Emodin induces apoptosis in human promyeloleukemic HL-60 cells accompanied by activation of caspase 3 cascade but independent of reactive oxygen species production.

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is an active constituent of Rheum palmatum, and showed inhibitory activity on lipopolysaccharide-induced NO production in our previous study. However, the apoptosis-inducing activity of emodin has remained undefined. Among three structurally related anthraquinones, including emodin, physcion, and chrysophanol, emodin showed the most potent cytotoxic effects on HL-60 cells, accompanied by the dose- and time-dependent appearance of characteristics of apoptosis including an increase in DNA ladder intensity, morphological changes, appearance of apoptotic bodies, and an increase in hypodiploid cells.