Xanthone is a monoamine oxidase A (MAO-A) inhibitor with an IC50 of 0.84 µM. Xanthon inhibits Norepinephrine and high-K+-induced vasoconstriction with IC50 values of 60.26 μM and 82.9 μM, respectively. Xanthon increases intracellular cyclic adenosine 3′,5′-monophosphate (cAMP) content and blocks Ca2+ channels. Xanthone is the scaffold of several pharmacologically active compounds[1][2].