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1.
对珍珠菜属(Lysimachia)植物中已报道的三萜类化合物化学结构和生物活性研究进行了综述。本属中的三萜皂苷均以齐墩果烷型五环三萜为苷元基本骨架,根据皂苷元结构,可将皂苷分为13β,28-环氧-齐墩果烷型(Ⅰ型)和12-烯-齐墩果烷型(Ⅱ型),同时论述了Ⅰ型和Ⅱ型皂苷元化学结构转换。  相似文献   

2.
香港坚木中的达玛烷型三萜   总被引:2,自引:0,他引:2  
从楝科植物香港坚木的树吉中分得了4个新的达玛烷型三萜,基于详细的光谱分析及与同类化合物的光谱数据比较鉴定了其结构,分别命名为:20R,24R-表-25-达玛烷烯-3-酮,16β-羟基达玛烷-20,25-二烯-3-酮,26-羟基达玛烷-20,24-二烯-3-酮和3β-乙酰基-7α,21S,25-三羟基-21S,23R-表-1(11)-达玛烷烯。  相似文献   

3.
对近10年来从美登木属植物中新发现的三萜类化合物的结构类型和生物活性进行了综述;指出了研究中存在的不足并提出了今后的研究方向。  相似文献   

4.
苦丁茶冬青化学成分的结构研究   总被引:22,自引:0,他引:22  
从苦丁茶冬青叶中分得4个新的三萜酯,及6个已知三萜,其化学结构分别由NMR,MS,IR等方法获得。这4个新三萜酯是:α-香树醇-3β-棕榈酸酯,11-羰基-α-香树醇-β-棕榈酸酯,3β-羟基-羽扇-20(29)-烯-24羰酸甲酯和羽扇-20(29)-烯-24-羰酸甲酯-3β-棕榈酸酯。  相似文献   

5.
西昌万寿菊花中化学成分的研究   总被引:1,自引:0,他引:1  
从万寿菊(Tagetes ereata L.)花中分得8个已知化合物,分别为丁香酸(Syringic acid,1),3,4二羟基苯甲酸(3,4-dihydroxybenzonic acid,2),β-香树脂醇(β-amyrin,3),槲皮万寿菊素(Quercetagetin,4),Quercetagetin 7-methyl(5),β-谷甾醇(β-sitosterol,6),豆甾醇(stigmasterol,7),正三十四烷(Tetratriacontane,8)。应用光谱法鉴定了所有化合物的结构。  相似文献   

6.
中药茅莓化学成分研究   总被引:10,自引:0,他引:10  
谭明雄  王恒山  黎霜  陈薇 《广西植物》2003,23(3):282-284,270
用溶剂提取和硅胶柱层析分离的方法 ,根据光谱分析鉴定中药茅莓的结构 ,分离并鉴定了 5个化合物 ,分别为β 谷甾醇 (Ⅰ )、蔷薇酸 (Ⅱ )、2α,3α,1 9α,2 3 tetrahydroxyurs 1 2 en 2 8 oicacid(Ⅲ )、β 葫萝卜甙 (Ⅳ )和悬钩子皂甙 (Ⅴ ) ,以上前四个化合物均为首次从该植物中分得  相似文献   

7.
本文综述了近十年来唐松草属植物化学成分的结构、来源及其药理活性的研究进展。  相似文献   

8.
毛花猕猴桃根中的一个新三萜化合物   总被引:5,自引:0,他引:5  
从毛花猕猴桃(Actindia eriantha Benth)的根中分离到三个结晶成分,根据光谱数据(MS,IR,~(12)CNMR,~1HNMR)和化学证明,R_6的结构为2α,3β,24-三羟基-12-烯-28-乌苏酸是一新化合物,其余两个成分分别为二十四碳酸和葡萄糖。  相似文献   

9.
三萜酚酸酯类化合物是一类结构新颖的天然产物,本文从植物来源、结构类型及生物活性等方面综述了三萜酚酸酯类化合物的研究进展。  相似文献   

10.
构树皮中三萜类化学成分   总被引:1,自引:0,他引:1  
对构树皮的化学成分进行进一步研究,通过反复硅胶柱层析从构树皮乙醇提取物的石油醚萃取部位中分离得到六个三萜成分,利用波谱技术及理化性质鉴定其化学结构分别为3β-乙酰氧基-甘遂-7-烯-24S,25二醇(1),3β-乙酰氧基-7,23-甘遂二烯-25-醇(2),羽扇豆醇(3),α-香树脂醇乙酸酯(4),3β,25-二羟基-7,23-甘遂二烯(5)和β-香树脂醇(6)。其中化合物1为新的甘遂烷型三萜,化合物2~5为首次从该植物中分离得到。  相似文献   

11.
12.
The simple-septate basidiomycetes: a synopsis   总被引:1,自引:1,他引:0  
The simple-septate basidiomycetes comprise more than 8,000 species that show a high morphological and ecological heterogeneity. To gain insight in the phylogenetic relationships within this group, we compared several ultrastructural features such as septal pore apparatus, form, and behavior of the spindle pole bodies, types of host–parasite interaction, presence or absence of colacosomes, symplechosomes, atractosomes, and cystosomes as well as nuclear rDNA sequences coding for small- and large-subunit rRNA. Based on our integrated analysis, we propose a new classification system for the simple-septate basidiomycetes with the subphylum Pucciniomycotina and the classes Agaricostilbomycetes, Atractiellomycetes, Classiculomycetes, Cryptomycocolacomycetes, Cystobasidiomycetes, Microbotryomycetes, Mixiomycetes, and Pucciniomycetes. We also propose the pucciniomycotinous taxa Cystobasidiales, Erythrobasidiales, Helicobasidiales, Mixiales, Naohideales, Pachnocybales, Spiculogloeales, and Kondoaceae and the new subphyla Agaricomycotina (equivalent to the current Hymenomycetes) and Ustilaginomycotina (equivalent to the current Ustilaginomycetes).  相似文献   

13.
A review of the literature on unusual metals as carcinogens was carried out. The metals covered are some of the rare earths, copper, silver, gold, mercury, germanium, tin, antimony, lead, platinum, palladium, aluminum, titanium, niobium, manganese, scandium, yttrium, indium, rhodium, and gallium.  相似文献   

14.
At one spectrum extreme, Astrobiology conjectures that for exoplanets with Goldilocks conditions, terrestrial-like life is inevitable. Moreover, it is envisaged that via panspermia, terrestrial-like life and its precursors are transferred among galaxies, stars, and within solar systems via transiting comets, asteroids, and planetoids. In addition, expelled stars, which have solar systems, it is inferred, transfer life as well. However, at the other extreme, we propose a paradigm shift that on some planets, subject to non- Goldilocks conditions, metal machine life could arise, ab initio, and evolve viruses, intelligence, and civilizations, conjointly. Accordingly, intelligent mechanized civilizations could readily and efficiently commence space exploration. Furthermore, as a counter paradigm shift, such civilizations could experiment and produce non-metallic life, based on carbon and other non-metal elements, under suitable conditions, related to Goldilocks life. Even a single example of validated interstellar or intergalactic communication received on the Earth would support the existence of life elsewhere. However, the communication platform should not be restricted to electromagnetic radiation. Other platforms should be included as well - one such example, which would require sophisticated technology, is neutrino communication. This is the case for any advanced civilization, be it metal-machine based, biological-based, and carbon-based. In sum, civilizations based on machine life, would be highly productive due to the longevity and hardiness of machine life. However, significant caveats are raised in this brief report, because possibly dissimilar psychologies and intelligence may lead to conflicts between metal machine life and biological life, inter-paradigm conflict.  相似文献   

15.
1. Acetylcholine receptors were initially defined as nicotinic or muscarinic, based on selective activation by two natural products, nicotine and muscarine. Several further nicotinic agonists have been discovered from natural sources, including cytisine, anatoxin, ferruginine, anabaseine, epibatidine, and epiquinamide. These have provided lead structures for the design of a wide range of synthetic agents.2. Natural sources have also provided competitive nicotinic antagonists, such as the Erythrina alkaloids, the tubocurarines, and methyllycaconitine. Noncompetitive antagonists, such as the histrionicotoxins, various izidines, decahydroquinolines, spiropyrrolizidine oximes, pseudophrynamines, ibogaine, strychnine, cocaine, and sparteine have come from natural sources. Finally, galanthamine, codeine, and ivermectin represent positive modulators of nicotinic function, derived from natural sources.3. Clearly, research on acetylcholine receptors and functions has been dependent on key natural products and the synthetic agents that they inspired.  相似文献   

16.
The phylogenetic relationships of the caryophyllidia-bearing dorids are studied, based on the examination of the type species of all the genera previously described. The phylogenetic hypothesis supports that the caryophyllidia-bearing dorids are a monophyletic group and the sister group of the clade formed by Astemnotus Ehrenberg, 1831 and Halgerda Bergh, 1880. Several genera previously considered as valid or regarded as uncertain are here synonymized: Peronodoris Bergh, 1904, Trippa Bergh, 1877, Phlegmodoris Bergh, 1878, Petelodoris Bergh, 1881, Kentrodoris Bergh, 1876, Audura Bergh, 1878, Centrodoris P. Fischer, 1883, Anisodoris Bergh, 1898, Awuka Er. Marcus, 1955, Rhabdochiia P. Fischer, 1883, Boreodoris Odhner, 1939, Dictyodoris Bergh, 1880, Gravieria Vayssiere, 1912, Aporodoris Ihering, 1886. The following genera are regarded as valid: Astemnotus, Atagema J.E. Gray, 1850, Jorunna Bergh, 1876, Platydoris Bergh, 1877, Diaulula Bergh, 1878, Rostanga Bergh, 1879, Halgerda Bergh, 1880, Baptodoris Bergh, 1884, Gargamella Bergh, 1894, Alloiodoris Bergh, 1904, Sclerodoris Eliot, 1904, Taringa Er. Marcus, 1955, Thorybopus Bouchet, 1977. The new genus Nophodoris is described based on two new species from New Caledonia deep waters. Two additional new species from New Caledonia belonging to the genera Atagema and Gargamella are also described. Nomenclatural and taxonomic problems are discussed, and several type species, neotypes and lectotypes are selected.  相似文献   

17.
The phylogeny of groups within Gobioidei is examined with molecular sequence data. Gobioidei is a speciose, morphologically diverse group of teleost fishes, most of which are small, benthic, and marine. Efforts to hypothesize relationships among the gobioid groups have been hampered by the prevalence of reductive evolution among goby species; such reduction can make identification of informative morphological characters particularly difficult. Gobies have been variously grouped into two to nine families, several with included subfamilies, but most existing taxonomies are not phylogenetic and few cladistic hypotheses of relationships among goby groups have been advanced. In this study, representatives of eight of the nine gobioid familes (Eleotridae, Odontobutidae, Xenisthmidae, Gobiidae, Kraemeriidae, Schindleriidae, Microdesmidae, and Ptereleotridae), selected to sample broadly from the range of goby diversity, were examined. Complete sequence from the mitochondrial ND1, ND2, and COI genes (3573 bp) was used in a cladistic parsimony analysis to hypothesize relationships among the gobioid groups. A single most parsimonious topology was obtained, with decay indices indicating strong support for most nodes. Major phylogenetic conclusions include that Xenisthmidae is part of Eleotridae, and Eleotridae is paraphyletic with respect to a clade composed of Gobiidae, Microdesmidae, Ptereleotridae, Kraemeriidae, and Schindleriidae. Within this five-family clade, two clades are recovered. One includes Gobionellinae, which is paraphyletic with respect to Kraemeriidae, Sicydiinae, Oxudercinae, and Amblyopinae. The other contains Gobiinae, also paraphyletic, and including Microdesmidae, Ptereleotridae, and Schindleriidae. Previous morphological evidence for goby groupings is discussed; the phylogenetic hypothesis indicates that the morphological reduction observed in many goby species has been derived several times independently.  相似文献   

18.
Foliar nutrient levels of broad-leaved tropical trees: A tabular review   总被引:1,自引:0,他引:1  
Foliar nutrient levels (N, P, S, K, Ca, Mg, Al, Fe, Mn, Zn, Cu, Mo, B), of about 40 tropical and subtropical broad-leaved trees, are listed and classified as deficient, low, intermediate, high, and toxic in each case according to the interpretation and evaluation of the reviewed author(s).  相似文献   

19.
This study describes a method for predicting and classifying oxygen-binding pro- teins. Firstly, support vector machine (SVM) modules were developed using amino acid composition and dipeptide composition for predicting oxygen-binding pro- teins, and achieved maximum accuracy of 85.5% and 87.8%, respectively. Sec- ondly, an SVM module was developed based on amino acid composition, classify- ing the predicted oxygen-binding proteins into six classes with accuracy of 95.8%, 97.5%, 97.5%, 96.9%, 99.4%, and 96.0% for erythrocruorin, hemerythrin, hemo- cyanin, hemoglobin, leghemoglobin, and myoglobin proteins, respectively. Finally, an SVM module was developed using dipeptide composition for classifying the oxygen-binding proteins, and achieved maximum accuracy of 96.1%, 98.7%, 98.7%, 85.6%, 99.6%, and 93.3% for the above six classes, respectively. All modules were trained and tested by five-fold cross validation. Based on the above approach, a web server Oxypred was developed for predicting and classifying oxygen-binding proteins(available from http://www.imtech.res.in/raghava/oxypred/).  相似文献   

20.
Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.  相似文献   

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