title: The antioxidant action of Polypodium leucotomos extract and kojic acid: reactions with reactive oxygen species.
abstract: Two natural products Polypodium leucotomos extract (PL) and kojic acid (KA) were tested for their ability to scavenge reactive oxygen species (.OH,.O2-, H2O2, 1O2) in phosphate buffer. Hydroxyl radicals were generated by the Fenton reaction, and the rate constants of scavenging were 1.6 x 10(9) M-1 s-1 for KA and 1.0 x 10(9) M-1 s-1 for PL, similar to that of ethanol (1.4 x 10(9) M-1 s-1). With superoxide anions generated by the xanthine/hypoxanthine system, KA and PL (0.2-1.0 mg/ml) inhibited.O2-dependent reduction of nitroblue tetrazolium by up to 30 and 31%, respectively. In the detection of 1O2 by rose bengal irradiation, PL at 1.0 mg/ml quenched singlet oxygen by 43% relative to azide and KA by 36%. The present study demonstrates that PL showed an antioxidant effect, scavenging three of four reactive oxygen species tested here. Unlike KA, PL did not significantly scavenge hydrogen peroxide.
authors.affiliation: Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901 Ribeirão Preto, SP, Brazil.
authors.forename: A J
authors.initials: AJ
authors.lastname: Gomes
authors.forename: C N
authors.initials: CN
authors.lastname: Lunardi
authors.forename: S
authors.initials: S
authors.lastname: Gonzalez
authors.forename: A C
authors.initials: AC
authors.lastname: Tedesco
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002021:Buffers; D016166:Free Radical Scavengers / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D011753:Pyrones / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D002021:Buffers; D016166:Free Radical Scavengers; D010936:Plant Extracts; D011753:Pyrones; D017382:Reactive Oxygen Species; C011890:kojic acid