title: Effect of (-)-epigallocatechin-3-gallate on respiratory burst of rat macrophages.
abstract: The toxic effects derived from overproduction of oxygen radicals [reactive oxygen species (ROS)] by immune cells can be partially abolished by the antioxidant activities of plant polyphenols. In the present study, we investigated the antioxidant action of a catechin, (-)-epigallocatechin-3-gallate (EGCG), on the respiratory-burst responses of rat peritoneal macrophages. EGCG at concentrations of 50-200 microM blocked the production of nitric oxide by macrophages stimulated in vivo with sodium thioglycollate then 5 days later in vitro with lipopolysaccharide and gamma-interferon. At 1-100 microM, EGCG also inhibited the extracellular liberation of oxygen radicals by resident peritoneal macrophages stimulated with the protein kinase C activator phorbol 12-myristate 13-acetate (PMA). At low concentrations (1-5 microM), EGCG increased the reduction of nitro blue tetrazolium (NBT) by the superoxide anions generated in the non-enzymatic system NADH/PMS, acting as a pro-oxidant agent, while at concentrations above 10 microM, EGCG acts as a scavenger of superoxide anions. These results show that EGCG is capable of modulating ROS production during the respiratory burst of rat peritoneal macrophages by acting as a superoxide anion scavenger. EGCG may therefore be useful in the prevention and treatment of diseases due to increased free radical production.
authors.affiliation: Departamento de Farmacología, Facultad de Farmacia, Universidad de Santiago de Compostela, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Alvarez
authors.forename: J
authors.initials: J
authors.lastname: Leiro
authors.forename: F
authors.initials: F
authors.lastname: Orallo
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002478:Cells, Cultured; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000187:drug effects* / Q000502:physiology
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D002392:Catechin; C045651:epigallocatechin gallate