title: Degradation mechanism of cyanobacterial toxin cylindrospermopsin by hydroxyl radicals in homogeneous UV/H₂O₂ process.
abstract: The degradation of cylindrospermopsin (CYN), a widely distributed and highly toxic cyanobacterial toxin (cyanotoxin), remains poorly elucidated. In this study, the mechanism of CYN destruction by UV-254 nm/H2O2 advanced oxidation process (AOP) was investigated by mass spectrometry. Various byproducts identified indicated three common reaction pathways: hydroxyl addition (+16 Da), alcoholic oxidation or dehydrogenation (-2 Da), and elimination of sulfate (-80 Da). The initiation of the degradation was observed at the hydroxymethyl uracil and tricyclic guanidine groups; uracil moiety cleavage/fragmentation and further ring-opening of the alkaloid were also noted at an extended reaction time or higher UV fluence. The degradation rates of CYN decreased and less byproducts (species) were detected using natural water matrices; however, CYN was effectively eliminated under extended UV irradiation. This study demonstrates the efficiency of CYN degradation and provides a better understanding of the mechanism of CYN degradation by hydroxyl radical, a reactive oxygen species that can be generated by most AOPs and is present in natural water environment.
authors.affiliation: Environmental Engineering and Science Program, University of Cincinnati , Cincinnati, Ohio 45221-0012, United States.
authors.forename: Xuexiang
authors.initials: X
authors.lastname: He
authors.forename: Geshan
authors.initials: G
authors.lastname: Zhang
authors.forename: Armah A
authors.initials: AA
authors.lastname: de la Cruz
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Shea
authors.forename: Dionysios D
authors.initials: DD
authors.lastname: Dionysiou
mesh_terms: D000470:Alkaloids / Q000737:chemistry; D001427:Bacterial Toxins / Q000737:chemistry* / Q000528:radiation effects; D001673:Biodegradation, Environmental / Q000528:radiation effects; D000087522:Cyanobacteria Toxins; D005374:Filtration; D006861:Hydrogen Peroxide / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry* / Q000528:radiation effects; D007700:Kinetics; D008387:Marine Toxins / Q000737:chemistry* / Q000528:radiation effects; D052998:Microcystins / Q000737:chemistry* / Q000528:radiation effects; D009820:Ohio; D010084:Oxidation-Reduction / Q000528:radiation effects; D012822:Silicon Dioxide / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D014466:Ultraviolet Rays; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry / Q000528:radiation effects; D060753:Water Quality
chemical_list: D000470:Alkaloids; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins; D052998:Microcystins; D013431:Sulfates; C089595:cylindrospermopsin; D017665:Hydroxyl Radical; D014498:Uracil; D012822:Silicon Dioxide; D006861:Hydrogen Peroxide