Studies on Scutellariae Radix. XII. Anti-thrombic Actions of Various Flavonoids from Scutellariae Radix

The flavonoid components, baicalein, baicalin, wogonin, wogonin-7-O-D-glucuronide, oroxylin A, skullcapflavone II, chrysin, (2S)-2', 5, 6', 7-tetrahydroxyflavanone and (2R, 3R)-2', 3, 5, 6', 7-pentahydroxyflavanone, obtained from the roots of Scutellaria baicalensis have been screened in comparison with two standard anti-thrombic agents, aspirin and heparin, for activity in experimental models of blood platelet aggregation or conversion of fibrinogen to fibrin. Baicalein, wogonin, oroxylin A, skullcapflavone II and chrysin at a concentration of 1.0 mM inhibited collagen-induced blood platelet aggregation. Chrysin was also found to inhibit adenosine diphosphate (ADP)-induced blood platelet aggregation. In the case of arachidonic acid-induced blood platelet aggregation, baicalein and wogonin were found to have an inhibitory action. Baicalein and baicalin among the test substances inhibited the conversion of fibrinogen to fibrin induced by thrombin. The effects of baicalein and baicalin on the experimental disseminated intravascular coagulation (DIC) induced by endotoxin in rats was examined ; both compounds prevented the decrease of blood platelets and fibrinogen in DIC rats.