Contignasterines, Anti-Inflammatory 2‑Aminoimidazole Steroids from the Sponge Neopetrosia cf. rava Collected in the Bismarck Sea

Sponges of the genus Neopetrosia are known for the production of a large diversity of bioactive metabolites. Contignasterines A (1) and B (2) were isolated as major metabolites of the sponge Neopetrosia cf. rava collected in the Bismarck Sea along with the known and highly bioactive steroid contignasterol (3) possessing a similar oxidized aglycone. Contignasterines are characterized by the presence of a 2-aminoimidazole branched on the side-chains of the oxidized steroid, and 1 also contains an unusual phosphate group at C-7. The anti-inflammatory activities of these compounds were investigated and revealed that all three compounds inhibited the production of pro-inflammatory mediators.