Sixty-three tannins and related polyphenols were intraperitoneally injected into mice at 4 d before intraperitoneal sarcoma-180 cell inoculation, and their antitumor activities were evaluated. The condensed tannins and related compounds all showed negligible activity. As regards the hydrolyzable tannins, active compounds were found among ellagitannins. In particular, dimeric ellagitannins such as oenothein B, rugosin E, rugosin D, gemin A and coriariin A showed significantly higher antitumor activity than agrimoniin, which we previously reported as an antitumor tannin. Coriariin A, which has four galloyl groups instead of two hexahydroxydiphenoyl groups of agrimoniin, showed the strongest activity. It seems to be essential for marked antitumor activity that ellagitannins should possess a dimeric structure with several galloyl groups on the glucose core.
The antitumor effect of oenothein B, a macrocyclic ellagitannin from Oenothera erythrosepala Bordas, on rodent tumors was studied, Oenothein B exhibited a strong antitumor activity against MM2 ascites tumors upon intraperitoneal administration to the mice before or after the tumor inoculation. The tannin also inhibited the growth of Meth‐A solid type tumor in mice. This antitumor effect of the tannin could not be attributed to its direct cytotoxic action on tumor cells, because the cytotoxicity was very weak in the presence of serum protein. When oenothein B was injected into the peritoneal cavity of mice, peritoneal exudate cells, including cytostatic macrophages, were induced. Furthermore, in the in vitro treatment of macrophages from mice and humans, the tannin stimulated release of an interleukin 1 (IL‐1)‐like activity and IL‐1β from the cells. These results suggest that oenothein B exerts its antitumor effect through potentiation of the host‐immune defense via activation of macrophages.
Forty-five ellagitannins and related compounds were intraperitoneally injected into mice once, 4 d before intraperitoneal inoculation of S-180 cells, and their antitumor activities were evaluated. When an antitumor-active tannin was defined as one producing a 70% increase or more in the mean life span of mice or one regressor out of six mice, twenty-one ellagitannins were active. Among monomeric ellagitannins, tellimagrandin II was most active. Most of the oligomeric ellagitannins, consisting of tellimagrandins I and II as the monomer unit, had a significant antitumor activity. Macrocyclic ellagitannins were all active. Oenothein B, among them, had the most potent antitumor activity. In contrast, ellagitannins containing a casuarictin or potentillin moiety in their molecules, except for extensively oligomerized ones, showed very low or negligible activity. These results suggest that tannins need the ellagitannin monomer units, having galloyl groups at the O-2 and O-3 positions on the glucose core(s), such as tellimagrandins, in order to exhibit a strong antitumor activity.
Abstract-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 MH1 34 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.
Abstract-To evaluate the antitumor activity of Agrimonia pi/osa LEDEB., the effects of the methanol extract from roots of the plant (AP-M) on several transplantable rodent tumors were investigated.AP-M significantly prolonged the life span of S180-, Meth-A fibrosarcoma and MM-2 mammary carcinoma-bearing mice by intraperitoneal (i.p.) pre-or postmedication. AP-M also inhibited the growth of 5-180 solid type tumor.On the other hand, the prolongation of life span induced by AP-M on S-180 ascites type tumor-bearing mice was markedly minimized or abolished by the pretreatment of cyclophosphamide.AP-M showed considerably strong cytotoxicity on MM-2 cells in vitro, but the effect was diminished to one-tenth by the addition of serum to the culture.Against the host animals, the peripheral white blood cells in mice were significantly increased from 2 to 5 days after the i.p. injection of AP-M.On 4th day after the injection of AP-M, the peritoneal exudate cells which possessed the cytotoxic activity on MM-2 cells in vitro were also increased to about 5-fold those in the non-treated control.
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