Many marine triterpene glycosides have in vitro and in vivo activities with very low toxicity, suggesting that they are suitable agents for the prevention and treatment of different diseases, particularly cancer. However, the molecular mechanisms of action of natural marine compounds in cancer, immune, and other various cells are not fully known. This review focuses on the structural characteristics of marine triterpene glycosides and how these affect their biological activities and molecular mechanisms. In particular, the membranotropic and membranolytic activities of frondoside A and cucumariosides from sea cucumbers and their ability to induce cytotoxicity and apoptosis have been discussed, with a focus on structure-activity relationships. In addition, the structural characteristics and antitumor effects of stichoposide C and stichoposide D have been reviewed along with underlying their molecular mechanisms.

Very low toxicity and various in vitro effects of triterpene glycosides make it a suitable agent for cancer prevention and treatment. The molecular mechanisms of action of marine triterpene glycosides, including Frondoside A and Cucumariosides on the apoptosis of cancer cells are not fully investigated. Frondoside A from sea cucumber Cucumaria frondosa and Cucumariosides from Cucumaria japonica are pentaosides and the main structural difference between Frondoside A and Cucumarioside A 2 -2 is in the functional group at C-16 of the aglycone (acetoxy or keto group) and the third carbohydrate unit in the carbohydrate chain. They strongly induce apoptosis of leukemic cells but Frondoside A-induced apoptosis is more potent and rapid than Cucumarioside A 2 -2-induced apoptosis. The effects of Frondoside A and A 2 -2 for cell death-inducing capability can be compared with attention paid to structure-activity relationships. In this review, the differential effects of Frondoside A and Cucumarioside on the apoptosis of leukemic cells are discussed.