Tridentatols D-H, nematocyst metabolites and precursors of the activated chemical defense in the marine hydroid Tridentata marginata (Kirchenpauer 1864).

The marine hydroid Tridentata marginata (Kirchenpauer 1864) produces tridentatols A-C (1-3), of which 1 is a potent deterrent to fish predation. This paper reports the structures of five additional secondary metabolites, tridentatols D-H (4-8), that have been isolated from this hydroid. When hydroid tissue is crushed, as attacking predators would do, tridentatols E-H (5-8), which do not deter fish feeding, are rapidly converted to tridentatols A-D (1-4), thereby repelling potential predators. Additionally, the tridentatols were isolated from this hydroid's nematocysts (i.e., stinging organelles), representing the first report of a nonprotein venom produced by cnidarian nematocysts. The structures of 4-8 were determined by interpretation of their spectral data.