Secondary Metabolites from the Roots of Astragalus trojanus

Abstract

Six novel cycloartane-type glycosides were isolated from the roots of Astragalus trojanus. Two of these, compounds 1 and 2, have (20R, 24S)-epoxy-3beta,6alpha,16beta,25-tetrahydroxycycloartane as the aglycon, while compounds 3-6 possess 3beta,6alpha,16beta,(24S), 25-pentahydroxycycloartane as the aglycon. The saccharide moieties linked to the C-3, C-6, and C-24 or C-25 positions of the aglycons in 1-6 contained either xylopyranose, glucopyranose, rhamnopyranose, or arabinopyranose units. Structure elucidation of compounds 1-6 was accomplished through the extensive use of 1D and 2D NMR techniques. In addition, a new oleanene glycoside (7) and a new tryptophan derivative (8) were also isolated and characterized.

Trojanosides I-K: New Cycloartane-Type Glycosides from the Aerial Parts of Astragalus trojanus.

“…Full assignments of the proton and carbon signals of the aglycon part of 1 were secured from its double quantum filtered correlation spectroscopy (DQF-COSY) and heteronuclear multiple quantum correlation spectroscopy (HMQC) spectra. The resonances assigned to the sapogenol moiety were in good agreement with trojanoside A, 10) . In order to substantiate our findings, deacetyl derivative of 1 was obtained by an alkaline deacetylation.…”

“…[7][8][9][10][11][12][13] We previously reported the isolation and the structure determination of trojanosides A-H from Astragalus trojanus. 10,11) In our continuing search, we have isolated three new cycloartane-type triterpene glycosides, named as trojanosides I-K (1, 2, 5), from the aerial parts of Astragalus trojanus. Here we report the isolation and the structural elucidation of 1, 2 and 5.…”

“…Taking into account the results of our comprehensive 1 Hand 13 C-NMR studies and previous knowledge derived from metabolites isolated from the genus Astragalus, [7][8][9][10][11][12][13] the main features of a cycloartane-type triterpene were evident: characteristic signals due to cyclopropane-methylene protons as an AX system (d 0.23, 0.64, J AX ϭ4. Full assignments of the proton and carbon signals of the aglycon part of 1 were secured from its double quantum filtered correlation spectroscopy (DQF-COSY) and heteronuclear multiple quantum correlation spectroscopy (HMQC) spectra.…”

Effects of triterpene saponins from Astragalus species on in vitro cytokine release

“…The names of compounds and relevant references are as follows (Figs. 1-3): brachyoside A (1) (Bedir et al, 1998a); brachyoside C (2) (Bedir et al, 1998a(Bedir et al, , 1999b; cyclocanthoside E (3) (Ç alis et al, 1999); cycloastragenol (4); brachyoside B (5) (Bedir et al, 1998a(Bedir et al, , 1999a; cyclocephaloside II (6) (Bedir et al, 1998a); astragaloside I (7) (Ç alis et al, 1997); astragaloside II (8) (Bedir et al, 1999b); astragaloside I (7) (Ç alis et al, 1997); astragaloside VII (10) (Bedir et al, 1999b); trojanoside A (11) (Bedir et al, 1999a); trojanoside H (12) (Bedir et al, 1999b); cyclocephaloside I (13) (Bedir et al, 1998b)…”

Two New Acylated Tridesmosidic Saponins from Astragalus armatus

“…By analysis of all the 1D-and 2D-NMR spectra of 1, the aglycone was identified as (3b,6a,16b, 20R,24S)-20,24-epoxycycloartane-3,6,16,25-tetrol, i.e., cycloastragenol, which is com- The isolation from the roots of A. membranaceus of compounds closely related to 1 and 2 with a b-d-glucopyranosyloxy instead of a b-d-xylopyranosyloxy group at position 6 of the aglycone has been reported [9]. From the roots of A. trojanus, a not acetylated tridesmoside of cycloastragenol having the same sugars than 1 and 2 (Xyl I, Xyl II, Glc) has been obtained [10]. Thus, A. armatus appears to be differentiated from the two other species by a 6-O-Xyl moiety combined with an acetylated 3-O-Xyl moiety.…”