Chemistry of the eupatoriinae

The known chemistry of subtribe Eupatoriinae, tribe Eupatorieae, Asteraceae, is reviewed critically and taxonomic implications are discussed.     

Four flavonoids from Ageratum strictum

Four new flavonoids, three flavanones and one chalcone, were isolated from aerial parts of Ageratum strictum. Their structures were establised as 3′6′-dihydroxy-2′, 4′-dimethoxy- 3, 4-methylenedioxy-chalcone, 6-hydroxy-5,7-dimethoxy-3′,4′-methylenedioxyflavanone, 6-hydroxy- 5,7,3′,4′-tetramethoxyflavanone and 6,4′-dihydroxy-5,7,3′-trimethoxyflavanone on the basis of spectral data and chemical degradation.     

Two polymethoxyflavones from Ageratum houstonianum

Besides agecorynin C, eupalestin and lucidin dimethyl ether, two new highly oxygenated flavones were isolated from Ageratum houstonianum. Their structures were established by spectroscopic and degradative evidence as 5, 6, 7, 8, 2′, 3′, 4′, 5′-octamethoxyflavone and 5, 6, 7, 2′, 3′, 4′, 5′-heptamethoxyflavone.     

Molecular Phylogeny of Eupatorieae (Asteraceae) Estimated from cpDNA RFLP and its Implication for the Polyploid Origin Hypothesis of the Tribe

Neomirandea (x=17 and 25), Ageratina (x=17) and Sclerolepis (x=15) with the higher chromosome base numbers, and the other includes Mikania (x=17) and the remaining genera with lower chromosome base numbers (x=10–11). However, the monophyly of the former clade is supported with a low bootstrap value. In the latter clade, Mikania (x=17) diverged first, then Stevia (x=11), and finally eight genera with x=10 diverged in succession. This result supports the hypothesis that the genera in the tribe Eupatorieae with x =10 evolved from an ancestor with a higher base number, and the tribe is of polyploid origin. Received 13 September 1999/ Accepted in revised form 20 January 2000     

Comparative Benzofuran Chemistry of Enceliopsis

Enceliopsis (Asteraceae) is a small genus of herbaceous perennials from the Great Basin desert of the U.S.A. Phytochemical analysis revealed the presence of several benzofuran derivatives in Enceliopsis argophylla, E. covillei and E. nudicaulis. The compounds were either identical or very similar to benzofurans isolated from Encelia and Flourensia which supports the close affinity of these genera, as suggested previously, based on morphological, cytological and breeding studies.     

Thirteen new species and two new combinations of Stevia (Asteraceae: Eupatorieae) from Mexico

Thirteen new species of the genusStevia are described and illustrated from Mexico:S. chilapensis, S. coahuilensis, S. crassifolia, S. ecatepecana, S. filodecaballoana, S. mascotensis, S. mexicana, S. oaxacana, S. oligophylla, S. potosina, S. rotundifolia, S. scabrelloides, andS. viejoana. In addition, two varieties,Stevia aschenborniana Sch. Bip. ex Klotzsch var.occidentalis Grashoff andS. palmeri A. Gray var.constricta Grashoff are herein redefined as being distinct species,S. occidentalis andS. constricta stat. nov.Stevia mexicana resemblesStevia trifida Lagasca but differs in the habit.     

Chloroplast DNA restriction site data support a narrowed interpretation ofEupatorium (Asteraceae)

Chloroplast DNA (cpDNA) restriction site analysis was used to assess relationships among samples of Eupatorieae from eastern North America. A total of 270 cpDNA variants was recorded from 35 species using 13 restriction enzymes. Phylogenetic analysis usingGalinsoga, Flaveria, andHelianthinae as outgroups indicated that samples ofAgeratina, Hofmeisteria, Mikania, andStevia, each of which have relatively high base chromosome numbers, formed an unresolved basal polytomy. The remaining samples examined formed a well-supported clade, within which there was a split betweenBrickellia, which hasx = 9, and a number of genera withx = 10. Within thex = 10 clade, there was an unresolved trichotomy, with one group ofAgeratum, Conoclinium, Fleischmannia, andCritonia, a second ofLiatris andTrilisa, and a third ofEupatorium s.s. Within theEupatorium s.s. clade there were three further clades, withE. sect.Verticillata diverging first, and a subsequent split between species originating from North America and those from Asia. The cpDNA restriction site data provided support for a relatively narrow interpretation ofEupatorium, and indicated that a high chromosome base number is plesiomorphic for Eupatorieae.     

Bioorganic Chemistry and the Origin of Life

Summary A challenging theme in bioorganic chemistry is the unification of established theories of biochemistry and organic chemistry to provide new patterns for interpretation and experimentation. Especially relevant examples of such interactions can be drawn from the field of enzyme catalysis and, in particular, the role of cofactors therein.Knowledge of the chemical mechanisms by which some of the cofactors function has progressed rapidly with the aid of studies of the cofactors themselves (or compounds of related structure, models) stripped of the accompanying apoenzyme. The striking successes in this field likely arise from a fundamental resemblance between bioorganic chemistry (especially coenzyme models) and chemical evolution before the appearance of coded polypeptide enzymes.     

Stylotrichium glomeratum (Asteraceae, Eupatorieae), a new species from Chapada Diamantina, Bahia, Brazil

Stylotrichium glomeratum (Asteraceae, tribe Eupatorieae, subtribe Gyptidinae) is described from Chapada Diamantina (Bahia, Brazil), where the genus is endemic. A key to the five species ofStylotrichium is presented.

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Descreve-seStylotrichium glomeratum (Eupatorieae, Asteraceae), uma nova espécie da Chapada Diamantina (Bahia, Brasil), onde este gênero é endêmico. é apresentada uma chave para as cinco espécies deStylotrichium.

     

龟鳖类血液学研究概述

龟鳖类血液学的研究涉及生理生态、系统进化、遗传、生物化学、病理学等相关领域,目前已测定了不少种类的血液生理和血液化学指标及这些指标因性别、季节、温度、盐度、潜水等因素的变化。但研究结果不尽相同,特别是白细胞分类、血清酶活性、生化指标的调节机制等还需要进一步研究。     

量子化学在生物分子领域的研究进展

量子化学的方法对生物分子研究的发展提供了全新的思路和方法。本文介绍了量子化学的基本计算方法,并综述了近两年来量子化学方法在生物分子领域的研究进展。     

诺贝尔化学奖授予CRISPR-Cas9基因编辑研究

2020年,诺贝尔化学奖授予现就职于德国马普感染生物学研究所的法籍科学家Emmanuelle Charpentier和美国加州大学伯克利分校的Jennifer Doudna,表彰她们发明CRISPR基因编辑方法.她们揭示了Cas9具有RNA介导的DNA核酸内切酶活性,可以切断任意DNA双链,产生双链断裂.她们指出CRISPR具有在活细胞中修改基因的作用,利用CRISPR-Cas9编辑工具,可以精确改变细胞中的DNA.由于简单、高效、廉价等特征,CRISPR已经成为最为流行的基因编辑技术,被称为基因编辑"魔剪".本文介绍了两位诺贝尔化学奖得主的研究成果,概述了CRISPR系统的发现历程,以及CRISPR-Cas9的功能和应用.     

Ent-norlabdane triols from Austroeupatorium inulaefolium

Two new ent-norlabdane triols were isolated from the above-ground parts of Austroeupatorium inulaefolium.     

天然药物化学实验教学改革与思考

天然药物化学是药学专业一门重要的专业基础课程。近年来,天然药物在世界范围内受到广为重视与青睐,而随着国家中医药现代化步伐的加快,对创新型药学专业人才的培养也提出了迫切的要求,天然药物化学实验在教学中的重要性与日俱增。为了进一步提高天然药物化学实验课程的教学效果,使之紧密切合学科发展的前沿,笔者根据本教研室在实验教学实践中的相关经验,结合该课程的特点与定位,总结了天然药物化学实验教学过程中存在的问题,并对课程改革进行了探讨与思考,针对课程重视程度低、教学中环保和可持续发展理念缺失、教学方法和手段单一、实验评价考核体系不合理等问题,提出了完善课程设计、严密教学方案、改进课程内容、改革考核标准等具体改进方法及措施。     

中国菊科泽兰族的一个新归化属——裸冠菊属

报道了在华南地区广西发现的菊科Asteraceae泽兰族EuPatorieae一个新归化属——裸冠菊属GymnDcDmnis DC．。它在形态上接近于下田菊属Adenostemma J．R．Forst．＆G.Forst．,但区别在于裸冠菊属无冠毛。依据在中国所采集的标本详细描述了该属在中国的唯一代表种裸冠菊Gymnocoronis spilanthoides （D．Don ex Hook．＆Arn.）DC．的形态特征,并讨论了其地理分布和进入中国的可能途径。     

Dihydrodendroidinic acid from Pleurocoronis pluriseta

The diterpenic acid, dihydrodendroidinic acid, was characterized from the aerial parts of Pleurocoronis pluriseta.     

美国生化学会会刊ASBMB today对转变《生命的化学》办刊思路的启示

本文针对中国生物化学与分子生物学会会刊——《生命的化学》面临的困境,并在分析美国生化学会(ASBMB)会刊ASBMB today的内容特点、栏目设置、经费来源等方面情况的基础上,提出了《生命的化学》的改革思路:读者定位——应继续坚持为广大会员服务的本色;内容定位——保留部分学术文章的同时,适当增加人文因素;市场定位——通过争取学会的支持及申请基金、吸引广告、创办网刊等途径解决随改版而来的办刊经费不足问题。     

Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate

This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the material with Au(III) ions. The synthesis method was derived from a sol-gel process used to produce micron-sized monosodium titanate (MST), with several key modifications, including altering reagent concentrations, omitting a particle seed step, and introducing a non-ionic surfactant to facilitate control of particle formation and growth. The resultant nMST material exhibits spherical-shaped particle morphology with a monodisperse distribution of particle diameters in the range from 100 to 150 nm. The nMST material was found to have a Brunauer-Emmett-Teller (BET) surface area of 285 m²g^-1, which is more than an order of magnitude higher than the micron-sized MST. The isoelectric point of the nMST measured 3.34 pH units, which is a pH unit lower than that measured for the micron-size MST. The nMST material was found to serve as an effective ion exchanger under weakly acidic conditions for the preparation of an Au(III)-exchange nanotitanate. In addition, the formation of the corresponding peroxotitanate was demonstrated by reaction of the nMST with hydrogen peroxide.     

A new okanin glycoside from the flowers of Coreopsis tinctoria Nutt.

Phytochemical investigation on the water-soluable portions of the EtOH extracts of the flowers of Coreopsis tinctoria Nutt. led to the isolation of six flavonoids, including a new okanin glycoside. The structures of these compounds were identified by spectroscopic analysis, chemical method, and comparison with the literature.