Isolation and Antifouling Activity of Azulene Derivatives from the Antarctic Gorgonian Acanthogorgia laxa

Three azulenoid sesquiterpenes ( 1  –  3 ) were isolated from the Antarctic gorgonian Acanthogorgia laxa collected by bottom trawls at −343 m. Besides linderazulene ( 1 ), and the known ketolactone 2 , a new brominated C 16 linderazulene derivative ( 3 ) was also identified. This compound has an extra carbon atom at C(7) of the linderazulene framework. The antifouling activity of compounds 1 and 2 was assayed in the laboratory with Artemia salina larvae, and also in field tests, by incorporation in soluble‐matrix experimental antifouling paints. The results obtained after a 45 days field trial of the paints, showed that compounds 1 and 2 displayed good antifouling potencies against a wide array of organisms. Compound 3 , a benzylic bromide, was unstable and for this reason was not submitted to bioassays. Two known cembranolides: pukalide and epoxypukalide, were also identified as minor components of the extract.