Identification of novel cytotoxic agents from the dinoflagellate symbiont of the gorgonian Erythropodium caribaeorum

Erythropodium caribaeorum is an octocoral known for its production of novel anticancer agents, such as eleutherobin and its analogs as well as for its complex association with symbiotic dinoflagellates (Zooxanthellae; genus Symbiodimum). With this in mind, two sets of experiments were conducted using the extracts of the symbiotic algal cells from Erythropodium caribaeorum: an isolation and characterization of a novel tri-hydroxy sterol and a bioassay-guided isolation of three additional compounds. All compounds exhibit significant bioactivity against the following three cell lines: the human melanoma cell line M14P, the colon cancer cell line RKO and the breast cancer cell line MDA-MB-231. Importantly, this study reports the first isolation of a bioactive polyhydroxy sterol from a gorgonian's symbiont and further suggests that these algae represent a promising sustainable resource for drug discovery.