Abstract: Two triterpenoid sapogenols Ⅰ and Ⅱ were obtained from the acidic hydrolysis products of the total saponin mixture of oxytropis ochrocephala bunge.Compound Ⅰ, the genuine sapogenol of the total saponin mixture, was identified as soyasapogenol B; compound Ⅱ, a new type artifact sapogenol, was determined to be olean-13(18)-ene-22a-chloro-33, 24-diol.We also isolated a minor saponin Ⅲ which was identified as 3-O-[β-D-glucopyranosyl(1→2)-β-D-glucuronopyranosyl] soyasapogenol B.This paper deals with the identification of compound Ⅰ, Ⅱ and Ⅲ, as well as the chemical transformations between them.The ¹³C NMRsignals of compound Ⅰ and Ⅱ were also assigned by using¹³C, ¹Hspin couplings and PRFT-¹³C NMRtechnique.

Key words: Oxytropis, Saponins, Soyasapogenol B