Antifouling activity of synthetic alkylpyridinium polymers using the barnacle modelPiazza, Veronica (Avtor) Dragić, Ivanka (Avtor) Sepčić, Kristina (Avtor) Faimali, Marco (Avtor) Garaventa, Francesca (Avtor) Turk, Tom (Avtor) Berne, Sabina (Avtor) Amphibalanus amphitriteantifoulingnatural product antifoulantsalkylpyridinium polymersHaliclona (Rhizoniera) saraibarnaclesettlement assaytoxicity assayswimming inhibition assayPolymeric alkylpyridinium salts (poly-APS) isolated from the Mediterranean marine sponge, Haliclona (Rhizoniera) sarai, effectively inhibit barnacle larva settlement and natural marine biofilm formation through a non-toxic and reversible mechanism. Potential use of poly-APS-like compounds as antifouling agents led to the chemical synthesis of monomeric and oligomeric 3-alkylpyridinium analogues. However, these are less efficient in settlement assays and have greater toxicity than the natural polymers. Recently, a new chemical synthesis method enabled the production of poly-APS analogues with antibacterial, antifungal and anti-acetylcholinesterase activities. The present study examines the antifouling properties and toxicity of six of these synthetic poly-APS using the barnacle (Amphibalanus amphitrite) as a model (cyprids and II stage nauplii larvae) in settlement, acute and sub-acute toxicity assays. Two compounds, APS8 and APS12-3, show antifouling effects very similar to natural poly-APS, with an anti-settlement effective concentration that inhibits 50% of the cyprid population settlement (EC$_{50}$) after 24 h of 0.32 mg/L and 0.89 mg/L, respectively. The toxicity of APS8 is negligible, while APS12-3 is three-fold more toxic (24-h LC$_{50}$: nauplii, 11.60 mg/L; cyprids, 61.13 mg/L) than natural poly-APS. This toxicity of APS12-3 towards nauplii is, however, 60-fold and 1200-fold lower than that of the common co-biocides, Zn- and Cu-pyrithione, respectively. Additionally, exposure to APS12-3 for 24 and 48 h inhibits the naupliar swimming ability with respective IC$_{50}$ of 4.83 and 1.86 mg/L.20142021-08-30 14:51:25Članek v reviji129230sl