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排序方式: 共有103条查询结果,搜索用时 297 毫秒
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Yessotoxins (YTXs) are a group of polyether toxins which have been previously reported as responsible for seafood contamination in several places worldwide. Despite their toxicity, which is not yet fully discussed, YTXs have been reported as an interference in the success of mouse bioassay for the determination of diarrhetic shellfish poisoning (DSP) toxins, and therefore, efficient and reliable analytical methodologies are required to evaluate their presence, avoiding false positives for DSP. High-performance capillary electrophoresis (HPCE) is presented in this work as an alternative to HPLC technique widely used for the analysis of YTXs. Improvements in the applicability of HPCE have been carried out through the development of different CE modes as well as different detection modes. With this aim, micellar electrokinetic chromatography (MEKC) has been considered for an increased selectivity while an increased sensitivity was achieved by using sample stacking. Moreover, the coupling of CE with mass spectrometry allowed the confirmation of YTXs present in the contaminated samples evaluated in this work. The results obtained showed the potential of CE as an alternative to HPLC for the analysis of YTXs present in naturally contaminated samples. 相似文献
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Jian‐Fei Bai Kento Yasumoto Taichi Kano Keiji Maruoka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8990-8993
A highly enantioselective synthesis of 1,4‐enynes is described that proceeds through an organocatalytic reaction between propargyl alcohols and trialkenylboroxines. Our strategy relies on acid‐mediated generation of the carbocationic intermediate from propargyl alcohols followed by enantioselective alkenylation with trialkenylboroxines. A range of chiral 1,4‐enynes were obtained in moderate to good yields with high levels of enantioselectivity. Use of a highly acidic chiral N‐triflyl phosphoramide catalyst, which has two distant Lewis basic oxygen atoms, was found to be crucial for both high reactivity and selectivity in the present reaction. 相似文献
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The chemistry and biological function of natural marine toxins 总被引:2,自引:0,他引:2
Yasumoto T 《Chemical record (New York, N.Y.)》2001,1(3):228-242
Studies on ciguatera fish poisoning led to clarification of the absolute stereochemistry of ciguatoxin, gambierol, gambieric acids, and maitotoxin. Anisotropic NMR reagents and fluorometric chiral HPLC reagents were effectively used together with synthesis of partial structures. Structures of 16 ciguatoxin congeners were successfully elucidated by FAB/MS/MS using samples of 5 microg or less. Stereochemical assignments were also achieved on dinophysistoxin-1, pectenotoxins, yessotoxins, polycavernoside-A, azaspiracid, and prymnesins. The toxins possessed poly-cyclic-ether structures and originated from unicellular algae. Biological functions are briefly described. 相似文献
37.
This paper describes an efficient, practical synthesis of 3,5-bis(trifluoromethyl)benzylamine via biomimetic transamination of 3,5-bis(trifluoromethyl)benzaldehyde with benzylamine. From a synthetic standpoint the reported procedure is highly operationally convenient and scalable as it does not require any chromatographic purification of the intermediate products. 相似文献
38.
Cyclic Guanidine Compounds from Toxic Newts Support the Hypothesis that Tetrodotoxin is Derived from a Monoterpene 下载免费PDF全文
Dr. Yuta Kudo Prof. Dr. Takeshi Yasumoto Prof. Dr. Dietrich Mebs Dr. Yuko Cho Prof. Dr. Keiichi Konoki Prof. Dr. Mari Yotsu‐Yamashita 《Angewandte Chemie (International ed. in English)》2016,55(30):8728-8731
The biosynthesis of tetrodotoxin (TTX), a potent neurotoxin consisting of a 2,4‐dioxaadamantane skeleton and a guanidine moiety, is an unsolved problem in natural product chemistry. Recently, the first C5–C10 directly bonded TTX analogue, 4,9‐anhydro‐10‐hemiketal‐5‐deoxyTTX, was obtained from toxic newts and its carbon skeleton suggested a possible monoterpene origin. On the basis of this hypothesis, screening of predicted biosynthetic intermediates of TTX was performed using two MS‐guided methods. Herein, five novel cyclic guanidine compounds from toxic newts are reported which commonly contain a cis‐fused bicyclic structure including a six‐membered cyclic guanidine. These structures could be biosynthetically derived from geranyl guanidine through oxidation, cyclization, and/or isomerization steps. LC–MS analysis confirmed the widespread distribution of the five novel compounds in toxic newt species. These results support the hypothesis that TTX is derived from a monoterpene. 相似文献
39.
Taniguchi M Uchio Y Yasumoto K Kusumi T Ooi T 《Chemical & pharmaceutical bulletin》2008,56(3):378-382
New brominated fatty acids (3, 5-8, 10) and new sterol esters (14-16) have been isolated from an unidentified marine sponge collected in Papua New Guinea. Their structures were determined on the basis of their spectroscopic data. A major component of the marine sponge (1) was tested for activities against Arutemia salina and some fungi. 相似文献
40.
Yasumoto K Nishigami A Aoi H Tsuchihashi C Kasai F Kusumi T Ooi T 《Chemical & pharmaceutical bulletin》2008,56(1):133-136
New aliphatic sulfates and sulfamates were isolated from Daphnia pulex as the Daphnia kairomones that induced morphological defense of a freshwater phytoplankton Scenedesmus gutwinskii var. heterospina (NIES-802). Their structures were determined by spectroscopic and synthetic studies. 相似文献