Alotaketals A and B, Sesterterpenoids from the Marine Sponge Hamigera Species that Activate the cAMP Cell Signaling Pathway

The new sesterterpenoids alotaketals A (1) and B (2) have been isolated from extracts of the marine sponge Hamigera sp. collected in Papua New Guinea. Their chemical structures were elucidated by analysis of spectroscopic data. Alotaketals A and B have the unprecedented alotane carbon skeleton, and they activate the cAMP cell signaling pathway with EC50's of 18 and 240 nM, respectively.