Printed in U.S.A. STRUCTURE-ACTIVITY RELATIONSHIIS IX A SERIES OF

The toxic effects of colchicine, the main alkaloid of Coichicum autumnale, have been known for many centuries. The toxicity of this compound is primarily attributable to its action on the mitotic apparatus whicim results in an arrest of cell division in metaphase. Even before time chemical structure of coichicine (fig. 1) was definitely established (Dewar, 1945; King et al., 1952) , relationships between time struc-tore of colchicine derivatives and their biologi-cal activity Imad been of considerable interest. Coichicine derivatives were used to identify those parts of the colchicine molecule whicim are essential for its specific action. In addi-tion, many of these compounds were tested for their ability to inhibit the growth of tumors. In vitro cultures of animal cells have proved to be especially useful as assay systems in qualmtitative studies of the cytotoxicity of mi-totic inhibitors, and this method has been applied, notably by Lettr#{233}and his group, to a considerable number of colchicine analog