[C21 steroids from the stems of Marsdenia tenacissima].

To study the C21 steroids of the stems of Marsdenia tenacissima (Roxb.) Wight et Arn, various chromatography methods were used for the isolation of the constituents and their structures were identified by spectral analysis. Eight C21 steroids were isolated from the CHCl3 extract, which were identified as 11alpha-O-tigloyl-17beta-tenacigenin B (1), 17beta-tenacigenin B (2), tenacigenoside A (3), 11alpha-O-2-methylbutyryl-12beta-O-acetyl tenacigenin B (4), tenacissoside H (5), marsdenoside A (6), tenacissoside G (7), and tenacissoside I (8). Among them, compound 1 is a new compound.