Antifouling activity of the sponge metabolite agelasine D and synthesised analogs on Balanus improvisus

Abstract

This study reports a screening study for antifouling (AF) activity of the natural compound agelasine D isolated from marine sponges of the genus Agelas and 20 synthesised analogs of agelasines and agelasimines. Agelasine D, together with two of the analogs, ie AV1003A and AKB695, displayed a strong inhibitory effect on settlement of Balanus improvisus cypris larvae. Agelasine D had an EC₅₀ value of 0.11 μM while the two analogs AV1033A and AKB695 had EC₅₀ values of 0.23 and 0.3 μM, respectively. None of these three compounds affected larval mortality as was the case with several of the analogs tested. Moreover, the effect of AV1033A and AKB695 was reversible. When cyprids after 24 h exposure to the compounds were transferred to fresh seawater, the settlement frequency compared with the controls was completely recovered. The properties of the agelasine D analogs AV1003A and AKB695 make them highly attractive candidates as AF agents in future marine coatings.

Keywords:

• agelsines
• secondary metabolites
• analogs
• barnacles
• biofouling
• marine

Acknowledgements

We kindly acknowledge the funding received by FORMAS through contract 21.0/2004-0623 and nr; 2006–2372), the Carl Trygger Foundation (nr CTS 07: 329), Helge Ax:son Johnson Foundation, the B and B Wåhlström Foundation and the Norwegian Research Council is gratefully acknowledged for a scholarship to A.V. (KOSK program, Grant 149339/431). We also thank the SOFOSKO students, Sara Rostedt and Anette Jansson.