Acanthosulfate, a sulfated hydroxyhydroquinone sesterterpenoid from the sponge Acanthodendrilla sp.

The marine sponge Acanthodendrilla sp. contains the proteasome inhibitor acanthosulfate ( 4), a disulfated merosesterterpene having a scalarane-type skeleton. The structure of acanthosulfate ( 4), which possesses an unusual configuration, was elucidated by interpretation of spectroscopic data.