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921.
Ventura B Durola F Frey J Heitz V Sauvage JP Flamigni L 《Chemical communications (Cambridge, England)》2012,48(7):1021-1023
The photophysical characterization of an extended zinc porphyrin is reported. Fusion of bis-tetraazaanthracene on the porphyrin ring causes an unusual dual luminescence ascribed to two non-equilibrated singlet excited states. 相似文献
922.
AM Rojas-Sepúlveda M Mendieta-Serrano MY Mojica E Salas-Vidal S Marquina ML Villarreal AM Puebla JI Delgado L Alvarez 《Molecules (Basel, Switzerland)》2012,17(8):9506-9519
The hydroalcoholic extract of the steam bark of B. fagaroides var. fagaroides displayed potent cytotoxic activity against four cancer cell lines, namely KB (ED50 = 9.6 × 10-2 μg/mL), PC-3 (ED50 = 2.5 × 10-1 μg/mL), MCF-7 (ED50 = 6.6 μg/mL), and HF-6 (ED50 = 7.1 × 10-3 μg/mL). This extract also showed anti-tumour activity when assayed on mice inoculated with L5178Y lymphoma cells. Bioactivity-directed isolation of this extract, afforded seven podophyllotoxin-type lignans identified as podophyllotoxin (1), β-peltatin-A-methylether (2), 5'-desmethoxy-β-peltatin-A-methylether (3), desmethoxy-yatein (4), desoxypodophyllotoxin (5), burseranin (6), and acetyl podophyllotoxin (7) by 1D and 2DNMR and FAB-MS analyses, and comparison with reported values. All the isolated compounds showed potent cytotoxic activity in the cell lines tested, especially compound 3, which exhibited greater activity than camptothecin and podophyllotoxin against PC-3 (ED50 = 1.0 × 10-5 μg/mL), and KB (ED50 = 1.0 × 10-5 μg/mL). This is the first report of the isolation of podophyllotoxin and its acetate in a Bursera species. 相似文献
923.
Francesco Sirci Laura Goracci David Rodríguez Jacqueline van Muijlwijk-Koezen Hugo Gutiérrez-de-Terán Raimund Mannhold 《Journal of computer-aided molecular design》2012,26(11):1247-1266
FLAP fingerprints are applied in the ligand-, structure- and pharmacophore-based mode in a case study on antagonists of all four adenosine receptor (AR) subtypes. Structurally diverse antagonist collections with respect to the different ARs were constructed by including binding data to human species only. FLAP models well discriminate ??active?? (=highly potent) from ??inactive?? (=weakly potent) AR antagonists, as indicated by enrichment curves, numbers of false positives, and AUC values. For all FLAP modes, model predictivity slightly decreases as follows: A2BR?>?A2AR?>?A3R?>?A1R antagonists. General performance of FLAP modes in this study is: ligand-?>?structure-?>?pharmacophore- based mode. We also compared the FLAP performance with other common ligand- and structure-based fingerprints. Concerning the ligand-based mode, FLAP model performance is superior to ECFP4 and ROCS for all AR subtypes. Although focusing on the early first part of the A2A, A2B and A3 enrichment curves, ECFP4 and ROCS still retain a satisfactory retrieval of actives. FLAP is also superior when comparing the structure-based mode with PLANTS and GOLD. In this study we applied for the first time the novel FLAPPharm tool for pharmacophore generation. Pharmacophore hypotheses, generated with this tool, convincingly match with formerly published data. Finally, we could demonstrate the capability of FLAP models to uncover selectivity aspects although single AR subtype models were not trained for this purpose. 相似文献
924.
925.
Although keratinocytes are relatively resistant to ultraviolet radiation (UVR) induced damage, repeated UVR exposure result in accumulated DNA mutations that can lead to epidermal malignancies. Keratinocytes play a central role in elaborating innate responses that lead to inflammation and influence the generation of adaptive immune responses in skin. Apart from the minor cellular constituents of the epidermis, specifically Langerhans cells and melanocytes, keratinocytes are the major source of cytokines. UVR exposure stimulates keratinocytes to secrete abundant pro-inflammatory IL-1-family proteins, IL-1α, IL-1β, IL-18, and IL-33. Normal skin contains only low levels of inactive precursor forms of IL-1β and IL-18, which require caspase 1-mediated proteolysis for their maturation and secretion. However, caspase-1 activation is not constitutive, but dependents on the UV-induced formation of an active inflammasome complex. IL-1 family cytokines can induce a secondary cascade of mediators and cytokines from keratinocytes and other cells resulting in wide range of innate processes including infiltration of inflammatory leukocytes, induction of immunosuppression, DNA repair or apoptosis. Thus, the ability of keratinocytes to produce a wide repertoire of proinflammatory cytokines can influence the immune response locally as well as systematically, and alter the host response to photodamaged cells. We will highlight differential roles played by each IL-1 family molecule generated by UV-damaged keratinocytes, and reveal their complementary influences in modulating acute inflammatory and immunological events that follow cutaneous UV exposure. 相似文献
926.
Marianna Carbone Laura Núñez-Pons Miriam Paone Francesco Castelluccio Conxita Avila Margherita Gavagnin 《Tetrahedron》2012,68(18):3541-3544
The chemical analysis of the ascidian Aplidium fuegiense resulted in the isolation of three novel meroterpenoids 2–4, structurally related to the main co-occurring known rossinone B (1). The structures of the new compounds were determined by interpretation of spectroscopic data. Compounds 1–4 were found to be selectively localized in the viscera of the ascidian. 相似文献
927.
Laura Pisani Stefano Superchi Alessandra D’Elia Patrizia Scafato Carlo Rosini 《Tetrahedron》2012,68(29):5779-5784
A versatile and straightforward approach to optically active cis-4,5-disubstituted γ- and δ-lactones by catalytic enantioselective addition of dialkyzincs to cinnamic aldehydes and RCM ring closure has been reported. The synthetic importance of the enantioselective dialkylzinc alkylation of aldehydes has been thus widened. Such an approach has then been employed for the enantioselective synthesis of naturally occurring γ-lactone flavors like (S)-5-ethyl-butanolide (6a) and (4S,5S)-cis-whisky lactone (6b) and extended to the preparation of δ-lactones like (5S,6S)-5-methyl-6-ethylpentanolide (9a), precursor of the pheromone serricornin. 相似文献
928.
el Hajjouji H Belmonte E García-López J Fernández I Iglesias MJ Roces L García-Granda S El Laghdach A López Ortiz F 《Organic & biomolecular chemistry》2012,10(29):5647-5658
ortho-Lithiation of N,N-diisopropyl-P,P-diphenylphosphinothioic amide using n-BuLi in the presence of TMEDA in diethyl ether followed by electrophilic trapping is described as an efficient method for the synthesis of ortho-functionalised derivatives in high yields. The structural modification of the phosphinothioic amide includes C-X (X = P, S, Si, Sn, I) and C-C bond forming reactions with a large variety of electrophiles. Additional applications based on functional group transformations are also reported. They include imine formation, desulfurization and Suzuki cross-coupling reactions on selected compounds. 相似文献
929.
Q Gao C Zaccaria M Tontini L Poletti P Costantino L Lay 《Organic & biomolecular chemistry》2012,10(33):6673-6681
The Gram-negative encapsulated bacterium Neisseria meningitidis type A (MenA) is a major cause of meningitis in developing countries, especially in the sub-Saharan region of Africa. The development and manufacture of an efficient glycoconjugate vaccine against MenA is greatly hampered by the poor hydrolytic stability of its capsular polysaccharide, consisting of (1→6)-linked 2-acetamido-2-deoxy-α-d-mannopyranosyl phosphate repeating units. The replacement of the ring oxygen with a methylene group to get a carbocyclic analogue leads to the loss of the acetalic character of the phosphodiester and consequently to the enhancement of its chemical stability. Here we report the synthesis of oligomers (mono-, di- and trisaccharide) of carba-N-acetylmannosamine-1-O-phosphate as candidates for stabilized analogues of the corresponding fragments of MenA capsular polysaccharide. Each of the synthesized compounds contains a phosphodiester-linked aminopropyl spacer at its reducing end to allow for protein conjugation. The inhibition abilities of the synthetic molecules were investigated by a competitive ELISA assay, showing that only the carba-disaccharide is recognized by a polyclonal anti-MenA serum with an affinity similar to a native MenA oligosaccharide with average polymerization degree of 3. 相似文献
930.
Septimiu Crivei Constantin Năstăsescu Laura Năstăsescu 《Journal of Pure and Applied Algebra》2012,216(10):2126-2129
We prove a generalization of the Mitchell Lemma, and we show that it is a key lemma that can be used in order to deduce in a unified easier way several important results. Thus, the Ulmer Theorem, the generalized Gabriel–Popescu Theorem and the generalized Takeuchi Lemma are all consequences of the generalized Mitchell Lemma. 相似文献