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1.
Masafumi Kikuchi Rie Kakuda Yasunori Yaoita Masao Kikuchi 《Helvetica chimica acta》2008,91(7):1236-1243
Four new secoiridoid glucosides, swertiajaposides C–F ( 1 – 4 , resp.), were isolated from the whole plant of Swertia japonica Makino together with two known compounds, 8‐hydroxy‐10‐hydrosweroside ( 5 ) and senburiside IV ( 6 ). The structures of 1 – 4 were elucidated on the basis of spectroscopic, chemical, and physicochemical evidence. 相似文献
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Wolf-H. Kunau 《Angewandte Chemie (International ed. in English)》1976,15(2):61-74
Although unsaturated fatty acids have long been known to accompany saturated fatty acids in most lipids, qualitative and quantitative determination of fatty acid patterns only became possible with the advent of modern analytical methods. Present day knowledge of the chemical structure, physical properties, and metabolism of unsaturated fatty acids provides the basis for the development of new concepts of their function. Thus unsaturated fatty acids crucially determine the properties of biological membranes. Moreover, essential fatty acids are precursors of prostaglandins. 相似文献
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Hao Gao Kui Hong Xue Zhang Hong‐Wei Liu Nai‐Li Wang Ling Zhuang Xin‐Sheng Yao 《Helvetica chimica acta》2007,90(6):1165-1178
The polyhydroxylated ergostane‐type sterol 9 , its derivatives 10 – 15 , and the fatty acid esters 1 – 8 were isolated from a fungus strain which was collected from mangrove areas at Wenchang, Hainan Province, P. R. China, exhibited potent cytotoxic activity, and was identified as Aspergillus awamori. The structures of 1 – 15 were elucidated by spectroscopic and chemical methods. Among them, the six steryl esters 1 – 6 of fatty acids were new compounds, i.e., (3β,5α,6α,22E)‐ergosta‐7,22‐diene‐3,5,6‐triol 6‐palmitate ( 1 ), (3β,5α,6α,22E)‐ergosta‐7,22‐diene‐3,5,6‐triol 6‐stearate ( 2 ), (3β,5α,6α,22E)‐ergosta‐7,22‐diene‐3,5,6‐triol 6‐oleate ( 3 ), (3β,5α,6α,22E)‐ergosta‐7,22‐diene‐3,5,6‐triol 6‐linoleate ( 4 ), (3β,5α,6β,22E)‐ergosta‐7,22‐diene‐3,5,6‐triol 6‐palmitate ( 5 ), and (3β,5α,6β,22E)‐ergosta‐7,22‐diene‐3,5,6‐triol 6‐stearate ( 6 ). The related known fatty acids stearic acid (=octadecanoic acid) and palmitic acid (=octadecanoic acid) were also obtained. A speculative biogenetic relationship of the metabolites is proposed. The known polyhydroxylated sterols and derivatives showed cytotoxic activities, in agreement with earlier reports. The cytotoxic activities against B16 and SMMC‐7721 cell lines of the new steryl esters 1 – 6 by the MTT method were weak. 相似文献
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Litwinienko G. Kasprzycka-Guttman T. 《Journal of Thermal Analysis and Calorimetry》1998,54(1):211-217
Oxidation of saturated fatty acids ethyl esters: laurate, myristate, palmitate and stearate was investigated by means of DSC
techniques under isothermal and non-isothermal conditions. The activation energies of isothermal oxidation were similar to
each other (112–123 kJ mol−1) and no influence of carbon length on the rate of oxidative decomposition was observed. Results obtained from non-isothermal
experiments were similar only for the first stage of oxidation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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《Journal of separation science》2017,40(11):2515-2521
In our present study, two groups of xanthones isomers (1‐hydroxy‐3,5,8‐trimethoxyxanthone and 1‐hydroxy‐3,7,8‐trimethoxyxanthone; 1,8‐dihydroxy‐3,7‐dimethoxyxanthone and 1,8‐dihydroxy‐3,5‐dimethanolxanthone) and other two xanthones (3‐methoxy‐1,5,8‐trihydroxyxanthone and 3,5‐dimethoxy‐1‐hydroxyxanthone) were separated from Swertia franchetiana . First, a solvent system composed of petroleum ether/methanol/water (2:1:0.6, v/v) was developed for the liquid–liquid extraction of these xanthones from the crude extract. Then, an efficient method was established for the one‐step separation of these six xanthones by high‐speed countercurrent chromatography using n‐hexane/ethyl acetate/methanol/ethanol/water (HEMEW; 6:4:4:2:4, v/v) as the solvent system. The results showed that liquid–liquid extraction could be well developed for efficient enrichment of target compounds. Additionally, high‐speed countercurrent chromatography could be a powerful technology for separation xanthones isomers. It was found ethanol could be a good methanol substitute when the HEMEW system could not provide good separation factors. 相似文献
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Shunichi Fukuzumi 《Helvetica chimica acta》2006,89(10):2425-2440
A proton‐coupled electron transfer (PCET) process plays an important role in the initial step of lipoxygenases to produce lipid radicals which can be oxygenated by reaction with O2 to yield the hydroperoxides stereoselectively. The EPR spectroscopic detection of free lipid radicals and the oxygenated radicals (peroxyl radicals) together with the analysis of the EPR spectra has revealed the origin of the stereo‐ and regiochemistry of the reaction between O2 and linoleyl (= (2Z)‐10‐carboxy‐1‐[(1Z)‐hept‐1‐enyl]dec‐2‐enyl) radical in lipoxygenases. The direct determination of the absolute rates of H‐atom‐transfer reactions from a series of unsaturated fatty acids to the cumylperoxyl (= (1‐methyl‐1‐phenylethyl)dioxy) radical by use of time‐resolved EPR at low temperatures together with detailed kinetic investigations on both photoinduced and thermal electron‐transfer oxidation of unsaturated fatty acids provides the solid energetic basis for the postulated PCET process in lipoxygenases. A strong interaction between linoleic acid (= (9Z,12Z)‐octadeca‐9,12‐dienoic acid) and the reactive center of the lipoxygenases (FeIII? OH) is suggested to be involved to make a PCET process to occur efficiently, when an inner‐sphere electron transfer from linoleic acid to the FeIII state is strongly coupled with the proton transfer to the OH group. 相似文献
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低酚棉籽仁中脂肪酸成分的研究 总被引:4,自引:0,他引:4
采用气相色谱法测定了9个低酚棉品种中棉籽仁的脂肪酸组成及相对含量。样品所含主要脂肪酸为棕榈酸、油酸、亚油酸。其中亚油酸含量最高,为58.90%~64.88%。与普通棉籽仁进行对比的结果表明,两者脂肪酸组成一致,但低酚棉的亚油酸与不饱和脂肪酸的平均含量均高于普通棉 相似文献
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Dr. Mieke M. E. Huijbers Dr. Wuyuan Zhang Dr. Fabio Tonin Dr. Frank Hollmann 《Angewandte Chemie (International ed. in English)》2018,57(41):13648-13651
The photoenzymatic decarboxylation of fatty acids to alkanes is proposed as an alternative approach for the synthesis of biodiesel. By using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) we demonstrate the irreversible preparation of alkanes from fatty acids and triglycerides. Several fatty acids and their triglycerides are converted by CvFAP in near‐quantitative yield and exclusive selectivity upon illumination with blue light. Very promising turnover numbers of up to 8000 were achieved in this proof‐of‐concept study. 相似文献
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Olena Affolter Angelika Baro Sabine Laschat Peter Fischer 《Helvetica chimica acta》2007,90(10):1987-1999
A convenient synthetic route to enantiomerically pure tropane‐diol building blocks is described. The reaction sequence started from tropenone derivatives 1 , which were dihydroxylated to give 6,7‐dihydroxytropanone derivatives 2 . After introduction of the methoxymethyl (MOM) protecting group in diol 2a , a lipase‐mediated resolution of the resulting racemic mono‐MOM ether (±)‐ 5d with vinyl acetate and vinyl trifluoroacetate gave the acetates (?)‐ 6d and (?)‐ 6f , respectively, with 96–99% ee, and MOM ether (+)‐ 5d with up to 89% ee. Deacetylation of (?)‐ 6d afforded quantitatively MOM ether (?)‐ 5d with 99% ee, the absolute configuration of which was assigned via the modified Mosher method to be (R) at C(6). Enzymatic treatment of unprotected diol 2a with vinyl trifluoroacetate or alkoxycarbonylation resulted in the formation of Cs‐symmetrical products 9 and 12 rather than the desired desymmetrized derivatives. 相似文献
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用石油醚作溶剂在索氏提取器中分别提取东北小鲵体内组织(皮、肌肉及内脏)中的粗脂肪油,所得萃取液分别用饱和氯化钠溶液及纯水洗涤后加入无水硫酸钠脱水过夜.用旋转蒸发除去萃取液中有机溶剂,于是获得3份油状液体分别为从小鲵的皮、肌肉及内脏提取的脂肪酸.从中分取0.20 mL于氢氧化钾溶液中加甲醇做甲酯化处理,用乙醚-正己烷(2... 相似文献
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Leif‐A. Garbe Katja Morgenthal Katrin Kuscher Roland Tressl 《Helvetica chimica acta》2008,91(6):993-1007
Epoxides of fatty acids are hydrolyzed by epoxide hydrolases (EHs) into dihydroxy fatty acids which are of particular interest in the mammalian leukotriene pathway. In the present report, the analysis of the configuration of dihydroxy fatty acids via their respective hydroxylactones is described. In addition, the biotransformation of (±)‐erythro‐7,8‐ and ‐3,4‐dihydroxy fatty acids in the yeast Saccharomyces cerevisiae was characterized by GC/EI‐MS analysis. Biotransformation of chemically synthesized (±)‐erythro‐7,8‐dihydroxy(7,8‐2H2)tetradecanoic acid ((±)‐erythro‐ 1 ) in the yeast S. cerevisiae resulted in the formation of 5,6‐dihydroxy(5,6‐2H2)dodecanoic acid ( 6 ), which was lactonized into (5S,6R)‐6‐hydroxy(5,6‐2H2)dodecano‐5‐lactone ((5S,6R)‐ 4 ) with 86% ee and into erythro‐5‐hydroxy(5,6‐2H2)dodecano‐6‐lactone (erythro‐ 8 ). Additionally, the α‐ketols 7‐hydroxy‐8‐oxo(7‐2H1)tetradecanoic acid ( 9a ) and 8‐hydroxy‐7‐oxo(8‐2H1)tetradecanoic acid ( 9b ) were detected as intermediates. Further metabolism of 6 led to 3,4‐dihydroxy(3,4‐2H2)decanoic acid ( 2 ) which was lactonized into 3‐hydroxy(3,4‐2H2)decano‐4‐lactone ( 5 ) with (3R,4S)‐ 5 =88% ee. Chemical synthesis and incubation of (±)‐erythro‐3,4‐dihydroxy(3,4‐2H2)decanoic acid ((±)‐erythro‐ 2 ) in yeast led to (3S,4R)‐ 5 with 10% ee. No decano‐4‐lactone was formed from the precursors 1 or 2 by yeast. The enantiomers (3S,4R)‐ and (3R,4S)‐3,4‐dihydroxy(3‐2H1)nonanoic acid ((3S,4R)‐ and (3R,4S)‐ 3 ) were chemically synthesized and comparably degraded by yeast without formation of nonano‐4‐lactone. The major products of the transformation of (3S,4R)‐ and (3R,4S)‐ 3 were (3S,4R)‐ and (3R,4S)‐3‐hydroxy(3‐2H1)nonano‐4‐lactones ((3S,4R)‐ and (3R,4S)‐ 7 ), respectively. The enantiomers of the hydroxylactones 4, 5 , and 7 were chemically synthesized and their GC‐elution sequence on Lipodex® E chiral phase was determined. 相似文献
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Donald MacNeil Anna Sundberg Lari Vähäsalo Bjarne Holmbom 《Journal of Dispersion Science and Technology》2013,34(2):269-276
Resin and fatty acids (RFAs) play a key role in deinking processes of recycled fiber after precipitation by calcium. The distribution of RFAs between the lipophilic/colloidal phase and the water phase, here called pKlw, was determined by gas chromatography for different emulsions of TMP pitch and fatty acid soaps in the presence of calcium ions. Resin acids were at least partially dissolved at alkaline conditions even at high calcium ion concentrations, while fatty acids were only slightly soluble. The structure of the component was an important factor, along with the calcium content present which made fatty acids practically insoluble. 相似文献
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