Inhibition of Nitric Oxide Production by Ethyl Digallates Isolated from Galla Rhois in RAW 264.7 Macrophages

widely known to possess potent anti-infl ammatory properties by reducing the production of pro-infl ammatory cytokine production, or stimulating the production of anti-infl ammatory cytokines, including interleukin-10 (Otterbein et al., 2003; Paine et al., 2010). Additionally, HO-1 over-expression protects against cytotoxicity induced by NO (Son et al., 2005). HO-1 expression is induced by binding of an upstream activator to the anti-oxidant response element (ARE) in its promoter region. Nuclear factor-erythroid-2-related factor (Nrf2), a transactivating protein, interacts with AREs and is known to play an essential role in the expression of HO-1 (Prawan et al., 2005). Galla Rhois, the gall derived from the nutgall sumac tree, Rhus javanica, has been used for the treatment of various diseases, including skin disease, diarrhea, dysentery, hemorrhage, and leucorrhea in traditional oriental medicine. A number of tannin-derived components isolated from Galla Rhois have been shown to possess various biological activities, including anti-bacterial (Kang et al., 2008) and anti-metastatic/ anti-invasion of tumor cells (Ata et al., 1996). In addition, previously we demonstrated that equilibrium mixture of ethyl Original Article Biomol Ther 19(4), 419-424 (2011)