Amentoflavone is a biflavonoid (bis-apigenin coupled at 8 and 3 positions, or 3,8-biapigenin) constituent of a number of plants including Ginkgo biloba, Chamaecyparis obtusa (hinoki), Biophytum sensitivum, Selaginella tamariscina, Hypericum perforatum (St. John's Wort) and Xerophyta plicata.
Amentoflavone can interact with many medications by being a potent inhibitor of CYP3A4 and CYP2C9, which are enzymes responsible for the metabolism of some drugs in the body. It is also an inhibitor of human cathepsin B.
Amentoflavone has a variety of in vitro activities including antimalarial activity, anticancer activity (which may, at least in part, be mediated by its inhibition of fatty acid synthase), and antagonist activity at the ú-opioid receptor (K<sub>e</sub> = 490 nmol L<sup>−1</sup>) as well as activity at the allosteric benzodiazepine site of the GABA<sub>A</sub> receptor as a negative allosteric modulator.