RESUMO
Extracts of Toona sinensis shoots were studied to identify the precursors of volatile sulfur-containing flavor molecules. T. sinensis was found to contain new compounds (S,S)-γ-glutamyl-(cis-S-1-propenyl)thioglycine, 1, (S,S)-γ-glutamyl-(trans-S-1-propenyl)thioglycine, 2, and γ-glutamyl-(cis-S-1-propenyl)-cysteine, 3. The structures of these compounds were determined by interpretation of multistage mass spectrometric (MS(n)), 1D, and 2D NMR data. The absolute configuration of 1 was established by comparison of experimental with computed infrared and vibrational circular dichroism spectra. Because of the flexibility of the molecule and the novelty of the structure, the configuration was further confirmed by X-ray crystallography. Compounds 1 and 2 are the first examples of norcysteine-containing metabolites reported from nature. They may release thiols via cleavage of the amide bond by proteases, followed by spontaneous decomposition of the resulting unstable alk(en)yl norcysteine moiety.
Assuntos
Cisteína/análogos & derivados , Meliaceae/química , Extratos Vegetais/química , Verduras/química , Dicroísmo Circular , Cristalografia por Raios X , Cisteína/metabolismo , Espectroscopia de Ressonância Magnética , Meliaceae/metabolismo , Estrutura Molecular , Extratos Vegetais/metabolismo , Verduras/metabolismoRESUMO
Jatrophalactam (1), a novel diterpenoid lactam possessing an unprecedented 5/13/3 tricyclic skeleton, was isolated from the roots of Jatropha curcas. The structure and relative configuration of jatrophalactam (1) were elucidated by extensive spectroscopic analysis and further determined by a single-crystal X-ray diffraction.
Assuntos
Diterpenos/isolamento & purificação , Jatropha/química , Lactamas/isolamento & purificação , Cristalografia por Raios X , Diterpenos/química , Diterpenos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Lactamas/química , Lactamas/farmacologia , Conformação Molecular , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Raízes de Plantas/químicaRESUMO
A new Daphniphyllum alkaloid daphnicyclidin L (1), containing a rare cyclopentadienyl anion, which is stabilized as a zwitterion by an internal iminium counterion, was isolated from the stem barks of Daphniphyllum macropodum Miq., together with four known alkaloids: daphnicyclidin D (2), daphnicyclidin H (3), deoxyyuzurimine (4), and yuzurimine (5). The structures were elucidated on the basis of spectroscopic data. The configuration of 1 was elucidated by single-crystal X-ray diffraction crystallography.