Differential effects of triterpene glycosides, frondoside A and cucumarioside A2‐2 isolated from sea cucumbers on caspase activation and apoptosis of human leukemia cells

Frondoside A is a pentaoside having an acetyl moiety at the aglycon ring and xylose as a third monosaccharide residue. Cucumarioside A2‐2 is a pentaoside having glucose as a third monosaccahride unit. We compared the effects of frondoside A and A2‐2 for cell death‐inducing capability with close attention paid to structure–activity relationships. Both frondoside A and A2‐2 strongly induced apoptosis of leukemic cells. Frondoside A‐induced apoptosis was more potent and rapid than A2‐2‐induced apoptosis. A2‐2‐induced but not frondoside A‐induced apoptosis was caspase‐dependent. This suggests that holothurians may induce apoptosis of leukemic cells caspase‐dependently or ‐independently, depending on the holothurian structure.