Inhibitory effect of ethyl acetate fraction from Cudrania tricuspidata on the expression of nitric oxide synthase gene in RAW 264.7 macrophages stimulated with interferon-γ and lipopolysaccharide

It was found that the production of nitric oxide (NO) by RAW 264.7 macrophages stimulated with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) could be markedly inhibited by the ethyl-acetate-soluble fraction of 80% aqueous methanolic extract of stem barks of Cudrania tricuspidata (EACT). Inhibition of NO production was achieved by reducing inducible nitric oxide synthase (iNOS) expression at protein and mRNA levels and by inactivating nuclear factor-kappaB (NF-kappaB), but not by inhibiting iNOS activity. Thus, further phytochemical and pharmacological studies may lead to isolation and structural identification of an inhibitor of iNOS from C tricuspidata, which has been used as a traditional medicine for curing inflammation. (C) 2001 Elsevier Science Inc. All rights reserved.