Two New Cytotoxic Triterpene Glycosides from the Sea Cucumber Holothuria scabra

Two new triterpene glycosides, scabraside A (1) and B (2), and a structurally known compound (3), were isolated from the sea cucumber Holothuria scabra (Holothuriidae) collected from the South China Sea. Structure of these compounds was elucidated by spectroscopic and chemical methods. The glycosides 1 and 2 exhibit the same common structural features, i.e., the presence of 12- and 17-hydroxy groups in the holostane-type triterpene aglycone with a 9(11)-ene bond, but are different in the side chains of the triterpene aglycone. The glycosides 1 and 2 had significant in vitro cytotoxicity against four human tumor cell lines in comparison to 10-hydroxycamptothecin.