Two series of urea and thiourea derivatives (1a–11a, 1b–11b) have been synthesized; all the 22 compounds were reported for the first time. Their anti-proliferative activities against the melanoma cell line B16-F10 were evaluated. Among the compounds tested, compound 6b exhibited the most potent activity in melanoma cells growth inhibition (IC50= 0.33 μ M). The bioassay tests showed that anti-proliferative activities of these novel compounds were ...