木脂素类化合物的全合成研究

综述了本研究小组近几年在木脂素全合成研究中取得的新进展。主要包括三部分：通过β-酮酸酯偶联反应来合成去甲二氢愈创木酸及多种其它类型木脂素;通过氧化银偶联和DDQ合环首次合成黄酮木脂素(±)-Sinaiticin;通过Sharpless不对称双羟化为关键步骤首次手性合成1,4-苯并二氧六环类新木脂素。     

肥牛木中一个新的降新木脂素

报道了肥牛木素(Ceplignan)的分离方法和结构鉴定结果.     

木脂素抗艾滋病病毒研究*

木脂素类化合物(lignans)具有抗癌、保肝、血小板活因子拮抗和抗氧化等重要生理活性.然而木脂素抗HIV的特性在90年代才被发现.作为一种源自于天然植物体内的艾滋病病毒抑制剂,它具有被开发成治疗艾滋病药物的可能性.本文综述了近年来关于木脂素类化合物抗艾滋病病毒的研究进展.     

二苯丁脂类木脂素及衍生物的合成和抗肿瘤活性研究

以胡椒醛和藜芦醛为原料, 通过Stobbe缩合和烷基化反应构建木脂素骨架、手性试剂拆分, 经官能团转换后, 得到了10个二苯丁脂类木脂素, 其中4个为天然产物. 合成得到的化合物进行了抗肿瘤活性测定, 结果表明, 部分化合物物具有较强的抑制乳腺癌细胞活性.     

α-苯基萘类木脂素内酯的合成进展

芳基萘类木脂素内酯是一类广泛分布于植物界的含有芳基萘骨架的天然产物,这些天然产物拥有广泛的生物活性,从而引起了人们的高度重视,成为近年来较活跃的研究领域之一。本文综述了自1980年以来的α-苯基萘类木脂素内酯化合物的化学合成方法,旨在为该类化合物的合成及开发提供参考。     

异维A酸新木脂素酯的合成与表征

以香草醛(或对羟基苯甲醛)和丙二酸为原料,经Knoevenagel反应、酯化、氧化银为氧化剂的自由基仿生氧化偶联反应合成了新木脂素3a,3b。3a,3b分别与异维A酸酯化,合成了两种新型的异维A酸新木脂素酯4a和4b。用1H NMR,IR和MS对它们的结构进行了表征。研究了异维A酸酯的反应机理。     

一个8-O-4'新木脂素化合物的对映选择性合成

报道了一条立体选择性合成赤式8-O-4'新木脂素的新路线. 以Sharpless双羟化反应构筑2个手性中心, 经过几步转化, 得到关键中间体6, 通过Mitsunobu反应进行偶联, 可以得到单一赤式的8-O-4'新木脂素化合物. 通过此路线, 立体选择性地合成了一个天然8-O-4'新木脂素的赤式异构体.     

杜仲中木脂素类化合物纯化工艺研究

对杜仲中木脂素类化合物松脂醇二葡萄糖甙(PDG)和丁香脂素二葡萄糖甙(SDG)进行分离纯化工艺研究。首先采用溶剂萃取法进行一次纯化,再采用大孔吸附树脂优化纯化工艺,最后采用硅胶柱色谱法同时分离、纯化杜仲中松脂醇二葡萄糖甙和丁香脂素二葡萄糖甙,采用反相高效液相色谱法跟踪检测纯度。纯化后得到两种晶体,经过UV、IR、MS和1HNMR定性分析确定为松脂醇二葡萄糖甙和丁香脂素二葡萄糖甙,其纯度分别为90.86%和91.73%,回收率分别为42.14%和47.17%。该纯化方法能获得高纯度的松脂醇二葡萄糖甙和丁香脂素二葡萄糖甙,操作简单、成本低。     

阿拉善马先蒿中新木脂素甙成分研究

阿拉善马先蒿中新木脂素甙成分研究高建军，刘自民，王继和，贾忠建（兰州大学有机化学研究所应用有机化学国家重点实验室，兰州，７３００００）关键词阿拉善马先蒿，玄参科，新木脂素甙前文［１］报道了从阿拉善马先蒿（ＰｅｄｉｃｕｌａｒｉｓａｌａｓｃｈａｎｉｃａＭ...     

丁烷型木脂素及衍生物的合成和生物活性

报道了一条合成丁烷木脂素的新路线. 以芳香醛为起始原料, Stobbe缩合和烷基化反应为关键步骤, 构建了木脂素骨架, 再经拆分及还原, 可得到相应的苏式和赤式异构体. 经官能团转化得到5个丁烷木脂素和8个丁醚木脂素, 其中3个天然产物为首次合成. 对合成产物进行抗HIV病毒和和抗疱疹病毒活性研究, 部分化合物显示出较高的抗病毒活性, 而且骨架构型对活性影响较大.     

Determination of the Free Radical Scavenging Activity of Lycium Extracts

Lycium species growing in Turkey have not so far been studied sufficiently. For this reason, non-polar and polar extracts obtained from the fruits of Lycium barbarum L. and L. Ruthenicum Murray (Solanaceae) were assessed both in vitro for their potential as free radical scavenger crude extracts and their phenolic composition. Fruits of Lycium species were sequentially extracted with petroleum ether, ethyl acetate, methanol, n-butanol, and water in a Soxhlet extractor. All the extracts were assessed for the scavenging of the nitrogen-centered free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH^.) by in vitro method. Furthermore, the composition of each extract was investigated both in terms of its Folin-Ciocalteau reactive components and its qualitative content. The phenolic compounds within the extracts were determined as benzoic acid and hydroxycinnamic acid derivatives, flavonoids, and anthocyanins according to their retention time and UV spectral data by HPLC-DAD system.     

Phytochemical Profile,Free Radical Scavenging and Anti-Inflammatory Properties of Acalypha Indica Root Extract: Evidence from In Vitro and In Vivo Studies

In our in vitro and in vivo studies, we used Acalypha indica root methanolic extract (AIRME), and investigated their free radical scavenging/antioxidant and anti-inflammatory properties. Primarily, phytochemical analysis showed rich content of phenols (70.92 mg of gallic acid/g) and flavonoids (16.01 mg of rutin/g) in AIRME. We then performed HR-LC-MS and GC-MS analyses, and identified 101 and 14 phytochemical compounds, respectively. Among them, ramipril glucuronide (1.563%), antimycin A (1.324%), swietenine (1.134%), quinone (1.152%), oxprenolol (1.118%), choline (0.847%), bumetanide (0.847%) and fenofibrate (0.711%) are the predominant phytomolecules. Evidence from in vitro studies revealed that AIRME scavenges DPPH and hydroxyl radicals in a concentration dependent manner (10–50 μg/mL). Similarly, hydrogen peroxide and lipid peroxidation were also remarkably inhibited by AIRME as concentration increases (20–100 μg/mL). In vitro antioxidant activity of AIRME was comparable to ascorbic acid treatment. For in vivo studies, carrageenan (1%, sub-plantar) was injected to rats to induce localized inflammation. Acute inflammation was represented by paw-edema, and significantly elevated (p < 0.05) WBC, platelets and C-reactive protein (CRP). However, AIRME pretreatment (150/300 mg/kg bodyweight) significantly (p < 0.05) decreased edema volume. This was accompanied by a significant (p < 0.05) reduction of WBC, platelets and CRP with both doses of AIRME. The decreased activities of superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase in paw tissue were restored (p < 0.05 / p < 0.01) with AIRME in a dose-dependent manner. Furthermore, AIRME attenuated carrageenan-induced neutrophil infiltrations and vascular dilation in paw tissue. For the first time, our findings demonstrated the potent antioxidant and anti-inflammatory properties of AIRME, which could be considered to develop novel anti-inflammatory drugs.     

4种黄酮小分子对DPPH自由基的清除作用及构效关系研究

通过紫外可见光谱测定了4种黄酮小分子芦丁、牡荆素、山奈素、金丝桃苷对DPPH自由基的清除率、稳定性及半抑制浓度(IC50),并以常用的天然抗氧化剂抗坏血酸作为对照,考察了其抗氧化效果,探讨了黄酮类化合物的抗氧化性与结构的关系。结果表明：不同的抗氧化剂清除DPPH自由基达到平衡的时间不同,芦丁所需时间最长。4种黄酮小分子及抗坏血酸均对DPPH自由基有清除效果,并存在一定的量效关系。对DPPH自由基的清除能力从大到小依次为金丝桃苷、抗坏血酸、芦丁、山奈素、牡荆素。结构分析表明,B环邻二酚羟基是黄酮类化合物抗氧化所必需的基团,其羟甲基化及A环羟基糖苷化不利于黄酮类化合物的抗氧化活性。而C环3-OH的糖苷化对抗氧化活性有利,且单糖苷优于双糖苷。     

Insecticidal Activity and Free Radical Scavenging Properties of Isolated Phytoconstituents from the Saudi Plant Nuxia oppositifolia (Hochst.)

Chromatographic purification of the alcoholic extract from the aerial parts of the Saudi plant Nuxia oppositifolia (Hochst.), Benth., resulted in five isolated phenolic compounds. Two flavones, hispidulin (1) and jaceosidin (2), and the phenylethanoid glycosides, verbascoside (3), isoverbascoside (4), and conandroside (5), were identified and their chemical structures were determined by spectroscopic analyses. The insecticidal activity of compounds 1 and 2, in addition to 11 compounds isolated in a previous research (6–16), was evaluated against the Yellow Fever mosquito, Aedes aegypti. Four compounds displayed adulticidal activity with LD₅₀ values of 2–2.3 μg/mosquito. Free radical scavenging properties of the plant extracts and compounds (1–5) were evaluated by measuring the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate radical cation (ABTS^•+) scavenging activity. All compounds exhibited notable activity, compared with the positive control, l-Ascorbic acid. This study suggests that N. oppositifolia could be a promising source of secondary metabolites, some with lethal adulticidal effect against Ae. aegypti.     

壳聚糖/羧甲基壳聚糖金属配合物对氧自由基的清除作用研究

以NADH-PMS-NBT体系产生超氧阴离子自由基(o2-·)和EDTANa2·Fe(Ⅱ)-H2O2体系产生 羟自由基(·OH)来研究壳聚糖Cu(Ⅱ)、Zn(Ⅱ)配合物、羧甲基壳聚糖Cu(Ⅱ)、Zn(Ⅱ)配合物时氧自由基的 清除作用。结果显示配合物对O2-·和·OH均具有明显的清除作用,其中铜(Ⅱ)配合物对O2-·的清除活 性最高,而锌(Ⅱ)配合物比铜(Ⅱ)配合物具有更强的清除·OH的能力,羧甲基壳聚糖Cu(Ⅱ)、Zn(Ⅱ)配合 物与含有相同金属离子的壳聚糖配合物相比对O2-·和·OH具有更高的抑制活性。     

Free Radical Scavenging Magnetic Iron-Based Nanoparticles in Hyperbranched and Linear Polymer Matrices

Magnetic iron nanoparticles are attracting a great deal of research and application interest in diversified fields. In this present investigation, iron nanoparticles were prepared by a in-situ chemical reduction technique in a combination of polyaniline (PANI)-polyacrylamide (PA) and PANI-hyperbranched polyurethane (HBPU) matrices to judge the suitability of hyperbranched system. The formation of the nanoparticles in polymer matrices has been investigated by FTIR, UV, XRD, SEM and TEM studies. Narrower size with better dispersion and more stable nanoparticles were found in a hyperbranched matrix system compared to a linear one. The particle size was found to be in the range of 10–20 nm and 12–35 nm in HBPU-PANI and PA-PANI matrices, respectively. Both the nanocomposites exhibit synergistic free radical scavenging capability towards 2,2-diphenyl-1-picrylhydrazyl (DPPH). The magnetic hysteresis loop of the nanocomposites indicates the super-paramagnetic behavior. The hyperbranched system is more thermostable than the linear system by 70°C.     

Screening of Humic Substances Extracted from Leonardite for Free Radical Scavenging Activity Using DPPH Method

Humic substances (HSs) have been researched for a long time and still manage to surprise humanity today. According to the latest research, in addition to their previously well-known effects, they also have antioxidant properties. However, this previous research does not examine the difference in the antioxidant effect of the fractions extracted/produced in different processes; they do not consider the light absorption of the HSs, which falsifies analysis based on the measurement of color change over time. In the present work, HS fractions were obtained from leonardite, the extraction processes can also be implemented on an industrial scale. The fractions were characterized by elementary analysis, UV–Vis and FT-IR spectroscopies, to prove that our self-extracted samples have similar characteristics to the International Humic Substances Society (IHSS) standard samples. The different methods of HS fractionation affected the elemental composition, and the spectral characteristics. The antioxidant effect was investigated using the DPPH method to screen the antioxidant efficiency of humic, fulvic, and himatomelanic acids. In addition, we compared our results with the IHSS standard samples to obtain a more comprehensive picture of the antioxidant effect of HSs extracted in different ways according to the DPPH method. Based on our results, the extraction method affects not only the physico-chemical properties but also the free radical scavenging activity of the fractions.     

Fenton反应考察抗坏血酸清除羟基自由基能力及动力学

自由基的清除对维持正常的生理活动和抗衰老具有重要意义。 抗坏血酸(V_C)是常用的天然抗氧化剂之一, 为了有效合理利用V_C的抗氧化性, 实验利用水杨酸捕捉Fenton反应产生的羟基自由基(·OH), 加入V_C考察与水杨酸竞争清除·OH的能力, 选择出最佳清除条件;并根据双底物反应特征, 拟合出Alberty方程, 得到了清除·OH的规律。 结果表明, 当V_C用量为4.54 mmol/L、温度为47 ℃条件下、反应90 min时, V_C对·OH的清除率达到最大, 为46.23%;拟合出的反应动力学参数最大反应速率为0.11 mmol/(L·min), 水杨酸和V_C 的特征常数分别为30.2和1.2×10^-3 mmol/L。 比较实验结果和拟合方程得到的数据, 二者非常接近, 相对误差在1.66%~5.40% 之间, 从而为合理利用抗坏血酸清除羟基自由基提供理论依据。     

褪色光度法测定羟自由基及常见食物的抗氧化活性

在用稀硫酸调节至pH 4的溶液中,生物染色剂玫瑰桃红R能被由Fenton反应产生的羟自由基(·OH)氧化而褪色.根据在520 nm波长处所测得的吸光度的消褪的程度(△A=A0-A1),实现了羟自由基存在量的光度测定,应用此方法还测定了自由基消除率,作为选择清除剂的判据;还测定了几种常见食品的抗氧化活性.从方法的操作和所测得的结果证明该方法具有操作简单、方便且稳定而经济.     

Radical Scavenging Activity of Antioxidants by Cyclic Voltammetry

This work investigates the reactivity of individual antioxidants with the free radicals generated by 2,2′-azobis(isobutironitrile) (AIBN). The consumption of antioxidants was followed by cyclic voltammetry. The fitting of such decay with a kinetic model yielded the rate constant of radical formation and the rate constant of radical inhibition exerted by each antioxidant. The antioxidant efficiency was defined as the ratio between and . The following ranking of antioxidants was obtained: α-tocopherol≫catechin≫retinyl acetate≫hydroxytyrosol≫oleuropein≫caffeic acid. Overall, the approach shows the utility of cyclic voltammetry to investigate the kinetic rates at which antioxidants react with radicals.