Antitrypanosomal cycloartane glycosides from Astragalus baibutensis.
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.
Caliş
Ihsan
I
Department of Pharmacognosy, Faculty of Pharmacy, Hacettepe University, TR-06100 Ankara.
Koyunoğlu
Semra
S
Yeşilada
Akgül
A
Brun
Reto
R
Rüedi
Peter
P
Taşdemir
Deniz
D
D000818:Animals; D000981:Antiprotozoal Agents / Q000737:chemistry* / Q000494:pharmacology*; D027883:Astragalus Plant / Q000737:chemistry*; D006027:Glycosides / Q000737:chemistry* / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D014315:Triterpenes / Q000737:chemistry*; D014345:Trypanosoma / Q000187:drug effects; D016833:Trypanosoma brucei rhodesiense
D000981:Antiprotozoal Agents; D006027:Glycosides; D014315:Triterpenes; C085352:cycloartane