Fourteen compounds including vanicoside B (1), vanicoside F (2), vanicoside E (3) and 5,6-dehydrokawain (4), aniba-dimer-A (5), 6,6′-((1α,2α,3β,4β)-2,4-diphenylcyclobutane-1,3-diyl)bis(4-methoxy-2H-pyran-2-one) (6), (+)-ketopinoresinol (7), isorhamnetin (8), 3,7-dihydroxy-5,6-dimethoxy-flavone (9), isalpinin (10), cardamomin (11), pinosylvin (12), 2-desoxy-4-epi-pulchellin (13) and β-sitosterol (14) were isolated from dichloromethane-soluble portion of Polygonum hydropiper. By using Alamar blue assay, compounds 2, 7, 8, 11 and 12 were fou...