Suberitane network, a taxonomical marker for Antarctic sponges of the genus Suberites? Novel sesterterpenes from Suberites caminatus

Two novel sesterterpenes 1 and 2 have been isolated from the Antarctic sponge Suberites caminatus. Their structures and relative stereochemistries were determined by spectroscopic methods. Compound 1 features a novel structural type of suberitane network, and an epimer of compound 2 seems to be the biogenetic precursor of 1 and suberitenones A and B. The exclusive prevalence of suberitane-derived sesterterpene metabolites in species of Suberites suggests that this skeleton may be a chemical marker of the genus.