title: Characterization of total retinoid-like activity of compounds produced by three common phytoplankton species.
abstract: Phytoplankton can produce various bioactive metabolites, which may affect other organisms in the aquatic environment. This study provides the first information on the total retinoid-like activity associated with both intracellular and extracellular metabolites produced by selected phytoplankton species that could play a role in teratogenic effects and developmental disruption in exposed organisms. The studied species included a coccoid cyanobacteria (Microcystis aeruginosa), a filamentous cyanobacteria (Aphanizomenon gracile) and a green alga (Desmodesmus quadricauda), all of which commonly occur in freshwater bodies in Europe. Methanolic extracts from cellular material and extracellular exudates were prepared from cultures cultivated in two light-intensity variants with five replicates for each species. The retinoid-like activity was evaluated by in vitro assays along with chemical analyses of two potent retinoic acids (all-trans retinoic acid (ATRA) and 9cis-RA). The mean total retinoid-like activity of metabolites produced by the three studied species representing different phytoplankton taxonomic groups ranged from 705 to 5572ng ATRA equivalent/g dry matter corresponding to 0.064-0.234ng ATRA/106cells. Retinoid-like activity was found in the cellular extracts of all species, while only the extracellular exudates of cyanobacteria exhibited detectable activity (41-1081ng ATRA/L). The greatest extracellular as well as total (extra- and intra- cellular together) retinoid-like activity was detected for Microcystis aeruginosa. The two potent retinoic acids studied were more frequently detected in cellular extracts than in extracellular exudates of all species. Their contribution to observed in vitro effects was relatively low for all tested samples (<10%), indicating a substantial contribution of other retinoid-like compounds to the overall activity. The results indicate possible influence of light intensity and cell density on the production of metabolites with retinoid-like activity and the cyanotoxin microcystin by the studied species. The recalculation of the results per dry weight, water volume, per 106cells and biovolume enables a direct comparison of the retinoid-like activity distribution between extracts and exudates and the use of the data for risk assessment in water bodies.
authors.affiliation: RECETOX - Research Centre for Toxic Compounds in the Environment, Masaryk University, Faculty of Science, Brno, Czechia.
authors.forename: Eliška
authors.initials: E
authors.lastname: Sychrová
authors.affiliation: RECETOX - Research Centre for Toxic Compounds in the Environment, Masaryk University, Faculty of Science, Brno, Czechia.
authors.forename: Jana
authors.initials: J
authors.lastname: Priebojová
authors.affiliation: RECETOX - Research Centre for Toxic Compounds in the Environment, Masaryk University, Faculty of Science, Brno, Czechia.
authors.forename: Marie
authors.initials: M
authors.lastname: Smutná
authors.affiliation: RECETOX - Research Centre for Toxic Compounds in the Environment, Masaryk University, Faculty of Science, Brno, Czechia.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Nováková
authors.affiliation: RECETOX - Research Centre for Toxic Compounds in the Environment, Masaryk University, Faculty of Science, Brno, Czechia.
authors.forename: Jiří
authors.initials: J
authors.lastname: Kohoutek
authors.affiliation: RECETOX - Research Centre for Toxic Compounds in the Environment, Masaryk University, Faculty of Science, Brno, Czechia. Electronic address: hilscherova@recetox.muni.cz.
authors.forename: Klára
authors.initials: K
authors.lastname: Hilscherová
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D000460:Chlorophyta / Q000737:chemistry; D000458:Cyanobacteria / Q000737:chemistry; D005060:Europe; D052998:Microcystins; D046931:Microcystis; D010839:Phytoplankton / Q000737:chemistry* / Q000378:metabolism* / Q000382:microbiology; D010936:Plant Extracts / Q000494:pharmacology; D012176:Retinoids / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D052998:Microcystins; D010936:Plant Extracts; D012176:Retinoids; D014212:Tretinoin
keywords: 9-Cis retinoic acid; All-trans-retinoic acid; Biomass extracts; Cyanobacteria; Exudates; Light conditions; Microcystin; Retinoic acid receptor; Retinoid-like activity