Abstract: ObjectiveTo discuss the effect of Saikosaponin a on mice's acute toxicity. MethodsMice's acute toxicities of different drug-delivery ways were tested respectively by the classic methods of acute toxicity. The MLD of ig and the LD50 of ip were calculated by a kilogram of body weight method, and continuously observing for 14 days.ResultsCaculated by Saikosaponin a, the MLD of ig is 790.5 mg·kg-1·d-1, the LD50 of ip is 72.511 mg·kg-1·d-1,and the 95% confidence interval is 66.523~78.894 mg·kg-1·d-1. The main acute toxicity symptoms and signs of dead mice are negligent action, then arising from rear limb weakness, unsteady gait, abdominal lying sleeping, drooping eyelids, lethargy, shortness of breath, continuous convulsions of hind legs, neurological inhibition, and eventually to death by ip. The surviving mice's weight gainings are more slower in 14 d obervation period and by anatomical observation of death mice, there are no other obvious abnormalities except hepatic pathological changes. ConclusionThe acute toxicity of intraperitoneal injection of Saikosaponin a is bigger than ig and we further confirm that Saikosaponin a is one of mainly toxical material compositions of Bupleurum. The "dose-time-poison"relationships of accumulated toxicity, biotransformation process in vivo and vitro, and the position and mechanism of toxic effects are to be further studied.

Key words: saikosaponin a, mice, acute toxicity, MLD, LD50