Bioactivity-guided fractionation of the methanolic extract of the aerial parts of EUSCAPHIS JAPONICA (Tunb.) Kantiz (Staphyleaceae), afforded a new compound, P-coumaroyl- D-malic acid 1-methyl ester (1), together with twelve known compounds, 3,7-dihydro-5-octanolide (2), blumenol A (3), megastigmane (4), gallic acid (5), stenophyllin H1 (6), methyl 5,7-dihydroxyoctanoate (7), TRANS-phytol (8), alpha-tocopherol (9), kaempferol (10), kaempferol 3-O-beta-D-glucopyranoside (11), quercetin (12) and quercetin 3-O-beta-D-glucopyranoside (13). Among them, compounds 1 - 5 and 8 - 13 significantly inhibited lipopolysacchride-induced nitric oxide production in murine BV2 microglial cells. Especially, compounds 5, 8, 10 and 12 exerted potent inhibitory activity comparable to that of NAME, used as positive control.