Anticancer effect of a Kampo preparation Daikenchuto.

No traditional Japanese and Chinese herbal preparations have been shown to be effective antitumor agents, and a Japanese herbal therapy (Kampo medicine) for cancer that causes fewer adverse drug reactions than orthodox pharmaceuticals is desired. Our present study demonstrated that a Kampo preparation Daikenchuto (DKT) exerts an antitumor effect against various cancer cells. We also discovered an antitumor factor in Japanese Zanthoxylum peel, which is an ingredient of DKT. Breast, esophageal, gastric, and colon cancer cell lines were individually incubated with DKT for 1-72 h, followed by assessment of tumor growth inhibition by MTT assay. The cancer cells were also analyzed for apoptotic changes after DKT treatment. Nude mice were used to establish a model of gastric cancer tumor growth and peritoneal disseminated metastasis, in which the number of peritoneal disseminations was evaluated after oral administration of DKT for 4 weeks. In addition, the antitumor effects of the individual DKT ingredients (viz., ginseng, Japanese Zanthoxylum peel, and processed ginger) and other Kampo preparations were also analyzed. The antitumor effect of DKT was demonstrated in gastric, breast, esophageal, and colon cancer cells. DKT treatment induced apoptosis in these cells. Oral administration of DKT had a tendency to reduce the growth and significantly reduced the peritoneal dissemination of gastric cancer in the nude mouse model compared with control. DKT exhibited a higher antitumor effect than other Kampo preparations. Furthermore, Japanese Zanthoxylum peel, an ingredient of DKT, showed a particularly potent antitumor effect. Our study indicated that DKT is useful as a Kampo preparation for cancer therapy. We also showed that Japanese Zanthoxylum peel, an ingredient of DKT, contains an antitumor factor.