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991.
Ji Won Cha Mei Jing Piao Ki Cheon Kim Jian Zheng Cheng Wen Yao Chang Lim Hyun Hee Kyoung Kang Eun Sook Yoo Young Sang Koh Nam Ho Lee Mi Hee Ko Jin Won Hyun 《Applied biochemistry and biotechnology》2014,172(5):2582-2592
The aim of the present study was to elucidate the protective properties of 3,4-dihydroxybenzoic acid (DBA) isolated from Cladophora wrightiana Harvey (a green alga) against ultraviolet B (UVB)-induced damage to human HaCaT keratinocytes. DBA exhibited scavenging actions against the 1,1-diphenyl-2-picrylhydrazyl radical, the superoxide anion, and the hydroxyl radical. Furthermore, DBA decreased the levels of intracellular reactive oxygen species generated by hydrogen peroxide or UVB treatment of the cells. DBA also decreased the UVB-augmented levels of phospho-histone H2A.X and the extent of comet tail formation, which are both indications of DNA damage. In addition, the compound safeguarded keratinocytes from UVB-induced injury by reversing the production of apoptotic bodies, overturning the disruption of mitochondrial membrane potential, increasing the expression of the anti-apoptotic protein, B-cell lymphoma 2, and decreasing the expression of the pro-apoptotic proteins, Bcl-2-associated X and cleaved caspase-3. Taken together, these results demonstrate that DBA isolated from a green alga protects human keratinocytes against UVB-induced oxidative stress and apoptosis. 相似文献
992.
Pai Liu Dr. Weiqiang Fu Prof. Peter Verwilst Dr. Miae Won Jinwoo Shin Dr. Zhengxu Cai Prof. Bin Tong Dr. Jianbing Shi Prof. Yuping Dong Prof. Jong Seung Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8513-8517
Heteroatom-containing spiropolymers were constructed in a facile manner by a catalyst-free multicomponent spiropolymerization route. P1a2b as the most potent of these spiropolymers, demonstrates cluster-triggered emission resulting from strong interactions with the MDM2 protein. By preventing the anti-apoptotic p53/MDM2 interaction, P1a2b triggers apoptosis in cancerous cells, while demonstrating a good biocompatibility and non-toxicity in non-cancerous cells. The combined results from solution and cell-based cluster-triggered emission studies, docking, protein expression experiments and cytotoxicity data strongly support the MDM2-binding hypothesis and indicate a potential application as a fluorescent cancer marker as well as therapeutic for this spiropolymer. 相似文献
993.
Minho Choi Sun-Woo Won Hyeju Jo Mayavan Viji Seung-Yong Seo Yeon-Ju Lee Hyi-Seung Lee Heesoon Lee Jin Tae Hong Young-Shin Kwak Jae-Kyung Jung 《Tetrahedron letters》2014
A facile and efficient method has been developed for the synthesis of novel thiazolyl carboxamide derivatives by direct reaction of the corresponding esters and 2-aminothiazole. Treatment of 2-aminothiozole with various carboxylic esters in the presence of t-butylmagnesium chloride provides the biologically significant thiazolyl carboxamide derivatives in good to excellent yields. 相似文献
994.
Nucleophilic Aromatic Substitution Reactions of meso‐Bromosubporphyrin: Synthesis of a Thiopyrane‐Fused Subporphyrin 下载免费PDF全文
Daiki Shimizu Hirotaka Mori Masaaki Kitano Won‐Young Cha Juwon Oh Dr. Takayuki Tanaka Prof. Dr. Dongho Kim Prof. Dr. Atsuhiro Osuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16194-16202
meso‐Bromosubporphyrin undergoes nucleophilic aromatic substitution (SNAr) reactions with arylamines, diarylamines, phenols, ethanol, thiophenols, and n‐butanethiol in the presence of suitable bases to provide the corresponding substitution products. The SNAr reactions also proceed well with pyrrole, indole, and carbazole to provide substitution products in moderate to good yields. Finally, the SNAr reaction with 2‐bromothiophenol and subsequent intramolecular peripheral arylation reaction affords a thiopyrane‐fused subporphyrin. 相似文献
995.
A Novel Vanadosilicate with Hexadeca‐Coordinated Cs+ Ions as a Highly Effective Cs+ Remover 下载免费PDF全文
Dr. Shuvo Jit Datta Won Kyung Moon Do Young Choi Prof. Dr. In Chul Hwang Prof. Dr. Kyung Byung Yoon 《Angewandte Chemie (International ed. in English)》2014,53(28):7203-7208
The effective removal of 137Cs+ ions from contaminated groundwater and seawater and from radioactive nuclear waste solutions is crucial for public health and for the continuous operation of nuclear power plants. Various 137Cs+ removers have been developed, but more effective 137Cs+ removers are still needed. A novel microporous vanadosilicate with mixed‐valence vanadium (V4+ and V5+) ions is now reported, which shows an excellent ability for Cs+ capture and immobilization from groundwater, seawater, and nuclear waste solutions. This material is superior to other known materials in terms of selectivity, capacity, and kinetics, and at very low Cs+ concentrations, it was found to be the most effective material for the removal of radioactive Cs+ ions under the test conditions. This novel vanadosilicate also contains hexadeca‐coordinated Cs+ ions, which corresponds to the highest coordination number ever described. 相似文献
996.
Inside Back Cover: Supramolecular Inhibition of Amyloid Fibrillation by Cucurbit[7]uril (Angew. Chem. Int. Ed. 29/2014) 下载免费PDF全文
997.
Ground porous silica monolith particles with an average particle size of 2.34 μm and large pores (363 Å) exhibiting excellent chromatographic performance have been synthesized on a relatively large scale by a sophisticated sol–gel procedure. The particle size distribution was rather broad, and the d(0.1)/d(0.9) ratio was 0.14. The resultant silica monolith particles were chemically modified with chlorodimethyloctadecylsilane and end‐capped with a mixture of hexamethyldisilazane and chlorotrimethylsilane. Very good separation efficiency (185 000/m) and chromatographic resolution were achieved when the C18‐bound phase was evaluated for a test mixture of five benzene derivatives after packing in a stainless‐steel column (1.0 mm × 150 mm). The optimized elution conditions were found to be 70:30 v/v acetonitrile/water with 0.1% trifluoroacetic acid at a flow rate of 25 μL/min. The column was also evaluated for fast analysis at a flow rate of 100 μL/min, and all the five analytes were eluted within 3.5 min with reasonable efficiency (ca. 60 000/m) and resolution. The strategy of using particles with reduced particle size and large pores (363 Å) combined with C18 modification in addition to partial‐monolithic architecture has resulted in a useful stationary phase (C18‐bound silica monolith particles) of low production cost showing excellent chromatographic performance. 相似文献
998.
Pd particles loading on TiO2-embedded multi-walled carbon nanotubes (MWCNTs), MWCNTs, and TiO2 particles were prepared via an impregnation method with palladium(II) chlorate solution followed by heat treatment at high temperature. To characterize the catalysts, BET surface area, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy were employed. The prepared catalysts were tested in degradation of methyl orange under visible light. Pd/TiO2-MWCNTs catalyst demonstrates the highest photocatalytic activity, and the phase transformation from PdO to Pd0 phase takes place at heat treatment of embedded TiO2. The nanoparticles size of TiO2 can be decreased by introduction of MWCNTs species. Combining structural characterization with kinetic study results we could conclude that the superior catalytic performance could arise due to the Pd/TiO2-MWCNTs catalyst’s structure. 相似文献
999.
Baeck Kyoung Lee Hwan Geun Choi Eun Joo Roh Won Koo Lee Taebo Sim 《Tetrahedron letters》2013,54(6):553-556
An efficient synthesis of (?)-8-epi-swainsonine, starting from a commercially available 1-(R)-α-methylbenzylaziridine-2-methanol, was developed. The synthetic route utilizes stereocontrolled Sharpless asymmetric dihydroxylation governed by AD-mix-β followed by an aziridine ring opening-cyclization sequence to generate the five membered N-heterocyclic ring system present in the bicyclic target. A subsequent stereoselective allylation and piperidine ring forming cyclization then produced a precursor that was converted into (?)-8-epi-swainsonine. 相似文献
1000.
A highly efficient method for the synthesis of 1,4-dideoxy-1,4-imino-d- and l-arabinitol (d-AB1, 1 and l-AB1, 3) and 1,4-dideoxy-1,4-imino-d- and l-xylitol (d-DIX, 2 and l-DIX, 4) starting from commercially available chiral aziridines was developed. The general strategy employs a sequence involving two-carbon homologation, dihydroxylation, and regioselective aziridine ring opening/intramolecular five-membered iminosugar ring formation. The facile use of recrystallization to generate pure diastereomers makes the routes more amenable to large-scale synthesis. 相似文献