Kuraridine

Kuraridine is a prenylated flavonol extract from the roots ofSophora flavescens. Kuraridine has an inhibitory effect on cGMP specific phosphodiesterase type 5(PDE5) (IC50=0.64 μM).

Kuraridine shows potent inhibitory activity (IC₅₀=0.64 μM) against cGMP PDE5 with 2.0- and 12.9-fold selectivity over PDE3 and PDE4, respectively^[1].
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)^[2].
Kuraridine induces a concentration–response curves for I_GABA enhancement (EC₅₀=4.0±2.4 μM) in Xenopus oocytes expressing GABA_A receptors composed of α1, β2, and γ2S subunits^[2].

References:
[1]. Hye Joo Shin, et al. A prenylated flavonol, sophoflavescenol: a potent and selective inhibitor of cGMP phosphodiesterase 5. Bioorg Med Chem Lett. 2002 Sep 2;12(17):2313-6.
[2]. Xinzhou Yang, et al. HPLC-based activity profiling for GABAA receptor modulators from the traditional Chinese herbal drug Kushen (Sophora flavescens root). Mol Divers.2011 May;15(2):361-72.