Ginkgetin, a Biflavone from Ginko biloba leaves, inhibits cyclooxygenases-2 and 5-lipoxygenase in mouse bone marrow-derived mast cells. 
Ginkgetin, a biflavone from Ginkgo biloba leaves, was previously reported to be a phospholipase A(2) inhibitor and this compound showed the potent antiarthritic activity in rat adjuvant-induced arthritis as well as analgesic activity.  This investigation was carried out to find effects on cyclooxygenase-2 (COX-2) in vitro effect.  Ginkgetin inhibits COX-2 dependent phases of prostaglandin D(2) (PGD(2)) generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with IC(50) values of 0.75 microM. Western blotting probed with specific anti-COX-2 antibodies showed that the decrease in quantity of the PGD(2) product was accompanied by a decrease in the COX-2 protein level.  In addition, this compound consistently inhibited the production of leukotriene C(4) (LTC(4)) in a dose dependent manner, with an IC(50) value of 0.33 microM. These results demonstrate that ginkgetin has a dual cyclooxygenase-2/5-lipoxygenase inhibitory activity.  Furthermore, this compound also inhibited degranulation reaction in a dose dependent manner, with an IC(50) value of 6.52 microM. Therefore, this compound might provide a basis for novel anti-inflammatory agents.