Spiroetherones A and B, sesquiterpene naphthoquinones, as angiogenesis inhibitors from the marine sponge Dysidea etheria

Spiroetherones A (1) and B (2), a pair of sesquiterpene naphthoquinones with an unprecedented “spiroetherane” carbon skeleton, were isolated from the marine sponge Dysidea etheria collected from the South China Sea. Their structures and absolute configurations were determined by spectroscopic analyses coupled with quantum chemistry DFT GIAO 13C NMR and ECD calculations. Spiroetherone A (1) showed anti-angiogenic activity in a zebrafish model with an IC50 value of 2.4 μM. In addition, the plausible biogenetic pathway of the two metabolites is proposed.