Inhibition of tumor cell transplantability by iron and copper complexes of 5-substituted 2-formylpyridine thiosemicarbazones.

The cytotoxicity of copper and iron complexes of 5-substituted 2-formylpyridine thiosemicarbazones against Ehrlich ascites tumor cells has been measured. Brief in vitro incubation of cells and drugs is followed by implantation into host mice. Subsequent degree of tumor development is a measure of cytotoxicity. A spectrum of activities for the iron complexes is observed, starting with the least active as designated by its 5-substitution: OH less than OCOCH3 approximately N(CH3)2 less than H less than CH3 approximately Cl approximately CF3. The last three complexes can prevent completely tumor growth in the new host. Copper complexes of 5-H and 5-CH3 also prevent successful tumor cell transplantation.