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81.
Celso Alves Joana Silva Susete Pinteus Eva Alonso Rebeca Alvario Adriana Duarte Diorge Marmitt Mrcia Inês Goettert Helena Gaspar Amparo Alfonso Maria C. Alpoim Luis M. Botana Rui Pedrosa 《Molecules (Basel, Switzerland)》2021,26(5)
Marine natural products have exhibited uncommon chemical structures with relevant antitumor properties highlighting their potential to inspire the development of new anticancer agents. The goal of this work was to study the antitumor activities of the brominated diterpene sphaerodactylomelol, a rare example of the dactylomelane family. Cytotoxicity (10–100 µM; 24 h) was evaluated on tumor cells (A549, CACO-2, HCT-15, MCF-7, NCI-H226, PC-3, SH-SY5Y, SK-ML-28) and the effects estimated by MTT assay. Hydrogen peroxide (H2O2) levels and apoptosis biomarkers (membrane translocation of phosphatidylserine, depolarization of mitochondrial membrane potential, Caspase-9 activity, and DNA condensation and/or fragmentation) were studied in the breast adenocarcinoma cellular model (MCF-7) and its genotoxicity on mouse fibroblasts (L929). Sphaerodactylomelol displayed an IC50 range between 33.04 and 89.41 µM without selective activity for a specific tumor tissue. The cells’ viability decrease was accompanied by an increase on H2O2 production, a depolarization of mitochondrial membrane potential and an increase of Caspase-9 activity and DNA fragmentation. However, the DNA damage studies in L929 non-malignant cell line suggested that this compound is not genotoxic for normal fibroblasts. Overall, the results suggest that the cytotoxicity of sphaerodactylomelol seems to be mediated by an increase of H2O2 levels and downstream apoptosis. 相似文献
82.
[reaction: see text] Chiral 2-acyl-3-allyl- or 2-acyl-3-benzyl-substituted perhydro-1,3-benzoxazines readily cyclized under irradiation to azetidin-3-ol derivatives. The diastereoselectivity of the cyclization is dependent on the nature of the substituents at the nitrogen atom. N-allyl-substituted derivatives yielded only two of the four possible diastereomers in moderate to good diastereomeric excess. The cyclization of N-benzyl derivatives was totally diastereoselective leading to a single diastereomer. The elimination of the menthol appendage lead to enantiopure 2,3-disubstituted azetidin-3-ol derivatives. 相似文献
83.
Internal pressures and cohesive energy densities of binary liquid mixtures of n-pentane+dichloromethane, n-pentane+methylacetate, 2-propanol+methylacetate and n-bytylamine+1,4-dioxane at 25°C have been evaluated from molar volumes surface tensions and enthalpies. The data obtained provide information about interactions in the binary liquid mixtures which can be correlated with results from other thermodynamic properties.Presented at the VI Congreso Argentino de Fisicoquímica, Santiago del Estero, Argentina, 1989. 相似文献
84.
Saléte Valgas Vanessa Lima Gonçalves Mauro C. M. Laranjeira Valfredo T. Fávere Rozangela Curi Pedrosa 《Macromolecular Symposia》2005,229(1):246-252
Summary: The purpose of this study was to produce malonylchitosan microspheres to be used as a pH sensitive matrix for the controlled delivery of drugs. Chitosan microspheres were obtained by the coacervation–phase separation method. The microspheres were then treated with malonic acid to obtain amidified chitosan microspheres. The resulting malonylchitosan microspheres were characterized by means of elemental analysis (CHN), infrared spectroscopy, conductometric titration and scanning electron microscopy (SEM). The data obtained from infrared spectroscopy, elemental analysis and conductometric titration of amino groups were consistent with the N-substitution of malonyl groups in the chitosan microspheres. In vivo studies for controlled delivery of enrofloxacin were performed in male Wistar rats and the results indicated increase and prolonged blood levels with delayed peak and improved bioavailability for malonylchitosan microspheres compared to commercial tablets. 相似文献
85.
A novel, direct,and high-yielding stereoselective method for enantiopure 1-substituted tetrahydroisoquinolines (THIQ) is described. The successful approach, which creates the stereocenter during the formation of the THIQ nucleus is based on (i) formation of chiral 2,3-substituted perhydro-1,3-benzoxazines derived from (-)-8-aminomenthol, (ii) diastereoselective intramolecular ring opening of the N,O-acetal moiety by an arylmetal generated from the substituent at the nitrogen atom in the perhydrobenzoxazine ring, and (iii) removal of the chiral auxiliary appendage. The starting perhydrobenzoxazines are easily prepared from (-)-8-aminomenthol and two different aldehydes, and the intramolecular opening is stereospecific, leading to a single stereoisomer. The method allows the preparation of a wide variety of enantiopure 1-substituted THIQ, with different substituents at C-1, by changing the nature of the starting aldehydes. 相似文献
86.
Christiam B. Figueroa Francesco Mercuri Renato H. L. Pedrosa 《Annali di Matematica Pura ed Applicata》1999,177(1):173-194
Summary We fix a left-invariant metric g in the eisenberg group,H
3, and give a complete classification of the constant mean curvature surfaces (including minimal) which are invariant with
respect to 1-dimensional closed subgroups of the connected component of the isometry group of (H
3, g). In addition to finding new examples, we organize in a common framework results that have appeared in various forms in
the literature, by the systematic use of Riemannian transformation groups. Using the existence of a family of spherical surfaces
for all values of nonzero mean curvature, we show that there are no complete graphs of constant mean curvature. We extend
some of these results to the higher dimensional Heisenberg groupsH
2n+1.
Entrata in Redazione il 2 aprile 1998.
The first author was supported by Fapesp (Brazil), the second was partially supported by Fapesp and CNPq (Brazil), and the
third was partially supported by Fapesp. 相似文献
87.
Spondias tuberosa (Anacardiaceae) leaves: profiling phenolic compounds by HPLC‐DAD and LC–MS/MS and in vivo anti‐inflammatory activity 下载免费PDF全文
Emerson Michell da Silva Siqueira Juliana Félix‐Silva Lorena Maria Lima de Araújo Julia Morais Fernandes Bárbara Cabral Jacyra Antunes dos Santos Gomes Alan de Araújo Roque José Carlos Tomaz Norberto Peporine Lopes Matheus de Freitas Fernandes‐Pedrosa Raquel Brandt Giordani Silvana Maria Zucolotto 《Biomedical chromatography : BMC》2016,30(10):1656-1665
Spondias tuberosa is a medicinal plant used by several local communities in northeast Brazil to treat infections, digestive disorders and inflammatory conditions. The study aimed to identify and quantify the major phenolic in hydroethanolic extract of leaves from S. tuberosa and to evaluate its anti‐inflammatory potential. The chemical profile of extract was analyzed by HPLC‐DAD and HPLC–MS. The in vivo anti‐inflammatory activity was investigated in carrageenan‐induced hind paw edema and peritonitis models in mice. Identified and quantified through HPLC‐DAD or HPLC‐MS analyses of S. tuberosa extract were the following compounds: chlorogenic acid, caffeic acid, rutin and isoquercitrin. The inflammatory response to carrageenan was significantly reduced in both models by S. tuberosa extract. In hind paw edema, the edematogenic response was reduced by up to 63.6% and the myeloperoxidase activity was completely inhibited. In the peritonitis model, the total cell migration into the peritoneal cavity was reduced by up to 65%. The results obtained give evidence of the anti‐inflammatory action of S. tuberosa and suggest the potential therapeutic benefit of this plant on inflammatory conditions. The chlorogenic acid, caffeic acid, rutin and isoquercitrin identified and quantified in S. tuberosa leaves enable us to suggest that these compounds could be used as chemical markers for quality control of derivative products from this species. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
88.
M.A. Pedrosa C. Hidalgo K.J. McCarthy A. López-Sánchez M.A. Ochando I. Pastor A. Baciero E. Calderón T. Estrada J. Herranz J. López-Razola B. V. Milligen D. Tafalla F. Tabarés The TJ-II Team N. Dreval A. Chmyga S.M. Khrebtov A.D. Komarov S. Kozachok L. Krupnik L. Eliseev A.V. Melnikov 《Czechoslovak Journal of Physics》2003,53(10):877-885
The influence of limiter biasing on plasma confinement, turbulence and plasma flows has been investigated in the TJ-II stellarator. Experimental results show that it is possible to modify global particle confinement and edge plasma parameters with both positive and negative biasing. Significant and minor modifications in the structure of plasma fluctuations have been observed during the transition to improved confinement regimes induced by limiter biasing. These results show evidence of electric field induced improved confinement via multiple mechanisms. The investigation of the relaxation of plasma potential and electric fields shows evidence of two different characteristic decay times. 相似文献
89.
C. Silva B. Goncalves M. A. Pedrosa C. Hidalgo K. McCarthy E. Calderon J. Herranz I. Pastor O. Orozco 《Czechoslovak Journal of Physics》2005,55(12):1589-1596
Edge polarization experiments were carried out on TJ-II using an electrode. It has been found that the plasma response is
different at densities below and above the threshold value to trigger the spontaneously development of E × B sheared flows. At low densities, the edge plasma potential is fully controlled by external biasing, while at higher densities
it is determined not only by external biasing but also by the electric fields spontaneous developed. Although an improvement
in particle confinement is observed for both polarities, a larger increase is observed for negative electrode bias.
Presented at the Workshop “Electric Fields, Structures and Relaxation in Edge Plasmas”, Tarragona, Spain, July 3–4, 2005. 相似文献
90.
3,5-Dimethylisothiazole reacts sequentially with lithiumdiisopropylamide (molar ratio 1:1) and alkyl halides (in excess) affording 5-alkyl-3-methylisothiazoles in excellent yields. When a two-fold excess of base is used, a mixture of 5-monoalkylated and 3,5-dialkylated products is obtained. Sodium amide was also tried as deprotonating agent, but the yield in final products was lower. 相似文献