180 sarcoma cells into ICR mice. Whilein vitro activity against tumor cells was assayed by the growth inhibition of cell lines of S180sarcoma,Smcc 7721,and HeLa.The effects of EPAH on immune function were evaluated by the influence on the thymus,spleen,and the number of lympho-cytes in blood stream,the influence on proliferation of lymphocytes,the killing activity of NK cells,and the production of NO,IL-1β,and TNF-α. Results EPAH inhibited in vivo S180sarcoma growth with the highest inhibitory rate of 66.79% and 47.93%in the test mice of pretreatment and simultaneous treatment,respectively.EPAH also displayedin vitroactivity against the test cell lines with the highest inhibitory rate being more than 60%at a concentration of 100μg/mL.EPAH was found to affect the immune function in mice including increasing the weight of thymus,spleen,and the number of lymphocytes in the blood stream,accele-rating the proliferation of lymphocytes,enhancing the killing activity of NK cells,and stimulating the production of NO,IL-1β,and TNF-α by macrophages.Conclusion EPAH is an effective antitumor agent.It inhibites the tumor cells directly and hence the growth of tumor.Its antitumor activity is probably realized by increasing the weight of immune organs and the number of immunocytes as well as lymphocyte proliferation,enhancing the killing activity of NK cells,facilitating the production of N0 and related cytok-ines in tumor-bearing mice."/>