title: Antioxidant properties of aqueous extracts from red tide plankton cultures.
abstract: The antioxidant properties of aqueous extracts from the dinophycean flagellates Gymnodinium impudicum and Alexandrium affine and the raphidophycean flagellate Chattonella ovata were examined. An electron spin resonance (ESR)-spin trapping method coupled with steady state kinetic analysis showed that all of the extracts directly scavenge superoxide, and that the superoxide scavenging potential of any of the extracts was comparable to that of L-ascorbic acid. As for hydroxyl radical scavenging, the Fenton reaction and the method of ultraviolet radiation to hydrogen peroxide were used as hydroxyl radical generation systems. All of extracts reduced the level of hydroxyl radicals in both of the systems, indicating that the extracts also directly scavenge hydroxyl radicals. Since the levels of phenolic compounds did not correlate with the antioxidant activities of the extracts, substances other than phenolic compounds also appeared to be attributable to the activities. It is of our interest that the scavenging activities of extract from G. impudicum against superoxide and hydroxyl radicals were increased by heat exposure at 100 degrees C and 200 degrees C respectively. Although the reason for the increased activities of the aqueous extract from G. impudicum is not clear, the heat-resistance of the extract from G. impudicum might make it a desirable antioxidant.
authors.affiliation: Research Center for Functional Food Materials, Sunny Health Co Ltd, Saito Biotechnology Incubator, Ibaraki, Osaka, Japan. y.niwano@sunnyhealth.co.jp
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Niwano
authors.forename: Emiko
authors.initials: E
authors.lastname: Sato
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kohno
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Matsuyama
authors.forename: Daekyung
authors.initials: D
authors.lastname: Kim
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Oda
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry*; D004141:Dinoflagellida / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000032:analysis; D006358:Hot Temperature; D017665:Hydroxyl Radical / Q000032:analysis; D010936:Plant Extracts / Q000737:chemistry*; D013481:Superoxides / Q000032:analysis; D014867:Water / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D010936:Plant Extracts; D014867:Water; D013481:Superoxides; D017665:Hydroxyl Radical