Plant extracts and/or secondary metabolites are receiving considerable attention as therapeutic agents for treating inflammatory diseases such as periodontitis, which affects the tooth supporting tissues. The aim of this study was to investigate the effect of a Grindelia robusta extract enriched in saponins and polyphenols on Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS)-induced inflammatory mediator (IL-6, TNF-a, RANTES, MCP-1, PGE(2) ) and matrix metalloproteinase (MMP-1, -3, -7, -8, -9, -13) secretion by macrophages. LPS induced a marked increase in the secretion of all inflammatory mediators and MMPs tested by macrophages, as determined by enzyme-linked immunosorbent assays. At non-cytotoxic concentrations, the G. robusta extract inhibited dose-dependently the secretion of IL-6, RANTES, MCP-1 and, to a lesser extent, PGE(2) and TNF-a. Such inhibition was also observed for MMP-1, -3, -7, -8, -9 and -13 secretion. This ability of G. robusta extract to reduce the LPS-induced secretion of inflammatory mediators and MMPs was associated with a reduction of nuclear factor-kappa B (NF-kB) p65 activation. The results suggest that G. robusta extract possesses an antiinflammatory therapeutic potential through its capacity to reduce the accumulation of inflammatory mediators and MMPs.