Sesquiterpenoid Aminoquinones from the Marine Sponge Dysidea sp.

Four new sesquiterpenoid arenarone derivatives, 18-aminoarenarone (1), 19-aminoarenarone (2), 18-methylaminoarenarone (3), and 19-methylaminoarenarone (4), and the new dimeric popolohuanone F (5), a derivative of 19-aminoarenarone (2) and arenarol (6), have been isolated from the Australian marine sponge Dysidea sp. together with the known compounds arenarol (6) and popolohuanone A (7). The structures of the new compounds 1-5 were established from extensive NMR spectroscopic data. Popolohuanones A (7) and F (5) and arenarol (6) showed DPPH radical scavenging activity with IC50 values of 35, 35, and 19 mu M, respectively.