The purpose of this study is to examine the toxic effects caused by xanthine oxidase/hypoxanthine(XO/HX) and the effects of herbal extracts such as Jingansikpungtang(JST) and Gamijingansikpungtang(GJST) on the treatment of the toxic effects. For this purpose, experiments with the cultured nerve cells from the spinal motor neurons of new born mice were done. The results of these experiments were as follows. XO/HX, a oxygen radical-generating system, decreased the survival rate of the cultured cells on NR assay. MTT assay, the amount of neurofilaments and increased the amount of total proteinand increased the lipid peroxidation and the amount of LDH JST has the efficacy of increasing the amount of neurofilaments and total protein, and decreasing the lipid peroxidation and the amount of LDH, GJST has efficacy of increasing the amount of neurofilaments and total protein, and decreasing lipid peroxidation and the amount of LDH. From the above results, it is concluded that JST and GJST have marked efficacy as a treatment for the damages caused in the XO/HX mediated oxidative stress. And JST and GJST are thought to have certain pharmacologicall effects. Further clinical study of this pharmacological effects of JST and GJST should be complemented.