Antitumor effect of agrimoniin, a tannin of Agrimonia pilosa Ledeb., on transplantable rodent tumors.

The effect of agrimoniin, a tannin contained in Agrimonia pilosa LEDEB., on ascites type and solid type rodent tumors was investigated. When agrimoniin was intraperitoneally (i.p.) administered at dosages over 10 mg/kg before or after the MM2 cell i.p. inoculation, this tannin almost completely rejected the tumor growth in the mice. This tannin prolonged the life span of mice bearing MM2 or cured by the intravenous or per oral pre- or postmedication. Agrimoniin also inhibited the growth of MH134 and Meth-A solid type tumors. Agrimoniin showed strong cytotoxicity on MM2 cells in vitro, but the activity was diminished to about 4% of the initial activity by the addition of fetal calf serum to the culture. On the other hand, i.p. injection of agrimoniin increased the number of peripheral white blood cells and the ratio of monocytes. On the 4th day after the i.p. injection of the tannin, cytotoxic adherent peritoneal exudate cells were also increased. The spleen of the mice was enlarged, and the spleen cells possessed the capacity to take up 3H-thymidine. Agrimoniin showed weak direct migration activity against spleen cells from non-treated mice. These results indicate that agrimoniin is a potent antitumor tannin and suggest that the antitumor effect may be due to this tannin enhancing the immune response of the host animals through the actions on tumor cells and some immunocytes.