Gnidilatimonoein from Daphne mucronata induced differentiation and apoptosis in leukemia cell lines

Among various treatments, plants play a crucial role in cancer chemotherapy. Base on literature data, different species of the thymeleaeceae family have been found to be good sources for anticancer agents. Therefore, our laboratory has initiated a research project on evaluating the anticancer properties of the Iranian medical plant, Daphne mucronata (Thymeleaeceae). Gnidilatimonoein is a new diterpene ester compound that is purified from Daphne mucronata with antiproliferative and anti-metastatic effects in different tumor cell lines. Based on the inhibitory role of this agent on the cell cycle progression of K562 cell line, we were interested to check gnidilatimonoein for induction of differentiation and apoptosis in different human leukemia ML-1, HL-60 and K562 cells. Cell viability was determined by trypan blue exclusion method. Cell differentiation was studied in terms of morphology, NBT reduction in leukemia cells (HL-60 and ML-1) and benzidine staining in erythroleukemia (K562) cells. Apoptosis was detected by fluorescence microscopy (Acridine orange/Ethedium bromide double staining), annexineV flow cytometry and DNA electrophoresis. After 48 hours of treatment with 10 µM gnidilatimonoein, 80-70% of HL-60 and ML1 cells showed NBT reduction. Indeed gnidilatimonoein induced monocyte differentiation of myeloid leukemia HL-60 and ML-1 cells but not K562 erythroluekemia cells. In this condition, we observed the growth inhibitory effect (60%) without substantial loss of viability (