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1.
Two new compounds have been isolated from the whole plant of Monochoria vaginalis and characterized as: (10Z)‐1‐(2,6‐dihydroxyphenyl)octadec‐10‐en‐1‐one ( 1 ) (20R, 24R)‐campest‐5‐ene‐3β, 4β‐diol ( 2 ) together with nine known ones. The structures of these compounds were elucidated on the basis of spectral data and chemical evidence. 相似文献
2.
Gerhard Klebe Thomas Mietzner Frank Weber 《Journal of computer-aided molecular design》1994,8(6):751-778
Summary A relative comparison of the binding properties of different drug molecules requires their mutual superposition with respect to various alignment criteria. In order to validate the results of different alignment methods, the crystallographically observed binding geometries of ligands in the pocket of a common protein receptor have been used. The alignment function in the program SEAL that calculates the mutual superposition of molecules has been optimized with respect to these references. Across the reference data set, alignments could be produced that show mean rms deviations of approximately 1 Å compared to the experimental situation. For structures with obvious skeletal similarities a multiple-flexible fit, linking common pharmacophoric groups by virtual springs, has been incorporated into the molecular mechanics program MOMO. In order to combine conformational searching with comparative alignments, the optimized SEAL approach has been applied to sets of conformers generated by MIMUMBA, a program for conformational analysis. Multiple-flexible fits have been calculated for inhibitors of ergosterol biosynthesis. Sets of different thrombin and thermolysin inhibitors have been conformationally analyzed and subsequently aligned by a combined MIMUMBA/SEAL approach. Since for these examples crystallographic data on their mutual alignment are available, an objective assessment of the computed results could be performed. Among the generated conformers, one geometry could be selected for the thrombin and thermolysin inhibitors that approached reasonably well the experimentally observed alignment. 相似文献
3.
圆裂短足软珊瑚Cladiella krempfi中的甾醇苷 总被引:2,自引:1,他引:2
软珊瑚中富含各种萜类、甾类和糖苷[1~ 3] .Christopher[4 ] 和 Bheemasankara[5] 等先后对圆裂短足软珊瑚 Cladiella krempfi中的次生代谢产物进行了研究 ,先后分离得到 5个西松烷二萜 .本文报道从广西涠洲半岛采集的圆裂短足软珊瑚 Cladiella krempfi中首次分离得到 2个甾醇苷 1和 2 ,其中 1是新化合物 .化合物 2曾从南中国海的豆荚软珊瑚 Lobophyton sp.中分离得到 ,它对人体鼻咽癌 (Cne 2 )和肝癌 (Pep-G2 )细胞生长有抑制作用[6 ] .化合物 1和 2的结构如下 :1 结果与讨论化合物 1经 Liebermann-Burchard试验呈甾醇正颜色反应 ,M… 相似文献
4.
Phytochemical investigation of the whole plant of Leontopodium nanum afforded a new coumarin named leontonanin ( 1 ), together with six known compounds, umbelliferone ( 2 ), 3,4′, 7‐trihydroxyflavone ( 3 ), oleanolic acid ( 4 ), β‐sitosterol ( 5 ), daucosterol ( 6 ) and stearic acid ( 7 ). The structure of compound ( 1 ) was elucidated by spectroscopic methods including 2D‐NMR techniques. 相似文献
5.
Reported here is identification of a 7-en-sterol and a 5-en-sterol which containsa cyclopropane ring in its side chain and is separated from the South China Seasponge Biemna sp..This leads to the isolation and identification of twelve sterols inthis marine sponge by using gas chromatography-mass spectrometry (GC-MS)analysis.The occurrence of 7-en-sterol and 5-en-sterol with a cyclopropane ring inits side chain from the south China Sea sponge was first reported here. 相似文献
6.
Summary The analysis of sterols in vegetable oils by off-line SFC followed by capillary GC-MS is described. The fractionation of the
sterols from the complex oil matrix is achieved by SFC on aminopropyl silicagel in less than 8 minutes. Injection and collection
of the sterol fraction is fully automated and time controlled. The sterols are analysed without derivatisation by capillary
GC-MS. Identification is performed by full scan electron ionisation and quantitation is carried out by extracted ion chromatography
at m/e 107, with cholesterol as internal standard. The analyses of the sterols from the sunflower oil and two olive oils illustrate
the possibilities of the method. 相似文献
7.
8.
Stereoselective synthesis of the chemoattractant sperm-activating and attracting factor (SAAF), isolated from the eggs of the ascidian Ciona intestinalis, was achieved via reductive 1,3-transposition of an allylic alcohol and the axial opening of an epoxide as key steps. This second-generation synthesis improved the total yield of SAAF over that of the first-generation synthesis and provided a key intermediate for synthesizing molecular probes of SAAF. 相似文献
9.
El Hattab N Daghbouche Y Hattab ME Piovetti L Garrigues S Guardia Mde L 《Talanta》2006,68(4):1230-1235
An analytical procedure was developed for the determination of the total amount of sterols in the red alga Asparagopsis armata, globally determined as cholesterol, which is the major sterol contained in red algae. Samples, previously saponified with KOH were preconcentrated on DSC-18 solid phase cartridges (SPE) and eluted with dichloromethane stabilized with β-amylene. Fourier transform infrared (FTIR) spectrometry was employed for selective detection at 1049 cm−1 with a baseline established between 1000 and 1079 cm−1. The results were compared to those obtained by high performance liquid chromatography (HPLC). The concentration obtained in actual samples from alga was 3.37% (w/w) by FTIR and 3.30% (w/w) by HPLC, showing a good comparability between the two methods. 相似文献
10.
A sperm-activating and attracting factor (SAAF) was isolated from the eggs of the ascidian Ciona intestinalis, and its structure was deduced with only approximately 4 μg of the specimen. Based upon the proposed structure, two epimers were synthesized from chenodeoxycholic acid in 16 steps. Comparison between synthetic and natural compounds led to the unambiguous structure determination of SAAF to be (3R,4R,7R,25S)-3,4,7,26-tetrahydroxycholestane-3,26-disulfate. The synthetic pure specimen was also utilized to confirm that both sperm-activation and attraction were elicited by a single compound. 相似文献