title: Effect-directed analysis reveals inhibition of zebrafish uptake transporter Oatp1d1 by caulerpenyne, a major secondary metabolite from the invasive marine alga Caulerpa taxifolia.
abstract: Caulerpa taxifolia is a marine alga of tropical and subtropical distribution and a well-known invasive species in several temperate regions. Its invasiveness mainly stems from the production of secondary metabolites, some of which are toxic or repellent substances. In this study we investigated the possible inhibitory effects of C. taxifolia secondary metabolites on the activity of two zebrafish (Danio rerio) uptake transporters that transport organic anions (Oatp1d1) and cations (Oct1). Both transporters were transiently transfected and overexpressed in human embryonic kidney HEK293T cells. Transport activity assays using lucifer yellow (LY) and 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP+) as model substrates were applied for the determination of Oatp1d1 and Oct1 interactors. A two-step Effect-Directed Analysis (EDA) procedure was applied for the separation and identification of compounds. We identified caulerpenyne (CYN) as the major metabolite in C. taxifolia and reveal its potent inhibitory effect towards zebrafish Oatp1d1 as well as weak effect on zebrafish Oct1 transport. The observed effect was confirmed by testing CYN purified from C. taxifolia, resulting in an IC50of 17.97 μM, and a weak CYN interaction was also determined for the zebrafish Oct1 transporter. Finally, using Michaelis-Menten kinetics experiments, we identified CYN as a non-competitive inhibitor of the zebrafish Oatp1d1. In conclusion, this study describes a novel mechanism of biological activity in C. taxifolia, shows that CYN was a potent non-competitive inhibitor of zebrafish Oatp1d1, and demonstrates that EDA can be reliably used for characterization of environmentally relevant complex biological samples.
authors.affiliation: Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Ruđer Bošković Institute, 10 000 Zagreb, Croatia. Electronic address: pmaric@irb.hr.
authors.forename: P
authors.initials: P
authors.lastname: Marić
authors.affiliation: Laboratory for Analytical Chemistry and Biogeochemistry of Organic Compounds, Division for Marine and Environmental Research, Ruđer Bošković Institute, 10 000 Zagreb, Croatia. Electronic address: ahel@irb.hr.
authors.forename: M
authors.initials: M
authors.lastname: Ahel
authors.affiliation: Laboratory for Analytical Chemistry and Biogeochemistry of Organic Compounds, Division for Marine and Environmental Research, Ruđer Bošković Institute, 10 000 Zagreb, Croatia. Electronic address: isenta@irb.hr.
authors.forename: I
authors.initials: I
authors.lastname: Senta
authors.affiliation: Laboratory for Analytical Chemistry and Biogeochemistry of Organic Compounds, Division for Marine and Environmental Research, Ruđer Bošković Institute, 10 000 Zagreb, Croatia. Electronic address: terzic@irb.hr.
authors.forename: S
authors.initials: S
authors.lastname: Terzić
authors.affiliation: Laboratory for Analytical Chemistry and Biogeochemistry of Organic Compounds, Division for Marine and Environmental Research, Ruđer Bošković Institute, 10 000 Zagreb, Croatia. Electronic address: Iva.Mikac@irb.hr.
authors.forename: I
authors.initials: I
authors.lastname: Mikac
authors.affiliation: Laboratory for Benthos, Institute of Oceanography and Fisheries, 21 000 Split, Croatia. Electronic address: zuljevic@izor.hr.
authors.forename: A
authors.initials: A
authors.lastname: Žuljević
authors.affiliation: Laboratory for Molecular Ecotoxicology, Division for Marine and Environmental Research, Ruđer Bošković Institute, 10 000 Zagreb, Croatia. Electronic address: smital@irb.hr.
authors.forename: T
authors.initials: T
authors.lastname: Smital
mesh_terms: D000818:Animals; D046068:Caulerpa / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D058865:Introduced Species; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D012717:Sesquiterpenes / Q000378:metabolism / Q000633:toxicity*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D026901:Membrane Transport Proteins; D012717:Sesquiterpenes; D029961:Zebrafish Proteins; C097889:caulerpenyne
keywords: Caulerpa taxifolia; Caulerpenyne; Effect-directed analysis (EDA); Oatp1d1; Oct1; Zebrafish