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6. Sterochemical analysis of hydroxylated docosahexaenoates produced by human platelets and rat brain homogenate

Author

Norman Salem, Shingu T, John W. Karanian, and H.Y. Kim

Subjects
Blood Platelets, Docosahexaenoic Acids, Stereochemistry, Lipoxygenase, Biochemistry, High-performance liquid chromatography, Gas Chromatography-Mass Spectrometry, Mass Spectrometry, Blood cell, Endocrinology, Structural isomer, medicine, Animals, Humans, Platelet, Chromatography, High Pressure Liquid, Chromatography, Chemistry, Brain, Stereoisomerism, Chiral phase, Rat brain, Rats, medicine.anatomical_structure, Docosahexaenoic acid, Racemic mixture
Abstract

The stereochemical configuration of hydroxylated products of docosahexaenoic acid (22:6w3) formed by human platelets and rat brain homogenate were characterized for the first time. Chiral phase HPLC was employed along with autooxidized 22:6w3 as reference material. The 14- and 11-hydroxy 22:6w3 (HDHE) products produced by human platelets were in the S configuration. Rat brain homogenate produced all of the ten possible positional isomers when incubated with 22:6w3. Their retention behavior on the reversed and chiral phase HPLC columns and GC/MS/EI analysis indicated that they were 20-, 17-, 16-, 14-, 13-, 11-, 10-, 8-, 7- and 4-HDHE. However, stereochemical analysis revealed that each positional isomer was a racemic mixture, suggesting that these were not formed by lipoxygenation but mainly by peroxidation process.

Published
1990
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7. MARRUBINONE-A AND MARRUBINONE-B, NEW LABDANE DITERPENOIDS FROM MARRUBIUM-ASTRACANICUM (LABIATAE)

Author

FUJITA, T, TAKEDA, Y, TAKAISHI, Y, IIDA, A, YESILADA, E, SEZIK, E, SHINGU, T, HONDA, G, TABATA, M, MIHARA, T, and TANAKA, Y

Abstract

Two new labdane diterpenoids, marrubinones A (1) and B (2), were isolated from aerial parts of Marrubium astracanicum collected in Turkey. Compounds 1 and 2 were mostly characterized by two-dimensional NMR. For determination of the absolute configuration, the modified Mosher's method was applied to the 12-hydroxy forms of 1 and 2. Compounds 1 and 2 are pentacyclic diterpenoids, which differ from each other only in the stereochemistry at C-13, and they were identified as 9 alpha,13S:15,16-diepoxy-12-oxo-14-labden-19,6 beta-olide and 9 alpha,13R:15,16-diepoxy-12-oxo-14-labden-19,6 beta-olide, respectively.

Published
1995

41. ChemInform Abstract: Fungal Metabolites. Part 3. Structural Elucidation of Antibiotic Peptides, Trichosporin‐B‐IIIb, ‐IIIc, ‐IVb, IVc, ‐IVd, ‐VIa and ‐VIb from Trichoderma polysporum. Application of Fast‐Atom Bombardment Mass Spectrometry/Mass Spectrometry to Peptides Containing a Unique Aib‐Pro Peptide Bond.

Author

IIDA, A., primary, OKUDA, M., additional, UESATO, S., additional, TAKAISHI, Y., additional, SHINGU, T., additional, MORITA, M., additional, and FUJITA, T., additional

Published
1991
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47. Discovery of Novel Brain Lipoxygenase Products Formed from Docosahexaenoic Acid (22:6w3).

Author

Shingu, T., Karanian, J. W., Kim, H. Y., Yergey, J. A., and Salem, N.

Abstract

It is known that alcohol exposure leads to a decline in brain docosahexaeonate (22:6w3). We hypothesized that alcohol could stimulate the metabolism of this polyunsaturated fatty to bioactive products. Several oxidized products of 22:6w3 were indeed observed when rat brain homogenate was incubated with 14C22:6w3 in vitro. A similar group of metabolites was formed in vivo from 14C-22:6w3 injected into the lateral ventricle. These metabolites were characterized by thermospray- and GC/MS as well as by the synthesis of standards using purified enzymes. Platelet lipoxygenase also proved useful in identifying one of the brain metabolites and served as a source of enzyme for preparative studies. Their physiological effects on smooth muscle tone and platelet aggregation will be presented. [ABSTRACT FROM PUBLISHER]

Published
1988
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