Abstract: The molecular structure of (25R,26R)-26-methoxyspirostan-5-ene-3-β-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopy ranosyl-(1→6)]-β-D-glucopyranoside, was elucidated by 1D NMR and 2D NMR for the first time, and its complete assignment of 1H and 13C NMR chemical shifts were also obtained. In particular, the analytical method of combining 1D TOCSY and 1D NOESY was applied to analyze overlapped 1H NMR signal of the sugar in detail, and a way to assign NMR signal of the sugar of steroidal saponin completely was established. Meantime, the quantitative determination of the above compound by 1H NMR has been developed in this paper. The optimum experimental conditions has been described. The linear regression coefficient was 0.9998, and RSD was 0.58％, its efficacy has been proved through the experiments of repeatability and linearity. This method is simple, reliable and accurate, and without reference compound. The data obtained could be very important for structure identification and structure-activity relationship research.

Key words: Lily, steroidal saponin, 1D TOCSY, 1D NOESY, quantitative determination