title: Effects of ionic radius of redox-inactive bio-related metal ions on the radical-scavenging activity of flavonoids evaluated using photometric titration.
abstract: Mg(2+) enhanced the scavenging activity of (+)-catechin and quercetin against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH˙), while Al(3+) decreased their activity. Such effects of Mg(2+) and Al(3+) were not observed for kaempferol. Na(+) and Ca(2+) with large ionic radii showed little effect on the DPPH˙-scavenging activity of these three flavonoids.
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences (NIRS), Inage-ku, Chiba 263-8555, Japan. nakanis@nirs.go.jp.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Waki
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ozawa
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamada
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nakanishi
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D001713:Biphenyl Compounds / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010783:Photometry; D010851:Picrates / Q000737:chemistry*
chemical_list: D001713:Biphenyl Compounds; D005419:Flavonoids; D016166:Free Radical Scavengers; D007477:Ions; D010851:Picrates; D000535:Aluminum; C004931:1,1-diphenyl-2-picrylhydrazyl; D008274:Magnesium