Robustolides A–C, three new briarane-type diterpenoids from the female gorgonian coral Ellisella robusta (Ellisellidae)

Three new briarane-type diterpenoids, designated as robustolides A–C (1–3), were obtained from the female gorgonian coral Ellisella robusta. The structures of briaranes 1–3 were elucidated by the interpretation of spectral data analysis and the structure of 1 was further confirmed by a single-crystal X-ray diffraction analysis. Briaranes 1 and 2 were found to show weak activity against the bacteria Pseudomonas aeruginosa and Staphylococcus aureus.