Green Tea Polyphenol Epigallocatechin-3-O-Gallate Attenuates Lipopolysaccharide-induced Nitric Oxide Production in RAW264.7 Cells

Abstract

Epigallocatechin-3-O-gallate (EGCG), the major polyphenol found in green tea, has been shown to downregulate inflammatory responses in macrophages; however, the underlying mechanism has not been understood. Overproduction of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) is known to be closely correlated with the pathology of a variety of diseases and inflammations. In this study, we investigated the inhibitory effect of EGCG on NO production and its molecular mechanism in lipopolysaccharide (LPS)-stimulated macrophage RAW264.7 cells. Besides a decrease in NO secretion, protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) also decreased in LPS-stimulated RAW264.7 macrophage cells treated with EGCG. These results suggest that EGCG possesses a potent anti-inflammatory activity.