Antifouling activity of synthetic alkylpyridinium polymers using the barnacle model.
Polymeric 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 (EC₅₀) 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 LC₅₀: 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 IC₅₀ of 4.83 and 1.86 mg/L.
ISMAR-CNR Institute of Marine Science, U.O.S. Genova, Via De Marini 6, 16149 Genova, Italy. veronica.piazza@ge.ismar.cnr.it.
Veronica
V
Piazza
Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana 1000, Slovenia. ivana84@gmail.com.
Ivanka
I
Dragić
Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana 1000, Slovenia. kristina.sepcic@bf.uni-lj.si.
Kristina
K
Sepčić
ISMAR-CNR Institute of Marine Science, U.O.S. Genova, Via De Marini 6, 16149 Genova, Italy. marco.faimali@ismar.cnr.it.
Marco
M
Faimali
ISMAR-CNR Institute of Marine Science, U.O.S. Genova, Via De Marini 6, 16149 Genova, Italy. francesca.garaventa@ismar.cnr.it.
Francesca
F
Garaventa
Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana 1000, Slovenia. tom.turk@bf.uni-lj.si.
Tom
T
Turk
Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana 1000, Slovenia. sabina.berne@bf.uni-lj.si.
Sabina
S
Berne
D000818:Animals; D057219:Biofouling / Q000517:prevention & control*; D047129:Haliclona / Q000378:metabolism*; D020128:Inhibitory Concentration 50; D007814:Larva; D008522:Mediterranean Sea; D011108:Polymers / Q000138:chemical synthesis / Q000302:isolation & purification / Q000494:pharmacology*; D011726:Pyridinium Compounds / Q000138:chemical synthesis / Q000302:isolation & purification / Q000494:pharmacology*; D001468:Thoracica / Q000187:drug effects*; D023382:Toxicity Tests, Acute; D059551:Toxicity Tests, Subacute
D011108:Polymers; D011726:Pyridinium Compounds