Amentoflavone from Biophytum sensitivum and its effect on COX-1/COX-2 catalysed prostaglandin biosynthesis.

Amentoflavone (I3', II8-biapigenin) was isolated from the roots of Biophytum sensitivum DC. (Oxalidaceae) and proved to be a selective inhibitor of cyclooxygenase (COX)-1 catalysed prostaglandin biosynthesis when tested in vitro with an IC (50) value of 12.4 microM (standard: indomethacin, IC (50) = 1.1 microM). Doses of up to 37 microM showed only a slight inhibition in the corresponding COX-2 assay. Quantification of amentoflavone was carried out by reversed phase HPLC in methanolic and aqueous extracts of the roots, stems and leaves. Highest amounts of amentoflavone were detected in methanolic extracts of roots and stems (0.26-0.35%), while considerably lower amounts were detected in the corresponding water extracts.