银木叶精油化学成分的研究

用毛细管气相色谱-质谱-计算机联用技术、毛细管气相色谱保留指数法和标准品叠加法分析了银木叶精油的化学成分。从分离出来的250个成分中,初步鉴定出59个成分,其含量占总组成的97.27％。最主要成分是樟脑(28.57％)等。     

夜合花叶的精油成份研究

利用气相色谱—质谱—计算机联用技术对夜合花[Magnolia coco(Lour.)DC.]叶的精油成份进行了分析。从分离出的139个色谱峰中鉴定出25个化合物,其含量占总组成的66.358％,主要成份是β-松油烯(37.570％),松油醇4(6.504％),α-蒎烯(3.499％),去氢白菖蒲烯(2.758％),芳樟醇(2.440％),1-(1,5-二甲基-4-己烯)苯(2.436％)等。     

超临界CO2提取栀子花头香精油组成研究

本文报道了用毛细血管气相色谱、色谱-质谱计算机联用技术以及薄层色谱等方法分析了采用超临界 CO_2提取的栀子花头香精油化学成分。从分离出来的58个峰中初步鉴定出24个组分,占色谱峰总面积的93％。其中主要成分是顺-3-已烯醇(1.68),惕各酸甲酯(3.92％),苯甲酸甲酯(37.34％),芳樟醇(20.54％),香苇醇(10.33％),惕各酸顺-3-已烯酯(20.30％)等。     

GC-MS分析伊犁绢蒿挥发油化学成分

利用水蒸气蒸馏法提取伊犁绢蒿挥发油,出油率为0．25％。采用色谱-质谱-计算机联用技术,从检出的30个成分中鉴定出28个,所鉴定成分占挥发油色谱总峰面积的98．66％。其主要化学成分为α-苎酮(78．74％)、樟脑(6．17％)、桧烯醇乙酸酯(1．94％)、β-苎酮(1．40％)、乙酸乙酯(1．14％)等,占总挥发油成分的89．46％。     

国产松露乙醚提取物的GC-MS分析

采用气相色谱-质谱(GC-MS)法分析我国云南产黑松露(Tuber indicum)乙醚提取物的化学成分.从中鉴定了56个化合物,占提取物总含量的87.37％,化合物组成特征:以脂肪酸类化合物为主,占59.98％,其中含亚油酸达26.51％;醇、酯、醛和烃类化合物分别占7.96％、2.79％、2.44％和13.12％,另外还含有少量的苯衍生物,占1.08％.     

四川米易逸生植物毛叶丁香罗勒精油化学成分研究

用气相色谱保留指数定性法,气相色谱-质谱-计算机联用技术和标准品叠加法研究了米易县的逸生植物——毛叶丁香罗勒(Ocimum gratissimum L.var.suvae Willd)的精油化学成分。从分离出的53个色谱峰鉴定出21个化合物.主要成分是丁香酚(84.500％)、顺-罗勒烯(4.567％)、顺-石竹烯(1.516％),α-依兰油烯(2.457％)。已鉴定成分相对含量占全油的96.641％.此精油的丁香酚含量明显高于其它地区栽培的同种植物.     

木姜子叶精油的化学成分研究

采用气相色谱-质谱联用仪对产于秦岭太白山的木姜子叶的挥发油成分进行分析鉴定,从分离出的79个峰中鉴定了32种成分,其含量占挥发油总量的90.59％,主要成分为1,3,3-三甲基-乙-氧杂双环[2,2,2]辛烷(59.96％),1,8-桉油醇(8.96％),香茅醛(6.86％),2-甲基-5-(1-甲基乙烯基)环己酮(4.34％)和澄花醇乙酯(3.19％)。     

广西小叶红叶藤挥发油化学成分及抗氧化性研究

采用气相色谱-质谱联用技术对小叶红叶藤挥发油的化学成分进行分析,并用DPPH·法、ABTS,+法和铁氰化钾还原法对其抗氧化能力进行研究.结果表明:从小叶红叶藤挥发油分离出221个色谱峰,共鉴定64个化合物,占挥发油总量的95.72％,主要成分为dl-薄荷酮(53.43％)、(E)-薄荷酮(14.20％)、5-甲基-2-...     

粘叶莸精油化学成分的研究

用气相色谱保留指数定性法,色谱-质谱-计算机联用实验和标准品迭加法分析了粘叶莸 (Caryopteris glutinosa) 精油的化学成分,从分离出的76个色谱峰中鉴定出30个化合物,并测定了它们的相对含量,其主要成分为β-蒎烯(52.630％)、柠檬烯(15.030％、α-蒎烯(13.810％),香叶烯(2.890％)、红没药烯(2.419％)、α- 烯 (1.074％) 和香桧烯 (1.010％)。     

大果木姜子精油化学成分的研究

用毛细管色谱-质谱-计算机联用,毛细管色谱-红外光谱-计算机联用,毛细管色谱保留指数和标准品叠加法,分析了大果木姜子(Cinnamomum migao H.W.Li)果实精油的化学成分。从分离出的63个峰中鉴定出47个成分,其中主要成分是1,8-桉叶素(23.75％),香桧烯(10.63％),柠檬烯(8.77％)和α-松油醇(6.36％)等。     

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.