Synthesis, cytotoxicity, and DNA-topoisomerase inhibitory activity of new asymmetric ureas and thioureas.

A new series of N-3,3-diphenylpropyl-N-(p-X-benzyl)-N'-phenylureas (5a-g) and thioureas (6a-g) were synthesized by the reaction of secondary amines and phenyl isocyanate or isothiocyanate. The cytotoxic effects of the urea and thiourea derivatives were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay against Ehrlich carcinoma and K562 human leukemia cells. Moreover, the activity of compounds in the inhibition of DNA topoisomerases I and II-alpha was tested. The results indicated that the compounds presented important and promising antiproliferative action.