The invention provides compounds of structural formula I or a salt thereof, and total saponins comprising such compounds in the preparation of anti-tumor agents. The present study of this invention showed that the compounds of formula I and the related total saponins had strong inhibitory effects on the proliferation of several human tumor cell lines, such as hepatocarcinoma, gastric cancer, colon cancer, breast cancer and melanoma cell lines, also the combination of structural formula I and the chemical agents could fairly well reduce toxicity and increase treatment effects.
