This study was carried out to investigate the anti-inflammatory effects of glycoprotein (UDN glycoprotein, 116-kDa) isolated from Ulmus davidiana Nakai, which has been used to heal inflammatory diseases in Korean herbal medicine. We found that UDN glycoprotein has strong scavenging effect on the production of intracellular superoxide anion (O(2)(-)), hydrogen peroxides (H(2)O(2)), and nitric oxide (NO) without any cytotoxicity, and that the glycoprotein also selectively normalizes the aberrant activation of manganese-superoxide dismutases (Mn-SOD) activity in lipopolysaccaride (LPS)-treated cancerous human colon epithelial cells (HCT-116 cells). The results obtained from electrophoretic mobility shift assay (EMSA) and Western blot analysis showed that UDN glycoprotein blocks the DNA binding activities of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), and attenuates the activities of NF-kappaB subunits (p50 and p65), and AP-1 subunits (c-Jun and c-Fos), respectively. To further verify the anti-inflammatory effect of UDN glycoprotein, we investigated the activity of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and matrix metalloproteinases-9 (MMP-9) in LPS-treated HCT-116 cells, using Western blot analysis and gelatin zymographic assay. Results in this study indicated that 200mug/ml of UDN glycoprotein has inhibitory effects on the activations of iNOS, COX-2, and MMP-9. Therefore, UDN glycoprotein, a natural antioxidant, is a potential modulator of inflammatory signal pathways in LPS-treated HCT-116 cells.