Dithranol (anthralin) and 10-butyryl dithranol (butantrone) do not morphologically transform cultured C3H 10T1/2 C18 mouse embryo fibroblasts.

The ability of dithranol and 10-butyryl dithranol to induce morphological cell transformation was studied in cultured C3H 10T1/2 C18 fibroblasts. The cells were incubated with different concentrations of the test compounds for 48 h and cultured for 5 weeks thereafter. At the end of the culture period the cultures were fixed, stained and examined for the presence of transformed foci. Dithranol and 10-butyryl dithranol did not increase the formation of transformed foci, while the positive control compound, 7,12-dimethylbenz(a)anthracene (DMBA), induced a high frequency of transformations significantly different from controls. Thus the in vitro cell transformation model with uninitiated C3H 10T1/2 C18 fibroblasts is not able to detect the weak tumorigenic action of dithranol and 10-butyryl dithranol which has been observed in mouse skin.