落叶松树皮单宁组分的研究(凝缩类单宁组分研究之一)

从兴安落叶松(Larix gmelini)树皮提取物中分离出来的水溶性单宁,通过花色素反应、硫解反应、间苯三酚反应、~(13)C-核磁共振、旋光、紫外光谱和红外光谱等方法研究,判定为原花青定。落叶松树皮原花青定的终端单元由(+)—儿茶素及(—)—表儿茶素组成,二者的比例为8:2,延伸单元由(+)—儿茶素及(—)—表儿茶素组成,二者的比例约为3:7,水溶性单宁分子的平均聚合度约为8。     

木麻黄及山槐树皮单宁组分的研究(凝缩类单宁组分研究之二)

从木麻黄(Casuarina equisetifolia)及山槐(Albizzia kalkora)树皮提取物中分离出来的水溶性单宁,通过各种降解反应及波谱方法研究,判定均为原花青定,且二者在化学组成上十分相似,它们的终端单位均由各占一半左右的(+)—儿茶素及(-)—表儿茶素组成,二者的比例为6:4。延伸单元亦均由(+)—儿茶素与(-)—表儿茶素组成,而以(-)—表儿茶素占绝大部分,二者的比例约为3:7。它们的分子中,2,3—反式与2,3—顺式单元的比例约为2:8。木麻黄和山槐树皮单宁的平均聚合度分别为12和14。     

落叶松树皮黄烷-3-醇及其聚合物研究

从落叶松[Larix gmelini (Rupr.)Rupr.]树皮中分离、鉴定了三种黄烷-3-醇,即(-)表阿夫儿茶素,( )儿茶素和(-)表儿茶素。以乙酰衍生物形式分离出四种二聚黄烷-3-醇(二聚原花青定)B1—B4,并通过与标样薄层共层析及其核磁共振氢谱进行了鉴定。对可溶于甲醇的多聚黄烷-3-醇(多聚原花青定)用甲苯-α-硫醚和醋酸进行了化学分解。根据分解产物确定, 落叶松树皮含有分别以( )儿茶素和(-)表儿茶素为终端单元之多聚黄烷-3-醇,其延伸单元亦由2,3反式和2,3-顺式3,5,7,3′,4′黄烷五醇所组成。用高效液相色谱定量测定了上述化学分解产物,并在此基础上得出该多聚黄烷-3-醇之平均聚合度为6-7,相应数均分子量为1700—2000。     

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。     

木榄花萼缩合单宁制备花青定及抗氧化能力研究

利用MALDI-TOF MS分析了红树植物木榄花萼缩合单宁的结构单元组成类型、平均聚合度和平均分子质量.并以木榄花萼缩合单宁为原料,通过HCl-正丁醇法酸解反应制备了花青定粗产品,同时测定了花青定粗产品对二苯基苦基苯肼自由基(DPPH·)的清除能力及铁离子还原/抗氧化能力(FRAP).结果表明:木榄花萼缩合单宁结构单元组成类型主要为儿茶素或表儿茶素,平均聚合度为7.5,平均分子质量为2 081.60 u;花青定粗产品具有较强的清除自由基能力,DPPH·半数抑制浓度(IC50)为43.889 mg/L,并具有较高的FRAP((7.718± 0.109)mmol/g).     

黑荆树树皮单宁组分研究——Ⅲ.原花色素的分离鉴定及其~(13)C NMR特征(英文)

从我国江西四年生黑荆树(Acacia mearnsii)树皮单宁中分离鉴定了三个二聚原花色素:刺槐亭醇-(4α→8)-儿茶素、菲瑟亭醇-(4β→8)-儿茶素和刺槐亭醇-(4β→8)-儿茶素。其中刺槐亭醇-(4β→8)-儿茶素为首次从黑荆树树皮中以天然形式分离得到,为一新天然化合物。文中首次对黑剂树树皮二聚原花色素的~(13)CNMR进行了报道,并就其特征和确定二聚原花色素的相对和绝对构型进行了讨论。     

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。     

薯莨单宁的提取及其抑菌活性研究

为了更好地利用薯莨Dioscorea cirrhosa资源,减少薯莨渣浪费,从薯莨和薯莨渣中提取生物活性成分,比较了薯莨提取物对几种重要植物病原菌的抑菌作用。结果显示,60%丙酮浸提法比75%乙醇提取法能获得较多提取物,且提取物中单宁含量较高,适合用于薯莨单宁提取。相同提取条件下,薯莨渣的浸提物得率比薯莨低50%,但两种提取物中单宁含量无明显差异。抑菌试验结果表明,薯莨的丙酮提取物对来自猴耳环Pithecellobium clypearia的炭疽病菌（暂定名为H30,Colletotrichum sp.）、拟茎点霉（暂定名为H63,Phomopsis sp.）和广藿香青枯病菌（暂定名为GHB2,Ralstonia sp.）均有明显的抑制效果。因此,薯莨和薯莨渣可望成为研制新型植物源杀菌剂的原料,为药用植物病害绿色防控提供新制剂。     

松树皮多聚原花青素片段化产物的分离鉴定及活性

采用多种柱层析手段,分别从基于茶多酚的思茅松和马尾松树皮多聚原花青素片段化反应产物中分离得到1个主要产物。通过MS、1H NMR和13C NMR波谱解析,其化学结构鉴定为(-)-表儿茶素-(4β-8)-(-)-表没食子儿茶素3-O-没食子酸酯(1)。结果表明,茶多酚中的(-)-表没食子儿茶素3-O-没食子酸酯(EGCG)在片段化反应中扮演着重要角色,化合物1是EGCG通过4β-8与(-)-表儿茶素C-4位上的正离子键合形成而来。采用DPPH、ABTS自由基清除活性测定方法评价了化合物1的抗氧化活性,其清除DPPH、ABTS自由基的能力均高于茶多酚、多聚原花青素及其片段化总产物,SC50值分别为6.12±0.03 g/m L和41.41±0.66 g/m L。     

金花茶花朵和叶片UPLC-QTOF-MS分析

[目的]鉴定分析金花茶花朵和叶片中主要化学成分、含量及其变化特征,为金花茶资源的进一步开发利用提供科学依据。[方法]利用超高效液相色谱-飞行时间质谱联用(UPLC-QTOF-MS)技术定性定量分析金花茶花瓣、雄蕊、老叶和新叶中花青苷、类黄酮及儿茶素类成分与含量。[结果]花青苷天竺葵素-3-O-葡萄糖苷和矢车菊素-3-O-葡萄糖苷均为金花茶中首次发现,其中,矢车菊素-3-O-葡萄糖苷仅存在于紫红色新叶中。类黄酮木犀草素-7-O-芸香糖苷和染料木苷为金花茶中首次发现,槲皮素-3-O-葡萄糖苷、槲皮素-7-O-葡萄糖苷、槲皮素-3-O-芸香糖苷和山柰酚-3-O-葡萄糖苷为金花茶叶片中首次发现。金花茶花瓣与雄蕊中花青苷相差不大,但却低于叶片尤其新叶;花朵中儿茶素类远高于叶片尤其新叶。金花茶花瓣和雄蕊中总黄酮及槲皮素-3-O-葡萄糖苷、槲皮素-3-O-芸香糖苷和山柰酚-3-O-葡萄糖苷均相差不大,但却远高于叶片。金花茶新叶中主要类黄酮成分木犀草素-7-O-芸香糖苷及总类黄酮明显高于老叶。[结论]金花茶中共鉴定出2种花青苷、6种类黄酮和2种儿茶素;槲皮素-3-O-葡萄糖苷等类黄酮是金花茶花朵呈现黄色的主要原因,矢车菊素-3-O-葡萄糖苷是金花茶新叶呈现紫红色的主要原因。     

Woody legumes as live support systems in yam cultivation

This paper reports on the use of three leguminous perennials (Leucaena leucocephala, Flemingia macrophylla and Gliricidia sepium) as live support systems in yam cultivation. In a planting arrangement in which yam rows alternated with rows of the woody species the tuber yields per ha were 3.4 (leucaena), 5.3 (flemingia) and 10.1 (gliricidia) ton fresh weight. TUKEY's L.S.D. value equalled 2.9 ton. Leucaena leucocephala is unsuitable as live support since the species shows a strong competitive power expressed in terms of leaf productivity and relative density of the root mass in the upper soil stratum, the zone explored by the yam crop. Flemingia macrophylla is unsuitable as support species mainly because of its structural weakness: Its branches do not sufficiently lignify to carry the yam leaf mass. The significantly higher tuber yield of the yam crop grown with Gliricidia sepium is a function of specific properties of the tree species: Low leaf productivity, a relatively weakly developed root system and an open architecture, which leaves sufficient space for a yam crop grown in association.     

盐酸-香草醛比色法测定油松针叶和树皮中原花青素的含量

原花青素为低聚黄烷化合物的总称,广泛存在于各种植物核、皮或种子中。笔者用甲醇作溶剂,以儿茶素为标准品,采用盐酸-香草醛比色法测定油松针叶和树皮中原花青素的含量。结果表明,油松针叶和树皮中原花青素的含量分别为6.0 g/100 g和3.91 g/100 g。     

Effect of the application of the leaf mulch of Gliricidia sepium on early development,leaf nutrient contents and tuber yields of water yam (Dioscorea alata)

This paper describes the effects of the leaf mulch of Gliricidia sepium on the development and yield of Water Yam, Dioscorea alata. Using leaf mulch, the time taken for the yam setts to sprout can be shortened by approximately 20 percent.Organic mulches contain considerable quantities of plant nutrients. Increasing amounts of mulch improved the leaf nutrient contents of the yam crop and resulted in significantly higher tuber yields. Over a tuber yield range up to c. 15 tons ha^–1 each additional ton DM Gliricidia sepium mulch applied resulted in a yield increment of about 2 ton yam tubers. A nutrient supply — nutrient extraction balance is discussed, comparing mulch applied and yam tubers harvested.Mulching as agricultural technique is a useful and affordable tool in adapting low external input cropping systems to local economic and environmental conditions.     

Constituents of the stem bark of Ormosia wayana.

The isolation of lupeol, beta-sitosterol acetate and three quinolizidinic alkaloids, (+)-lupanine, (-)-sparteine and (-)-3 beta-hydroxy-13 alpha-tigloyloxy-lupanine (1), from the stem bark of Ormosia wayana is reported.     

An Error Correction Modeling (ECM) of the Determinants of Deforestation in Nigeria

Abstract

Persistent deforestation is one of the major constraints to sustainable economic development in Nigeria. This study used the Error Correction Mechanism (ECM) to determine the economic factors influencing deforestation. The data were national aggregates collected from several secondary sources for 1961-2000. Data analysis showed that there were at least 7 cointegrating vectors in the estimated model. Also, the dynamic unrestricted short-run parameters of cereal cropland growth rates (0.564), tuber cropland growth rates (-1.961), permanent cropland growth rate (22.136), tuber yield (0.126), livestock population (-2.156), human population (-9.214), other land areas (0.281), agricultural Gross Domestic Product (0.156), and roundwood production (0.684) had significant impact on deforestation (p < 0.05). The study recommends that efforts to address further deforestation should include enforcement of laws guiding the cutting of forest trees and research development to ensure development of crop hybrids that are resistant to environmental Stress, among others.     

Antimicrobial flavonoids from the stem bark of Erythrina burttii

The chloroform extract of the stem bark of Erythrina burttii showed antifungal and antibacterial activities using the disk diffusion method. Flavonoids were identified as the active principles. Activities were observed against fungi and Gram(+) bacteria, but the Gram(-) bacteria Escherichia coli was resistant.     

Biological screening of Bangladeshi mango mistletoe bark extracts

The ethyl acetate extract of the Bangladeshi mango mistletoe (Loranthus globosus) bark was found to be most effective against both Gram (+) and Gram (-) bacteria and it also showed good cytotoxicity with a LC50 10.83 microg/ml.     

Antibacterial and antifungal activities of Angiopteris evecta

The leaves, stem bark, stem heart wood, root and tubers of Angiopteris evecta were successively extracted with petrol, dichloromethane, ethyl acetate, butanol and methanol. All the fractions exhibited a wider spectrum of antibacterial activity. The dichloromethane and ethyl acetate fractions of the leaves and stem bark were particularly good and were the only fractions exhibiting antifungal activity. All fractions of the tuber with the exception of petrol, exhibited very good antibacterial activity.