Isolation and structure elucidation of feeding deterrent diterpenoids from the sea pansy, Renilla reniformis

Four new briarane diterpenoids, renillins A-D (1-4), and the known compound renillafoulin C (5) were isolated from the sea pansy, Renilla reniformis. The structures and relative stereochemistry were elucidated by the interpretation of spectroscopic data. Using laboratory feeding assays, all compounds tested at natural concentrations significantly deterred feeding by the predatory lesser blue crab, Callinectes similis, while renillins C (3) and D (4) also deterred feeding by the predatory mummichog fish, Fundulus heteroclitus. Renillins A (1) and B (2) were found to possess an oxygenation pattern without precedent in this skeletal class.