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41.
A versatile countercurrent chromatography with upright multilayer coil planet centrifuge, named upright countercurrent chromatography (UCCC), was applied to the isolation and purification of celastrol from the roots of Celastrus orbiculatus Thunb. The crude celastrol was obtained by elution with petroleum ether from ethanol extracts using a 15 cm length and 5 cm I.D. of silica gel flash chromatography. Preparative UCCC (Fig. 1) with a two-phase system composed of petroleum ether (b. p. 60 ~ 90 ℃ )-ethyl acetate-tetrachloromethanemethanol-water ( 1:1:8:6: 1, v/v) was successfully performed, yielding 705 mg celastrol at 99.5 % purity from 1020 rng of the crude extract in one step separation. 相似文献
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在量子化学对SiH与H2O和H2S反应计算的基础上,运用统计热力学和Wigner校正的Eyring过渡态理论,计算了上述两反应在200~2000 K温度范围内的热力学函数、平衡常数、频率因子A和速率常数随温度的变化。计算结果表明,两反应在低温下具有热力学优势,而在高温下具有动力学优势。比较两反应的计算结果发现,在相同的温度下,SiH与H2O反应比SiH与H2S反应放热较多,但速率常数却较小。SiH与H2O反应和前文报道的SiH与HF反应的比较表明,SiH与H2O反应放热较少,而且在相同温度下,速率常数也较小。 相似文献
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对活性天然产物(+)-7-deoxynimbidiol非对映异构体的外消旋体cis-(±)-7-deoxynimbidiol进行了合成和衍生, 共得到了8个新型三环二萜化合物; 对合成的新化合物进行了抗肿瘤活性的实验研究, 其中化合物5d对人体乳腺癌瘤株MCF7表现出了较强的抑制作用(IC50=7.49 μg/mL), 可能作为新型抗肿瘤药物先导化合物. 相似文献
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IntroductionRecentlymuchattentionhasbeendevotedtothesynthesisofα ,β unsaturatednitrilessincetheyareim portantstructuralfeatureofseveralnaturallyoccurringbi ologicallyactivecompounds .1,2 Theintroductionoffluo rineortrifluoromethylgroupintobiologicallyactiv… 相似文献
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Owing to no complications caused by solid supports, such as adsorptive sample loss and deactivation, tailing of solute peaks, and contamination, countercurrent chromatography (CCC) has been an area of intense research since the first introduction of CCC in 1970,[1] and various apparatus and broad applications have been advanced[2,3]. For these developments, the type-J synchronous planet centrifuge has received considerable attention, which relies not only on its relatively simple mechanic design, but also on its high partition efficiency and short elution time caused by mixing and settling for the efficient chromatographic separations. In the past, however, almost all of type-J centrifuges rotated slowly were disposed horizontally due to the original design and some experiments that gravis plays an important role at a low rotary speed as similar to type-V rotating multilayer helical tube in unit gravity[4-9]. In fact,we discovered that the upright apparatus holds more retention of stationary phase than the horiziontal aparatus when large standard tubings were used as mutilayer coil column and the aparatus was operated under same contions. We report here a new coil planet centrifuge with four upright cylindrical columns for large scale countercurrent chromatographic preparation. The design principle and apparatus of UCCC is as samilar to type-J multilayer coil planet centrifuge. Four uptight cylindrical column holders are symmetrically arranged around the centrifuge axis as similar to the type-J HSCCC with three horizontal multilayer coils connected in series[8] . A series of experiments indicat that upright CCC has many advantages over the horizontal CCC when using a large-bore tube as multilayer coil column for large scale countercurrent chromatographic separation.Upright CCC provide a versatile countercurrent chromatographic method for large-scale preparation from very crude sample. It has good preparative capacity and flexible suitability to various sample and two-phase system.The present apparatus not only can be operated at a high speed as similar as commonly used HSCCC for the system having short settling time and but also can be run at a low speed for the system having relative long settling time. Because of automatical control and seal-free flow through device, the uptight CCC apparatus may be readily scaled up to industrial preparation. 相似文献