Popolohuanones G - I, Dimeric Sesquiterpene Quinones with IL-6 Inhibitory Activity from the Marine Sponge Dactylospongia elegans

Chemical investigation of the marine sponge Dactylospongia elegans, collected from the South China Sea, afforded three new dimeric sesquiterpene quinones, popolohuanones G - I (1 - 3), together with two known analogs, popolohuanones B (4) and C (5). The new structures were determined by HR-ESI-MS and 1D- and 2D-NMR analyses. All the five compounds showed no cytotoxic activity against five human cancer cell lines, while popolohuanone H (2) showed potent inhibitory activity against IL-6, an inflammatory cytokine, at the concentration of 10 m.