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Hydrogen/Deuterium Exchange Mass Spectrometry for Probing the Isomeric Forms of Oleocanthal and Oleacin in Extra Virgin Olive Oils.
Molecules
February 2023
Dipartimento di Chimica, Università degli Studi di Bari "Aldo Moro", Via E. Orabona 4, 70126 Bari, Italy.
Reversed-phase liquid chromatography and electrospray ionization with Fourier-transform single and tandem mass spectrometry (RPLC-ESI-FTMS and FTMS/MS) were employed for the structural characterization of oleocanthal (OLEO) and oleacin (OLEA), two of the most important bioactive secoiridoids occurring in extra virgin olive oils (EVOOs). The existence of several isoforms of OLEO and OLEA was inferred from the chromatographic separation, accompanied, in the case of OLEA, by minor peaks due to oxidized OLEO recognized as oleocanthalic acid isoforms. The detailed analysis of the product ion tandem MS spectra of deprotonated molecules ([M-H]) was unable to clarify the correlation between chromatographic peaks and specific OLEO/OLEA isoforms, including two types of predominant dialdehydic compounds, named , containing a double bond between carbon atoms C8 and C10, and a group of diasteroisomeric closed-structure (i.
View Article and Find Full Text PDFSynthesis of (Z)-alkene and (E)-fluoroalkene-containing diketopiperazine mimetics utilizing organocopper-mediated reduction-alkylation and diastereoselectivity examination using DFT calculations.
J Org Chem
May 2006
Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
We have carefully examined the organocopper-mediated reduction-alkylation of gamma-acetoxy or gamma,gamma-difluoro-alpha,beta-unsaturated-delta-lactams for the synthesis of (Z)-alkene- or (E)-fluoroalkene-containing diketopiperazine mimetics. Reduction of acetates 2, 12, 14, and difluorolactam 18 with higher-order cuprate reagents (Me3CuLi2 x LiI x 3 LiBr), followed by trapping the resulting metal dienolate with an electrophile in a one-pot procedure gave alpha-alkylated-beta,gamma-unsaturated-delta-lactams in good yields. Because of side-chain steric repulsion, we found that alkylation using relatively large electrophiles such as BnBr gave mostly 3,6-trans isomers by kinetic trapping of metal enolates.
View Article and Find Full Text PDFLanosterol 14-demethylase activity expressed in rat brain microsomes.
J Biochem
November 1996
Department of Bioengineering, Faculty of Engineering, Soka University, Tokyo.
The occurrence of sterol 14-demethylase in rat brain microsomes was confirmed. The brain microsomes from adult rats converted lanosterol into its 14-demethylated products, 4,4-dimethylcholesta-8, 24-dienol, and 4,4-dimethylcholesta-8,14,24-trienol, in the presence of NADPH and molecular oxygen. This metabolism of lanosterol was inhibited by carbon monoxide and ketoconazole, a potent inhibitor of sterol 14-demethylase P450 (P45014DM or CYP51).
View Article and Find Full Text PDFSterols of the spongeTethya amamensis: Occurrence of (24E)-24-ethylidenecholesta-5,7-dienol, (24E)-24-propylidenecholesta-5,7-dienol, and (24Z)-24-propylidenecholesta-5,7-dienol.
Lipids
March 1983
Faculty of Fisheries, University of Kagoshima, 4-50-20 Shimoarata, 890, Kagoshima, Japan.
The spongeTethya amamensis, collected from Kagoshima Bay, Japan, contained at least 24 sterols, including Δ(5)-sterols (82.2% of total sterols) and Δ(5, 7)-sterols (17.8%).
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