Alpha-viniferin was previously isolated as a cyclooxygenase (COX)-2 inhibitor from Carex humilis (Cyperaceae) and is an oligomeric stilbene compound with benzofuran (BF) moieties in its chemical structure. In the present study, a chemically synthetic BF compound, named as 3,3-dimethyl-2,3,4,6,7,8,9,10,11,12,13,14,15,16,17,18-hexadecahydro-1H-benzo[b] cyclopentadeca[d]furan-1-one, was discovered to inhibit bacterial lipo polysaccharide (LPS)-induced prostaglandin $E_2$ $(PGE_2)$ production in macrophages RAW 264.7. The BF compound exhibited a selectively preferred inhibitory effect on COX-2 activity over COX-1 activity. Furthermore, BF compound inhibited LPS-induced COX-2 expression at transcription level. As a down-regulatory mechanism of COX-2 expression shown by BF compound, suppression of nuclear factor $(NF)-{kappa}B$ activation has been demonstrated. BF compound inhibited LPS-induced $NF-{kappa}B$ transcriptional activity and nuclear translocation of $NF-{kappa}B$ p65, in parallel, but did not affect LPS-induced degradation of inhibitory ${kappa}B{alpha}$ protein $(I{kappa}B{alpha})$. Taken together, anti-inflammatory effect of BF compound on $PGE_2$ production was ascribed by its down-regulatory action on LPS-induced COX-2 synthesis in addition to inhibitory action on enzyme activity of COX-2.