Effect of (-)-epigallocatechin-3-gallate on respiratory burst of rat macrophages |
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Authors: | Alvarez E Leiro J Orallo F |
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Affiliation: | Departamento de Farmacología, Facultad de Farmacia, Universidad de Santiago de Compostela, Spain. |
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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. |
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