鄂西香茶菜中挥发油成分分析

采用水蒸汽蒸馏法分别从鄂西香茶菜的叶、花和果实中提取挥发油,并用气相色谱-质谱联用技术（GC-MS）对其挥发油中的化学成分进行分离和结构鉴定,运用气相色谱峰面积归一化法确定各成分的相对百分含量。从鄂西香茶菜的3种挥发油中共鉴定出39种成分,分别从叶、花及果实中鉴定出18、19和23种成分,其中只有6种成分在这3个部位都被鉴出,3种不同部位得到的挥发油成分差异较大。它们的挥发油中主要成分为单萜、倍半萜和二萜类化合物。     

道孚香茶菜的二萜成分

从河南省新县产道孚香茶莱[Rabdosia dawoensis(Hand. Mazz.)Hara]叶中分离到两个二萜化合物,根据各种光谱数据推断一个为新化合物,其化学结构为:对映-11α-羟基-3α,6β,7α-一三乙酰氧基-16-贝壳杉烯-15-酮,命名为道孚香茶菜甲素(dowoensin A),另一个为已知化合物信阳冬凌草甲素(xindongnin A).     

苍山香茶菜素的化学结构

由采自云南大理苍山的苍山香茶菜[Rabdosia bulleyana(Diels)Hara]叶的乙醚抽提物中,分到一个新的对映-贝壳杉烯型二萜化合物,命名为苍山香茶菜素(bulleya-nin)。根据光谱和化学证据,其化学结构被阐明为对映-12β-羟基-1α,3α,7β,14α-四乙酰氧基-16-贝壳杉烯-15-酮(Ⅰ)(ent-12β-hydroxy-1α,3α,7β,14α-tetraacetoxy-16-Kauren-15-oneⅠ)。收率为生药的0.4％,它对小鼠艾氏腹水癌ECA,小鼠肉瘤S-180,小鼠肝癌腹水均显示较强抑制。 苍山香茶菜素及其衍生物的~1H NMR数据,苍山素和脱氢苍山素的~(13)C NMR 数据已指定。~(13)C NMR的指定是结合应用质子噪声去偶,偏共振去偶和相关化合物的比较。     

鄂西香茶菜中一个新的苯取代二酮

从青海产鄂西香茶菜(Isodon henryi)的叶中分离得到1个新的苯取代二酮,利用波谱技术鉴定其结构.同时,还得到了8个已知化合物.     

苍山香茶菜素的结构更正

在编写“天然产贝壳杉烯型二萜成分”一书的过程中,作者对不同结构类型的贝壳杉烯型二萜,各种官能团在不同位置的取代,所引起的~1H和~(13)C化学位移的变化,仔细认真地进行了系列对照研究,从中发现了一些规律性(另报)。 本文根据上述规律性,简要阐明苍山香茶菜素的结构更正。     

鄂西香茶菜素的结构

从鄂西香茶菜[Rabdosia henryi (Hemsl.)Hara]叶中分得一个新的二萜化合物,命名为鄂西香茶菜素(henryin),根据光谱和化学证据,结构为(Ⅱ)式。另外还分得了已知化合物kamebakaurin(Ⅰ),kamebacetal A(Ⅲ)和另一个新化合物(结构将另文报道)。根据初步抗癌试验,化合物(Ⅰ)、(Ⅱ),(Ⅲ),对ECA细胞均有一定的细胞毒活性。     

受害前后的九里香嫩梢对柑橘木虱的吸引作用及其挥发物成分分析

柑橘木虱 Diaphorina citri Kuwayama是黄龙病的传播媒介,九里香 Murraya paniculate L.是柑橘木虱最重要的寄主植物。本研究比较了受柑橘木虱为害前后的九里香对其趋性的影响,并在此基础上,分析受害前后的九里香嫩梢挥发物组成成分。结果表明,与未受为害的九里香相比,受为害后的九里香对柑橘木虱的吸引作用显著增强,而且受害后继续保留柑橘木虱的九里香吸引作用更强。受木虱为害前后九里香挥发物成分差异较大,相同组分含量差异也比较明显。仅存在于受为害后的九里香挥发物共有8种,分别为γ-橄榄烯、α-愈创木烯、Epi-β-檀香烯、顺式-β-金合欢烯、(+)-香橙烯、α-菖蒲二烯、十四甲基环七硅氧烷、α-绿叶烯;而仅存在于未受为害的九里香挥发物为6种,为别为孕烯醇酮、β-榄香烯、2,6-二叔丁基苯醌、异丙茴香醚、1-（1,5-二甲基己基）-4-甲基苯、α-柏木烯。这些差异物质可能在柑橘木虱的寄主定位中起着重要作用。     

近无毛灰岩香茶菜的研究

从云南省会泽县产近无毛灰岩香茶莱〔Rabdosia calcicola (Hand. -Mazz.) Hara var. subculva (Hand. -Mazz.) C. Y. Wu et H. W. Li〕叶中分得两个二萜化合物,一个为新化合物,命名为灰岩香茶菜甲素(calcieolin A),另一个为已知化合物维西香茶菜甲素(weisiensin A),经各项光谱数据和化学反应确定,灰岩香茶菜甲素为3β-羟基-1α,6α,7β,11β-四乙酰氧基-对映-贝壳杉-16-烯-15-酮(1);维西香茶菜甲素结构应为3β,6α-二羟基-1α,7β,11β-三乙酰氧基-对映—贝壳杉-16-烯-15酮(2)。     

Xerophinoid C, 旱生香茶菜中一个新的二萜糖苷化合物

从旱生香茶菜(Isodon xeropene)枝叶的乙酸乙酯部位分离到一个新的松香烷型二萜苷类化合物。通过现代波谱技术,确定其结构为16,18-二羟基-7,15(17)-二烯-对映-松香烷-3α-O-β-D-吡喃葡萄糖苷。     

蓝萼香茶菜化学成分的研究

从长白山产蓝萼香茶菜[Ralxlosia Japonica(Burm.f.)Hara var.glaucocalyx(Maxim.)Hara]地上全草中分得13个化合物,根据理化常数和波谱学数据分别鉴定为：木栓酮(1)、β-谷淄醇(2)、乙酰熊果酸(3)、齐墩果酸(4)、熊果酸(5)、蓝萼香茶菜素A(6)、2α-羟基熊果酸(7)、2α,3α-二羟基熊果酸(8)、ent-7β,14α,15三羟基-16-贝壳杉烯-3-酮(9)、山香三萜二烯酸(10)、槲皮素(11)、β-谷甾醇3-O-β-D-吡喃葡萄糖苷(12)和果糖(13)。化合物8为第一次从该植物中分得,化合物10为第一次从该属植物中分得。     

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.