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Lúcio AS Almeida JR Barbosa-Filho JM Pita JC Branco MV Diniz Mde F Agra Mde F da-Cunha EV da Silva MS Tavares JF 《Molecules (Basel, Switzerland)》2011,16(8):7125-7131
Phytochemical investigation of Anaxagorea dolichocarpa Sprague & Sandwith led to isolation of three azaphenanthrene alkaloids: eupolauramine, sampangine and imbiline 1. Their chemical structures were established on the basis of spectroscopic data from IR, HR-ESI-MS, NMR (including 2D experiments) and comparison with the literature. Sampangine and imbiline 1 are being described in the Anaxagorea genus for the first time. Eupolauramine and sampangine show concentration-dependent antitumoral activity in leukemic cells K562 with IC(50) of 18.97 and 10.95 μg/mL, respectively. 相似文献
44.
Carneiro VA Santos HS Arruda FV Bandeira PN Albuquerque MR Pereira MO Henriques M Cavada BS Teixeira EH 《Molecules (Basel, Switzerland)》2011,16(1):190-201
Croton nepetaefolius is a native plant from northeastern Brazil that belongs to the Euphorbiaceae family. The biological action of this plant has been extensively explored, being the secondary metabolites responsible for its properties alkaloids, diterpenes, and triterpenes. This study aimed to evaluate the ability of casbane diterpene (CD), isolated from the ethanolic extract of C. nepetaefolius, to inhibit microbial growth and biofilm formation of several clinical relevant species (bacteria and yeasts). It was found that CD possessed biocidal and biostatic activity against the majority of the species screened, with minimal active concentrations ranging between 125 and 500 μg/mL. In addition, it was observed that biofilm formation was inhibited even when the planktonic growth was not significantly affected. In conclusion, CD showed potential to be a natural tool for the treatment of diseases caused by different infectious microorganisms. 相似文献
45.
Rafael de Souza Monteiro Lílian W. C. Paes José Walkimar de M. Carneiro Donato A. G. Aranda 《Journal of Cluster Science》2008,19(4):601-614
The adsorption of CO on Fe, Pt and Co clusters was modeled by the DFT approach using the B3LYP and the BPW91 functionals together
with the LANL2DZ and the 6-31G(d) basis set. These calculations show that although CO adsorbs more strongly on Pt than on
either Fe or Co, the dissociation energy on Fe and on Co is lower than the corresponding dissociation energy on Pt. Therefore,
the activation energy for dissociation is not determined by the adsorption energy. Additionaly, the CO bond distances also
do not show any correlation to the adsorption energy. 相似文献
46.
We present in this paper a way to perform the mapping of the spin-1 Blume–Capel model into a random-cluster model, and analyze thermodynamic properties of the former model in terms of geometric properties of clusters generated in the random-cluster representation. It is shown that there are two different relevant types of cluster, and that one of them is the exact analogue of the type of cluster generated in the Ising model. We use this result to derive expressions for thermodynamical properties on the second-order transition line which are equivalent to the ones found in the Ising model. The other type of cluster is responsible for the first-order transitions, and we may see the tricritical point as a point where both types of cluster compete on the same footing. 相似文献
47.
Josiane Durrieu Raymond Kraemer Jacques Navech 《Magnetic resonance in chemistry : MRC》1973,5(9):407-412
The PMR spectra of some new 1,3,2-oxazaphosphorinanes are analysed. In one case, after elimination of the P? H spin coupling, the spectra give rise to a particular ABKLXY pattern in which certain coupling constants between vicinal protons are zero. The ABKLXY system where JAK = JAL = JBK = JBL is studied and most of the parameters of the related compound are calculated. The ring conformation is discussed and the free energy is given; for one oxazaphosphorinane, the calculation of the torsional angle of the C4? C5 and C5? C6 fragments is described. 相似文献
48.
Absintholide is a new guaianolide dimer whose structure and stereochemistry has been elucidated on the basis of high resolution n.m.r. 相似文献
49.
Neutron inelastic scattering has been used to study the longitudinal and one of the transverse acoustic phonons, propagating along the [001]1 direction in triclinic K1.75[Pt(CN)4]·1.5H2O. This material appears to be a quasi-one-dimensional conductor, with a commensurate distortion. We observe a reasonably well defined Kohn anomaly, which shows little temperature dependence between 80 and 300 K. 相似文献
50.
Josiane Durrieu Raymond Kraemer Jacques Navech 《Magnetic resonance in chemistry : MRC》1972,4(5):709-719
After elimination of the P? H spin coupling, the PMR spectra of the title 1,3,2-oxazaphosphorinanes give rise to an ABXY pattern where JAX = JAY = JBX = 0. The particular ABXY system where JAY = JBX = 0 is studied to calculate the expression of the E7, E8, E9 and E10 energy-levels and the frequency of the transitions connected to these energy-levels. The relative sign of the 3JP? O? C? H and 3JP? N? C? H coupling constants is given by INDOR experiments. The ring conformation is discussed. 相似文献