Antithrombotic effect of geniposide and genipin in the mouse thrombosis model

Geniposide is one of the constituents of Gardenia fruit (Gardenia jasminoides Ellis, Rubiaceae), which has been used in traditional medicine. Although its anti-inflammatory and antithrombotic effects have been reported, the way it acts is still unclear. We have investigated the effects of geniposide and its metabolite genipin on thrombogenesis and platelet aggregation. In an in vivo model, geniposide and genipin significantly (P < 0.05) prolonged the time required for thrombotic occlusion induced by photochemical reaction in the mouse femoral artery. In an in vitro study, both geniposide and genipin inhibited collagen-induced, but did not inhibit arachidonate-induced, mouse platelet aggregation. However aspirin, a cyclooxygenase inhibitor, inhibited arachidonate-induced platelet aggregation but only partially inhibited the collagen-induced one. We also showed, by measuring PLA₂-catalyzed arachidonic acid release, that geniposide inhibited phospholipase A₂ (PLA₂) activity. We conclude that geniposide showed an antithrombotic effect in vivo due to the suppression of platelet aggregation. PLA₂ inhibition by geniposide is one possible anti-platelet mechanism.