We have investigated the anti-inflammatory effects of madecassic acid and madecassoside isolated from Centella asiatica (Umbelliferae) on lipopolysaccharide (LPS)-stimulated RAW 264.7 murine macrophage cells. Both madecassic acid and madecassoside inhibited the production of nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1beta), and IL-6. However, madecassic acid more potently suppressed these inflammatory mediators than did madecassoside. Consistent with these observations, madecassic acid inhibited the LPS-induced expression of iNOS and COX-2 at the protein level and of iNOS, COX-2, TNF-alpha, IL-1beta, and IL-6 at the mRNA level in RAW 264.7 macrophage cells, as determined by Western blotting and RT-PCR, respectively. Furthermore, madecassic acid suppressed the LPS-induced activation of nuclear factor-kappaB (NF-kappaB), and this was associated with the abrogation of inhibitory kappa B-alpha (IkappaB-alpha) degradation and with the subsequent blocking of p65 protein translocation to the nucleus. These results suggest that the anti-inflammatory properties of madecassic acid are caused by iNOS, COX-2, TNF-alpha, IL-1beta, and IL-6 inhibition via the downregulation of NF-kappaB activation in RAW 264.7 macrophage cells.
Georg Thieme Verlag KG Stuttgart-New York.