title: The toxicity and enzyme activity of a chlorine and sulfate containing aeruginosin isolated from a non-microcystin-producingPlanktothrixstrain.
abstract: The toxicity of six differentPlanktothrixstrains was examined in acute toxicity assays with the crustaceanThamnocephalus platyurus. The presence of toxicity in two strains could be explained by the occurrence of microcystins. The other fourPlanktothrixstrains were not able to produce microcystins due to different mutations in the microcystin synthetase (mcy) gene cluster. In these strains, toxicity was attributed to the presence of chlorine and sulfate containing compounds. The main representative, called aeruginosin 828A, of such a compound in thePlanktothrixstrain 91/1 was isolated, and structure elucidation by 2D-NMR and MS methods revealed the presence of phenyllactic acid (Pla), chloroleucine (Cleu), 2-carboxy-6-(4'-sulfo-xylosyl)-octahydroindole (Choi), and 3-aminoethyl-1-N-amidino-Δ-3-pyrroline (Aeap) residues. Aeruginosin 828A was found to be toxic forThamnocephalus platyuruswith a LC50value of 22.4 µM, which is only slightly higher than the toxicity found for microcystins. Additionally, very potent inhibition values for thrombin (IC50= 21.8 nM) and for trypsin (IC50= 112 nM) have been determined for aeruginosin 828A. These data support the hypothesis that aeruginosins containing chlorine and sulfate groups, which were found in microcystin-deficientPlanktothrixstrains, can be considered as another class of toxins.
authors.affiliation: Limnological Station, Institute of Plant Biology, University of Zürich, Seestrasse 187, CH-8802 Kilchberg, Switzerland.
authors.forename: Esther
authors.initials: E
authors.lastname: Kohler
authors.affiliation: University of Basel, Department of Chemistry, St. Johanns-Ring 19, CH-4056 Basel, Switzerland.
authors.forename: Verena
authors.initials: V
authors.lastname: Grundler
authors.affiliation: University of Basel, Department of Chemistry, St. Johanns-Ring 19, CH-4056 Basel, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Häussinger
authors.affiliation: Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria.
authors.forename: Rainer
authors.initials: R
authors.lastname: Kurmayer
authors.affiliation: University of Basel, Department of Chemistry, St. Johanns-Ring 19, CH-4056 Basel, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Gademann
authors.affiliation: Limnological Station, Institute of Plant Biology, University of Zürich, Seestrasse 187, CH-8802 Kilchberg, Switzerland.
authors.forename: Jakob
authors.initials: J
authors.lastname: Pernthaler
authors.affiliation: Limnological Station, Institute of Plant Biology, University of Zürich, Seestrasse 187, CH-8802 Kilchberg, Switzerland.
authors.forename: Judith F
authors.initials: JF
authors.lastname: Blom
keywords: inhibitor; mcy gene cluster; microcystin; microcystin-deficient; toxin