- New cytotoxic secondary metabolites from marine bryozoan Cryptosula pallasiana
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A new sterol, (23R)-methoxycholest-5,24-dien-3β-ol (1), two new ceramides, (2S,3R,4E,8E)- 2-(tetradecanoylamino)-4,8-octadecadien-l,3-diol (6) and (2S,3R,2′R,4E,8E)-2-(tetradecanoylamino)- 4,8-octadecadien-l,3,2′-triol (7), together with three known sterols (2-4), a lactone (5) and two ceramides (8,9), were isolated from the marine bryozoan Cryptosula pallasiana, collected at Huang Island of China. The structures of the new compounds were elucidated by extensive spectroscopic analyses, chemical methods and quantum electronic circular dichroism (ECD) calculations. Among the isolated compounds, sterol 1 possessed a rare side chain with a methoxy group at C-23, and a double bond between C-24 and C-25. Ceramides 6 and 7 possessed 14 carbons in their long-chain fatty acid base (FAB), which were different from the normal ceramides with 16 carbons in the FAB. Moreover, compounds 5 and 8 were isolated for the first time from marine bryozoans. Compounds 1-9 were evaluated for their cytotoxicity against human tumor cell lines HL-60, Hep-G2 and SGC-7901. The results showed that lactone 5 appears to have strong cytotoxicity against the test tumor cell lines, with IC50 values from 4.12 μM to 7.32 μM, and sterol 1 displayed moderate cytotoxicity with IC50 values between 12.34 μM and 18.37 μM, while ceramides 6-9 showed weak cytotoxicity with IC50 ranging from 21.13 μM to 58.15 μM.
- Tian, Xiang-Rong,Gao, Yan-Qing,Tian, Xiao-Lin,Li, Jiao,Tang, Hai-Feng,Li, Yu-Shan,Lin, Hou-Wen,Ma, Zhi-Qing
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- Chiral Surfactant-Type Catalyst: Enantioselective Reduction of Long-Chain Aliphatic Ketoesters in Water
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A series of amphiphilic ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neat water. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π interaction and the strong hydrophobic interaction of long aliphatic chains between the catalyst and the substrate in the metallomicelle core played a key role in the catalytic transition state. Synergistic effects between the metal-catalyzed site and the hydrophobic microenvironment of the core in the micelle contributed to high stereoselectivity. (Chemical Equation Presented).
- Lin, Zechao,Li, Jiahong,Huang, Qingfei,Huang, Qiuya,Wang, Qiwei,Tang, Lei,Gong, Deying,Yang, Jun,Zhu, Jin,Deng, Jingen
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p. 4419 - 4429
(2015/05/13)
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- Gas chromatography/electron-capture negative ion mass spectrometry for the quantitative determination of 2- and 3-hydroxy fatty acids in bovine milk fat
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2- and 3-hydroxy fatty acids (2- and 3-OH-FAs) are bioactive substances reported in sphingolipids and bacteria. Little is known of their occurrence in food. For this reason, a method suitable for the determination of OH-FAs at trace levels in bovine milk fat was developed. OH-FAs (and conventional fatty acids in samples) were converted into methyl esters and the hydroxyl group was derivatized with pentafluorobenzoyl (PFBO) chloride to give PFBO-O-FA methyl esters. These derivatives with strong electron affinity were determined by gas chromatography interfaced to mass spectrometry using electron-capture negative ion in the selected ion monitoring mode (GC/ECNI-MS-SIM). This method proved to be highly sensitive and selective for PFBO-O-FA methyl esters. For the analysis of samples, two internal standards were used. For this purpose, 9,10-dideutero-2-OH-18:0 methyl ester (ISTD-1) from 2-OH-18:1(9c) methyl ester as well as the ethyl ester of 3-PFBO-O-12:0 (ISTD-2) was synthesized. ISTD-1 served as a recovery standard whereas ISTD-2 was used for GC/MS measurements. The whole-sample cleanup consisted of accelerated solvent extraction of dry bovine milk, addition of ISTD 1, saponification, conversion of fatty acids into methyl esters by use of boron trifluoride, separation of the methyl esters of OH-FAs from nonsubstituted FAs on activated silica, conversion of OH-FAs methyl esters into PFBO-O-FA methyl esters, addition of ISTD-2, and measurement by GC/ECNI-MS-SIM. By this method, ten OH-FAs were quantified in bovine milk fat with high precision in the range from 0.02 ± 0.00 to 4.49 ± 0.29 mg/100 g of milk fat.
- Jenske, Ramona,Vetter, Walter
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experimental part
p. 5500 - 5505
(2010/03/25)
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- Cerebrosides from Fomitopsis pinicola (Sw. Ex Fr.) Karst.
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A cerebroside fraction was obtained from the bruit bodies of fomitopsis pinicola using column chromatography and then separated into six compounds by reversed-phase HPLC.The sugar component of all cerebrosides was D-glucose.The major fatty acids were 2-hydroxyfatty acids (C14-C18), the long chain base was identified as 9-methyl-C18-4,8-sphingadienine which is widely distributed in fungi and reported to be essential for the fruit-inducing activity of fungi.Based on degradation studies, fast atom bombardment mass spectrometry, and different 1H and 13C NMR investigations, the structure of the main cerebroside (1) was determined to be (4E,8E,2S,3R,2'R)-N-2'-hydroxypalmityl-1-O-β-D-glucopyranosyl-9-methyl-4,8-sphingadienine. - Keywords: Cerebroside; Glycolipid; Fomitopsis pinicola; 1H and 13C NMR
- Striegler, S.,Haslinger, E.
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p. 755 - 762
(2007/10/03)
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- Mode of Metabolism of 1-Tetradecene by Candida Yeasts and Citrates Production
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Metabolic pathways for the oxidation of 1-tetradecene by Candida lipolytica were investigated and compared with those for Candida tropicalis in oder to elucidate the difference in the productivity of citrates reported in the previous paper.No difference was found in the pathways for the initial stage of oxidation of 1-tetradecene between the two strains, indicating that the difference in the productivity of citrates is not attributable to the metabolic pathways.The metabolic rate of 1-tetradecene with C. lipolytica was found to be much lower than that with C. tropicalis.The production of citrates was much enhanced in the presence of surfactants which were known to be stimulative for microbial metabolism of hydrocarbons and 11-15 g/liters was attained on the 6th day of cultivation.
- Terasawa, Masato,Takahashi, Joji
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p. 2433 - 2442
(2007/10/02)
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