Prepapation of 20(R)-ginsenoside Rh_2 and Rg_3,anticancer principles from leaf saponins of panax notoginseng

20(R)-ginsenoside-Rh_2,ginsenoside-Rg_3 and 20(S)-ginsenoside Rg_3 were prepared by the hydrolysis of leaf saponins of Panax notoginseng(Burk.)F.H.Chen with solution of 50% acetic acid and then column chromatography on silica gel.Their structures were characterized by spectroscopic analysis,chemical degradation and comparison with authentic samples.