Isolation of Nor-secofriedelanes from the Sedative Extracts of Galphimia glauca
| Autor: | Rogelio Pereda-Miranda, Jorge Lozada-Lechuga, Mabel Fragoso-Serrano, Alexandre T. Cardoso Taketa, María Luisa Villarreal |
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| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular medicine.drug_class Molecular Conformation Pharmaceutical Science Galphimia glauca Pharmacognosy High-performance liquid chromatography Malpighiaceae Analytical Chemistry Triterpene Drug Discovery Galphimia medicine Hypnotics and Sedatives Mexico Nuclear Magnetic Resonance Biomolecular Chromatography High Pressure Liquid Pharmacology chemistry.chemical_classification Plants Medicinal Chromatography Molecular Structure biology Organic Chemistry biology.organism_classification Complete resolution Triterpenes Terpenoid Complementary and alternative medicine chemistry Sedative Molecular Medicine |
| Zdroj: | Journal of Natural Products. 67:644-649 |
| ISSN: | 1520-6025 0163-3864 |
| Popis: | Preparative-scale recycling HPLC was used for the complete resolution of a complex mixture of nor-secofriedelanes into five major peaks (I-V) from the sedative methanolic extracts prepared from the aerial parts of Galphimia glauca. Argentation chromatography was used to show peaks I, II, IV, and V to be mixtures of isomers around the E-ring double bond, represented by the endocyclic C-20, C-21 double-bond isomers, galphimines A (3), B (1), D (4), and E (2), and the C-20, C-29 exocyclic forms, galphimines F-I (5-8). Galphimine C (9), isolated from peak III, corresponded to the C-19, C-20 double-bond isomer of the previously known major sedative constituent galphimine B. The characterization of all the new triterpenes (3-9) was performed primarily by high-field NMR spectroscopy. Comparison between experimental and calculated (1)H-(1)H vicinal coupling constants and the analysis of molecular mechanics structures revealed that the ring B of these compounds exists in a boatlike conformation. The absolute configuration for the stereogenic carbinol center at C-4 was established by the application of the Mosher ester derivatization technique carried out in NMR tubes. |
| Databáze: | OpenAIRE |
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