Flavonoids with Bradykinin Antagonistic Effects from Scutellariae Radix

Seven flavonoid components were isolated from fr. C of Scutellariae radix which showed antagonistic effects against bradykinin(BK). The results indicated that two oxygen functions (either -OH or $-OCH_3$) at 2'- and 6'-positions and/or an oxygen function at 6-position of flavone seemed to be favored for the BK inhibitory activities. Skullcapflavone-II(IV) which contains $6-OCH_3$, 2'-OH and $6-OCH_3$ in the structure was the most active among the flavones tested.