STYDIES ON THE ISOLATIONS AND STRUCTURES OF BAOHUOSIDS-Ⅰ, Ⅵ, Ⅶ AND BAOHUOSU

Chemical studies of the herb Epimedium davidii Franch. have led to the isolation of a series of flavonoids including some new ones. This paper deals with the isolation of eight other flavonoid compounds-E₁, E₃, E₁₁, E₁₃, E₁₆, E₁₇, E₈ and E₁₅, and the structural determination of four new compounds as well as the identification of three known flavonoidglycosides. On the basis of spectroscopic analysis (UV, IR, MS, ¹HNMR and ¹³CNMR), acidic and enzymic hydrolysis, as well as the determination of their phyisical constants the structures of four new natural occurring compounds-E₁, E₁₁, E₁₆ and E₁₅ were elucidated as 3, 5, 7, -trihydroxy-4'-methoxyl-8-prenylflavone-3-O-α-L-rhamnopyranoside, 3, 5, 7-trihdroxy-4'-methoxyl-8-prenylflavone-3-O-α-L-rhamnopyranosyl (4←1)-α-L-rhamnopyranosyl-7-O-β-D-glucopyranoside, 3, 5, 7-trihydroxy-4'-methoxyl-8-prenylflavone 3-α-L-rhamnopyranosyl ( 4←1 ) -β-D-glucopyranoside and 5, 7, 4'-trihydroxy-3', 5'-dimethoxyl-8-prenylflavone and named as baohuoside-Ⅰ, baohuoside-Ⅵ, baohuoside-Ⅶ and baohuosu, respectively. The three other known flavonoids-E₃, E_(13) and E₈ were identified as icariin, icaritin and tricin. The full structure of the flavonoldiglycoside E_(17) is expected to be further determined. Tricin was discovered in the genus E pimedium for the first time.