Steroidal saponins from the aerial parts of Tribulus alatus Del.

Six steroidal glycosides (1-6) were isolated from the aerial parts of Tribulus alatus Del. (Zygophyllaceae), together with one known cholestane, one spirostane, and six flavonol glycosides. Among them, 1 and 2 possess a furostane-type aglycone, 3 and 6 a cholestane structure, and 4 and 5 a spirostane skeleton. Their structural elucidation was accomplished by extensive spectroscopic methods including 1D (1H, 13C, 13C DEPT, TOCSY, ROESY) and 2D NMR experiments (DQF-COSY, HSQC, HMBC) as well as ESI-MS analysis.