RESUMEN
The 50% inhibition doses ( ID50 ) of tetrandrine and demethyl tetrandrine on DNA synthesis in L7712 and Sl80 cells are 2.6, 3 .5mg/ L and 27.5, 24.5mg/L respectively. The DNA synthesis inhibition is likely due to DNA template damage caused by both natural products. The inhibition of DNA, RNA and protein syntheses by tetrandrine or demethyl tetrandrine increased with incubating time. The inhibiting activities of two natural products on DNA and RNA synthesis are s-tronger than on protein. There are no differences either in inhibiting activity or in inhibiting mechanism between two natural products.
RESUMEN
It was found that the proliferation of mice L7712 leukemic cells in vitro was markedly inhibited by 5 mg/L GP1 and VP10 The inhib itory rate increased with the incubation time. At a concentration of 0 .04-20mg/L, the mitotic index ( MI ) of GP1 group increased, but the MI of VP16 group decreased. After L7712 cells were treated with GP, 5 mg/L for 12 h the MI reached the highest point which was 8 times as high as that of the control, at the same time, the MI of VP16 ( 5 mg/L) group was about one-third of that of the control. The result of the combination of GP1 with VP16 showed that VP16 could antagonize the effect of GP on MI of L7712 cells. After being treated by GP1 and VP18 for 24 h, serious damage of L7712 cells could be observed. Both drugs inhibited the incorporation of (3H) TdR into DNA of S180, ascitic hepatoma (AH), L1210 and L7712 cells incubated for 24 h. It was further observed that S180 and L7712 cells were more sensitive than other cells to both drugs.