A cycloartane triterpene 3β, 16β diglucoside from Astragalus trigonus and its non natural 6-hydroxy epimer

• Published in: Phytochemistry (Oxford) Vol. 49; no. 3; pp. 845 - 852
• Main Authors: Verotta, Luisella, Orsini, Fulvia, Tatò, Marco, El-Sebakhy, Nadia A., Toaima, Soad M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.10.1998; Elsevier
• Subjects: Biological and medical sciences; Chemical constitution; Fundamental and applied biological sciences. Psychology; Plant physiology and development; Astragalus trigonus; 3β, 6β, 16β trihydroxy 9, 19 cyclolanost-24-ene 3β, 16β diglucopyranoside; roots; cycloartane triterpene glucoside; 3β, 6α, 16β trihydroxy 9, 19 cyclolanost-24-ene 3β, 16β diglucopyranoside; Fabaceae; Leguminosae; Molecular structure; Dicotyledones; Angiospermae; Glucoside; Triterpene; Isolation; Spermatophyta; Medicinal plant
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/S0031-9422(97)00869-8

Compound ( 1) was isolated from A. trigonus and its structure elucidated by spectral means. Its 6-hydroxy epimer was prepared. The conformational preferences of both compounds were studied by molecular modeling techniques. The detailed investigation of Astralagus trigonus DC roots, led to the isolation of a new cycloartan-3β, 16β diglucoside, whose structure was elucidated by extensive use of 1D- and 2D- high field (600 MHz) NMR techniques. The NaBH 4 reduction of the natural 6-oxo 3β, 16β diglucoside, previously isolated from the same plant, afforded the 6-epi-derivative of the new compound. The conformational preference of both these compounds has been investigated by high field 1H NMR spectroscopy and molecular modeling techniques.