美登木内生真菌lr88蒽醌类代谢产物的研究

美登木内生真菌lr88采自云南西双版纳美登木的叶中.从该菌的固体培养物中分离得到3个蒽醌类成分,通过波谱分析鉴定为1-羟基-8-甲氧基蒽醌(1),1,3,6,8-四羟基蒽醌(2)及1,8-二羟基蒽醌(3).     

不同光质对毛脉酸模中蒽醌类成分的影响

通过红色、黄色、绿色、蓝色滤光膜对毛脉酸模进行遮膜处理。采用高效液相色谱法对毛脉酸模根样品中的蒽醌类成分含量进行测定,研究光质对毛脉酸模根次生代谢产物蒽醌类成分的影响。进行了方差分析。二年生黄膜处理中蒽醌类成分含量显著性高于处理组及空白组。一年生空白组及对照组中蒽醌类成分含量显著性高于处理组。结果表明黄膜处理显著提高二年生毛脉酸模中中蒽醌类成分含量。     

虎杖根茎中蒽醌类成分的体外抗氧化活性

采用超声波提取法用体积分数80%乙醇对虎杖(Reynoutriajaponica Houtt.)根茎中的蒽醌类成分进行粗提,并利用D101大孔吸附树脂对粗提液进行纯化.以Vc为阳性对照,采用体外动物实验研究了虎杖根茎中蒽醌类成分对小白鼠肝组织匀浆中谷胱甘肽过氧化物酶(GSH-px)活力及对H2O2诱导的MDA含量和红细胞氧化溶血的影响,并采用化学模拟体系分析了其对DPPH·自由基的清除能力、对Fe3+的还原能力以及与Fe2+的螯合能力.结果表明:虎杖根茎中蒽醌类成分含量丰富,粗提物含量达到55.86 mg·g-1,纯化后含量达到44.77 mg·g-1.质量浓度l0、20、30和40μg·mL-1的蒽醌类成分可显著增强GSH-px活力、降低由H2O2诱导产生的MDA含量,并对H2O2诱导产生的红细胞氧化溶血有较强的抑制作用;质量浓度2、4、6和8μg·mL-1的蒽醌类成分对DPPH·自由基具有良好的清除能力,质量浓度6、8、12和16μg·mL-1蒽醌类成分对Fe3+具有较强的还原能力,而质量浓度5、10、15和20μg·mL-1蒽醌类成分对Fe2+则具有很强的螯合能力.随质量浓度的提高,虎杖蒽醌类成分及阳性对照Vc的各项抗氧化活性指标均逐渐增强,呈现出明显的量效关系,且虎杖根茎中蒽醌类成分的各项抗氧化指标均优于相同质量浓度的Vc.研究结果显示:虎杖根茎中的蒽醌类成分具有较强的抗氧化活性,不仅能够直接清除过量的自由基,也可以通过增强体内的抗氧化系统以抑制自由基的产生.结合他人研究结果,对虎杖资源的开发利用提出了一些建议.     

何首乌不同器官和组织中蒽醌和茋类化合物的分布

目的探讨何首乌(Polygonum multiflorum Thunb.)不同营养器官和组织中蒽醌类和茋类化合物的分布,为合理利用何首乌提供科学依据.方法采用数码显微鉴定和TLC对何首乌的不同器官和组织部位进行了比较研究.结果从器官来看,何首乌藤茎、地下茎和块根中均含有蒽醌(大黄素和大黄素甲醚)和芪类(2,3,5,4'-四羟基二苯乙烯-2-O-β-D-葡萄糖苷)而叶和嫩茎则不舍;从组织部位来看,蒽醌类成分主要分布于韧皮部,而茋类成分主要分布于周皮和韧皮部,木质部最少.结论蒽醌类和茋类成分的产生与周皮的形成有一定的关系.蒽醌类化合物的含量可能与韧皮部的发达程度有关,茋类化合物主要产生和贮藏于薄壁细胞中.     

盐酸米托蒽醌聚乙二醇化脂质体的制备及包封率考察

目的:制备盐酸米托蒽醌聚乙二醇化(PEG化)脂质体,建立包封率测定方法.方法:采用乙醇注入结合高压均质法制备空白PEG化脂质体;以铵根离子梯度法进行主动载药制备盐酸米托蒽醌PEG化脂质体;采用G-25葡聚糖凝胶色谱分离脂质体和游离药物;使用紫外-可见分光光度法测定脂质体的包封率.结果:空白脂质体平均粒径为88.7nm,载药后粒径为95.3nm;在所建立色谱条件下,脂质体与游离米托蒽醌分离良好;盐酸米托蒽醌在0.5～10μg·ml-1范围内线性关系良好(R 2=0.9997),精密度高;脂质体的平均包封率大于96％.结论:乙醇注入-高压均质法结合铵根离子主动载药法适用于制备盐酸米托蒽醌PEG化脂质体;所建立分析方法简单快捷、准确可靠,可用于盐酸米托蒽醌长循环脂质体包封率的测定.     

毛脉酸模内生真菌蒽醌类次生代谢产物的筛选及含量分析

本文通过对毛脉酸模内生真菌的发酵培养得到其次生代谢产物,采用HPLC法对内生真菌中蒽醌类成分进行筛选。以大黄素、大黄酸、大黄酚、大黄素甲醚、芦荟大黄素五种蒽醌类成分为参照,筛选出3株真菌含大黄素、3株真菌含大黄酸、5株真菌含芦荟大黄素,其中含量最高为683μg/g、最低为8μg/g。将各菌株所含成分与各菌株分离部位的相应成分进行比较,相对宿主植物而言各菌株均有较高的含量。本实验分析方法准确、快捷,适用于毛脉酸模内生真菌的代谢产物研究。     

何首乌不同器官和组织中蒽醌和芪类化合物的分布

目的探讨何首乌（Polygonum multiflorumThunb．）不同营养器官和组织中葸醌类和芪类化合物的分布,为合理利用何首乌提供科学依据。方法采用数码显微鉴定和TLC对何首乌的不同器官和组织部位进行了比较研究。结果从器官来看,何首乌藤茎、地下茎和块根中均含有蒽醌（大黄素和大黄素甲醚）和芪类（2,3,5,4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷）而叶和嫩茎则不含;从组织部位来看,蒽醌类成分主要分布于韧皮部,而芪类成分主要分布于周皮和韧皮部,木质部最少。结论蒽醌类和芪类成分的产生与周皮的形成有一定的关系,蒽醌类化合物的含量可能与韧皮部的发达程度有关,芪类化合物主要产生和贮藏于薄壁细胞中。     

诺丽发酵果汁中抗氧化物质的研究

本实验针对茜草科植物诺丽的发酵果汁中抗氧化物质进行了定性和定量研究。采用系统预实验法对其不同极性的洗脱部位可能含有的化学成分进行预实验,探索了各个部位的化学成分。采用DPPH·自由基清除、ABTS+·自由基清除和FRAP三种实验方法对各部位洗脱物的抗氧化活性进行了测定,结果显示50%~90%乙醇洗脱部位抗氧化能力最强,此部位主要含有多酚类、黄酮类、香豆素内酯类和蒽醌类成分,并且研究表明抗氧化能力与多酚成分的含量成极显著相关。本研究结果表明多酚类物质是诺丽发酵果汁发挥抗氧化作用的主要功能成分。     

高速逆流色谱结合半制备液相色谱制备甘青青兰中3种活性成分

采用高速逆流色谱（HSCCC）结合液相色谱法制备甘青青兰（Dracocephalum tanguticum Maxim.）中绿原酸、胡麻甙-6″-乙酯、迷迭香酸,建立快速分离制备甘青青兰中活性成分的方法。采用半制备型高效液相色谱（SP-HPLC）富集甘青青兰乙酸乙酯萃取物中绿原酸、胡麻甙-6″-乙酯、迷迭香酸,再用制备液相（Pre-HPLC）和HSCCC对富集物进行分离纯化,获得54 mg化合物Ⅰ、130 mg化合物Ⅱ和200 mg化合物Ⅲ,纯度分别为96.9%、97.9%和95.1%,经核磁共振碳谱（¹³CNMR）和氢谱（¹HNMR）分别鉴定为绿原酸、胡麻甙-6″-乙酯和迷迭香酸。本实验方法适用于甘青青兰乙酸乙酯萃取物中绿原酸、胡麻甙-6″-乙酯和迷迭香酸的分离制备,并避免了传统分离方法操作繁多、试剂消耗量大、不可回收等弊端,为分离甘青青兰活性成分、制备对照品等研究提供了参考依据。     

中低压制备色谱制备茜草蒽醌成分的研究

建立新的中低压制备色谱技术,分离纯化茜草蒽醌单体.先采用高压液相色谱技术分析所分离产物的纯度,再用核兹共振谱、红外、质谱分析确证单体的化学结构.结果表明:用中低压色谱分离茜草的乙醇提取物而得到的4个单体,其纯度分别为99.87％、99.56％、99.42％、98.21％,结构鉴定为从石油醚萃取物中分离得到的单体为大叶茜...     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.