title: [Preparative purification and characterization of [Dha7] microcystin RR].
abstract: One variant of microcystins was isolated and purified with cyanobacteria natural bloom as the starting material, which was collected in Dianchi Lake, China. The separation protocol involved extraction of cyanobacterial cells by 75% aqueous methanol, isolation by reversed-phase flash chromatography, and purification by reversed-phase semipreparative HPLC. The structure and purity of purified microcystin was identified with electrospray ionization mass spectrometry, UV spectrophotometer, and analytical HPLC. The purified microcystin was assigned as [Dha7]MCRR (purity > 95%), which was a demethylated variant of MCRR. The structure of purified microcystin was identified as cyclo-(Ala-Arg-MeAsp-Arg-Adda-Glu-Dha) with molecular weight of 1023. There was a maximum absorbance at 239 nm in its UV spectrum (200-300 nm). This variant of microcystins occurred frequently, and sometimes could become the main variant in waterbloom from Dianchi Lake.
authors.affiliation: College of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, China. xiaoguo_chen@tom.com
authors.forename: Xiao-guo
authors.initials: XG
authors.lastname: Chen
authors.forename: Li-li
authors.initials: LL
authors.lastname: Yang
authors.forename: Bang-ding
authors.initials: BD
authors.lastname: Xiao
authors.forename: Xing-qiang
authors.initials: XQ
authors.lastname: Wu
authors.forename: Xin-yang
authors.initials: XY
authors.lastname: Dong
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry / Q000302:isolation & purification*; D002681:China; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D052998:Microcystins / Q000737:chemistry / Q000302:isolation & purification*; D046931:Microcystis / Q000254:growth & development / Q000378:metabolism*; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D014871:Water Microbiology
chemical_list: C492352:((Dha)7)-microcystin-RR; D001427:Bacterial Toxins; D003470:Culture Media; D052998:Microcystins