Immunopontentiating activities of the purified polysaccharide from evening primrose in H22 tumor-bearing mice

► Evening primrose is an Oenothera species native to North America. ► The polysaccharide EPP was isolated from evening primrose for the first time. ► EPP exhibits a potent inhibitory effect on transplanted H22 tumors in mice. ► EPP improve the immune status of tumor-bearing mice. ► There is no toxicity on the liver and kidney post EPP treatment in mice.