In vitro cytostatic activity of some amino acid 4-N-substituted cytosines.
Cytotoxicity of 22 amino acid 4-N-substituted cytosine derivatives was studied on KB and HeLa human tissue cultures. A 4-N-(1H-2-oxo-4 pyrimidyl)-tryptamine with ED50 activity values of 0.145 x 10(-3) mole/l and ED0 = 0.4 x 10(-5) mole/l showed the highest cytotoxic activity and was qualified for further in vivo investigation. The secondary modification of tryptamine substituent seems to be a determining factor of the cytotoxic activity of 4-N-pyrimidinyl amino acids. The activity of the investigated compounds was inversely dependent on their solubility limited by the results of the solubility-activity relationship analysis.