A cyclooxygenase (COX) inhibitory biflavonoid from the seeds of Semecarpus anacardium.

Semecarpus anacardium Linn., Anacardiaceae, is being most commonly used in India for the treatment of rheumatoid arthritis and other inflammatory disorders. Bioactivity guided fractionation of ethyl acetate extract led to the isolation of major active principle, tetrahydroamentoflavone (THA), a biflavonoid. The in vitro cyclooxygenase (COX-1) catalyzed prostaglandin biosynthesis assay of THA gave an IC(50) value of 29.5 microM (COX-1) and 40.5% inhibition at 100 microg/mL (COX-2). The in vivo carrageenan induced paw edema assay resulted in dose dependent anti-inflammatory effect of THA and the activity was comparable to that of ibuprofen, one of the well known NSAIDs.