Abstract: The whole plant of Phyllanthus urinaria L.(Euphorbiaceae) were used to investigate on their chemical constituents and bioactivities,fourteen flavonoids were isolated from the EtOAc fraction derived from 95% EtOH extract of P.urinaria by a combination of various chromatographic techniques,including column chromatography over silica gel and Sephadex LH-20 as well as reversed-phase HPLC.The structures of these flavonoids were determined on the basis of spectroscopic analysis including MS and NMR data．They were identified as quercetin-3-(4"-O-acetyl)-O-α-L-rhamnopyranoside-7-O-α-L-rhamnopyranoside (1),quercetin-7-O-α-L-rhamnoside (2),quercetin-3-O-α-L-rhamnoside (3),quercetin-3-O-β-D-glucopyranoside (4),rutin (5),quercetin (6),kaempferol (7),kaempferol-3-O-α-L-rhamnoside (8),luteolin (9),luteolin-7-O-β-D-glucoside (10),buddleoside (11),kaempferol-3-O-β-D-glucopyranosyl-(1→6)-α-L-rhamnoside (12),naringin (13),hesperidin (14).All the compounds,except for 5-7,were isolated from P.urinaria for the first time.Compounds 6,9 and 10 showed potential cytotoxic effects,and all of these compounds had antioxidant activity to some extent.

Key words: Phyllanthus urinaria, flavonoids, cytotoxicity, antioxidation