Dysiarenone, a Dimeric C21 Meroterpenoid with Inhibition of COX-2 Expression from the Marine Sponge Dysidea arenaria.

Dysiarenone (1), a dimeric C21 meroterpenoid featuring an unprecedented 2-oxaspiro[bicyclo[3.3.1]nonane-9,1'-cyclopentane] carbon skeleton, was isolated from the marine sponge Dysidea arenaria. The structure of 1 was determined by HRMS and NMR spectroscopic analyses coupled with ECD calculations. Dysiarenone showed inhibitory activities against COX-2 expression and the production of prostaglandin E2 with an IC50 value of 6.4 μM in LPS-stimulated RAW264.7 macrophages.