Antioxidant and Anti-inflammatory Activities of Butanol Extract of Melaleuca leucadendron L.

Melaleuca leucadendron L. has been used as a tranquilizing, sedating, evil-dispelling and pain-relieving agent. We examined the effects of M. leucadendron L. extracts on oxidative stress and inflammation. M. leucadendron L. was extracted with methanol (MeOH) and then fractionated with chloroform ($CHCl_3$) and butanol (BuOH). Antioxidant activity of the MeOH extract and BuOH fraction were higher than that of both ${\alpha}$-tocopherol and butyrated hydroxytoluene (BHT). Total phenol content in the extracts of M. leucadendron L., especially the BuOH fraction, well correlated with the antioxidant activity. The anti-inflammatory activity of BuOH extracts were investigated by lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$) production, and cyclooxygenase-2 (COX-2) expression in RAW 264.7 macrophages. The BuOH fraction significantly inhibited LPS-induced NO and $PGE_2$ production. Furthermore, BuOH extract of M. leucadendron L. inhibited the expression of COX-2 and iNOS protein without an appreciable cytotoxic effect on RAW264.7 cells. The extract of M. leucadendron L. also suppressed the phosphorylation of inhibitor ${\kappa}B{\alpha}$ ($I{\kappa}B{\alpha}$) and its degradation associated with nuclear factor-${\kappa}B$ (NF-${\kappa}B$) activation. Furthermore, BuOH fraction inhibited LPS-induced NF-${\kappa}B$ transcriptional activity in a dose-dependent manner. These results suggested that M. leucadendron L. could be useful as a natural antioxidant and anti-inflammatory resource.