Australindolones, New Aminopyrimidine Substituted Indolone Alkaloids from an Antarctic Tunicate Synoicum sp.

Five new alkaloids have been isolated from the lipophilic extract of the Antarctic tunicate Synoicum sp. Deep-sea specimens of Synoicum sp. were collected during a 2011 cruise of the R/V Nathanial B. Palmer to the southern Scotia Arc, Antarctica. Crude extracts from the invertebrates obtained during the cruise were screened in a zebrafish-based phenotypic assay. The Synoicum sp. extract induced embryonic dysmorphology characterized by axis truncation, leading to the isolation of aminopyrimidine substituted indolone ( 1 - 4 ) and indole ( 5 - 12 ) alkaloids. While the primary bioactivity tracked with previously reported meridianins A-G ( 5 - 11 ), further investigation resulted in the isolation and characterization of australindolones A-D ( 1 - 4 ) and the previously unreported meridianin H ( 12 ).