Evaluation of the antifouling properties of 3-alyklpyridine compounds

Abstract

One of the most promising alternative technologies to antifouling (AF) biocides based on toxic heavy metals lies in the development of natural eco-friendly biocides. The present study evaluates the AF potential of structurally different compounds containing a 3-alkylpyridine moiety. The products, namely poly 3-alkylpyridinium salts, saraine, and haminols, were either extracted or derived from natural sources (the sponges Haliclona sp. and Reniera sarai and the mollusc Haminoea fusari), or obtained by chemical synthesis. All the molecules tested showed generally good anti-settlement activity against larvae of the barnacle Amphibalanus (=Balanus) amphitrite (EC₅₀ values between 0.19 and 3.61 μg ml⁻¹) and low toxicity (LC₅₀ values ranging from 2.04 to over 100 μg ml⁻¹) with non-target organisms. For the first time, the AF potential of a synthetic monomeric 3-alkylpyridine was demonstrated, suggesting that chemical synthesis is as a realistic way to produce large amounts of these compounds for future research and development of environmentally-friendly AF biocides.

Keywords:

• poly-alkylpyridins
• haminols
• saraine-1
• anti-settlement activity
• Amphibalanus (=Balanus) amphitrite
• Tigriopus fulvus

Acknowledgements

DB was supported by a Marie Curie FP6 RTN fellowship from the European Community Program MRTN-CT-2004-512301. The authors thank Dr Maria Grazia Aluigi (University of Genoa, Italy) for help with the inhibition of acetylcholinesterase assay, Dr Guido Villani (CNR-ICB) for H. fusari collection, Mr Antonio Esposito (CNR-ICB) for the work on fractionating and screening the Haliclona sp. extract, and Dr Conxita Avila (University of Barcelona, Spain) for identification of the Antarctic sponge. The authors also kindly acknowledge Prof. Micha Ilan (Tel Aviv University) for valuable advice and comments on the manuscript, Ms Naomi Paz (Tel Aviv University) for editorial help, the staff of CNR-ISMAR, especially Dr Veronica Piazza, for the help with barnacle and algal rearing, and the staff of CNR-ICB for technical support. Many thanks also to the three anonymous referees for constructive remarks on the manuscript.