Anti-inflammatory activity of aculeatin and toddaculin, which are coumarins with a similar structure isolated from Toddalia asiatica (L.) LAM., was evaluated using lipopolysaccharide (LPS)-stimulated RAW264 mouse macrophage cells. Both aculeatin and toddaculin significantly inhibited mRNA expression of inflammatory mediators and nitric oxide production. Furthermore, Toddaculin suppressed LPS-induced phosphorylation of p38 and extracellular signal-regulated kinase (ERK)1/2 and inhibited LPS-induced activation of nuclear factor-kappaB (NF-κB). However, aculeatin did not exhibit such effects, suggesting that aculeatin and toddaculin suppress LPS-induced inflammation of RAW264 cells via different mechanisms. The cellular uptake of these compounds was also evaluated. Toddaculin was detected in RAW264 cells after 4 and 24 h. However, aculeatin levels were not observed in RAW264 cells at all incubation intervals. These results indicate that de-epoxidation of a prenyl group can increase hydrophobicity of molecule and is thought to accelerate cellular uptake and/or interactions with the phospholipid bilayers of cell membranes.
Keywords: Toddalia asiatica; aculeatin; anti-inflammation; coumarin; macrophage; toddaculin.