[Studies on the isolation and structures of baohuoside-II, III, IV and V].

Seventeen constituents were isolated from the dried herb of Epimedium davidii Franch. This paper reports the structural determination and identification of nine flavonoids. The structures of four new natural occurring compounds-E_2, E_6, E_7 and E_(10) were elucidated as 3, 5, 7, 4'-tetrahydroxy-8-prenylfavone-3-O-α-L-rhamnopyranoside, 3, 5, 7, 4'-tetrahydroxy-8-prenylflavone-3-O-α-L-rhamnopyranosyl (4←1)-α-L-rhamnopyranoside, 3, 5, 7, 4'-tetrahydroxy-8-pre-nylflavone-3,7-O-α-L-dirhamnopyranoside and 3, 5, 7, 4'-tetrahydroxy-8-prenylflavone-3-O-α-L-rhamnopyransyl (4←1)-α-L-rhamnopyranosyl-7-O-β-D-glueopyranoside and named as baohuoside-Ⅱ, Ⅲ, Ⅳ and Ⅴ, respectively, byspectroscopic data (UV, IR, MS, ~1H-and ~(13)CNMR) and chemical reactions. The five other flavonoids-E_5, E_9, E_(12), E_4 and E_(14) were identified as epimedoside-C, epimedo-side-A, desmethylicaritin, hyperin and kaempferol-3-dirhamnoside, respectively, on the basis of spectral analysis and physicochemical properties. Hyperin and kaemp-ferol-3-dirhamnoside were found in the genus Epimedium for the first time.