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1.
A method employing a wide pore polymeric reversed phase column has been developed for the separation of most of the chlorophylls and related compounds previously described as occurring in marine microalgae. The high selectivity toward molecular shape of this kind of stationary phase has enabled compounds of very similar structure, such as chlorophylls c1, c2 and Mg-divinylpheoporphyrin a5 monomethyl ester, and chlorophyll a and the phytol-substituted chlorophyll c-like pigments, which commonly coelute on monomeric bonded phases, to be resolved in a single run. Some of these pigments, formerly thought to be a single compound, have, in fact, been demonstrated to be groups of two or more. The method has been successfully applied to both algal cultures and natural sea water samples. When visible light absorbance detection was used, the method proved suitable for separation of various carotenoids. 相似文献
2.
Maculalactones A, B and C from the marine cyanobacterium Kyrtuthrix maculans are amongst the only compounds based on the tribenzylbutyrolactone skeleton known in nature and (+) maculalactone A from the natural source possesses significant biological activity against various marine herbivores and marine settlers. We now report a concise synthesis of racemic maculalactone A in five steps from inexpensive starting materials. Maculalactones B and C were synthesized by a minor modification to this procedure, and the synthetic design also permitted an asymmetric synthesis of maculalactone A to be achieved in around 85% ee. The (+) and (−) enantiomers of maculalactone A were assigned, respectively, to the S and R configurations on the basis of the chiral selectivity expected for catecholborane reduction of an unsymmetrical ketone in the presence of Corey's oxazoborolidine catalyst. Surprisingly, it appeared that natural (+) maculalactone A was biosynthesized in K. maculans in a partially racemic form, comprising ca. 90-95% of the (S) enantiomer and 5-10% of its (R) enantiomer. Coincidentally therefore, the percentage enantiomeric excess of the product obtained from asymmetric synthesis almost exactly matched that found in nature. 相似文献
3.
A new 20-membered macrolide designated exiguolide has been isolated from the marine sponge Geodia exigua, and its structure determined by interpretation of spectroscopic data. Exiguolide specifically inhibited fertilization of sea urchin (Hemicentrotus pulcherrimus) gametes but not embryogenesis of the fertilized egg. 相似文献
4.
5.
Alessio Porta 《Tetrahedron》2007,63(19):3989-3994
A highly enantioselective synthesis of the (8S,12S)-enantiomer of preclavulone A and its methyl ester is described featuring the Julia protocol for installing the (Z)-double bond in the lower chain. This procedure is suitable for the preparation of labeled preclavulone analogues for biosynthetic studies on marine clavulones. 相似文献
6.
Zeisler R 《Analytical and bioanalytical chemistry》2004,378(5):1277-1283
NIST maintains a portfolio of more than 1300 standard reference materials (SRM), more than a third of these relating to measurements in the biological and environmental fields. As part of the continuous renewal and replacement efforts, a set of new marine sediments has been recently developed covering organic and inorganic determinations. This paper describes the steps taken in sample preparation, homogeneity assay, and analytical characterization and certification with specific emphasis on SRM 2702 inorganics in marine sediment. Neutron activation analysis showed the SRM to be highly homogeneous, opening the possibility for use with solid sampling techniques. The certificate provides certified mass fraction values for 25 elements, reference values for eight elements, and information values for 11 elements, covering most of the priority pollutants with small uncertainties of only several percent relative. The values were obtained by combining results from different laboratories and techniques using a Bayesian statistical model. An intercomparison carried out in field laboratories with the material before certification illustrates a high commutability of this SRM.Electronic Supplementary Material Supplementary material is available in the online version of this article at 相似文献
7.
Two unprecedented degraded sterols, aplykurodinone-1 (1) and -2 (2), have been isolated from the skin of the marine anaspidean Syphonota geographica, collected along the coasts of Greece. The structures and the relative stereochemistry were established by spectroscopic analysis and confirmed by chemical correlation with related known compounds. 相似文献
8.
Wakako Tsugawa Shuichi Horiuchi Mitsuharu Tanaka Hitoshi Wake Koji Sode 《Applied biochemistry and biotechnology》1996,56(3):301-310
A novel glucose dehydrogenase (GDH) from a marine bacteriumCytophaga marinoflava IFO 14170 was isolated from its membrane fraction. This GDH catalyzes the oxidation of a hydroxy group of glucose, but does
not react in its C-l position. This enzyme is composed of a single peptide with a mol wt of 67,000. The GDH can react under
high salinity. The optimum pH is around 8.0, showing a typical property of marine bacterial enzymes. Using this novel enzyme,
an enzymatic determination of 1,5-anhydro-D-glucitol (1,5AG) utilizing 2,6-dichrolophenolindophenol (DCIP) and phenazine methosulfate
(PMS) as electron mediators was caried out. A good linear correlation was observed from 0.5 mM to 4 mM of 1,5AG. 相似文献
9.
J. Stephen Clark Rebecca P. Freeman Andrew W. Thomas Claire Wilson 《Tetrahedron letters》2004,45(47):8639-8642
A concise enantioselective synthesis of the cyclic ether core of the marine natural product (+)-laurenyne has been accomplished using ring-closing metathesis for medium-ring construction. 相似文献
10.
J. M. Bayona J. Grimalt J. Albaigs W. Walker B. W. de Lappe R. W. Risebrough 《Journal of separation science》1983,6(11):605-611
Analyses of hydrocarbon fractions from different areas of the marine environment are described to illustrate the possibilities and limitations of high resolution gas chromatography (HRGC) in the analysis of environmental samples. Examples are given of dissolved, particulate, and sedimentary hydrocarbons and organochlorine compounds; the importance of an adequate sampling of the marine environment is stressed. HR chromatographic profiles obtained in two columns of low and high polarity (SE-52 and PEG 20M) permit the sources and transport pathways of both natural and anthropogenic hydrocarbons to be traced. Analysis of tissues of marine mammals, which metabolize or excrete many of the biogenic and petrogenic hydrocarbons present in other areas of the marine environment, may provide an opportunity to obtain relatively clean profiles of many anthropogenic compounds of interest. The plotting of mass chromatograms from data compiled by COM-GC-MS remains the most appropriate method for the conclusive indentification of these compounds. 相似文献