Abstract
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.
