| Abstract
| - In this study, we examined the antitumor effect of marine algae extracts on human hepatoma andleukemia cells. Ethyl acetate extracts from Colpomenia sinuosa (Cs-EA), Halimeda discoidae (Hd-EA), and Galaxaura oblongata (Go-EA) directly inhibited the growth of human hepatoma HuH-7 cellsand leukemia U937 and HL-60 cells in a time- and dose-dependent manner. Specifically, these algaeextracts induced apoptosis of U937 and HL-60 cells as evaluated by detection of hypodiploid cellsusing flow cytometry and observation of condensed and fragmented nuclei in algae extract-treatedcells. Intracellular reactive oxygen species (ROS), especially hydrogen peroxide and superoxide anion,were increased about 2−3-fold in U937 cells treated with Cs-EA for 3−5 h. Interestingly, antioxidantN-acetylcysteine effectively blocked Cs-EA-, Hd-EA-, and Go-EA-induced apoptosis, suggesting thatROS is a key mediator in the apoptotic signaling pathway. In conclusion, our results show that algaeextracts induce apoptosis in human leukemia cells through generation of ROS. Keywords: Colpomenia sinuosa; Halimeda discoidea; Galaxaura oblongata; apoptosis; reactive oxygenspecies
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