Antitrypanosomal Cycloartane Glycosides fromAstragalus baibutensis

Abstract

Baibutoside (5), a new cycloartane-type triterpene glycoside, has been isolated from the roots of Astragalus baibutensis along with four known glycosides, acetylastragaloside I (1), and astragalosides I, II, and IV (2-4, resp.). The structure elucidation of the compounds were achieved by a combination of one- and two-dimensional NMR techniques (DQF-COSY, HSQC, HMBC, and ROESY), and mass spectrometry (ESI-MS), where all the compounds were shown to have cycloastragenol (=(20R,24S)-3beta,6alpha,16beta,25-tetrahydroxy-20,24-epoxy-9,19-cyclolanostane) as aglycone. All compounds were tested for in vitro antiprotozoal activity. Compounds 1-4 displayed notable activity vs. Trypanosoma brucei rhodesiense, with acetylastragaloside I (1) being the most potent (IC50 9.5 microg/ml). Acetylastragaloside I (1) was also lethal to T. cruzi (IC50 5.0 microg/ml), and it is the first cycloartane-type triterpene with remarkable trypanocidal activity against both T. brucei rhodesiense and T. cruzi. However, it exhibits some cytotoxicity on mammalian cells.

Cycloartane-Type Saponins from Astragalus Tmoleus var. Tmoleus

“…Chemotaxonomic significance: According to the APG III (2009) classification [22], four families belong to the Fabales order, Fabaceae, Polygalaceae, Quillajaceae and Surinaceae. Among them, Fabaceae is the only family containing cycloartane-type (9,19 cyclo-lanostane) triterpenoids, which are common in the genus Astragalus [3][4][5][6][7][8][9][10][11][12]. Our results confirm that triterpene saponins with a cycloartane-type skeleton might be chemotaxonomically significant for the genus Astragalus [19].…”

“…Roots of these plants are used in Turkish folkloric medicine as an antiperspirant, diuretic, and tonic drug and for the treatment of diabetes mellitus, nephritis, leukemia, and uterine cancer [2]. Earlier investigations of Turkish Astragalus species resulted in the isolation of 45 cycloartane glycosides including five different aglycones and about 30 new compounds [3][4][5][6][7][8][9][10][11][12].…”

A Review of Recent Research Progress on the Astragalus Genus

“…As the summarized results shown in Table 1, Table 2 and Table 3 and Figure 1, Figure 2, Figure 3 and Figure 4, 46 kinds of Astragalus species have been studied for their chemical constituents in recent years [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,…”

“…So the 20,24-epoxycycloartane-type saponins like 64 – 107 are derived from secondary metabolic pathways. Also there are usually 20 R , 24 S ( 64 – 10 1 ) [6,10,12,13,22,26,27,28,39,42,43,44,45,46,47,48,49,50,51,52,53] or 20 S ,24 R ( 102 – 107 ) [54,55,56,57] steric configurations.…”