title: Isolation and identification of eight microcystins from thirteen Oscillatoria agardhii strains and structure of a new microcystin.
abstract: Microcystins (cyclic heptapeptide hepatotoxins), isolated from 13 freshwater Oscillatoria agardhii strains from eight different Finnish lakes by high-performance liquid chromatography, were characterized by amino acid analysis, fast atom bombardment mass spectrometry (FABMS), and tandem FABMS (FABMS/collisionary-induced dissociation/MS). All strains produced two to five different microcystins. In total, eight different compounds, of which five were known microcystins, were isolated. The known compounds identified were [D-Asp3]MCYST (microcystin)-LR, [Dha7]MCYST-LR, [D-Asp3]MCYST-RR, [Dha7]MCYST-RR, and [D-Asp3,Dha7]MCYST-RR. This is the first time that isolation of these toxins from Oscillatoria spp., with the exception of [D-Asp3]MCYST-RR, has been reported. Three of the strains produced a new microcystin, and the structure was assigned as [D-Asp3,Mser7]MCYST-RR. The structures of two new microcystins, produced as minor components by one Oscillatoria strain, could not be determined because of the small amounts isolated from the cells. Four strains produced [Dha7]MCYST-RR as the main toxin, but [D-Asp3]MCYST-RR was clearly the most abundant and most frequently occurring toxin among these isolates of O. agardhii.
authors.affiliation: Department of Applied Chemistry and Microbiology, University of Helsinki, Finland.
authors.forename: R
authors.initials: R
authors.lastname: Luukkainen
authors.forename: K
authors.initials: K
authors.lastname: Sivonen
authors.forename: M
authors.initials: M
authors.lastname: Namikoshi
authors.forename: M
authors.initials: M
authors.lastname: Färdig
authors.forename: K L
authors.initials: KL
authors.lastname: Rinehart
authors.forename: S I
authors.initials: SI
authors.lastname: Niemelä
mesh_terms: D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000737:chemistry* / Q000302:isolation & purification; D000458:Cyanobacteria / Q000737:chemistry*; D005387:Finland; D005618:Fresh Water; D052998:Microcystins; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000302:isolation & purification; D014871:Water Microbiology
chemical_list: D001427:Bacterial Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C078588:microcystin