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Photogeneration of the free radicals and singlet oxygen by chrysophanol from rheum

Science China Chemistry 2004年第5期47卷 381-387页

作者： RAO Jing1,2, XIE Jie1, ZHAO Jingquan1 & ZHU Teng2 1. Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100080, China 2. University of Science and Technology Beijing, Beijing 10083, China 1. Key Laboratory of Photochemistry Center for Molecular Science Institute of Chemistry The Chinese Academy of Sciences 100080 Beijing China 2. University of Science and Technology Beijing 10083 Beijing China

In the current work, chryosphanol (MHAQ) was isolated and purified from rheum, and the photosensitization activities were studied. In nitrogen-saturated DMSO solution, irradia- tion of chryosphanol (MHAQ) with visible light (>430 nm) produced the semiquinone radical anions (MHAQ??), which was intensified significantly by an electron donor NADH, suggesting electron transfer between the excited and ground state photosensitizer molecules. In an air-saturated DMSO solution, superoxide radical anions (O2 ), trapped by DMPO, were detected. ?? It was proved that O2 was not originated from the singlet oxygen (1O2) but dependent on DMPO, ?? chrysophanol, oxygen and the irradiation time. The singlet oxygen and OH could also be pro- ? duced by the photosensitization of the photosensitizer. These suggest that chrysophanol pos- sesses the photosensitization activity via Type I mechanism and Type II mechanism. To evaluate the photosensitization activities of MHAQ, emodin and mixed anthraquinone derivatives ex- tracted from rheum, the relative productivities of O2 were estimated to be 1.8, 1.1 and 1.0 re- ?? spectively and the quantum yields for singlet oxygen to be 0.36, 0.53 and 0.14 respectively. Therefore, these low-cost pigments may be potentially used as phototherapeutic medicine for some kind of vascular diseases or photo-activated pesticides.

关键词： chrysophanol, ESR, semiquinone radical anions, superoxide radical anions, hydroxyl radical, singlet oxygen.

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Nitric oxide and oxygen radicals induced apoptosis via bcl-2 and p53 pathway in hypoxia-reoxygenated cardiomyocytes

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Science China(Life Sciences) 2003年第1期46卷 28-39页

作者：沈剑刚丘幸生姜泊张德良忻文娟 Peter C.W.Fung 赵保路 Laboratory of Visual Information Processing Center for Brain and Cognitive Sciences Institute of Biophysics Chinese Academy of Sciences Beijing 100101 China Institute of Chinese Medicine First Military Medical University Guangzhou 510515 China

Neonatal rat cardiomyocytes were subjected to 24 h of hypoxia 95%N2/5%CO2 and 24 h of hypoxia plus 4 h of reoxygenation 95%O2/5%CO2. 24 h of hypoxia increased the levels of NO, --23NO/NO, TBARS and LDH. 24 h of hypoxia plus 4 h of reoxygenation decreased the levels of NO, --23NO/NO, but further increased TBARS and LDH. The hypoxia up-regulated the expression of bcl-2, p53 and p21/waf1/cip1 but the reoxygenation down-regulated the expression of bcl-2, and further up-regulated p53 and p21/waf1/cip1. The hypoxia increased cell apoptosis and reoxygena-tion further increased both apoptotic and necrotic cell death. NO, -23NO/NO, TBARS, DNA frag-mentation and cell apoptosis were enhanced by SNP and inhibited by L-NAME respectively. In addition, SOD/catalase down-regulated the expression of p53, p21/wafl/cipl and TBARS but up-regulated bcl-2 and increased indirectly the level of NO, --23NO/NO, and inhibited DNA frag-mentation. The results suggest that hypoxia-induced cell death is associated with the activation of NO, bcl-2 and p53 pathway, while hypoxia-reoxygenation induced cell death via the generation of reactive oxygen species and activation of p53 pathway. The present study clarified that NO may be an initiative signal to apoptotic cell death and the activation of bcl-2, p53 and p21/waf1/cip1 path-way in hypoxic and hypoxia-reoxygenated cardiomyocytes.

关键词： apoptosis, hypoxia-reoxygenation, nitric oxide, oxygen radical, bcl-2, p53, p21/waf1/cip1.

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Pulse radiolysis of one-electron oxidation of rare tricyclic nucleoside derivative

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Science China Chemistry 2003年第2期46卷 144-151页

作者：赵红卫江致勤窦大营吴铁一王文锋杜小行姚思德 Shanghai Institute of Nuclear Research Chinese Academy of Sciences Department of Chemistry Tongji Unviersity

One-electron oxidation of N-4-desmethylwyosine (dYt), a derivative of rare tricyclic nucleoside wyosine with several oxidative radicals, has been studied by using pulse radiolysis. The transient spectra of the radicals dYt˙+ and dYt(-H)˙ and the pK a of the radical cation were measured. The rate constants of reactions of dYt with SO 4 ˙? and CO 3 ˙? radicals have been determined and related reaction mechanisms were discussed.

关键词： rare tricyclic nucleoside derivative, one-electron oxidation, pulse radiolysis, radical, transient absorption spectra.

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Synthesis, crystal structure and magnetic properties of a novel manganese(II)-nitronyl nitroxide-azido(μ_(1,1) and μ_(1,3)) one-dimensional complex

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Science China Chemistry 2003年第6期46卷 533-541页

作者：王利亚刘志亮张晨曦刘占泉廖代正姜宗慧阎世平 Department of Chemistry Nankai UniversityTianjin 300071 China Department of ChemistryLuoyang Teachers CollegeLuoyang 471022 China Department of Chemistry Nankai UniversityTianjin 300071 China Department of Chemistry Nankai UniversityTianjin 300071 China State Key Laboratory of Coordination ChemistryNanjing UniversityNanjing 210093 China Department of Chemistry Nankai University.Tianjin 300071 China

A novel one-dimensional manganese(II) complex containing nitronyl nitroxide radical [Mn2(IM2-py)2(Ac)2(μ1,1-N3)(μ1,3-N3)·EtOH]n was synthesized and characterized structurally and magnetically. It crystallizes in the monoclinic space group p21/n. Each Mn(II) ion is six-coordinated in a distorted octahedral environment. The two N atoms of the nitronyl nitroxide radical and the two O atoms of acetate ligands are in the equatorial plane, whereas the two different azido bridging ligands are in trans axial position. Mn(II) ions are linked by nitrogen atom of μ1,1-azido and oxygen atoms of two carboxy groups to form a Mn-Mn unit. Mn-Mn units are linked by azido ligands through μ1,3 bridging style to form a one-dimensional chain. The compound is connected by the coordination bonds, π-π interactions and hydrogen bonds as a three-dimensional structure. Magnetic susceptibility data support that there are stronger antiferromagnetic interactions between the radical and Mn(II) ion, weak antiferromagnetic interactions between the Mn-R units, and very weak antiferromagnetic interactions between the R-Mn-Mn-R units.

关键词： nitroxide radical, manganese complex, azido, crystal structure, magnetism.

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Quantum chemical study of chlorine-dissociation of oxalyl chloride (ClCO)_2→2Cl+2CO

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Science China Chemistry 2003年第1期46卷 19-24页

作者：戴年珍李宗和 Department of Chemistry Beijing Normal University Beijing 100875 China

The multi-bond dissociation dynamics of oxalyl chloride ((ClCO)2) is investigated by ab initio calculation. Dissociation of C-Cl bond of oxalyl chloride in the ground state is of barrierless. After the absorption of a photon, (ClCO)2 is excited to the first excited state and one of its C-Cl bonds is broken to yield Cl and ClCOCO* free radicals. In addition, ClCOCO* with high energy is prone to release energy (Q), and to turn into ClCOCO in the ground state. The energy (Q) is ade-quate for ClCOCO to break down into ClCO and CO, and even for ClCO into Cl and CO. The result is consistent with the experimental data that Kong reported.

关键词： oxalyl chloride, UV photodissociation, multi-bond dissociation, ClCOCO free radical, ab initio.

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Reaction of carotenoids with CCl3OO· by using pulse radiolysis

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Science China Chemistry 2003年第1期46卷 57-63页

作者：赵文恩姚思德王强钱素平王文峰韩雅珊 Chemical Engineering College Zhengzhou University Zhengzhou 450002 China Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research Chinese Academy of Sciences Shanghai 201800 China Crop Germplasm Resources Institute Chinese Academy of Agricultural Sciences Beijing 100081 China College of Food Sciences China Agricultural University Beijing 100094 China

The interactions of carotenoids (bixin, β-carotene and lycopene) with CCl3OO. in aqueous and i-propylalcohol solution saturated with air have been studied by pulse radiolysis. For bixin and β-carotene reaction products from forming process, absorbing in the region of 650 nm, is observed with concomitant carotenoid bleaching (bixin at 500 nm, β-carotene at 450 nm). Their rate constants from forming process are 1.78 ×108 and 7.8 ×107 mol-1 · L · s-1 respectively. However, in the case of lycopene, no such a forming process of reaction as bixin and β-carotene can be observed although there is the bleaching reaction (rate constant 4 ×107 mol-1 · L · s-1). The results suggest that the carotenoid radical cation and an additional radical are produced in the case of bixin and β-carotene, whereas lycopene undergoes electron transfer with CCl3OO., forming cation radical.

关键词： bixin, β-carotene, lycopene, trichloromethyl peroxyl radical, pulse radiolysis, transient absorption.

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