C21 steroid derivatives from the Dai herbal medicine Dai-Bai-Jie, the dried roots of Marsdenia tenacissima, and their screening for anti-HIV activity.

Twenty-three new C21 steroidal glycosides, marstenacissides C1-C10 (1-10), D1-D7 (11-17) and E1-E6 (18-23), and four new C21 steroids, 11α,12ß-O-ditigloyl-tenacigenin C (24), 11α-O-benzoyl-12ß-O-tigloyl-tenacigenin C (25), 11α-O-tigloyl-12ß-O-benzoyl-tenacigenin C (26) and 11α-O-tigloyl-12ß-O-benzoyl-marsdenin (27), were isolated from the Dai herbal medicine Dai-Bai-Jie, derived from the roots of Marsdenia tenacissima. The chemical structures of all compounds were established by spectroscopic techniques, including high-resolution mass spectrometry and NMR spectroscopy, as well as by comparison with reported spectral data. The anti-HIV activities of these compounds were screened, and the compounds obtained displayed inhibitory effects against HIV-1 with inhibition rates of 36.4-81.3% at 30 µM.