用双波长薄层色谱扫描仪监测反应进程

在棓酸类单宁的水解过程中,通过用双波长薄层色谱扫描仪对薄层图扫描,可以迅速地掌握水解进程。采用本方法用量微,方法简便、可靠,灵敏度高。可用于棓子单宁水解生产过程,监测反应进程。 本文所论棓酸类单宁(gallotannins)取材于黄栌属(Cotinus)植物黄栌(Cotinus coggygria)的叶子。经化学分析,已证实黄栌叶富含水解类单宁,其含量约占干叶重的16％。将其水解,可制得棓酸(gallic acid)。     

利用多菌种共培养降解橡椀单宁制备鞣花酸

以橡单宁为原料 ,通过培养、分离筛选出了 14种菌株。研究了单一菌株培养和混合菌株共培养对橡单宁生物降解的影响 ,证实了用降解速率快但耐单宁性较差的菌株与耐单宁性好但降解速率较慢菌株共培养 ,可以显著提高橡单宁的生物转化率和鞣花酸的产率 ,两者分别达到 6 8%和 2 3%。所建立的生物降解的方法可用于由橡单宁制备鞣花酸     

柠檬桉叶化学成分研究(四报)——单宁组分研究

从柠檬桉叶醇提取物中分离和鉴定了倍酸,鞣花酸和栗木鞣花素等化合物。研究表明柠檬桉叶单宁为鞣花单宁类化合物,并有较多的C-甙类鞣花单宁,这类单宁系首次从桉树属植物发现。     

利用多菌种共培养降解橡宛单宁制备鞣花酸

以橡宛单宁为原料，通过培养、分离筛选出14种菌株。研究了单一菌株培养和混合菌株共培养对橡宛单宁生物降解的影响，证实了用降解速率快但耐单宁性较差的菌株与耐单宁性好但降解速率较慢菌株共培养，可以显著提高橡宛单宁的生物转化率和鞣花酸的产率，两者分别达到68％和23％。所建立的生物降解的方法可用于由橡宛单宁制备鞣花酸。     

杨梅不同部位单宁含量与结构研究

对杨梅的叶、枝和树皮的总酚含量与可溶缩合单宁含量进行了测定,并利用基质辅助激光解吸附飞行时间质谱(MALDI-TOFMS)详细研究了不同部位中缩合单宁的类型、聚合度及聚合物的分布情况。结果表明:树皮的总酚含量最高(43.56%),叶次之(34.69%),枝最低(18.53%);树叶的可溶缩合单宁含量最高(25.67%),皮次之(17.93%),枝最低(8.01%);3组分的缩合单宁都以(表)棓儿茶素-3-O-棓酸酯(EGCG/GCG)为基本结构单元的原翠雀定,且大部分聚合物的结构单元之间存在A型和B型两种连接方式,但其中叶和枝缩合单宁的聚合度要大于树皮。     

单宁-醛-胶原的反应——对植醛结合鞣机理的再认识

以黑荆树单宁为植物鞣剂，嗯唑烷为醛鞣剂，较系统地研究了氢键、疏水键、胶原氨基在植鞣、醛鞣和植-醛结合鞣中的作用。证实了植-醛结合鞣的反应机理与已有的认识有很大的区别。醛类化合物即使在植鞣后加入，其主要的反应基团仍然是皮胶原的氨基。但是当单宁分子中含有亲核活性较高的反应基团时，醛类化合物可以在皮胶原和单宁分子之间形成交联键。这种交联作用可以对提高皮胶原的热稳定性产生协同效应，而且使单宁与皮胶原的结合稳定性进一步加强，能够抵御氢键破坏试剂和疏水键破坏试剂的作用。采用缩合类单宁时，容易形成胶原-醛-单宁交联键；但采用水解类单宁时，形成这种交联键的几率很小。     

五倍子单宁组份分离、鉴定的研究——(Ⅰ)低分子量组份和醇解产物的分离鉴定

本文报道了棓子单宁中低分子量组份和醇解产品的分离鉴定。由商品单宁酸中萃取的试样和用棓子单宁醇解而得到的产品,经甲基化后,用GC-MS鉴定,用结晶法、薄层色谱法分离出的纯样,用MS、IR、UV鉴定,结果表明,萃取试样中包含有棓酸、二棓酸等。醇解产品中包含有棓酸、二棓酸、二棓酸乙酯、棓酸乙酯、棓酸甲酯等,并可能含有醇与棓酸缩合的化合物。     

毛杨梅及油柑树皮单宁组分的研究(凝缩类单宁组分研究之二)

从毛杨梅(Myrica esculenta)及油柑(Phyllanthus emblica)树皮提取物分离出米的单宁,通过各种降解反应及波谱方法研究判定,毛杨梅单宁是局部带有3-o-棓酰基的原翠雀定。油柑单宁是由局部带有3-o-棓酰基的原翠雀定与原花青定组成的混合型原花色素。两种单宁分子的组成单元大部分具有2,3-顺式构型。     

光催化提高黑荆树单宁与甲醛反应能力研究

为提高黑荆树单宁与甲醛反应能力,以纳米TiO 2为催化剂对黑荆树单宁进行紫外光催化降解。以降解物的甲醛结合量为指标,分析催化剂用量对黑荆树单宁降解产物甲醛反应能力的影响。采用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)测定黑荆树单宁和具有最大甲醛结合量黑荆树单宁降解产物的分子量和聚合度。采用傅里叶转换红外光谱(FT-IR)对黑荆树单宁及具有最大甲醛结合量黑荆树单宁降解产物的官能团进行表征。结果表明,催化剂用量对降解物甲醛结合量的影响较大,当紫外光功率为400 W、溶液初始质量浓度为60 g/L、反应温度为(35±5)℃、纳米TiO 2添加量为4%(质量分数,以黑荆树单宁质量计)、降解时间为10 h时,降解物的甲醛结合量达到最大值(1.13 g/g),超过了苯酚和间苯二酚的甲醛结合量(0.89 g/g和0.94 g/g),有替代苯酚和间苯二酚与甲醛反应制备木材用胶黏剂的潜能。MALDI-TOF MS分析表明,黑荆树单宁的聚合度和分子量均有明显地下降趋势,降解物分子量分布集中于低分子量部分。FT-IR分析表明,单宁结构中连接棓酰基的醚键、棓儿茶素的苯环骨架、芳醚键、单元间C—C连接键均被破坏。以上结果表明,可通过紫外光催化降解调控黑荆树单宁的化学组成并降低其聚合度和分子量,获得的降解物具有良好的甲醛反应能力。     

改性松香-缩合单宁酯的制备及性质

在微波辐照下,以吡啶作催化剂,通过缩合单宁与改性松香酰氯的O-酰化反应,以改性松香和不同级分或树种的缩合单宁为原料,合成了一系列改性松香-缩合单宁酯.利用UV、IR、TG-DTA和元素分析等方法对目标产物进行了分析和表征,并测试了它们的抗氧化性及其钠盐的表面活性.结果表明,改性松香-缩合单宁酯的油溶性普遍好于缩合单宁,在花生油中表现出良好的抗氧化性,且去氢枞酸-毛杨梅树皮缩合单宁酯的抗氧化性能最佳.改性松香-缩合单宁酯的钠盐比缩合单宁的钠盐具有更优良的表面活性,其降低表面张力能力强弱顺序为:HR-WT钠盐＞HR-ET钠盐＞DR-ET钠盐＞DR-WT钠盐＞DHA-WT钠盐≈DHA-MET钠盐＞DHA-ET钠盐＞ET钠盐;不同松香改性产物钠盐的表面张力和临界胶束浓度有一定差异,但差别不大,其中氢化松香改性产物钠盐的表面活性最好,歧化松香改性产物钠盐的表面活性次之,去氢枞酸改性产物钠盐的表面活性最差.改性松香-缩合单宁酯钠盐对苯的乳化力都超过了60min,具有很好的乳化能力.改性松香-缩合单宁酯钠盐起泡比顺序为:氢化松香-黑荆树树皮缩合单宁酯钠盐＞歧化松香-黑荆树树皮缩合单宁酯钠盐＞去氢枞酸-黑荆树树皮缩合单宁酯钠盐＞去氢枞酸-毛杨梅树皮缩合单宁酯钠盐＞毛杨梅树皮缩合单宁钠盐.     

Neuroprotective activity of galloylated cyanogenic glucosides and hydrolysable tannins isolated from leaves of Phyllagathis rotundifolia

The galloylated cyanogenic glucosides based on prunasin (1-7), gallotannins (8-14), ellagitannins (15-17), ellagic acid derivatives (18, 19) and gallic acid (20) isolated from the leaves of Phyllagathis rotundifolia (Melastomataceae) were investigated for their neuroprotective activity against hydrogen peroxide (H₂O₂)-induced oxidative damage in NG108-15 hybridoma cell line. Among these compounds, the gallotannins and ellagitannins exhibited remarkable neuroprotective activities against oxidative damage in vitro as compared to galloylated cyanogenic glucosides and ellagic acid derivatives in a dose-dependent manner. They could be explored further as potential natural neuroprotectors in various remedies of neurodegenerative diseases.     

五倍子生物活性研究进展

五倍子是我国特有的林特产品,具有抗菌、抗病毒、生理调控等生物活性。其主要组成和活性成分是一类水解性的植物单宁——五倍子单宁,广泛应用于医药、化工、矿冶、电子、食品和饲料等行业。本研究对近10年来五倍子生物活性的研究进展及应用展望进行综述。     

Chemical structures of the condensed tannins in the fruits of Diospyros species

The structural variety of the condensed tannins (proanthocyanidins) in the fruits of 16Diospyros species are reported. Eleven species contained condensed tannins mostly consisting of a mixture of catechin (CA) and gallocatechin (GCA) repeating units; the other five species did not. The GCA content in the CA-GCA total varied from 0.3% to 84.6%. The number of esterified gallic acid per one flavan repeating unit (degree of galloylation, DG) ranged from 0.01 to 0.89. The GCA content was found to be proportional to the DG values. Thus, 16Diospyros species tested may be classified into five groups by the analytical data of their condensed tannins. It may be interesting to compare their structural characteristics with those of the condensed tannins in other fruits, leaves, woods, and barks from the viewpoint of their biosynthesis and function in the plants.Part of this paper was presented at the 46th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1995     

Polyphenols from Eucalyptus consideniana and Eucalyptus viminalis

From the leaves of Eucalyptus consideniana and E. viminalis, known hydrolysable tannins, galloyl esters and ellagitannins, were isolated. Flavonol glycosides were also isolated from the leaves of E. consideniana. The spectral data of the dimeric ellagitannin, oenothein B (1), are reported.     

Cytotoxic ellagitannins from Reaumuria vermiculata

Three ellagitannins and one disulfated flavonol were isolated from the aerial parts of Reaumuria vermiculata L. Besides that, 16 known compounds were characterized as well. The structures of all compounds were elucidated on the basis of spectroscopic data including 1D and 2D NMR and ESI HR-FTMS. The in vivo antioxidant activity using the oxygen radical absorbance capacity (ORAC) method, of the extract, its column fractions and two of the isolated ellagitannins was accomplished. In addition, a possible cytotoxicity of the extract and two of the new ellagitannins on HaCaT human keratinocytes and the activity of both compounds against the prostate cancer cell line (PC-3) were also assessed, whereby a potent cytotoxicity with IC(50) less than 1μg/ml was determined for both compounds. Besides, the extract exhibited a potential cytotoxic effect against four different solid tumor cell lines, namely liver (Huh-7), colorectal (HCT-116), breast (MCF-7) and prostate (PC-3). The IC(50)s were found to be substantially low (ranged from 1.3±0.15 to 2.4±0.22μg/ml) with relatively low resistance possibility reaching to 0% in the case of Huh-7 cell.     

Condensed tannins in Leucaena and their relation to psyllid resistance

Leucaena species and hybrids were examined to determine the relative content of condensed tannins and its relationship to susceptibility to defoliation by the Leucaena psyllid (Heteropsylla cubana). The interspecific Leucaena hybrid KX2 (L. leucocephala × L. pallida) was examined for variability of condensed tannin levels. A broad range of condensed tannin values were found which indicate potential for improved forage value through selection for KX2 trees with lower condensed tannin while maintaining psyllid resistance. A significant correlation was not found linking condensed tannins and psyllid resistance.     

Seasonal variation and ecological importance of tannin and nutrient concentrations in Casuarina equisetifolia branchlets and fine roots

In this study, we investigated the effects of environmental factors on plant phenolic variability, seasonal dynamics of total phenolic content(TP),extractable condensed tannins(ECT), protein-bound condensed tannins(PBCT), fiber-bound condensed tannins(FBCT), total condensed tannins(TCT), protein precipitation capacity(PPC) and nutrient content in the branchlets and fine roots of Casuarina equisetifolia. TP and TCT concentrations in branchlets were lowest in the spring, then increased in summer and autumn, similar to the seasonal dynamics in air temperature. TP and TCT concentrations in fine roots were highest in summer, coinciding with heavy precipitation. In general, TP and TCT concentrations were higher in branchlets than in fine roots. No significant difference was found in C concentration among various seasons for either branchlets or fine roots. Branchlets had significantly higher N and P concentrations than fine roots in most seasons. The C/N and N/P ratios in branchlets were significantly lower than in fine roots in all seasons, except summer. The relationship between branchlets and fine roots was significant for C, P and FBCT, but no significant relationships were found for N, TP, ECT, PBCT and TCT.Additionally, TP and TCT content were each significantly correlated with PPC in branchlets and in fine roots. Both TP/N and TCT/N ratios were highest in the autumn for the branchlets and in the summer for fine roots. The results indicate that high temperatures lead to increased tannin production in branchlets, but that the tannin content in fine roots is mainly affected by precipitation. Tannin content was greater in branchlets than in fine roots, which may indicate that selective pressure is greater on branchlets than on fine roots.     

五倍子单宁对啤酒稳定性的影响

单宁是植物的次生代谢产物。酿酒时单要从大麦和酒花转入啤酒，成为啤酒的重要成分。大麦单宁为缩合单元，以原花色素的二聚体、三聚体为主。在糖化和洗糟时低聚的原药色素因氧化聚合成高分子单宁而急剧减少。酒花单宁出由水解单宁、缩合单宁构成，其中含有活泼羟基的花色苷和类单宁能延迟啤老化口味的产生和提高胶体稳定性。五倍子单宁是 的资源，添加五倍子单宁６ｇ／１００Ｌ于麦汁和啤酒中，可降低麦汁中子区氮５ｍｇ／１００ｍ