共查询到20条相似文献,搜索用时 15 毫秒
1.
Two new stilbenoids, cis‐?‐viniferin (3) and 2b, 14b‐dehydro‐bisresveratrol (4) were synthesized by photooxidation reaction of trans‐?‐viniferin (2) prepared from tram‐resveratrol (1). Pentamethoxyl trans‐?‐viniferin (5) and pentamethoxyl cis‐?‐viniferin (6) were also obtained by methylation of trans‐?‐viniferin (2) with (MeO)2SO2. Their structures were elucidated on the basis of spectral evidence. Compounds 3 and 4 showed potent inhibition of TNF‐α at concentrations of 10?‐5 mol.L?1 with inhibitory ratios of 51.43% and 36.64%. respectively. 相似文献
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Cyperaceae is a cosmopolitan plant family with approx. 5000 species distributed worldwide. Several members of this family are used in traditional medicines for the treatment of different diseases. In the last few decades, constituents with great chemical diversity were isolated from sedges, and a wide range of biological activities were detected either for crude extracts or for pure compounds. Among the isolated compounds, phenolic derivatives are the most important, especially stilbenoids, and flavonoids. To date, more than 60 stilbenoids were isolated from 28 Cyperaceae species. Pharmacological investigation of Cyperaceae stilbenoids revealed that several compounds possess promising activities; mainly antiproliferative, antibacterial, antioxidant and anthelmintic effects. Isolation, synthesis and pharmacological investigation of stilbenes are increasing constantly. As Cyperaceae species are very good sources of a wide variety of stilbenes, and several of them occur in large amount worldwide, they are worthy for phytochemical and pharmacological investigations. Moreover, stilbenes are important from chemotaxonomical point of view, and they play a key role in plant defense mechanisms as well. This review summarizes the stilbenoids isolated from sedges, and their biological activities. 相似文献
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Sensitized photooxidation of isoeugenol gave 6 products. The elucidation of the structures of those products and the mechanism of their formation are discussed. 相似文献
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Alexander K. Mengele Dominik Weixler Avinash Chettri Maite Maurer Fabian Lukas Huber Prof. Gerd M. Seibold Prof. Benjamin Dietzek Prof. Bernhard J. Eikmanns Prof. Sven Rau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):16840-16845
A series of three Ru(II) polypyridine complexes was investigated for the selective photocatalytic oxidation of NAD(P)H to NAD(P)+ in water. A combination of (time-resolved) spectroscopic studies and photocatalysis experiments revealed that ligand design can be used to control the mechanism of the photooxidation: For prototypical Ru(II) complexes a 1O2 pathway was found. Rudppz ([(tbbpy)2Ru(dppz)]Cl2, tbbpy=4,4'-di-tert-butyl-2,2'-bipyridine, dppz=dipyrido[3,2-a:2′,3′-c]phenazine), instead, initiated the cofactor oxidation by electron transfer from NAD(P)H enabled by supramolecular binding between substrate and catalyst. Expulsion of the photoproduct NAD(P)+ from the supramolecular binding site in Rudppz allowed very efficient turnover. Therefore, Rudppz permits repetitive selective assembly and oxidative conversion of reduced naturally occurring nicotinamides by recognizing the redox state of the cofactor under formation of H2O2 as additional product. This photocatalytic process can fuel discontinuous photobiocatalysis. 相似文献
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Yueh-Hsiung Kuo 《中国化学会会志》1986,33(1):95-97
Photooxidation of furan derivatives followed by reduction with methyl sulfide affords cis-enediones in excellent yields. 相似文献
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R. K. Wells J. P. S. Badyal 《Journal of polymer science. Part A, Polymer chemistry》1992,30(13):2677-2681
Strips of polystyrene held in a flowing O2 or N2O atmosphere have been exposed to 240-600 nm radiation. The extent of photooxidation has been followed by x-ray photoelectron spectroscopy (XPS). Although N2O is a more reactive gas than O2, it produces a less oxidized polymer surface. This surprising observation can be correlated to the photochemistry occurring at the gas/polystyrene interface. © 1992 John Wiley & Sons, Inc. 相似文献
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Photooxidation of glycated and non‐glycated phosphatidylethanolamines monitored by mass spectrometry
Tânia Melo Eduarda M. P. Silva Cláudia Simões Pedro Domingues M. Rosário M. Domingues 《Journal of mass spectrometry : JMS》2013,48(1):68-78
Phosphatidylethanolamines (PE) are one of the major components of cells membranes, namely in skin and in retina, that are continuously exposed to solar UV radiation being major targets of photooxidation damage. In addition, due to the presence of the free amine group, PE can also undergo glycation, in hyperglycemic conditions which may increase the susceptibility to oxidation. The aim of this study is to develop a model, based on mass spectrometry (MS) analysis, to identify photooxidative degradation of selected PE (POPE: PE 16:0/18:1, PLPE: PE 16:0/18:2, PAPE: PE 16:0/20:4) and glycated PEs due to UV irradiation. Photooxidation products were analysed by electrospray ionization MS (ESI‐MS) and tandem MS (ESI‐MS/MS) in positive and negative mode. Emphasis is placed in the influence of glycation in the generation of distinct photooxidation products. ESI‐MS spectra of PE after UV photo‐irradiation showed mainly hydroperoxy derivatives, due to oxidation of unsaturated fatty acyl chains. Glycated PE gave rise to several new photooxidation products formed due to oxidative cleavages of the glucose moiety, namely between C1 and C2, C2 and C3, and C5 and C6 of this sugar unit. These new products were identified by ESI‐MS/MS in positive mode showing distinct neutral loss depending on the different structure of the polar head group. These new identified advanced glycated photooxidation products may have a deleterious role in the etiology of diabetic retinopathy and in diabetic retinal microvascular complications. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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WU Hongbo WANG Xiao & CHEN Jianmin Department of Environmental Science Engineering Fudan University Shanghai China 《中国科学B辑(英文版)》2005,48(1):31-37
Carbonyl sulfide (COS) is one of the most abun-dant sulfur containing gases in the troposphere andlower stratosphere[1,2]. It is relatively inert in the tro-posphere and can be transported into the stratosphere,where it dissociates under the solar ultravi… 相似文献
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Heo SK Ju SA Kim GY Park SM Back SH Park NH Min YJ An WG Nguyen TT Kim SM Kim BS 《Experimental & molecular medicine》2012,44(2):149-158
The development of gastric cancer (GC) is closely related to chronic inflammation caused by Helicobacter pylori infection, and herpes virus entry mediator (HVEM) is a receptor expressed on the surface of leukocytes that mediates potent inflammatory responses in animal models. However, the role of HVEM in human GC has not been studied. Previously, we showed that the interaction of HVEM on human leukocytes with its ligand LIGHT induces intracellular calcium mobilization, which results in inflammatory responses including induction of proinflammatory cytokine production and anti-bacterial activities. In this study, we report that leukocytes from GC patients express lower levels of membrane HVEM (mHVEM) and have lower LIGHT-induced bactericidal activities than those from healthy controls (HC). In contrast, levels of soluble HVEM (sHVEM) in the sera of GC patients were significantly higher than in those of HC. We found that monocyte membrane-bound HVEM is released into the medium when cells are activated by proinflammatory cytokines such as TNF-α and IL-8, which are elevated in the sera of GC patients. mHVEM level dropped in parallel with the release of sHVEM, and release was completely blocked by the metalloprotease inhibitor, GM6001. We also found that the low level of mHVEM on GC patient leukocytes was correlated with low LIGHT-induced bactericidal activities against H. pylori and S. aureus and production of reactive oxygen species. Our results indicate that mHVEM on leukocytes and sHVEM in sera may contribute to the development and/or progression of GC. 相似文献
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A piezoelectric nucleic acid sensor was constructed ofr detection of tumor necrosis factor gene.Two methods were employed for immobilization of nucleic acid probe on gold electrode of piezoelectric crystal.The results show that polyethyleneimine adbesion and glutaraldehyde cross-linking method has higher sensitivity,stability and selectivity than protein A method.The solid-phase nucleic acid hybridization of oligo unclecotides and tumor necrosis factor target gene sequence were monitorde using this sensor.Tumor necrosis factor gene sequence(580bp) was detected by this nucleic acid sensor for the first time. 相似文献
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IntroductionThegenediagnosistechnology ,alsocallednucleicacidprobetechnology ,hasbecomeanattractivemethodinthefieldsofbiochemistryandclinicalmedicine .Itisprovedtobeconvenientandsafeusingnon radioactivereagentswithelectrochemicalandopticaldetector.Espe c… 相似文献
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Selective Photooxidation of a Mustard‐Gas Simulant Catalyzed by a Porphyrinic Metal–Organic Framework 下载免费PDF全文
Dr. Yangyang Liu Dr. Ashlee J. Howarth Prof. Joseph T. Hupp Prof. Omar K. Farha 《Angewandte Chemie (International ed. in English)》2015,54(31):9001-9005
The photooxidation of a mustard‐gas simulant, 2‐chloroethyl ethyl sulfide (CEES), is studied using a porphyrin‐based metal–organic framework (MOF) catalyst. At room temperature and neutral pH value, singlet oxygen is generated by PCN‐222/MOF‐545 using an inexpensive and commercially available light‐emitting diode. The singlet oxygen produced by PCN‐222/MOF‐545 selectively oxidizes CEES to the comparatively nontoxic product 2‐chloroethyl ethyl sulfoxide (CEESO) without formation of the highly toxic sulfone product. In comparison to current methods, which utilize hydrogen peroxide as an oxidizing agent, this is a more realistic, convenient, and effective method for mustard‐gas detoxification. 相似文献
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Amit Raj Sharma Gaurav Gajurel Izzeldin Ahmed Krystian Roedel Fabricio Medina-Bolivar 《Molecules (Basel, Switzerland)》2022,27(18)
Prenylated stilbenoids such as arachidin-1 and arachidin-3 are stilbene derivatives that exhibit multiple pharmacological activities. We report an elicitation strategy using different combinations of cyclodextrin, hydrogen peroxide, methyl jasmonate and magnesium chloride to increase arachidin-1 and arachidin-3 production in peanut hairy root cultures. The treatment of hairy root cultures with cyclodextrin with hydrogen peroxide selectively enhanced arachidin-1 yield (132.6 ± 20.4 mg/L), which was 1.8-fold higher than arachidin-3. Similarly, cyclodextrin combined with methyl jasmonate selectively enhanced arachidin-3 yield (178.2 ± 6.8 mg/L), which was 5.5-fold higher than arachidin-1. Re-elicitation of the hairy root cultures further increased the levels of arachidin-1 and arachidin-3 by 24% and 42%, respectively. The ethyl acetate extract of the culture medium was consecutively fractionated by normal- and reversed-phase column chromatography, followed by semi-preparative HPLC purification on a C18 column to yield arachidin-1 with a recovery rate of 32% and arachidin-3 with a recovery rate of 39%, both at higher than 95% purity. This study provided a sustainable strategy to produce high-purity arachidin-1 and arachidin-3 using hairy root cultures of peanuts combined with column chromatography and semi-preparative HPLC. 相似文献
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Mechanism for the Nonadiabatic Photooxidation of Benzene to Phenol: Orientation‐Dependent Proton‐Coupled Electron Transfer 下载免费PDF全文
Dr. Xue‐Ping Chang Prof. Dr. Ganglong Cui Prof. Dr. Wei‐Hai Fang Prof. Dr. Walter Thiel 《Chemphyschem》2015,16(5):933-937
An efficient catalytic one‐step conversion of benzene to phenol was achieved recently by selective photooxidation under mild conditions with 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone (DDQ) as the photocatalyst. Herein, high‐level electronic structure calculations in the gas phase and in acetonitrile solution are reported to explore the underlying mechanism. The initially populated 1ππ* state of DDQ can relax efficiently through a nearby dark 1nπ* doorway state to the 3ππ* state of DDQ, which is found to be the precursor state involved in the initial intermolecular electron transfer from benzene to DDQ. The subsequent triplet‐state reaction between DDQ radical anions, benzene radical cations, and water is computed to be facile. The formed DDQH and benzene‐OH radicals can undergo T1→S0 intersystem crossing and concomitant proton‐coupled electron transfer (PCET) to generate the products DDQH2 and phenol. Two of the four considered nonadiabatic pathways involve an orientation‐dependent triplet PCET process, followed by intersystem crossing to the ground state (S0). The other two first undergo a nonadiabatic T1→S0 transition to produce a zwitterionic S0 complex, followed by a barrierless proton transfer. The present theoretical study identifies novel types of nonadiabatic PCET processes and provides detailed mechanistic insight into DDQ‐catalyzed photooxidation. 相似文献
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Byun HS Won M Park KA Kim YR Choi BL Lee H Hong JH Piao L Park J Kim JM Kweon GR Kang SH Han J Hur GM 《Experimental & molecular medicine》2008,40(2):186-195
Previous studies have demonstrated that rottlerin, a specific PKCdelta inhibitor, potentiates death receptor- mediated apoptosis through a cytochrome c-dependent or -independent pathway. However, its ability to regulate necrotic cell death, as well as the underlying mechanism, remains unknown. We found that in murine fibrosarcoma L929 cells, treatment with rottlerin protected the cells against TNF-induced necrosis, whereas it sensitized the cells to apoptosis induced by co-treatment with Hsp90 inhibitor geldanamycin and TNF, in a manner independent of its ability to inhibit PKC-delta. TNF treatment induced rapid accumulation of mitochondrial superoxide (O2-) through the Nox1 NADPH oxidase when cells undergo necrosis. Moreover, pretreatment with rottlerin failed to induce the GTP-bound form of small GTPase Rac1 by TNF treatment, and subsequently suppressed mitochondrial O2- production and poly(ADP-ribose) polymerase activation, thus inhibiting necrotic cell death. Therefore, our study suggests that Nox1 NADPH oxidase is a new molecular target for anti-necrotic activity of rottlerin upon death-receptor ligation. 相似文献
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Kim WK Sul OJ Kwak JS Hur HY Latour AM Koller BH Kwon BS Jeong CS 《Experimental & molecular medicine》2010,42(12):805-810
Tumor necrosis factor receptor-related 2 (TR2, HVEM or TNFRSF-14) plays an important role in immune responses, however, the mechanisms regulating its expression are unclear. To understand the control of TR2 gene expression, we studied the upstream region of the gene. Gel supershift assays revealed inducible binding of nuclear factor of activated T cells (NFAT) to a putative NFAT site within the TR2 promoter. Furthermore, cotransfection of a dominant negative NFAT construct, or siRNA for NFAT, resulted in increased expression of a TR2 reporter gene. Our findings demonstrate that NFAT negatively regulates TR2 expression in activated T cells. 相似文献
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Rutin, a glycoside of flavonol, inhibits osteoclast formation induced by receptor activator of NF-kappaB ligand (RANKL) in bone marrow-derived macrophages. It reduces reactive oxygen species produced by RANKL and its inhibitory effect results from reduced levels of TNF-alpha. Rutin also lowers NF-kappaB activation in response to RANKL. 相似文献
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Photocatalytic Synthesis of Dihydrobenzofurans by Oxidative [3+2] Cycloaddition of Phenols 下载免费PDF全文
Travis R. Blum Dr. Ye Zhu Sarah A. Nordeen Prof. Tehshik P. Yoon 《Angewandte Chemie (International ed. in English)》2014,53(41):11056-11059
We report a protocol for oxidative [3+2] cycloadditions of phenols and alkenes applicable to the modular synthesis of a large family of dihydrobenzofuran natural products. Visible‐light‐activated transition metal photocatalysis enables the use of ammonium persulfate as an easily handled, benign terminal oxidant. The broad range of organic substrates that are readily oxidized by photoredox catalysis suggests that this strategy may be applicable to a variety of useful oxidative transformations. 相似文献