Abstract: Phytochemical studies on the active part of Juncus effusus resulted in the isolation of nine compounds using LC-MS and chromatographic techniques (Silica gel,Al₂O₃,Sephadex LH-20 and HPLC).Their structures were identified as effusol (1),dehydroeffusol (2),juncusol (3),juncuenin G (4),dehydrojuncuenin D (5), 5-(hydroxymethyl)-1-methylphenanthrene-2,7-diol (6),oleanic acid (7),2-formyl-5-hydroxymethylfuran (8) and maltol-3-O-β-D-glucopyranoside (9) by HR-ESI-MS and NMR methods.Compounds 8 and 9 were obtained from the genus Juncus for the first time,and compound 9 was firstly isolated from natural resource. Compounds 1,3 and 4 showed significantly activity on 5-HT_1A- receptor with agitating rates of 65.35±6.70%,71.33±7.39% and 64.11±5.33%,and on MT₂ receptor with agitating rates of 62.77±12.06%,67.28±9.26% and 56.21±11.43% at the concentration of 1.0 mM.Compounds 2,5 and 6 possessed moderate activities agitating 5-HT_1A and MT₂ receptors.These results provided valuable information for the further study and utilization of J.effusus.

Key words: Juncus effusus, chemical constituents, 5-HT_1A receptor, MT₂ receptor, LC-MS