Search results for "cyclic"
showing 10 items of 2439 documents
Oxamidato complexes. Part 4. Electrochemical study of the copper(III)/copper(II) couple in monomeric N,N?-bis(substituent)oxamidatocopper(II) complex…
1993
The electrochemical behaviour of a series of monomeric N,N′-bis(substituent)oxamidato copper(II) complexes of formula Na2[Cu(3,5,3′,5′-X4obbz)]·4H2O [X = Cl (1), Br (2), I (3) and obbz = oxamidobis(benzoato)], Na2-[Cu(obbz)]·4H2O (4), Na2[Cu(5,5′-Me2obbz)]·4H2O (5), Na2[Cu(4,5,4,5′-(MeO)4obbz)]·4H2O(6),Na2[Cu(obp)]· 3.5H2O (7) (obp = oxamidobis(propionato)) and Na2[Cu(pba)]·6H2O (8), [pba = propylenebis(oxamate)] has been investigated by cyclic voltammetry, rotating disk electrode and coulometry in water and dimethylsulphoxide (dmso) solutions. NaNO3 (0.1 M) and n-Bu4NPF6 (0.1 M) were used as supporting electrolytes in H2O and dmso respectively, all solutions being thermostatted at 25 °C. I…
Electrochemistry of copper complexes with macrocyclic polyamines containing pyrazole units.
2006
The voltammetric behaviour of bi- and mono-nuclear complexes formed in solution by Cu(2+) with three polyazacyclophanes containing pyrazole units in aqueous solution is described. Cyclic and square wave voltammetric responses at glassy carbon electrodes indicate that the reduction of copper-macrocycle complexes in solution takes place in two successive one-electron per Cu transfer processes coupled with preorganization and protonation reactions that mimic the behaviour of superoxide dismutase. The electrochemistry of ternary Cu(2+)-receptor-dopamine complexes exhibits significant differences with respect to the protection of the neurotransmitter from post-electron transfer cyclization react…
Identification of Bioactive Compounds in Polar and Nonpolar Extracts of Araujia sericifera
2017
Abstract Araujia sericifera is a native perennial, climbing laticiferous shrub from South America that is currently naturalized in many other countries. Previous data describe promising properties for A. sericifera, but no systematic study of its bioactive compounds and possible medicinal applications has been conducted to date. In the present study, aerial parts of A. sericifera (leaves, stems, and fruits) were explored by combining GC-MS and NMR spectroscopy analysis for both nonpolar (hexane) and polar (methanol) extracts. The hexanic extracts contained high amounts of pentacyclic triterpenes including two new metabolites, 3-tigloyl germanicol (18) and 3-tigloyl lupeol (19). The methanol…
Continuous images of arcs: Extensions of Cornette's Theorem
2015
In [J.L. Cornette “Image of a Hausdorff arc” is cyclically extensible and reducible Trans. Am. Math. Soc., 199 (1974), pp. 253–267], Cornette proved that a locally connected Hausdorff continuum X is the continuous image of an arc if and only if each of its cyclic elements is the continuous image of an arc. Cyclic elements form a closed null cover of X by retracts of X. We generalize Cornette's result to closed null covers of X with a dendritic structure. We give examples to show that some of our conditions are necessary and we pose some open questions.
Biological activities of Schottenol and Spinasterol, two natural phytosterols present in argan oil and in cactus pear seed oil, on murine miroglial B…
2014
International audience; The objective of this study was to evaluate the biological activities of the major phytosterols present in argan oil (AO) and in cactus seed oil (CSO) in BV2 microglial cells. Accordingly, we first determined the sterol composition of AO and CSO, showing the presence of Schottenol and Spinasterol as major sterols in AO. While in CSO, in addition to these two sterols, we found mainly another sterol, the Sitosterol. The chemical synthesis of Schottenol and Spinasterol was performed. Our results showed that these two phytosterols, as well as sterol extracts from AO or CSO, are not toxic to microglial BV2 cells. However, treatments by these phytosterols impact the mitoch…
Electrophysiological and Behavioral Responses of Oriental Fruit Moth to the Monoterpenoid Citral Alone and in Combination With Sex Pheromone
2013
The monoterpenoid citral synergized the electroantennogram (EAG) response of male Grapholita molesta (Busck) antennae to its main pheromone compound Z8-12:OAc. The response to a 10-μg pheromone stimulus increased by 32, 45, 54, 71 and 94% with the addition of 0.1, 1, 10, 100 and 1,000 μg of citral, respectively. There was no detectable response to 0.1, 1, or 10 μg of citral; the response to 100 and 1,000 μg of citral was 31 and 79% of the response to 10 μg of Z8-12:OAc. In a flight tunnel, citral affected the mate-seeking behavior of males. There was a 66% reduction in the number of males orientating by flight to a virgin calling female when citral was emitted at 1,000 ng/min ≍1 cm downwind…
The influence of electron delocalization upon the stability and structure of potential N-heterocyclic carbene precursors with 1,3-diaryl-imidazolidin…
2010
Targeting N-heterocyclic carbenes (NHCs) with increased π-acceptor character featuring N-fluorophenyl substituents, the molecular 2-chloro-1,3-bis(fluorophenyl)imidazolidine-4,5-diones (1a–c) were isolated from the condensation of the corresponding formamidine with oxalyl chloride. These formal adducts of NHCs with hydrogen chloride demonstrated reactivity akin to that of alkyl halides: 1,3,1′,3′-tetrakis(2,6-dimethylphenyl)-[2,2′]diimidazolidinyl-4,5,4′,5′-tetraone (2b) was formed via the reductive coupling of 1b, while 1,3-bis(2,6-diisopropylphenyl)-4,5-dioxoimidazolidin-2-yl acetate (3c) was formed as the result of a metathesis reaction with mercury(II) acetate. Chloride abstraction resu…
Emerging brominated flame retardants and dechlorane-related compounds in European eels (Anguilla anguilla) from Latvian lakes
2017
Abstract Fifteen halogenated flame retardants (HFRs) including seven emerging brominated flame retardants (EBFRs) and eight dechlorane-related compounds (DRCs) were analyzed in eels (Anguilla anguilla) sampled from five Latvian lakes. Out of the seven EBFRs, hexabromocyclododecane (HBCD) and decabromodiphenyl ethane (DBDPE) were found in eels in quantifiable concentrations, up to 6.58 and 33.0 ng g−1 lipid weight (l.w.), respectively. The mean total concentration of DRCs (∑DRC) in the samples was 0.62 ng g−1 l.w. and the geographical distribution of DRC contamination was nearly uniform among the selected lakes. Dechlorane 602 (Dec 602) was the predominant component, whereas the composition …
Pharmacological blockade of the fatty acid amide hydrolase (FAAH) alters neural proliferation, apoptosis and gliosis in the rat hippocampus, hypothal…
2015
Endocannabinoids participate in the control of neurogenesis, neural cell death and gliosis. The pharmacological effect of the fatty acid amide hydrolase (FAAH) inhibitor URB597, which limits the endocannabinoid degradation, was investigated in the present study. Cell proliferation (phospho-H3(+) or BrdU(+) cells) of the main adult neurogenic zones as well as apoptosis (cleaved caspase-3(+)), astroglia (GFAP(+)), and microglia (Iba1(+) cells) were analyzed in the hippocampus, hypothalamus and striatum of rats intraperitoneally treated with URB597 (0.3 mg/kg/day) at one dose/4-days resting or 5 doses (1 dose/day). Repeated URB597 treatment increased the plasma levels of the N-acylethanolamine…
Urban organic aerosol composition in eastern China differs from north to south:Molecular insight from a liquid chromatography-mass spectrometry (Orbi…
2021
Air pollution by particulate matter in China affects human health, the ecosystem and the climate. However, the chemical composition of particulate aerosol, especially of the organic fraction, is still not well understood. In this study, particulate aerosol samples with a diameter of ≤2.5 µm (PM2.5) were collected in January 2014 in three cities located in northeast, east and southeast China, namely Changchun, Shanghai and Guangzhou. Organic aerosol (OA) in the PM2.5 samples was analyzed by an ultrahigh-performance liquid chromatograph (UHPLC) coupled to a high-resolution Orbitrap mass spectrometer in both negative mode (ESI-) and positive mode electrospray ionization (ESI+). After non-targe…