Kuraridine is a prenylated flavonol extract from the roots of Sophora flavescens . Kuraridine has an inhibitory effect on cGMP specific phosphodiesterase type 5 ( PDE5 ) ( IC 50 =0.64 μM) In Vitro Kuraridine shows potent inhibitory activity (IC 50 =0.64 μM) against cGMP PDE5 with 2.0- and 12.9-fold selectivity over PDE3 and PDE4, respectively. Kuraridine induces pronounced chloride inward currents in the absence of GABA. Thecurrents does not exceed 10% of the maximal I GABA induced by a saturating GABA concentration (1 mM). Kuraridine induces a concentration–response curves for I GABA enhancement (EC 50 =4.0±2.4 μM) in Xenopus oocytes expressing GABA A receptors composed of α1, β2, and γ2S subunits. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:PDE5 0.64 μM (IC 50 )