Aim To investigate the chemical composition of Ranunculus sieboldii Miq..Methods Repeated column chromatography over silica gel, polyamide and RP-18 followed by gelfiltration on sephadex LH-20 were used to isolate chemical constituents, and their structures wereelucidated by extensive spectroscopic methods (UV, IR, MS, ~1H NMR, ^(13)C NMR) including 2D NMR(COSY, HMQC, HMBC, NOESY) techniques and by direct comparing spectral data with those reported inliterature. Results Five flavonoid glycosides named apigenin-4'-O-α-L-rhamnopyranoside (1),apigenin-7-O-β-D-glucopyranosyl-4'-O-α-L-rhamnopyranoside (2), apigenin-8-C-α-L-arabinopyranoside(3), apigenin-8-C-β-D-ga-lactopyranoside (4) , tricin-7-O-β-D-glucopyranoside (5), together withtricin (6), luteolin (7), scopoletin (8), esculetin (9), scoparone (10), ferulic acid (11),protocatechuic acid (12) , and tematolide (13) were isolated from the 95% etha-nolic extract of itswhole plant, and their cytotoxic activities were preliminarily tested. Conclusion Compounds 1-12were obtained from this genus and compound 13 from this species for the first time. Furthermore,compound 1 was for the first time isolated from nature while the ^(13)C NMR data of compounds 2 and3 are reported for the first time. The bioassay revealed that compound 1 was active against BEL-7407and A549 cell lines (IC_(45) 43, 77 μg·mL^(-1)), 8 and 10 showed inhibitory activities on KB celllines (IC_(50) 78, 44 μg·mL^(-1)) and HL-60 cell lines (Ic_(50) 85, 85 μg·mL^(-1)), while 7exerted moderate cytotoxic activities on KB, BFL-7407, A549 and HL-60 cell lines with their IC_(50)being 51, 55, 44 and 10 μg·mL^(-1) , respectively.
