褐藻多酚连三羟基的测定

褐藻多酚具有抗氧化活性 ,羟基是决定褐藻多酚化学性质和生物学活性的最主要的官能团［５］。褐藻多酚结构中除通常的间羟基外 ,还具有部分连三羟基。可以肯定 ,由于连三羟基特殊的化学特征 ,其含量及其在总羟基中所占比例 ,必然会影响褐藻多酚的性质。因此 ,测量褐藻多酚连三羟基的含量和其在总羟基含量中所占比例对深入研究褐藻多酚性质是非常必要的 ,它可为探讨褐藻多酚的构效关系和生成机理提供定量研究的手段［３］。以往的研究者只以间苯三酚为标准物对褐藻多酚中总羟基进行过测定 ,核磁共振研究虽然表明褐藻多酚中除间三羟基外还含有…     

Eckol类褐藻多酚的研究进展

褐藻多酚是广泛存在于褐藻中的以间苯三酚为结构单元的一类植物多酚。eckol类褐藻多酚具有广泛的药理活性。本文综述了近20年eckol类褐藻多酚在种类、结构以及药理活性等方面的研究进展。     

褐藻多酚的结构单元及生成机理

在褐藻多酚研究中，传统的观战即间苯三酚是褐藻多酚的结构单元，在多酚结构规律方面不能地解释６种酚类分子的成因。作者在理论分析和综合前人实验结果的基础上，提出１，２，３，５－四羟基苯为褐藻多酚的结构单元，它在褐藻细胞中的存在形式为１，２，３，５－四羟基苯－２，５－二硫酸酯或１，２，３，５－四羟基苯－２－硫酸酯或并指出褐藻多酚可能的生成机理，初步为不同种类多酚分子的生成规律提供了一种统一的、清晰的解释。     

褐藻多酚含量的季节变化

褐藻多酚的季节变化研究具有重要的理论意义，对海黍子和鼠尾藻褐藻多酚的含量测定结果表明，褐藻多酚含量的季节变化范围分别在１．５￣３．１％之间以及０．８￣１．８％之间。另外，ＰＶＰ吸附率也有相应的变化，分别在５１￣６９％之间以及４１￣６３％之间。     

褐藻中多酚化合物的研究进展

褐藻门约有２５０属 ,１５００种以上 ,是海藻中比较高级的一大类群。由于其具有分布广、藻体大、生长快等特点 ,潜在的经济价值巨大。而且 ,我国蓬勃兴起的居于世界领先水平的海藻养殖业 ,为我国海藻工业提供了极为丰富的原料。传统上 ,褐藻综合利用产品包括褐藻胶、甘露醇、碘和氯化钾等。近２０余年来 ,随着对褐藻的次级代谢产物———褐藻多酚化合物( ｐｈｌｏｒｏｔａｎｎｉｎｓ)研究的深入 ,其独特的生物活性日益受到人们的关注。本文对褐藻多酚研究进展作简要综述。１褐藻多酚的发现１８４７年 ,德国藻类学家Ｎａｇｅｌｉ通过光学显…     

中国常见褐藻的多酚含量测定

褐藻多酚是从褐藻中提取出的新型海洋天然物质,具有生物活性和医药价值,因而对开发海洋药物具有重要意义。它与陆生植物单宁质的化学反应性能基本相同(Ogino,1962),因此可采用单宁质的测量分析技术对其进行分析。Temple(1982)认为单宁质的测量技术可分为容量分析、重量分析、比色分析和色谱分析,由于容量分析、重量分析方法缺乏化合物结构选择性,而色谱分析更适用于组分的分离,且操作条件复杂;因而目前国内外大多数国家采用美国分析化学协会(Association of Official Analytical Chemists,AOAC,1970)的比色分析方法,即使钨钼酸盐氧化酚类化合物形成有色的钼蓝复合物,然后作比色分析。本文采用此法对我国几种常见褐藻进行了多酚含量分析。     

褐藻淀粉硫酸酯的血脂澄清和降血脂作用的研究

褐藻淀粉(Laminaran),是褐藻体内具有的一种多糖。它的化学结构是由C_1—C_3结合的β—D吡喃葡萄糖多聚化合物,将其磺酸化即可得褐藻淀粉硫酸酯。经药理试验证明磺酸化程度低的褐藻淀粉硫酸酯,具有一定的降血脂作用,该有效成分无甚不良反应,堪称为防止动脉粥状硬化和治疗高血脂症的药物。我国沿海褐藻类的产量丰富,为褐藻淀粉的提取提供了广阔的天然资源。若能将褐藻综合利用,制成治疗冠心病的药物,这将对海洋资源的利用,开辟一个新的领域。这是一个十分有实践意义的研究课题。褐藻淀粉硫酸酯的性质和药效,因藻源、提取方法、分子量的大小及磺酸化的程度等不同而有差异。因此,在研制过程中,除进行提取和磺酸化的研究外,必须结合药理作用的观察,方能确定褐藻淀粉硫酸酯的作用价值。本实验采用我国沿海马尾藻类—铜藻Sargassum horneri(Turn.)C.Ag为原料,经提取、磺化、制成褐藻淀粉硫酸酯钠,并进行了药理研究和安全实验。     

褐藻多糖硫酸酯的结构与生物活性研究

褐藻多糖硫酸酯(fucoidan,FPS)是所有褐藻中所固有的细胞间多糖,存在于细胞壁基质中。生长于潮间带、长时间与空气接触的褐藻种类中,如多年生的墨角藻(Fucus vesiculosus)类,其褐藻多糖硫酸酯的含量可高达20%;生长在较深处的海带(Saccharina japonica)类中含量较低,约为1%~2%。褐藻多糖硫酸酯是一类独特的结合有硫酸基的水溶性杂聚糖,其化学组成和结构非常复杂,以岩藻糖和硫酸基为主,随着褐藻的种类不同还含有半乳糖、木糖、糖醛酸等其他成分。褐藻多糖硫酸酯具有多种生物活性,目前针对墨角藻、泡叶藻(Ascophyllum nodosum)、鼠尾藻(Sargassum thunbergii)等褐藻中的褐藻多糖硫酸酯研究较多,发现其具有免疫调节、抗病毒、抗肿瘤、抗凝血、抗氧化等生物活性。本文主要就褐藻多糖硫酸酯的提取、纯化、结构及生物活性等方面研究进行综述。     

羊栖菜不同分子质量褐藻多酚抗氧化活性研究

将羊栖菜(Sargassum fusiforme)经浸提、萃取和超滤等步骤获得不同分子质量的褐藻多酚。用普鲁士蓝法检测其总抗氧化能力;采用 DPPH、羟自由基试剂盒、超氧阴离子试剂盒评价其对 DPPH、羟自由基和超氧阴离子的清除能力。结果显示,羊栖菜褐藻多酚主要以高分子质量的形式存在;乙酸乙酯相组分各项抗氧化指标均好于水相,且乙酸乙酯相分子质量大于30000组分对羟自由基与超氧阴离子的清除能力比没食子酸、Vc和VE强。     

褐藻多糖硫酸酯的结构与生物活性研究

褐藻多糖硫酸酯（fucoidan,FPS）是所有褐藻中所固有的细胞间多糖,存在于细胞壁基质中。生长于潮间带、长时间与空气接触的褐藻种类中,如多年生的墨角藻（Fucus vesiculosus）类,其褐藻多糖硫酸酯的含量可高达20%;生长在较深处的海带（Saccharina japonica）类中含量较低,约为1%~2%。褐藻多糖硫酸酯是一类独特的结合有硫酸基的水溶性杂聚糖,其化学组成和结构非常复杂,以岩藻糖和硫酸基为主,随着褐藻的种类不同还含有半乳糖、木糖、糖醛酸等其他成分。褐藻多糖硫酸酯具有多种生物活性,目前针对墨角藻、泡叶藻（Ascophyllum nodosum）、鼠尾藻（Sargassum thunbergii）等褐藻中的褐藻多糖硫酸酯研究较多,发现其具有免疫调节、抗病毒、抗肿瘤、抗凝血、抗氧化等生物活性。本文主要就褐藻多糖硫酸酯的提取、纯化、结构及生物活性等方面研究进行综述。     

鼠尾藻中褐藻多酚化合物的抑菌活性研究

采用平板生长抑制法对鼠尾藻(SargassumthunbergiiKuntze)中多酚化合物的抑菌活性进行研究。结果表明,在一定浓度范围内试样对除大肠杆菌外的受试菌均有较明显的抑菌活性,抑菌活性的大小与多酚浓度和分子质量密切相关。其中,透析内液对溶藻胶弧菌(Vibrioalginolyticus)和鳗弧菌(V.anguillarum)、透析外液对鳗弧菌和副溶血弧菌(V.parahaemolyticus)的抑制效果尤其明显。     

海带褐藻多酚对绿烂海带表面分离的一株细菌的抑菌效果研究

海带苗绿烂病暴发严重威胁海带养殖生产,给海带养殖业造成巨大经济损失.研究发现,海带中的多酚化合物可以抵御海带病害初期病原体侵入.为研究多酚对绿烂海带表面附生菌的抑菌效果,在病烂部位分离出一株细菌,通过16s rRNA基因测序的方法,证实该细菌为小孔芽孢杆菌(Bacillus foraminis).进一步以健康海带为原料...     

Use of lipids and their degradation products as biomarkers for carbon cycling in the northwestern Mediterranean Sea

Changes in phytoplankton composition and degradation of particulate organic matter (POM) in the northwestern Mediterranean Sea were studied using time-series sediment trap samples collected during the spring of 2003 at the DYFAMED station. Lipid biomarkers (pigments, fatty acids, sterols, acyclic isoprenoids, alkenones and n-alkanols) were used to identify the main contributors to the POM produced during two phytoplankton blooms, while the effects of photooxidation, autoxidation and biodegradation were differentiated using characteristic lipid degradation products. Traps collected material corresponding to pre-bloom, bloom and post-bloom periods. Pigment analyses in the integrated (0-200 m) water column samples indicated that diatoms dominated the initial stages of the bloom event, with smaller amounts of haptophytes and pelagophytes. During the second part of bloom event there was a switch to haptophyte dominance with significant contributions from diatoms and pelagophytes, and an increased contribution from cryptophytes. Fatty acid distributions in the trap samples reflected contributions from marine bacteria, phytoplankton and zooplankton. Photooxidation and autoxidation products of monounsaturated oleic, cis-vaccenic and palmitoleic acids were detected along with photooxidation products from the chlorophyll side-chain. The relatively good correlation between the variation of U₃₇^K′ index and specific phytol autoxidation product percentage allowed us to attribute the alterations of U₃₇^K′ observed during the pre-bloom period and in the deeper traps to the involvement of selective autoxidative degradation processes. A variety of sterol oxidation products formed by biohydrogenation, autoxidation and photooxidation were detected. Sterol degradation products appeared to be less suited than oxidation products of monounsaturated fatty acids for the precise monitoring of the degradation state of POM, but their stable functionalized cyclic structure constitutes a useful tool to estimate the part played by biotic and abiotic processes. In these waters, biotic degradation generally predominates, but abiotic degradation is not negligible and, as expected, the extent of biotic degradation increases with depth. To obtain a more complete picture of POM degradation, the use of a pool of lipid degradation products (i.e. from unsaturated fatty acids, the phytyl side-chain and sterols) should be employed.     

The fate of marine lipids: Biotic vs. abiotic degradation of particulate sterols and alkenones in the Northwestern Mediterranean Sea

Sterol and alkenone compositions in suspended particle and surface sediment samples collected in the Northwestern Mediterranean Sea during the MEDFLUX program were used to evaluate the relative importance of biotic and abiotic degradation processes on marine organic matter. Alkenone concentrations decreased much more rapidly (~ 500 fold) between 5 and 800 m than Δ⁵-sterols (~ 100-fold) or POC (~ 100-fold). The diverse functional groups attached to the stable tetracyclic carbon skeleton of Δ⁵-sterols appeared to be useful for estimating the relative effects of biotic vs. abiotic (photooxidation and autoxidation) degradation. Products of abiotic degradation predominated over products of biotic degradation in suspended particles in the NW Mediterranean. For alkenones, the U₃₇^K′ index increased from 0.43 to 0.55 with increasing water depth, and a good correlation between variations of U₃₇^K′ and concentrations of specific Δ⁵-sterol autoxidation products points to selective autoxidation of alkenones in suspended particles. Stereomutated alkenones (with cis double bonds) were detected in the surface sediment, allowing us to estimate that stereomutation resulted in a + 0.05 increase in U₃₇^K′. Therefore, abiotic degradation may be another factor effect on alkenone-derived paleothermometry.     

非均匀剪切流场中液晶聚合物微观结构的无网格模拟

基于宏观流场控制方程与微观分子取向扩散方程耦合的微-宏观双尺度模型,率先采用无网格方法对液晶聚合物在非均匀剪切流场中的微观结构进行了模拟研究.无网格方法精度高、稳定性好的特性保证了模拟结果的可靠性.研究了Deborah数对平板Poiseuille流中液晶聚合物微观结构的影响,预测出非均匀剪切流场中液晶聚合物的一种单一结构和五种复合结构.指出在复合结构的过渡区,分子运动具有不稳定性,可能产生瑕疵.     

Testing phenanthrene distribution properties of virgin plastic pellets and plastic eroded pellets found on Lesvos island beaches (Greece)

Plastic pellets have been characterized as toxic pollutant carriers throughout the world oceans and coastal zones. However, their sorptive properties are not yet well understood. In the present study, virgin pellets and plastic eroded pellets (PEP) are used to elucidate their distribution characteristics through distribution kinetic studies. Distribution occurs through diffusion into the pellet for all materials (polyethylene, polyoxymethylene, and PEP) except polypropylene (PP). Although diffusion into the polymer happens with similar rates for both freshwater and saltwater external solutions, apparent diffusion is dependent on the solution salinity because it results in higher equilibrium distribution coefficients. Distribution coefficient into the PEP is higher and diffusion is slower than into the virgin materials. This is attributed to increased crystallinity of the PEP due to weathering. PP demonstrates diffusion rates that are increased by salinity and is apparently faster than into the other polymers suggesting a surface diffusion process.