Dissertation committee:
1. Ντέντος Σκαρλάτος, Αναπλ. Καθηγητής ΕΚΠΑ Τμήμα Βιολογίας
2. Ρούσσης Βασίλειος, Καθηγητής, ΕΚΠΑ Τμήμα Φαρμακευτικής
3. Ζερβουδάκη Σουλτάνα, Ερευνήτρια Α΄, Ελληνικό Κέντρο Θαλασσίων Ερευνών, Ινστιτούτο Ωκεανογραφίας
4. Ιωάννου Ευσταθία, Επίκ. Καθηγήτρια, ΕΚΠΑ Τμήμα Φαρμακευτικής
5. Παπαζαφειρη Παναγιώτα, Αναπλ. Καθηγήτρια, ΕΚΠΑ Τμήμα Βιολογίας
6. Τσιτσιλώνη Ουρανία, Καθηγήτρια, ΕΚΠΑ Τμήμα Βιολογίας
7. Χονδρογιάννη Νίκη, Ερευνήτρια Β΄, Εθνικό Ίδρυμα Ερευνών
Summary:
The subject of this doctoral thesis is the study of the antifouling properties of chemical compounds isolated and identified by marine organisms, as well as the analysis of the toxicity of these chemicals in target organisms, non-target organisms along with fish and human cell lines.
The goal of the doctoral thesis is to identify one or more chemicals that will exhibit antifouling activity against marine organisms that cause biofouling, but also exhibit an ecotoxic profile that is compatible with modern environmentally friendly requirements for the use of chemicals in the market.
The term marine biofouling refers to the colonization of subterranean artificial surfaces by micro- and macro-organisms. The main effect of this phenomenon is mainly found in ship hauls, whose speed and fuel consumption are largely influenced by the presence of biofouling. Another important parameter stems from the fact that maritime transport has significant economic and environmental impacts as vessels traveling global commercial routes transport marine organisms from one place on Earth to another. Biofouling also affects other marine industries, such as the aquaculture, oil and gas industry, wind farms and passenger ships. In recent years, scientists have been working very strongly on this issue trying to invent new antifouling methods that should be environmentally friendly.
The present study focuses on finding one (or more) environmentally friendly chemicals, alternative to those that already exist, originating from the marine natural environment.
Completion of the experimental study was followed by a rigorous process of screening and rejecting secondary metabolites in terms of their ability to prevent the establishment of the balanus Amphibalanus amphitrite. Balanus are invertebrates that are considered to be the major causative agents of biofouling.
The secondary metabolites were isolated from species of the genus Laurencia and also from the molluscs of the genus Aplysia, which are known to feed on the genus Laurencia. Bromospherol, which was isolated from the red algae, Sphaerococcus coronopifolius, has been used as a reference and activity criterion and which has been previously shown to have potent antifouling activity against Amphibalanus amphitrite. Of the 25 secondary metabolites analyzed for their
antifouling properties, 8 were selected and tested for their toxicity to the crustacean, Artemia sp., and 2, 6 secondary metabolites were rejected for their toxicity to the diatom Chaetoceros gracilis, 3, and finally, 3 secondary metabolites were tested in cytotoxicity experiments in 2 cell lines: One trout liver cell line (RTL-W1) and one human epithelial cell line (HEK293).
Compounding the overall results of the experimental approaches, it is suggested that the compound, perforenol, a sesquiterpene isolated from the species of the genus Laurencia, exhibits equal antifouling activity compared to bromosphaerol, whereas it exhibits relatively better ecotoxic profile. Finally, both secondary metabolites do not alter the establishment behavior of cyprids of Amphibalanus amphitrite as shown by immunoblotting experiments on the SIPC protein deposited by the cyprids during exploration of the substrate where they will settle.
It is concluded that perforenol is a fairly active antifouling chemical and deserves further investigation of its behavior as an antifouling agent in antifouling paints.
Keywords:
Laurencia, biofouling, bromosphaerol, Amphibalanus amphitrite, perforenol
