→TTT isomerization reaction of the open forms of the 1',3'-dihydro-8-bromo-6-nitro- 1',3',3'-trimethylspiro[2H-1-benzopyran-2,2'-(2H)indole (8-Br-6-nitro-BIPS) system. The calculations were carried out in vacuo and in methylene chloride solution at different temperatures. Results are compared with the available experimental values of free energy difference and activation energy in solution.
Synthesis and characterization of 4,6-O-butylidene-N-(2-hydroxybenzylidene)-beta-D-glucopyranosylamine: crystal structures of 4,6-O-butylidene-alpha-…
2002
4,6-O-Butylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine was synthesized and characterized using analytical, spectral and single-crystal X-ray diffraction methods. 1H and 13C NMR studies showed the presence of the β-anomer, which has also been confirmed by the crystal structure. The molecular structure of this compound showed the presence of the tridentate ONO ligation-core. Both precursors, 4,6-O-butylidene-α-D-glucopyranose and 4,6-O-butylidene-β-D-glucopyranosylamine were characterized using single crystal X-ray diffraction. The α-anomeric nature of the former and β-anomeric nature of the latter were proposed based on 1H NMR studies and were confirmed by determining the crystal …
Mukaiyama–Michael Reactions with Acrolein and Methacrolein: A Catalytic Enantioselective Synthesis of the C17–C28 Fragment of Pectenotoxins
2013
Enantioselective iminium-catalyzed reactions with acrolein and methacrolein are rare. A catalytic enantioselective Mukaiyama-Michael reaction that readily accepts acrolein or methacrolein as substrates, affording the products in good yields and 91-97% ee, is presented. As an application of the methodology, an enantioselective route to the key C17-C28 segment of the pectenotoxin using the Mukaiyama-Michael reaction as the key step is described.
CCDC 166683: Experimental Crystal Structure Determination
2002
Related Article: A.K.Sah, C.P.Rao, P.K.Saarenketo, E.Kolehmainen, K.Rissanen|2001|Carbohydr.Res.|335|33|doi:10.1016/S0008-6215(01)00201-4
Synthesis of toxyloxanthone B
2014
A synthesis of the naturally occurring xanthone toxyloxanthone B is described, in which the key step is the regioselective addition of a methyl salicylate to a substituted benzyne, followed by cyclization of the intermediate aryl anion to form the xanthone, the regiochemistry of the aryne addition being confirmed by X-ray crystallography. Subsequent introduction of the pyran ring by [3,3]-rearrangement and deprotection completed the synthesis.
Halothane inhibits endothelium-dependent relaxation elicited by acetylcholine in human isolated pulmonary arteries.
1997
This study examined whether a clinically relevant concentration of the volatile anaesthetic halothane modifies the endothelium-dependent relaxation produced by acetylcholine (3 nM-10 microM), histamine (1 pM-0.1 microM) and anti-human immunoglobulin E (1:1000) in human isolated pulmonary arteries submaximally precontracted with noradrenaline. An inhibitor of nitric oxide formation, N(G)-nitro-L-arginine (100 microM), attenuated acetylcholine-induced relaxation but failed to inhibit histamine- and anti-human immunoglobulin E-induced relaxation. Indomethacin (2.8 microM, a cyclooxygenase inhibitor) preferentially reduced the relaxation to histamine and anti-human IgE. Halothane (2%) significa…
Effect of storage on quality parameters and phenolic content of Italian extra-virgin olive oils
2019
The quality of extra virgin olive oils is affected mainly by hydrolytic and oxidative reactions. The present paper investigated the changes of major and minor components and oxidation indices of three monovarietal extra virgin olive oils after 18 months of storage at room temperature and in dark glass bottles conditions. After storage, the basic quality parameters such as free acidity, peroxide values, extinction coefficients, fatty acids composition, chlorophyll and carotenoid content, did not exceed the upper limits set by European Community Regulations for extra-virgin olive oils. Given the importance of the phenolic fraction, UHPLC-HESI-MS metodology was used. A decrease in 3,4-DHPEA-ED…