Meisoindigo (N-Methylisoindigotin, Methylisoindigotin, Dian III), a derivative of Indigo naturalis, is an active compound of a Chinese anti-leukemia medicine that has been effectively used in the treatment of chronic myelogenous leukemia (CML). In vitro cell line studies have shown that this agent might induce apoptosis and myeloid differentiation of acute myeloid leukemia (AML).