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排序方式: 共有472条查询结果,搜索用时 15 毫秒
71.
中药柴胡不同采收期的皂甙含量 总被引:4,自引:0,他引:4
中药柴胡不同采收期的皂甙含量潘泽惠庄体德周雪林林湘(江苏省中国科学院植物研究所,南京210014)(黑龙江双鸭山矿务局师范学校,双鸭山155125)OnseasonalchangesofthetotalsaponinsinChinesetradit... 相似文献
72.
73.
Bupleurum is a genus largely distributed in temperate regions of the Northern
Hemisphere. In China 36 species, 17 varieties and 7 forms have hitherto been reported and
most of them are used as Chinese traditional drugs under the name of Chai-Hu. Chai-Hu is
one of the most popular drugs used ever since the ancient time and is prescribed principally
in the treatment of fevers and influenza. In this article, the authors report two new species, B. kunmingense Y. Li et S. L. Pan and B. polyclonum Y. Li et S. L. Pan which were
discovered in Yunnan Province based on morphological studies and preliminary phytochemical tests. The ultraviolet spectrums and thin layer chromatograms of the essential oil and
the crude saikosaponins of the two new species are similar to those of B. chinense DC., the
standard material medica of Chai-Hu. Moreover, two new saikosaponin spots located between saikosaponin a and c in TLC were discovered in the two new species, and this could
be served as a chemical evidence for identification purpose. In the histochemistry examination, the reaction of saikosaponin with color developing agent in parenchyma of the roots of the two new species is obviously more significant than that of B. chinense DC. and this phenomenon has also been proved to be true by TLC of the crude saikosaponin extracts of these two new species. It is suggested that the two new species be used as a substitute ofhigh quality for Chai-Hu. 相似文献
74.
Indole-3-Acetic Acid Control on Acidic Oat Cell Wall Peroxidases 总被引:2,自引:0,他引:2
Incubation of oat coleoptile segments with 40 μm indoleacetic acid (IAA) induced a decrease of 35–60% in peroxidase activity at the cell wall compartment. Treatment with
IAA also produced a similar decrease in the oxidation of NADH and IAA at the cell wall. Isoelectric focusing of ionic, covalent,
and intercellular wall peroxidase fractions showed that acidic isoforms (pI 4.0–5.5) were reduced preferentially by IAA treatment.
Marked differences were found between acidic and basic wall isoperoxidases in relation to their efficacy in the oxidation
of IAA. A peroxidase fraction containing acidic isoforms oxidized IAA with a V
max/s0.5 value of 2.4 × 10−2 min−1· g fw−1, 4.0 times higher than that obtained for basic peroxidase isoforms (0.6 × 10−2 min−1· g fw−1). In contrast, basic isoforms were more efficient than acidic isoperoxidases in the oxidation of coniferyl alcohol or ferulic
acid with H2O2 (5.6 and 2.1 times, respectively). The levels of diferulate and lignin in the walls of oat coleoptile segments were not altered
by treatment with IAA. The decrease in cell wall peroxidase activity by IAA was related more to reduced oxidative degradation
of the hormone than to covalent cell wall cross-linking.
Received November 1, 1998; accepted December 14, 1998 相似文献
75.
Olga Berejnaia Hao WangMarc Labroli Christine YangCharles Gill Jianying XiaoDavid Hesk Reynalda DeJesusJing Su Christopher M. TanPayal R. Sheth Michael KavanaDavid G. McLaren 《Analytical biochemistry》2017
The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has created an urgent need for new therapeutic agents capable of combating this threat. We have previously reported on the discovery of novel inhibitors targeting enzymes involved in the biosynthesis of wall teichoic acid (WTA) and demonstrated that these agents can restore β-lactam efficacy against MRSA. In those previous reports pathway engagement of inhibitors was demonstrated by reduction in WTA levels measured by polyacrylamide gel electrophoresis. To enable a more rigorous analysis of these inhibitors we sought to develop a quantitative method for measuring whole-cell reductions in WTA. Herein we describe a robust methodology for hydrolyzing polymeric WTA to the monomeric component ribitol-N-acetylglucosamine coupled with measurement by LC-MS/MS. Critical elements of the protocol were found to include the time and temperature of hydrofluoric acid-mediated hydrolysis of polymeric WTA and optimization of these parameters is fully described. Most significantly, the assay enabled accurate and reproducible measurement of depletion EC50s for tunicamycin and representatives from the novel class of TarO inhibitors, the tarocins. The method described can readily be adapted to quantifying levels of WTA in tissue homogenates from a murine model of infection, highlighting the applicability for both in vitro and in vivo characterizations. 相似文献
76.
基于染色体计数和ITS序列初步探讨横断山区柴胡属植物(伞形科)的系统发育 总被引:3,自引:0,他引:3
横断山区是中国柴胡属Bupleurum植物的分布中心。本文对横断山区6个种2变种进行了染色体记数报道,其中4个种2变种是首次报道。对横断山区的10个种4个变种、中国北方(河北和黑龙江)的3个种的nrDNA ITS进行测序,同时从GenBank里面下载同属的来自非洲和地中海西部的16个nrDNA ITS序列数据,结合染色体数目变化结果,初步探讨了横断山区柴胡属植物的系统发育。结果表明横断山区可能是现代柴胡属植物的频度中心和多样分布中心之一。它们的祖先种可能是非洲北部的木本柴胡属植物B.fruticosum,或者是地中海西部的柴胡属植物,推测是通过中东和高加索扩散而形成的,其中与非洲南部特有种B.mundtii的亲缘关系也较近;染色体基数演化趋势是:8是较原始基数,6和7是次生基数,其染色体异基数变异和多倍化可能是物种形成、进化以及向外扩散的主要方式;在ITS系统发育树中,中国柴胡属植物染色体基数为8的种类聚为一支,染色体基数为6和7的种类聚为了一支,不支持舒璞等(1998)关于中国柴胡属的属下分类系统。结合已有的形态学、细胞学、孢粉学证据和ITS系统发育树,建议窄竹叶柴胡B.marginatum var.stenophyllum独立成种。 相似文献
77.
Purple acid phosphatase in the walls of tobacco cells 总被引:1,自引:0,他引:1
Purple acid phosphatase isolated from the walls of tobacco cells appears to be a 220 kDa homotetramer composed of 60 kDa subunits, which is purple in color and which contains iron as its only metal ion. Although the phosphatase did not require dithiothreitol for activity and was not inhibited by phenylarsine oxide, the enzyme showed a higher catalytic efficiency (kcat/Km) for phosphotyrosine-containing peptides than for other substrates including p-nitrophenyl-phosphate and ATP. The phosphatase formed as a 120 kDa dimer in the cytoplasm and as a 220 kDa tetramer in the walls, where Brefeldin A blocked its secretion during wall regeneration. According to our double-immunofluorescence labeling results, the enzyme might be translocated through the Golgi apparatus to the walls at the interphase and to the cell plate during cytokinesis. 相似文献
78.
铁皮石斛茎段诱导丛生芽的研究 总被引:32,自引:0,他引:32
以铁皮石斛Dendrobium candidum Wall.ex Lindl.的茎段作外植体,比较不同的培养基、激素等因素对茎段分化丛生芽的影响,以及不同浓度的香蕉汁和活性炭对试管苗生根的影响。结果表明:1/2MS较好,BA作用优于KT、ZT,最适浓度为2.0mg/L;丛生芽培养于1/2MS 10%香蕉汁 0.5%AC的培养基上,生根效果最好。 相似文献
79.
狭叶柴胡的抗过敏活性及其有效成分 总被引:4,自引:0,他引:4
本文以compound 48/80在体外诱导大鼠腹腔肥大细胞释放组胺,评价狭叶柴胡及其成分的抗过敏活性。狭叶柴胡醇提物及正丁醇部分(100μg/mL)、乙酸乙酯及水部分(10,100μg/mL)显著减少组胺释放,以乙酸乙酯部分的作用最强,狭叶柴胡挥发油(100μg/mL)对组胺释放呈现一定的促进作用。从乙酸乙酯部分分离得到异鼠李素和槲皮素两种主要化合物,均显著抑制组胺释放,表明黄酮为狭叶柴胡抗过敏作用的有效成分。 相似文献
80.
A detailed analysis of Bupleurum fruticosum oil was carried out by combination of GC (RI), GC/MS, and 13C‐NMR analyses. After fractionation by column chromatography, 34 components accounting for 97.8% of the oils were identified. The main component was β‐phellandrene (67.7%), followed by sabinene (9.3%), and limonene (5.6%). The evolution of the chemical composition according to the stages of development of the plant was investigated as well as the composition of leaf, twig, and flower oils. A solvent‐free microwave extraction (SFME) of aerial parts was carried out and the composition of the extract compared with that of the essential oil. Finally, 57 oil samples isolated from aerial parts of individual plants, collected all around Corsica, were analyzed, and the data were submitted to statistical analysis. Although the contents of the main components varied, only one group emerged, accompanied with some atypical compositions. 相似文献