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81.
Jian‐You Li Ying Peng Ling‐Zhi Li Pin‐Yi Gao Chang Gao Su‐Xia Xia Shao‐Jiang Song 《Helvetica chimica acta》2013,96(2):313-319
Two new abietane‐type diterpenoids, named triptobenzene R ( 1 ) and triptobenzene S ( 2 ), together with three known abietane‐type diterpenoids, triptophenolide ( 3 ), triptonodiol ( 4 ), and triptonoterpene methyl ether ( 5 ), were isolated from the roots of Tripterygium wilfordii Hook . f. Their structures and relative configurations were established by detailed spectral studies, including 1D‐ and 2D‐NMR (HSQC, HMBC, and NOESY), and HR‐ESI‐TOF‐MS, and by comparison with published data. Their absolute configurations were assigned by the CD technique, applied for the first time to abietane diterpenes from Tripterygium wilfordii. Compound 2 is the first abietane‐type norditerpenoid isolated from the genus Tripterygium. 相似文献
82.
Sainan Zhang Zhengcai Ju Huida Guan Lu Yu Zhengtao Wang Yuqing Zhao 《Biomedical chromatography : BMC》2019,33(11)
Notoginsenoside R1 (NGR1), a diagnostic protopanaxatriol‐type (ppt‐type) saponin in Panax notoginseng, possesses potent biological activities including antithrombotic, anti‐inflammatory, neuron protection and improvement of microcirculation, yet its pharmacokinetics and metabolic characterization as an individual compound remain unclear. The aim of this study was to investigate the exposure profile of NGR1 in rats after oral and intravenous administration and to explore the metabolic characterization of NGR1. A simple and sensitive ultra‐fast liquid chromatographic–tandem mass spectrometric method was developed and validated for the quantitative determination of NGR1 and its major metabolites, and for characterization of its metabolic profile in rat plasma. The blood samples were precipitated with methanol, quantified in a negative multiple reaction monitoring mode and analyzed within 6.0 min. Validation parameters (linearity, precision and accuracy, recovery and matrix effect, stability) were within acceptable ranges. After oral administration, NGR1 exhibited dose‐independent exposure behaviors with t1/2 over 8.0 h and oral bioavailability of 0.25–0.29%. A total of seven metabolites were characterized, including two pairs of epimers, 20(R)‐notoginsenoside R2/20(S)‐notoginsenoside R2 and 20(R)‐ginsenoside Rh1/20(S)‐ginsenoside Rh1, with the 20(R) form of saponins identified for the first time in rat plasma. Five deglycometabolites were quantitatively determined, among which 20(S)‐notoginsenoside R2, ginsenoside Rg1, ginsenoside F1 and protopanaxatriol displayed relatively high exploration, which may partly explain the pharmacodynamic diversity of ginsenosides after oral dose. 相似文献
83.
A high‐performance liquid chromatographic (HPLC) method for enantioseparation of bupropion was developed using two isothiocyanate‐based chiral derivatizing reagents, (S)‐1‐(1‐naphthyl) ethyl isothiocyanate, (S)‐NEIT, and (R)‐α‐methyl benzyl isothiocyanate, (R)‐MBIT. The diastereomers synthesized with (S)‐NEIT were enantioseparated by reversed‐phase HPLC using gradient elution with mobile phase containing water and acetonitrile, whereas diastereomers synthesized with (R)‐MBIT were enantioseparated using triethyl amine phosphate buffer and methanol. Derivatization conditions were optimized and the method was validated for accuracy, precision and limit of detection. The limit of detection was found to be 0.040–0.043 µg/mL for each of the diastereomers prepared with (S)‐NEIT. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
84.
有机溶剂中(R)-醇腈酶催化不对称合成(R)-苯乙醇腈 总被引:3,自引:0,他引:3
研究了来源于杏仁的(R)-醇腈酶在有机溶剂异丙醚中催化苯甲醛与HCN不对称合成(R)-苯乙醇腈,初步探讨了来源于不同杏仁的(R)-醇腈酶的筛选、最适酶量的确定以及底物HCN与苯甲醛的配比、底物浓度、酶的微环境pH和反应温度对不对称合成反应的影响.结果发现,来源于苦杏仁的(R)-醇腈酶优于来源于甜杏仁的(R)-醇腈酶.优化的反应条件为:最适酶量150g/L,HCN与苯甲醛的配比2.5,苯甲醛浓度300mmol/L,酶的微环境pH5.4,反应温度0~5℃.在该优化反应条件下,反应平衡转化率和产物的光学纯度均高达99%以上. 相似文献
85.
86.
87.
Asymmetric total synthesis of the sex pheromones of Japanese beetle and currant stem girdler, (R)‐japonilure (1) and (4R,9Z)‐9‐octadecen‐4‐olide (2), has been achieved. 相似文献
88.
Chiral γ-lactones of both enantiomers were synthesized with more than 90% optical purities. The key step was Novozym 435–catalyzed hydrolysis of racemic N-benzyl-4-acetoxyalkylamides. Additionally, because (R)-γ-lactones are predominant in apricot, mango, peach, passion fruit, and strawberry, synthesis was attempted using only one enantiomer selectively. The (R)-enantimer was synthesized with more than 80% total yield and more than 90% optical purity by a combination of Novozym 435–catalyzed hydrolysis and the Mitsunobu reaction. 相似文献
89.
90.
The first enantioselective total synthesis of 5-acetoxygoniothalamin 1 and 5-acetoxyisogoniothalamin oxide 2 was achieved through the Sharpless kinetic resolution of recemic secondary 2-furylmethanol 5 and the Mitsunobu reaction. At the same time we developed a short synthetic route for 6R-( )-goniothalamin 3 and (6R,7R,8R)-( )-goniothalamin oxide 4. And according to this route the configuration of 5-acetoxygoniothalamin 1 was confirmed as (5S,6S). 相似文献