A TUMOR-CELL GROWTH INHIBITOR FROM POLYGONUM-HYPOLEUCUM OHWI

Polygonum hypoleucum Ohwi (P. hypoleucum Ohwi) has been used as a Chin ese medicine for a long time. In the present study, four anthraquinone s, emodin, emodin 1-O-beta-D-glucoside (49A), physcion (62A), and phys cion 1-O-beta-D-glucoside (50A) were identified from P. hypoleucum Ohw i and their inhibitory effects on various tumor cells proliferation we re investigated. On a percentage basis, emodin had the highest suppres sing activity on the various tumor cells proliferation. At 10 mu g/ml, the percentage inhibition on K562 cells proliferation for emodin, 49A , 62A, and 50A were 97+/-3.4%, 18+/-7.3%, 24+/-3.6%, and 31+/-8.9%, re spectively. However, inhibitory activities of 10 mu g/ml of emodin, 49 A, 62A, or 50A on Raji cells proliferation were 96+/-5.0%, 25+/-5.0%, 22+/-3.2%, and 28+/-4.3%, respectively. It was also found that the bot h C1 and C3 positions of emodin were important for antitumor action. T he IC50s of emodin, 49A, 62A, and 50A on various tumor cells were also calculated. The IC50 of emodin on K562 cells was significantly lower than on Raji, HeLa, Calu-1, Wish, and Vero cells (1.5+/-0.2 vs. 2.8+/- 0.4 mu g/ml, P < 0.01; 1.5+/-0.2 vs. 8.4+/-1.6 mu g/ml; 1.5+/-0.2 vs. 8.9+/-1.0 mu g/ml; 1.5+/-0.2 vs. 8.7+/-0.5 mu g/ml; 1.5+/-0.2 vs. 3.5/-0.12 mu g/ml; P < 0.001). The results indicated that K562 and Raji c ells were more sensitive to emodin treatment. Cell viability test indi cated that inhibitory effect of emodin on various tumor cell lines was not through direct cytotoxicity. It suggested P. hypoleucum Ohwi incl uded a tumor cell growth inhibitor.