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991.
3-Aryl-4-(5-aryl-Δ2-1,2,4-oxadiazolin-3-yl)sydnones (5) were synthesized in high yields by the reaction of 3-arylsydnone-4-carboxamide oximes (prepared from the corresponding 3-arylsydnone-4-carbonitriles) with aromatic aldehydes in the presence of acid catalysts. No reaction occurred when aliphatic aldehydes were used. The oxadiazolin-3-ylsydnones (5) were easily converted into the corresponding 3-aryl-4-(5-aryl-1,2,4-oxadiazol-3-yl)sydnones by N-bromosuccinimide oxidation. The 3-arylsydnone-4-carbonitrile oxides were synthesized in good yields by N-bromosuccinimide oxidation of the corresponding 3-arylsydnone-4-carboxaldehyde oximes. 相似文献
992.
Lan Chun Tu Chien-Shu Chen I-Ching Hsiao Ji-Wang Chern Chi-Hung Lin Ya-Ching Shen Sheau Farn Yeh 《Chemistry & biology》2005,12(12):7613-1324
Mana-Hox, an analog of beta-carbolines with anticancer activity, induces aberrant mitosis and delays mitotic exit. However, the cellular target is not known. In this study, we visualized the intracellular localization of Mana-Hox. Mana-Hox rapidly penetrated into cells (within 1 min) and concentrated on disorganized metaphase chromosomes after 13 hr of exposure. We demonstrated that Mana-Hox is a noncovalent DNA binder that can interact with DNA through intercalation and/or through minor groove binding. Furthermore, Mana-Hox also inhibits topoisomerase II relaxation activity in vitro, suggesting that Mana-Hox could perturb mitotic chromosome decatenation. Overall, Mana-Hox binding to DNA plays a critical role in the induction of aberrant mitosis and contributes to its anticancer activity. 相似文献
993.
Madsen SJ Sun CH Tromberg BJ Yeh AT Sanchez R Hirschberg H 《Photochemistry and photobiology》2002,76(4):411-416
The effects of combined photodynamic therapy (PDT) and ionizing radiation are studied in a human glioma spheroid model. The degree of interaction between the two modalities depends in a complex manner on factors such as PDT irradiation fluence, fluence rate and dose of ionizing radiation. It is shown that gamma radiation and PDT interact in a synergistic manner only if both light fluence and gamma radiation dose exceed approximately 25 J cm(-2) and 8 Gy, respectively. Synergistic interactions are observed only for the lower fluence rate (25 mW cm(-2)) investigated. The degree of interaction appears to be independent of both sequence and the PDT or ionizing radiation time intervals investigated (1 and 24 h). Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assays show that low-fluence rate PDT is very efficient at inducing apoptotic cell death, whereas neither high-fluence rate PDT nor ionizing radiation produces significant apoptosis. Although the mechanisms remain to be elucidated, the data imply that the observed synergism is likely not due to gamma-induced cell cycle arrest or to PDT-induced inhibition of DNA repair. 相似文献
994.
In this study, separation and determination of nine preservatives ranging from hydrophilic to hydrophobic properties, which are commonly used as additives in various pharmaceutical and cosmetic products, by micellar electrokinetic chromatograpy (MEKC) and microemulsion electrokinetic chromatography (MEEKC) were compared. The effect of temperature, buffer pH, and concentration of surfactant on separation were examined. In MEKC, the separation resolution of preservatives improved markedly by changing the sodium dodecyl sulfate concentration. Temperature and pH of running buffers were used mainly to shorten the magnitude of separation time. However, in order to detect all preservatives in a single run in a MEEKC system, a microemulsion of higher pH was needed. The separation resolution was improved dramatically by changing temperature, and a higher concentration of SDS was necessary for maintaining a stable microemulsion solution, therefore the separation of the nine preservatives in MEEKC took longer than in MEKC. An optimum MEKC method for separation of the nine preservatives was obtained within 9.0 min with a running buffer of pH 9.0 containing 20 mM SDS at 25 degrees C. A separation with baseline resolution was also obtained within 16 min using a microemulsion of pH 9.5 which composed of SDS, 1-butanol, and octane, and a shorter capillary column at 34 degrees C. Finally, the developed MEKC and MEEKC methods determined successfully preservatives in various cosmetic and pharmaceutical products. 相似文献
995.
The natural abundance carbon-13 nuclear magnetic resonance spectra of 3-arylsydnone, 3-aryl-4-formylsydnone, 4-acetyl-3-arylsydnone, 3-aryl-4-cyanosydnone as well as some derivatives of the above compounds have been studied. The data indicate that the electron withdrawing effect on the C4 atom of the sydnone ring decreases in the sequence: C≡N>COCH3~CHO. The solvent effect on the chemical shift has also been investigated. 相似文献
996.
Rhodium particles in nanometer size were prepared by impregnating alumina powders with aqueous solutions containing rhodium salts. The dispersion (D) of rhodium crystallites on the prepared samples was estimated by dioxygen adsorption measured at 300 K. Phenomena of oxidizing the supported crystallites with 2.5 × 104 Pa O2 in a temperature range between 280 and 870 K were calorimetrically studied. Extent of oxidation may be distinguished into three stages, i.e., adsorption on surface (T < 300 K), progressive penetration into bulk, and formation of a stable bulk oxide (T> 700 K), on raising the oxidation temperature. Heat of dioxygen adsorption varies only slightly with the dispersion (D) of rhodium and has a value of 294 ± 6 kJ (mol O2)−1. Chemical stoichiometry of the bulk oxide formed, however, varies with the dispersion of rhodium crystallites. A dioxide (RhO2) (f H = 225 ± 3 kJ (mol O2)−1) and a sesquioxide (Rh2O3) (f H = 273 ± 3 kJ (mol O2)−1) was formed at D < 60% and D> 80%, 相似文献
997.
Intramolecular Diels‐Alder reaction (IMDA) precursors are easily available starting from addition of ester functionalized zinc‐copper reagents to cyclohexadienyl‐ and cycloheptadienylirontricarbonyl cation salts. The resulting cyclic 1,3‐dienes containing an α,β‐unsaturated ester functionality underwent smoothly IMDA reaction to afford bridged tricyclic compounds. Bridged heterotricyclic skeletons were also available via IMDA reaction of cyclic 1,3‐dienes bearing an imine or aldehyde functionality. 相似文献
998.
Wen-Yann Yeh Yen-Chung Liu Gene-Hsiang Lee 《Journal of organometallic chemistry》2004,689(6):1014-1018
[Cp4Fe4(CO)4] (1) reacts with p-BrC6H4Li and MeOH in sequence to afford the functionalized cluster [Cp3Fe4(CO)4(C5H4-p-C6H4Br)] (2), while the reaction of 2 with n-BuLi and MeOH produces [Cp2Fe4(CO)4(C5H4Bu)(C5H4-p-C6H4Br)] (3). The double cluster [Cp3Fe4(CO)4(C5H4)]2(p-C6H4) (4) has been prepared by treatment of [Cp4Fe4(CO)4] with p-C6H4Li2 and MeOH in sequence. The electrochemistry of 2 and 4, as well as the crystal structure of 4 have been investigated. 相似文献
999.
1000.