迷迭香单体的抗氧化活性

采用柱层析方法对迷迭香抗氧化剂(Rao)进行分离,分离出8个含量较高的单体.用光度法、ESR法、滴定法测定了迷迭香的8个单体、单体组合及Rao的抗氧化活性,并分析了抗氧化活性与其结构的关系.结果表明,在单体中,对超氧阴离子自由基及羟基自由基清除率最高的是槲皮素,分别为82.6%和87.1%.对香烟烟气自由基平均清除率最高的是迷迭香二酚,清除率为48.17%.单体活性最强的槲皮素和迷迭香二酚组合后,其抗氧化活性高于单体.活性强的抗氧化剂对油脂过氧化的抑制效果好,但作用时间较短.     

抗氧化剂活性的电子顺磁共振（EPR）研究

抗氧化剂在化工、食品以及生命科学等领域具有重要的作用,近年来更是由于其在解决与人类健康相关问题方面所起到的重要作用而受到广泛重视。本综述较为详细地介绍了利用电子顺磁共振（EPR）技术测定抗氧化剂活性的原理和方法,系统总结了近年来在天然抗氧化剂以及合成抗氧化剂化学活性方面的EPR研究最新进展,特别是定量测定表征抗氧化活性...     

气相色谱-质谱法同时测定食用植物油中三种抗氧化剂

本文研究了用乙醇提取食用植物油中的丁基羟基茴香醚(BHA)、二丁基羟基甲苯(BHT)和叔丁基对苯二酚(TBHQ),并用气相色谱-质谱法对三种抗氧化剂进行分离与测定。方法的线性范围为0.100~20.0 mg/L,检出限为:BHA,3.33μg/L;BHT,3.02μg/L;TBHQ,37.9μg/L。平均回收率为80.6%~123%,相对标准偏差为2.01%~8.77%。该方法具有简便、快速、准确、无毒等特点,应用于大豆油、花生油、芝麻油、菜籽油、茶油、食用调和油中的抗氧化剂的测定,结果令人满意。     

新型紫罗兰酮基双查尔酮缩氨基硫脲的合成及抗肿瘤活性

根据活性亚结构拼接原理,通过紫罗兰酮与(取代)苯甲醛反应合成了紫罗兰酮基双查尔酮,然后经与氨基硫脲缩合得到一系列未见报道的新型含紫罗兰酮、查尔酮及氨基硫脲3种优势结构单元的杂化体,它们的化学结构经傅里叶变换红外光谱(FT-IR)、核磁共振波谱(~1H NMR、~(13)C NMR)、元素分析及质谱(MS)等测试技术所证实。采用溴化噻唑蓝四氮唑(MTT)法初步测定其体外抗肿瘤活性(乳腺癌细胞(MCF-7),肝癌细胞(Hep G2),肺癌细胞(A549)),结果表明,对于不同类型的肿瘤细胞,化合物展现较好的增殖抑制活性。尤其是化合物3a与3b对MCF-7细胞展现较强的抗增殖活性,半数致死量(IC_(50))值分别为10.83和7.62μmol/L,化合物3e对A549细胞显示一定的增殖抑制活性效果(IC_(50)值为13.36μmol/L),化合物3f对Hep G2细胞表现了高效的抗增殖活性(IC_(50)值为8.55μmol/L)。目标物的抗增殖活性与紫罗兰酮结构及查尔酮环上不同电子效应的取代基有关。     

化学发光法比较5种抗氧化剂的活性

抗氧化剂是一种重要的食品添加剂,实验发现抗氧化剂对K3Fe(CN)6-鲁米诺化学发光体系产生的化学发光具有强烈的抑制作用,并且抗氧化剂对化学发光强度的抑制程度与其抗氧化活性在一定范围成线性关系.据此,结合流动注射技术建立快速测定抗氧化剂抗氧化活性的新方法。分析对比了维生素C,二丁基羟基甲苯,特丁基对苯二酚,维生素E,柠檬酸等5种抗氧化剂的抗氧化活性。其结果是:抗氧化活性由强到弱的顺序是:特丁基对苯二酚>二丁基羟基甲苯>维生素C>维生素E>柠檬酸。本文还对发光体系受到抑制作用可能的机理进行了探讨。     

氧氟沙星-Fenton体系荧光法测定和评价中草药抗氧化活性北大核心CSCD

研究利用荧光法测定和评价中草药抗氧化活性。氧氟沙星(Ofloxacin,OFL)能产生强荧光,在酸性环境中,Fenton反应产生的羟基自由基(·OH)能氧化OFL使其荧光猝灭,加入抗氧化剂或含有抗氧化成分的中草药可清除·OH使与OFL反应的·OH量减少,导致OFL荧光猝灭程度减弱。OFL荧光猝灭程度与加入抗氧化剂量或中草药中抗氧化成分的量呈定量关系,据此建立了一种测定和评价中草药抗氧化活性的新方法。应用该法测定和评价了7种常见中草药抗氧化活性,其中夏枯草、连翘和黄连的抗氧化活性较强。该方法操作简单,体系稳定,可用于中草药抗氧化活性测定和评价。     

胰岛素样生长因子-1对血管平滑肌细胞PI3K／PTEN信号通路的影响

目的：探讨胰岛素样生长因子-1(IGF-1)促血管平滑肌细胞(VSMC)增殖的细胞内信号转导机制。方法：体外培养的兔血管平滑肌细胞分3组处理，以细胞计数、噻唑盐比色法测定细胞增殖能力，以磷脂酰肌醇-3激酶(PI3K)特异性抑制剂渥漫青霉素(WT)孵育细胞间接反映PI3K作用。Western Blot定量磷酸酶PTEN表达水平，免疫沉淀、特异底物diC16PIP3绿色试剂法测定PTEN脂质磷酸酶活性。结果：IGF-1(100μg／L)使细胞计数及MTT比色A值分别增加至对照组的2．8倍和3．8倍，WT抑制VSMC增殖，并完全逆转IGF-1的作用(均P<0.01)。各浓度IGF-1对PTEN蛋白表达水平无明显影响，其对PTEN活性的抑制呈浓度(10～100μg／L)及时间(3min～24h)依赖性(均P<0．01)。结论：IGF-I促VSMC增殖作用与活化PI3K蛋白激酶的促生长活性及抑制PTEN脂质磷酸酶的负性调节细胞生长作用有关。     

Cy5-Fe2+-H2O2光度法测定天然抗氧化剂的抗氧化活性

在缓冲溶液中,Fenton体系产生的羟基自由基能迅速与五甲川菁染料(Cy5)作用使其褪色,在647 nm处测定体系吸光度的变化,可间接测定羟基自由基的生成量。抗氧化剂的加入可部分消除溶液中的羟基自由基,从而使溶液的吸光度下降程度减弱。据此建立了一种测定抗氧化剂对羟基自由基清除率的新方法。利用所建立的方法测试了抗氧化剂2,6-二叔丁基对甲基苯酚以及几种天然抗氧化剂的抗氧化活性,得到了满意的结果。该方法操作简便、稳定性好,可以作为一种简便的筛选抗氧化剂的方法。     

微流控芯片毛细管电泳法检测细胞内活性氧与细胞凋亡关系

建立了微流控芯片毛细管电泳激光诱导荧光同时测定细胞内活性氧和凋亡信号的方法。先用AlexaFluor488 annexin V细胞凋亡试剂盒标记细胞凋亡的外翻磷脂酰丝氨酸,再用双氢罗丹明123(DHR123)标记细胞内活性氧,用PBS将细胞调整为终密度1.2×106cells/mL的细胞悬液。细胞群经反复冻融法破碎后,以20 mmol/L硼砂(pH 9.2)作电泳缓冲溶液,分离电压1.2 kV,进样时间60 s,1 min内可完成活性氧和细胞凋亡信号的同时测定。方法简单、快速,细胞内活性氧和DHR123的反应产物(Rh123)在0.5～3μmol/L浓度范围内线性关系良好,相关系数(r)为0.998,检出限(S/N=3)为0.058μmol/L,可用于细胞内活性氧的定量分析。测得HepG2肝癌细胞活性氧含量为0.16μmol/L,被阿霉素诱导凋亡后,细胞内活性氧含量升高至1.77μmol/L。     

N_(12)-乙基取代吲哚咔唑衍生物的合成及细胞毒活性研究

合成了9个新的N12-乙基取代吲哚咔唑衍生物6~14,其结构经1H NMR、13C NMR和HRESIMS确定.用噻唑蓝(MTT)法测试了衍生物对人肺癌细胞A549、肝癌细胞Hep G-2和宫颈癌细胞Hela的细胞毒活性.用细胞计数试剂盒-8(Cell Counting Kit-8,CCK-8)法测试了衍生物对白血病细胞K562的细胞毒活性.结果显示,化合物7~9对K562的细胞毒活性与阳性对照阿霉素(ADM)相近,半数抑制浓度(IC50)为0.43~0.93μmol/L.化合物8和12对Hela的活性与阳性对照相近,IC50分别为1.23和0.43μmol/L.化合物13的盐酸盐14对所测试的4种肿瘤细胞株均有较强的抑制活性,IC50值在0.23~1.72μmol/L之间,可作为抗肿瘤先导化合物进行深入研究.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.