Lucidone inhibits iNOS and COX-2 expression in LPS-induced RAW 264.7 murine macrophage cells via NF-kappaB and MAPKs signaling pathways

The anti-inflammatory mechanism of lucidone isolated from the fruits of Lindera erythrocarpa Makino was investigated. Our data indicate that lucidone significantly inhibits the production of NO and PGE(2) autacoids in LPS-induced RAW 264.7 murine macrophage cells. Moreover, it also notably decreased the secretion of tumor necrosis factor-alpha (TNF-alpha). Consistent with these observations, the mRNA and protein expression levels of iNOS and COX-2 were also inhibited by lucidone in a dose-dependent manner. Lucidone also reduced the translocation of NF-kappaB induced by LPS, which is associated with the prevention of the degradation of I-kappaB, and subsequently decreased p65/p50 protein levels in the nucleus. Lucidone also inhibited NF-kappaB activation by impairing the binding of NF-kappaB to its cis-acting element. In addition, lucidone inhibited JNK and p38MAPKs signals, which are the most significant signals involved in NO, PGE(2) and TNF-alpha production; NF-kappaB/AP-1 activation was also inhibited by lucidone. Taken together, the anti-inflammatory activity of lucidone might be caused by the inhibition of iNOS and COX-2 expressions through downregulation of NF-kappaB and AP-1 binding.