New Catalytic Methods for the Preparation of Tryptophans and Pyrroloindolines: Total Synthesis of (+)-Naseseazines A and B and (–)-Aspergilazine A

Tryptophan and unnatural tryptophan derivatives are important building blocks for the total synthesis of natural products, as well as the development of new drugs, biological probes, and chiral small molecule catalysts. This thesis describes various catalytic methods for the preparation of tryptophan derivatives as well as their functionalization and use in natural product total synthesis.

Herein, the tandem Friedel–Crafts conjugate addition/asymmetric protonation reaction between 2-substituted indoles and methyl 2-acetamidoacrylate to provide enantioenriched trytophans is reported. This method inspired further work in the area of transition metal catalyzed arylation reactions. We report the development of the coppercatalyzed arylation of tryptamine and tryptophan derivatives. The utility of these transformations is highlighted in the five-step syntheses of the natural products (+)-naseseazine A and B. Further work on the development of a mild and general Larock indolization protocol to access unnatural tryptophans is also discussed.

Indole and carbazole alkaloids from Glycosmis montana with weak anti-HIV and cytotoxic activities

A diprenylated indole, (E)-3-(3-hydroxymethyl-2-butenyl)-7-(3-methyl-2-butenyl)-1H-indole (1), and six known carbazole alkaloids were isolated from the twigs and leaves of Glycosmis montana Pierre (Rutaceae). Their structures were determined on the basis of analysis of spectral evidence including 1D and 2D NMR and MS. The alkaloids (1-3) exhibited weak to moderate take in vitro inhibitory activity against HIV replication in C8166 cells, and they (as well as carbalexine A and B) had cytotoxic activity against the human leukaemia cell line CCRF-CEM. (c) 2005 Elsevier Ltd. All rights reserved.

Composition of volatile oil of Primula obconica in Central China

Primula obconica was introduced to Europe from Hubei, China in 1880, and has been cultivated worldwide as one of popular ornamental plants. The volatile oil of wild P. obconica collected from its original place, Yichang, Hubei was first investigated. A total of 43 compounds constituting 93.49% of the oil were identified by using GC and GC-MS. The major compounds were methyl 2,4-dihydroxy-5-methyl benzoate (30.41%), methyl 2,6-dihydroxy-4-methyl benzoate (29.27%), and hypnone (8.92%) etc. In comparison with the published data of some European cultivars, the native P. obconica seems to be allergen-free due to absence of primin and miconidin.

Isolation by phage display and characterization of a single-chain antibody specific for O-6-methyldeoxyguanosine

New approaches of making single chain Fv antibodies against O-6-methyl-2'-deoxyguanosine (O(6)MdG) have been demonstrated by using the phage antibody display system. Using O(6)MdG as an antigen, 21 positive clones were identified by ELISA from this library, one of which, designated H3, specifically binds to O(6)MdG with high affinity. The H3 scFv antibody has an affinity constant (K-aff) of 5.94 x 10(11)(mol/L)(-1). H3 scFv has been successfully used to detect O-6 MdG in DNA hydrolyses from yeast or E. coli cells treated with a DNA methylating agent. To our knowledge, this is the first report of the selection of a specific scFv against DNA adducts. The results demonstrate the potential applications of the phage display technology for the detection of DNA lesions caused by mutagens and carcinogens.

活性氧自由基与嘧啶碱基及其核苷反应的ESP研究

本文以MNP（2-methyl-2-nitrosopropane）为捕捉剂，利用自旋捕捉技术和ESR方法，室温条件下，研究了活性氧自由基与嘧啶碱基及其核苷在水溶液中的反应。确定了所产生的自由基类别，讨论了自由基的形成机制。在本工作中，我们在下列三种体系中，研究了活性氧自由基与嘧啶碱基及其核苷的反应。1.核黄素（B_2）水溶液中，O_2~-与嘧啶碱基及其核苷的反应。2.H_2O_2水溶液中，OH与嘧啶碱基及其核苷的反应。3.γ射线辐照水溶液过程中，OH与嘧啶碱基及其核苷的反应。在核黄素（B_2）水溶液中，通过U.V.光辐照，我们得到了活性氧自由基与尿嘧啶、胞嘧啶、胞苷、脱氧胞苷、胸腺嘧啶、胸腺核苷反应所产生的自由基，及由这些自由基与MNP自旋加合物的ESR谱。确认了自由基Ⅰ，Ⅱ，Ⅲ，Ⅳ，Ⅴ，Ⅵ的存在。为了判别与嘧啶碱基或嘧啶核苷反应的活性氧自由基的种类，我们在下列三种条件下进行了测试：（1）加入适量DETAPAC（2）通N_2或Ar除O_2；（3）加入H_2O_2酶，均未得到ESR信号。据此，我们排除了O_2~-与嘧啶碱基或嘧啶核革直接反应的可能性。确认与嘧啶碱基或嘧啶核苷发生直接反应的是OH，其形成是Fenton反应的结果。 Fe~(2+) ＋ O_2~- → H_2O_2 ＋ Fe~(3+) （a） Fe~(2+) ＋ H_2O_2 → ·OH ＋ OH~- ＋ Fe~(3+) （b）Fe~(3+) ＋ O_2~- → Fe~(2+)＋O_2 （c）通过Fenton反应，O_2~-转化成·OH，间接与嘧啶或核苷发生了反应。U.V.光照含有MNP和1％H_2O_2的样品水溶液，我们确定了·OH与嘧啶碱基及其核苷反应所产生的自由基Ⅰ，Ⅱ，Ⅲ，Ⅳ，Ⅴ，Ⅵ，Ⅶ，Ⅷ，Ⅸ，Ⅹ。发现，·OH与尿嘧啶及其核苷，胞嘧啶及其核苷的反应，主要有二种形式：其一，·OH加合到嘧啶环的C_5－C_6双键上，形成C_5位或C_6位自由基；其二，·OH夺取C_5位上的H，开成C_5'位自由基。·OH不与胸腺核苷的糖单元发生反应，仅与其嘧啶环反应，形成Nu位和C_5位自基。γ射线辐照过程中，·OH与嘧啶碱基及其核苷的反应与H_2O_2体系中的情况类似。辐照剂量则对反应的影响较大，低于1.0 * 10~4 rad，不发生反应；1.0 * 10~6 rad，则发生交联反应，只有1.0 * 10~5 rad的辐照剂量比较适宜。

野桂花的化学成分研究

首次从野桂花（Osmanthus yunnanensis Fr. P. S. Green）地上部分95%乙醇提取物中通过色谱分离得到20个化合物, 其中化合物20为新化合物。基于波谱数据它们被鉴定为(E)-阿魏酸二十烷基酯(1)、β-谷甾醇(2)、羽扇豆醇(3)、齐墩果酸(4)、7-oxo-β-sitosterol(5)、乙酰齐墩果酸(6)、(6′-O-palmitoyl)-sitosterol 3-O-β-D-glucoside(7)、rotundioic acid(8)、地榆糖甙Ⅱ(9)、27-O-(E)-对羟基肉桂酰-28-齐墩果酸(10)、27-O-(Z)-对羟基肉桂酰-28-齐墩果酸(11)、hycandinic acid ester(12)、绿原酸丁酯(13)、4,5-二咖啡酰奎尼酸丁酯(14)、4,5-dihydroxyprenyl caffeate(15)、28-O-β-D-glucopyranosyl rotundioic acid (16)、4-(6-O-caffeoyl-β-D-glucopyranosyloxy)-5-hydroxyprenyl caffeate (aohada-glycoside C, 17)、 4-β-D-glucopyranosyloxy-5-hydroxy-prenyl caffeate (aohada-glycoside A, 18)、β-胡萝卜甙(19)以及3-[O-β-D-(6-O-咖啡酰吡喃葡萄糖)]-甲基-2-烯-γ-内酯 (20)。化合物13、14、15和17有较强的α-葡萄糖甙酶抑制活性。当浓度为1 mg/ml时，它们对α-葡萄糖甙酶的抑制分别为61.5%、95.5%、72.1%、62.6%，活性高于阿卡波糖。 综述了木犀属植物化学成分及1993年以来苯丙素甙类化合物活性研究进展。 Twenty compounds were isolated from the 95% ethanol extract of the aerial parts of Osmanthus yunnanensis Fr. P. S. Green by chromatography for the first time. On the basis of spectral data, they were identified as (E)-ferulic acid eicosyl ester (1), β-sitosterol (2), lupenol (3), oleanolic acid (4), 7-oxo-β-sitosterol (5), acetyloleanolic acid (6), (6′-O-palmitoyl)-sitosterol 3-O-β-D-glucoside (7), rotundioic acid (8), ziyu glycosideⅡ (9), 3β-hydroxy-27-p-(E)-coumaroyloxy-olean-12-en-28-oic acid (10), 3β-hydroxy-27-p-(Z)-coumaroyloxyolean-12-en-28-oic acid (11), hycandinic acid ester (12), chlorogenic acid butyl ester (13), 4,5-di-O-caffeoylquinic acid butyl ester (14), 4,5-dihydroxyprenyl caffeate (15), 28-O-β-D-glucopyranosyl rotundioic acid (16), 4-(6-O-caffeoyl-β-D-glucopyranosyloxy)-5-hydroxyprenyl caffeate (aohada- glycoside C, 17), 4-β-D-glucopyranosyloxy-5-hydroxyprenyl caffeate (aohada- glycoside A, 18), β-daucosterol(19) and 3-[O-β-D-(6-O-caffeoylglucopyranosyl)]- methyl-2-en-γ-lactone (20). Compound 20 is a new one. Compounds 13, 14, 15 and 17 inhibit α-glucosidase with corresponding inhibitory rate of 61.5%, 95.5%, 72.1% and 62.6% at a concentration of 1 mg/ml, higher than acarbose. The chemical studies on Osmanthus genus and bioactivities of phenylpropanoid glycosides were summarized.

钮子瓜和袋花忍冬的化学成分研究

钮子瓜（Zehneria maysorensis Arn.）是一种常用的中草药，其性味苦、凉，主要功效为清热利湿、散风止痛，主治膀胱炎、头痛。体外活性筛选实验表明，袋花忍冬（Lonicera saccata Rehd.）95%乙醇提取物的乙酸乙酯部分对血管紧张素转化酶显示较强的抑制活性。为明确钮子瓜的药用物质基础和袋花忍冬中具有ACE抑制活性的成分，首次对两个植物的成分进行了研究。 1. 从钮子瓜95%乙醇提取物中主要通过色谱方法首次分离了14个化合物，通过波谱方法鉴定为(2S,3S,4R,10E)-2-[(2R)-2-羟基二十四烷酰基氨基]-10-十八烷-1,3,4-三醇（1）、(2S,3S,4R)-2-二十四烷酰基氨基-十八烷-1,3,4-三醇 （2）、胡萝卜苷（3）、swertish （4）、苯甲酸（5）、水杨酸（6）、loliolide （7）、胸腺嘧啶（8）、尿嘧啶（9）、(23Z)-9,19-环阿尔廷-23-烯-3β,25-二醇（10）、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇（11）、十六烷酸 1-甘油酯（12）、大豆脑苷Ⅰ（13）和(22E,24S)-24-甲基-5α-胆甾-7,22-二烯-3β,5α,6β-三醇（14）。其中化合物4为一黄酮碳苷，具有旋转异构现象，有止痛作用；化合物6具有抗炎、镇痛、减热的活性，它们可能是钮子瓜药用物质基础的一部分。 2. 从袋花忍冬95%乙醇提取物中首次分离并鉴定了16个已知化合物：胡萝卜苷（3）、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇（11）、十六烷酸 1-甘油酯（12）、E-p-coumaryl behenate (15)、谷甾醇（16）、2,6-dihydroxyhumula-3(12), 7(13),9(E)-triene (17)、环阿尔廷-25-烯-3β,24ξ-二醇 (18)、二十四烷酸 (19)、2,4-二羟基-3,6-二甲基苯甲酸甲酯 (20)、乌苏酸 (21)、柚皮素 (22)、木犀草素 (23)、柏双黄酮（24）咖啡酸 (25)、洋芹素（26）和木犀草素-7-O-β-D-葡萄糖苷 (27)。其中木犀草素（23）和咖啡酸（25）含量较高，它们为抑制ACE活性的成分。 3．综述了黄酮碳苷的旋转异构现象。 Zehneria maysorensis is a folk medicine for the treatment of cystitis and headache. The ethyl acetate soluble fraction of the 95% ethanol extract of Lonicera saccata showed obvious ACE inhibitory activity in vitro. To reveal their active constitutents, they were subjected to chemically study. From the 95% ethanol extract of the whole plants of Zehneria maysroensis fourteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were characterized to be (2S,3S,4R,10E)-2-[(2R)-2-hydroxytetracosanoylamino]-10-octadecene-1,3,4-triol (1), (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol (2), daucosterol (3), swertish (4), benzoic acid (5), salicylic acid (6), loliolide (7), thymine (8), uracil (9), (23Z)-9,19-cycloart-23-ene-3β,25-diol (10), (20S,22E,24R)-5α,8α-epidioxy-ergosta- 6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), soya-cerebroside (13) and (22E,24S)-24-methyl-5α-cholesta-7,22-diene-3β,5α,6β-triol (14). Compound 4, a C-glycosylflavone, showed a very interesting rotational isomerism. Compounds 4 and 6 may be the active constituents of Zehneria maysorensis considering their sedative and anti-inflammation activity, respectively. From the whole plants of Lonicera saccata, sixteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were identified to be daucosterol (3), (20S,22E,24R)-5α,8α-epidioxy- ergosta-6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), E-p-coumaryl behenate (15), β-sitosterol (16), 2,6-dihydroxyhumula-3(12),7(13),9(E)-triene (17), cycloart-25-ene-3β,24ξ-diol (18), tetracosanoic acid (19), methyl 2,4-dihydroxy- 3,6-dimethylbenzoate (20), ursolic acid (21), naringenin (22), luteolin (23), cupressuflavone (24), caffeic acid (25), apigenin (26) and luteolin-7-O-β-D- glucopyranoside (27). Luteolin (23) and caffeic acid (25) were the ACE inhibitory active constituents. Rotational isomerism for C-glycosylflavonoid was reviewed.

丁香和升麻的化学成分研究

本论文由三部分共四章组成。第一部分介绍丁香化学成分的研究成果，第二部分为升麻的化学成分研究，第三部分综述了环菠萝蜜烷三萜结构和活性关系的研究现状。 第一部分包括第一和第二章。第一章介绍了丁香（Eugenia caryophyllataThunb.）花蕾的化学成分和结构鉴定。采用正、反相硅胶柱层析等各种分离方法，从其乙醇提取物的乙酸乙酯萃取物和正丁醇萃取物中共分离出34 个化合物，它们的结构类型分属黄酮、三萜、鞣质等。其中1 个为新的酚苷类化合物，其结构经波谱分析鉴定为2-O-(6'-O-没食子酰基)-b-D-葡萄糖基苯甲酸甲酯（24），另外还有12 个化合物为首次从该植物中分离得到。第二章介绍了丁香挥发油的气相色谱- 质谱联用（ GC-MS ）和正丁醇萃取物的高效液相色谱- 质谱联用（HPLC-MS/MS）分析，尝试简单快速地检测丁香挥发油及极性部分的主要化学成分的方法。 第二部分为第三章。本章介绍了传统中药升麻（Cimicifuga foetida L.）根部乙醇提取物化学成分的分离纯化和结构鉴定。通过正、反相硅胶柱层析等分离纯化方法和MS、NMR 等波谱解析技术，共分离鉴定了20 个化合物，主要为环菠萝蜜烷三萜，其中5 个新三萜化合物分别鉴定为cimicidol-3-one（38）、3'-O-乙酰基升麻苷H-1（41）、2'-O-乙酰基升麻苷H-1（42）、(3b,12b,16b)-12-乙酰氧-16,23-环氧-9,19-环羊毛甾烷-22-烯-24-酮3-O-b-D-吡喃木糖苷（44）和升麻碱（54）。新化合物54 为结构新颖的环菠萝蜜烷三萜皂苷生物碱，这是首个发现的具有环菠萝蜜烷三萜骨架的生物碱，也是从升麻属植物中发现的第一个三萜生物碱，它的结构通过多种波谱解析，特别是2D-NMR 的充分应用，并结合化学降解和反应得到证实。此外，还介绍了分离得到的一种具有明显抑制破骨细胞活性的化合物(QS29)的体外活性研究。 第三部分即第四章，综述了升麻属植物中环菠萝蜜烷三萜与其生物活性的构效关系研究现状。 This dissertation consists of three parts. In the first and the second parts, thechemical constituents from the flower buds of Eugenia caryophyllata and therhizomes of Cimicifuga foetida were reported. The third part is a review on astructure-activity relationship of the cycloartane triterpenoid from Cimicifuga species. The first part is composed of two chapters. The chapter 1 is about the isolationand identification of the chemical constituents from the flower buds of E.caryophyllata. A new phenolic glucoside gallate, methyl 2-O-(6’-O-galloyl)-b-D-glucopyranosylbenzoate (24), together with thirty-three known compounds has beenisolated from the ethanol extract of the flower buds of E. caryophyllata throughrepeated column chromatography on normal and reversed phase silica gel. Thestructure of the new compound was elucidated on the basis of spectral and chemicalevidence. Those kno wn compounds were belonged to flavone, triterpenoid, tannin andsome simple compounds. Among them, 12 compounds were isolated from the titleplant for the first time. The second chapter describes the capillary GC-MS analysis ofthe volatile components and the HPLC-MS/MS analysis of the polar constituents fromthe flower buds of E. caryophyllata, in order to detect the main constituents in thecrude extract rapidly and precisely. The third chapter is about the chemical constituents of the rhizomes C. foetida, atraditional Chinese medicine which was used as anti-inflammatory, analgesic andantipyretic agents. Our investigation of the bioactivities constituents of the rhizomesof C. foetida led to the isolation of five new cycloartane triterpenoids, which werecharacterized as cimicidol-3-one (38), 3'-O-acetyl cimicifugoside H-1 (41),2'-O-acetyl cimicifugoside H-1 (42), (3b,12b,16b)-12-acetoxy-16,23-epoxy-9,19-cyclolanost-22-ene-24-one 3-O-b-D-xylopyranoside (44) and cimicifugadine (54),along with fifteen known compounds through repeated column chromatography onnormal and reversed phase silica gel. Among them, 54 is a novel cycloartanealkaloid and first discovered as a new type alkaoid from nature. The structures ofthese compounds were elucidated on the basis of spectral and chemical evidence, andcimicidol-3-one was confirmed by X-ray crystallography analysis. Moreover, onecompound exhibited strong anti-osteoporosis activity in vitro experiment. The fourth part is a review on a structure-activity relationship analysis of thecycloartane triterpenoid from Cimicifuga species.

Selective hydrogenation of unsaturated aldehydes in a poly(ethylene glycol)/compressed carbon dioxide biphasic system

Hydrogenation of alpha,beta-unsaturated aldehydes (citral, 3-methyl-2-butenal, cinnamaldehyde) has been studied with tetrakis(triphenylphosphine) ruthenium dihydride (H2Ru(TPP)(4)) catalyst in a poly(ethylene glycol) (PEG)/ compressed carbon dioxide biphasic system. The hydrogenation reaction was slow under PEG/ H-2 biphasic conditions at H-2 4 MPa in the absence of CO2. When the reaction mixture was pressurized by a non-reactant of CO2, however, the reaction was significantly accelerated.

Synthesis and properties of novel soluble polyimides having a spirobisindane-linked dianhydride unit

A new synthetic procedure was elaborated allowing the preparation of semiaromatic dianhydride. N-Methyl protected 4-chlorophthalic anhydride was nitrated with HNO3 to produce N-methyl-4-chloro-5-nitrophthalimide (1). The aromatic nucleophilic substitution reaction between 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1-spirobisindane and 1 afforded spirobisindane-linked bis(N-methylphthalimide) (2), which was hydrolyzed and subsequently dehydrated to give the corresponding dianhydride (3). The latter was polymerized with five different aromatic diamines to afford a series of aromatic polyimides. The properties of polyimides such as inherent viscosity, solubility, UV transparency and thermal stability were investigated to illustrate the contribution of the introduction of spirobisindane groups into the polyimide backbone. The resulting polyimides were readily soluble in polar solvents such as chloroform, THF and N-methyl-2-pyrrolidone. The glass-transition temperatures of these polyimides were in the range of 254-292 degrees C. The tensile strength, elongation at break, and Young's modulus of the polyimide film were 68.8-106.6 MPa, 5.9-9.8%, 1.7-2.0 GPa, respectively. The polymer films were colorless and transparent with the absorption cutoff wavelength at 286-308 nm.

A new class of high T-g and organosoluble polynaphthalimides

A new class of soluble six-membered ring polynaphthalimides (PNIs) was synthesized from asymmetrical fluorinated naphthalenesubstituted monomers. All the resulting PNIs were easily soluble in many organic solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO). and chloroform. They also showed good thermal stability with glass transition temperature of 340-386 degrees C, 10% weight loss temperature in excess of 529 degrees C. Polyimide 3c could be solution-cast into tough and flexible film. The film had a tensile strength, elongation at break, and Young's modulus of about 117.6 Wa, 23.6%, and 1.77 GPa, respectively. The gas permeation property of the film of 3c was investigated with oxygen permeability coefficient (PO2 = 3.99) and permeability selectivity coefficient of oxygen to nitrogen (P-O2/P-N2 = 5.27). Therefore, these materials are expected to be a good alternative to PIs based on five-membered rings with applications in gas separation membranes.

Atom transfer radical polymerization of butadiene using MoO2Cl2/PPh3 as the catalyst

Atom transfer radical polymerization has been used to successfully synthesize polybutadiene. This was achieved by using MoO2Cl2/triphenyl phosphine as the catalyst and the various organic halide compounds such as methyl-2-chloropropionate, CCl4, 1,4-dichloromethyl benzene, I-phenylethyl chloride, and benzyl chloride as initiators. The monomer conversion increased up to 50% with polymerization time. The polydispersity indices of the polymers were as high as above 1.5. However, the polymerizations were controlled and the polydispersity indices of the polymers were less than 1.5 throughout the polymerization in reverse atom transfer radical polymerization. The chemical structure of the polymer obtained was characterized by (HNMR)-H-1 and FTIR. The valency states of molybdenum in this reactive system were detected by UV-vis spectra.

Hydrazine-based polyimides from isomeric bis(chlorophthalimide)s

3,3-Dichloro-N,N'-biphthalimide (3,3'-DCBPI), 3,4'-dichloro-N,N'-biphthalimide (3,4'-DCBPI), and 4,4'-dichloro-N,N'X-biphthalimide (4,4'-DCBPI) were synthesized from 3- or 4-chlorophthalic anhydrides and hydrazine in glacial acetic acid. The yield of 3,3'-DCBPI (90%) was much higher than that of 4,4'-DCBPI (33%) because of the better stability of the intermediate, 3-chloro-N-aminophthalimide, and 3,3'-DCBPI. A series of hydrazine-based polyimides were prepared from isomeric DCBPIs and 4,4-thiobisbenzenethiol (TBBT) in N,N-dimethylacetamide in the presence of tributylamine. Inherent viscosity of these polymers was in the range of 0.51-0.69 dL/g in 1-methyl-2-pyrrolidinone (NMP) at 30 degrees C. These polyimides were soluble in 1,1,2,2-terachloroethane, NMP, and phenols. The 5% weight-loss temperatures (T(g)s) of the polymers were near 450 degrees C in N-2. Their glass-transition temperatures (T(g)s) determined by dynamic mechanical thermal analysis and differential scanning calorimetry increased according to the order of polyimides based on 4,4'-DCBPI, 3,4'-DCBPI, and 3,3'-DCBPI. The hydrolytic stability of these polymers was measured under acid, basic, and neutral conditions and the results indicated that the order was 3,3'-DCBPI/TBBT > 3,4'-DCBPI/TBBT > 4,4'-DCBPI/TBBT.

Copolymerization of dichlorodiphenylsulfone with bis(chlorophthalimide) catalyzed by NiBr2/PPh3/Zn

A new high-performance material, poly(sulfone-imide) was prepared by Ni(0)-catalyzed coupling of aromatic dichlorides containing imide structure and 4,4'-dichlorodiphenylsulfone. The copolymers were produced with high yield and moderate to high inherent viscosities of 0.52-1.13 dL/g. Wide-angle X-ray diffractograms revealed that the polymers were amorphous. Most of the polymers exhibited good solubility and could be readily dissolved in various solvents such as N-methyl-2-pyrrolidinone(NMP) and N,N-dimethylacetamide (DMAc). These polysulfone-imides had glass-transition temperatures between 317 and 345 degreesC and 10% weight loss temperatures in the range of 450476 degreesC in nitrogen atmosphere. The tough polymer films, obtained by casting from cresol solution, had a tensile strength range of 21 158 MPa and a tensile modulus range of 2.1-3.3 GPa.

The antioxidative effect of icariin in human erythrocytes against free-radical-induced haemolysis

Icariin (2-(4'-methoxyl phenyl)-3-rhamnosido-5-hydroxyl-7-glucosido-8-(3'-methyl-2-butyleny"chromanone) is the major component in Herba Epimedii used in traditional Chinese medicine for the treatment of atherosclerosis. This work focuses on the antioxidative effect of icariin on freeradical-induced haemolysis of human erythrocytes, in which the initial free radical derives from the decomposition of 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) at physiological temperature. To reveal the structure-activity relationship of icariin, the antioxidant effects of two structural analogues of icariin, acacetin (2-(4'-methoxylphenyl)-5,7-dihydroxylchromone) and norwogonin (2-phenyl-5,7,8-trihydroxylchromone), on the same experimental system were examined as well. It was found that all these chromone derivatives (Chm-OHs) dose-dependently protected human erythrocytes against free-radical-induced haemolysis. The order of antioxidative activity was nonvogoni-n > acacetin > icariin by the analysis of the relationship between the concentration of Chm-OHs and the prolongation percentage of the lag time of haemolysis (PP%). It was also proved that the phenyl hydroxyl group attached to the chromone ring at 7-position cannot trap the free radical- On the contrary, phenyl hydroxyl groups at the 5- and 8-position in nonvogonin made it a significant antioxidant in AAPH-induced haemolysis.