title: Baicalin inhibits the fenton reaction by enhancing electron transfer from Fe (2+) to dissolved oxygen.
abstract: Sho-saiko-to is an herbal medicine that is known to have diverse pharmacological activities and has been used for the treatment of various infectious diseases. Here, we examined the effects of baicalin, a compound isolated from Sho-saiko-to, and the effects of the iron chelator quinolinic acid on the Fenton reaction. The control reaction mixture contained 0.1 M 5,5-dimethyl-1-pyrroline N-oxide (DMPO), 0.2 mM H 2 O 2, 0.2 mM FeSO 4( NH 4)2 SO 4, and 40 mM sodium phosphate buffer (pH 7.4). Upon the addition of 0.6 mM baicalin or quinolinic acid to the control reaction mixture, the ESR peak heights of DMPO/OH radical adducts were measured as 32% ± 1% (baicalin) and 166% ± 27% (quinolinic acid) of that of the control mixture. In order to clarify why baicalin and quinolinic acid exerted opposite effects on the formation of hydroxyl radicals, we measured oxygen consumption in the presence of either compound. Upon the addition of 0.6 mM baicalin (or quinolinic acid) to the control reaction mixture without DMPO and H 2 O 2, the relative oxygen consumption rates were found to be 449% ± 40% (baicalin) and 18% ± 9% (quinolinic acid) of that of the control mixture without DMPO and H 2 O 2, indicating that baicalin facilitated the transfer of electrons from Fe (2+) to dissolved oxygen. Thus, the great majority of Fe (2+) turned into Fe (3+), and the formation of hydroxyl radicals was subsequently inhibited in this reaction.
authors: Department of Chemistry, Wakayama Medical University, Wakayama 641-0011, Japan.
authors: Daisuke
authors: D
authors: Nishizaki
authors: Hideo
authors: H
authors: Iwahashi
mesh_terms: D004365:Drugs, Chinese Herbal / Q000737:chemistry; D004579:Electron Transport / Q000187:drug effects*; D005296:Ferrous Compounds / Q000737:chemistry*; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology*; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000737:chemistry; D006878:Hydroxides / Q000737:chemistry; D007502:Iron Chelating Agents / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D010100:Oxygen / Q000737:chemistry*; D017378:Quinolinic Acid / Q000494:pharmacology; D013268:Stimulation, Chemical
chemical_list: D004365:Drugs, Chinese Herbal; D005296:Ferrous Compounds; D005419:Flavonoids; D005609:Free Radicals; D006878:Hydroxides; D007502:Iron Chelating Agents; C461320:shosaiko-to; C038044:baicalin; C031356:hydroxide ion; D006861:Hydrogen Peroxide; D017378:Quinolinic Acid; D010100:Oxygen
keywords: Baicalin; Fenton Reaction; Hydroxyl Radicals; Iron Chelation; Oxygen Consumption; Quinolinic Acid; Sho-Saiko-To