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Active Oxygen Generation as a Possible Mechanism of Selenium Toxicity

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Biomedical and Environmental Sciences 1997年第2期10卷 333-339页

作者： YOSHIYUKISEKO NOBUMASAIMURA schoolofpharmaceuticalsciences KitasatouniversityShirokaneMinato－ku schoolofpharmaceuticalsciences

Selenium plays an important role in scavenging active oxygen (AO) species as an essential constituent of glutathione peroxidase. On the other hand, several reports proposed a possible induction of toxic AO by selenium compounds in vitro. However, some of these experiments including ours, were revealed to conclude on the basis of experimental artifacts, and to have problems in the interpretation of *** or principles so far used for the detection of AO species generated by selenium compound were measurement of chemiluminescence from lucigenin or luminol by AO species,the spectrophotometric analysis of reduction of ferricytochrome c or nitroblue tetrazolium (NBT) by superoxide anion (O2-), electron spin resonance (ESR) spectra using dimethylpyrroline oxide (DMPO) as a spin trapping agent, the deoxyribose decomposition by hydroxyl radical (HO), the salicylate hydroxylation by HO, and the strand breakage of DNA by AO. Many of these methods together with their principles seem to have some defects which prevent clear conclusion as stated below. (i) Lucigenin was found to mediate the formation of O2- in the presence of selenite and reduced glutathione (GSH). Therefore, lucigenin is not a suitable reagent. (ii) Luminol may also mediate O2- generation in the presence of HO. (iii) ferricytochrome c can be reduced to ferrocytochrome c in the mixture of selenite and GSH in the absence of oxygen. Moreover, the spectrophotometric method is interfered by turbidity of elemental selenium formed under some conditions in the reaction mixture containing selenite and GSH. (iv) NBT is also reduced by selenium compounds in the absence of O2.(v) ESR signals of AO species were obtained in the reaction mixture containing selenite and GSH, or in the solution of hydrogen selenide in the presence of O2. However, selenide decomposed spin adduct of DMPO with HO' (DMPO-OH). Therefore, the intensity of the signals is not quantitative. (vi) CuZn-SOD is not necessarily a good tool to prov the

关键词：活性氧硒毒性机制 GSH

The Benzoylation of 6-Methyluracil and 5-Nitro-6-methyluracil

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Chinese Chemical Letters 2005年第3期16卷 287-289页

作者： ZhiLiZHANG PengHAN XiaoYanMA JieLIU XiaoWeiWANG JunYiLIU schoolofpharmaceuticalsciences PekingUniversityBeijing100083

Methyluracil and 5-nitro-6-methyluracil react with variable molar quantities of benzoyl chloride in acetonitrile-pyridine at room temperature to give 1-N, 3-N-dibenzoyl-6- methyluracil 3b and 1-N-benzoyl-5-nitro-6-met... 详细信息

关键词： 1-N 3-N-Dibenzoyl-6-methyluracil 1-N-benzoyl-5-nitro-6-methyluracil 6-methyl- uracil 5-nitro-6-methyluracil benzoylation.

An Unusual Reductive Ring-opening Reaction of Phthalimide with Sodium Hydride in DMF

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Chinese Chemical Letters 2004年第7期15卷 777-778页

作者： XiangBaoMENG HuiLI QingLI ZhongJunLI DepartmentofChemicalBiology SchoolofPharmaceuticalSciencesPekingUniversityBeijing100083

An unusual reductive ring-opening reaction of phthalimide with sodium hydride in anhydrous DMF was observed for the first time. The presumed mechanism was described in detail.

关键词： Phthalimide benzylation reduction ring-opening.

Solid-phase Synthesis of PNA Monomer by Ugi Four-component Condensation Reaction

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Chinese Chemical Letters 2005年第5期16卷 585-588页

作者： WenHaoWANG XiaoMinZOU XinZHANG YiQiuFU PingXU DepartmentofMedicinalChemistry SchoolofPharmaceuticalSciencesPekingUniversityBeijing100083

Peptide nucleic acids (PNA) oligomers were synthesized in most cases by peptide synthesis from N-protected monomers. In this work a new method of obtaining PNA monomer by Ugi four-component condensation reaction was tested by solid-phase synthesis. The Fmoc protected PNA monomer was build up with thymin-1-yl acetic acid, 3-methylbutyl aldehyde, Fmoc protected aminoethyl isocyanide and Gly-Wang resin.

关键词： Peptide nucleic acids (PNA) Ugi four-component condensation reaction (U-4CR) Solid-phase synthesis Isocyanide.

Assembly of a Library of Trisaccharides as Mimics of Sialyl Lewis Xvia Random Combination Strategy

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Chinese Chemical Letters 2004年第4期15卷 379-382页

作者： XiangBaoMENG HuiLI QingLI TieMingCHENG ZhongJunLI DepartmentofChemicalBiology SchoolofPharmaceuticalSciencesPekingUniversityBeijing100083

A small library containing six positional isomers of fucosyl on the modified lactoside backbone as mimics of the Sialyl Lewis X was synthesized via random combinatorial glycosylation, which was charactered by ESI-MS a... 详细信息

关键词： SLe^x selectin oligosaccharide synthesis random combinatorial glycosylation.

An Efficient and Green Procedure for the Knoevenagel Condensation Catalyzed by Urea

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Chinese Journal of Chemistry 2005年第6期23卷 745-748页

作者：孙崎史兰香葛泽梅程铁明李润涛 schoolofpharmaceuticalsciences PekingUniversityBeijing100083China

An efficient and green procedure for the urea catalyzed Knoevenagel condensation was developed. In the presence of a catalytic ammount of urea, stoichiometric aldehyde and active methylene compound reacted under solve... 详细信息

关键词： Knoevenagel condensation green procedure urea catalyst active methylene

Two New Sequiterpenoids from Helicteres angustifolia

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Chinese Chemical Letters 2005年第1期16卷 49-52页

作者： XinDongGUO ZhiShuHUANG YaDanBAO LinKunAN LinMA LianQuanGU schoolofpharmaceuticalsciences ZhongshanUniversityGuangzhou510080／／GuangzhouProductQualitySupervisionandTestingInstituteGuangzhou510100 schoolofpharmaceuticalsciences ZhongshanUniversityGuangzhou510080 SchoolofChemistryandChemicalEngineering.ZhongshanUniversity Guangzhou510275 schoolofpharmaceuticalsciences ZhongshanUniversityGuangzhou510080／／SchoolofChemistryandChemicalEngineeringZhongshanUniversityGuangzhou510275

A new sesquiterpenoid lactone, 3,6,9-trimethyl-pyrano[2,3,4-de]chromen-2-one (1) and a novel sesquiterpenoid quinone, 6-[2-(5-acetyl-2,7-dimethyl-8-oxo-bicyclo[4.2.0]octa-1,3,5- trien-7-yl)-2-oxo-ethyl]-3,9-dimethylnaphtho[1,8-bc]pyran-7,8-dione (2) together with a known perezone (3) were isolated from the roots of Helicteres angustifolia. The structures were elucidated as mainly on the basis of 1D and 2D NMR spectroscopic data.

关键词： Helicteres angustifolia Sterculiaceae sesquiterpenoid lactone sesquiterpenoid quinone.

The Different Fluorescent Response of Quin 2 to the Binding of Ca^(2+) and La^(3+) and its Application

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Chinese Chemical Letters 2004年第10期15卷 1197-1200页

作者： JianHU XiaoDaYANG KuiWANG DepartmentofChemicalbiology SchoolofPharmaceuticalSciencesPekingUniversityBeijing100083

The fluorescence spectra of Quin 2, (2-[(2-bis-[carboxymethyl] amino-5-methylphenoxy) methyl]-6-methoxy-8-bis [carboxymethyl] aminoquiniline), a Ca2+ probe, were investigated upon incubation with Ca2+ or La3+. The results showed that binding of La3+ to Quin 2 resulted in different fluorescent spectrum from that of Ca2+. Based on this observation, a fluorescent method was developed for simultaneously determination of the dissociation rates of Ca2+ and La3+ from a Ca-La- calmodulin complex (Ca2La2CaM).

关键词： Quin 2 fluorescence Ca2+ La3+ calmodulin.

Comparison of intestinal absorption of two insulin-mimic vanadyl complexes using Caco-2 monolayers as model system

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Chinese Science Bulletin 2003年第9期48卷 876-881页

作者： YANGXiaogai YUANLan WANGKui YANGXiaoda DepartmentofChemicalBiology SchoolofPharmaceuticalSciencesPekingUniversityBeijing100083China AnalyticalCenterofPekingUniversity Beijing100083China NationalResearchLaboratoriesofNaturalandBiomimeticDrugs SchoolofPharmaceuticalSciencesPekingUniversityBeijing100083China LaboratoriesofPreventiveDrugs SchoolofPharmaceuticalSciencesPekingUniversityBeijing100083China

Intestinal absorption of two oxovanadium complexes, vanadyl acetylacetonate (VO(acac)2) and bis (maltolato)-oxovanadium (VO(ma)2), has been compared using Caco-2 monolayers as a model system. The two compounds are similar in chemical structures but different in glucose-lowering effects. Our experimental results show that they are both transported via passive diffusion with apparent permeabilty coefficients (apical→basolateral) of (82.0 ± 6.7)× 10-7 and (14.6 ± 0.7)× 10-7 cm· s-1, respec-tively. This suggests that absorptivity of VO(acac)2 is much higher than that of VO(ma)2. This difference may be related to the metabolism of either compound, or its ligand, or both in the course of the transport. However, This difference in absorption will cause the great difference in bioavailability,which might account for better efficacy of VO(acac)2 than VO(ma)2 as the insulin-mimic agent.

关键词：氧矾根络合物 Caco-2 肠内吸收模型系统胰岛素模拟物 ADME