Certain irinoid-producing plants have been used as herbal anti-inflammatory remedies. Here we evaluated whether catalposide (CATP), a single compound isolated from irinoid-producing plant Catalpa ovata, has a potential for preventing or ameliorating diseases characterized by mucosal inflammation. Preliminary microarray-based gene expression test revealed that CATP, which alone did not significantly affect expression of any of the >8,000 genes analyzed, attenuated the expression of tumor necrosis factor-α (TNF-α)-induced proinflammatory genes including interleukin-8 (IL-8) in human intestinal epithelial HT-29 cells. Down-regulation of IL-8 mRNA accumulation was also reflected by the decreased IL-8 secretion in CATP-treated HT-29 cells. The signal transduction study revealed that CATP significantly attenuates TNF-α-mediated p38 and extracellular signal-regulated kinase (ERK) phosphorylation. Further, CATP reduced NF-κB-mediated transcriptional activation as well as Iκ-Bα degradation. To establish the in vivo relevance of these findings, we examined whether CATP could affect intestinal inflammation in vivo using the mouse model of trinitrobenzene sulfonic acid (TNBS)-induced inflammatory colitis. Intrarectal administration of CATP dramatically reduced the weight loss, colonic damage, and mucosal ulceration that characterize TNBS colitis. Moreover, CATP suppressed the expression of TNF-α, interleukin-1β, and intercellular adhesion molecule-1 along with the inhibition of NF-κ B p65 translocation into nucleus in TNBS colitis. Collectively, current results demonstrate that CATP may be an effective agent for the treatment of diseases characterized by mucosal inflammation.