Ginkgolide B is a natural non-selective blocker of 5-HT3A channel. Ginkgolide is extracted from the leaves, roots and bark of the tree Ginkgo bilboa. Ginkgolide B has an effective concentration of 500-1000 μM and an IC50 of 730 μM for the 5-HT3A receptor and an IC50 of 3.9 mM for the 5-HT3B receptor thus enabling discrimination between the two. Ginkgolide also binds to anion Cys-loop receptors such as GABA and glycine receptors. Ginkgolide does not displace the specific 5-HT3 receptor antagonist granisetron, thus confirming that it does not act at the agonist binding site. In addition, inhibition by Ginkgolide at 5-HT3A receptors is weakly use-dependent, and recovery of the receptor is also activity dependent, indicating channel block as the mechanism of inhibition. Ginkgolide is widely used in traditional medicine and has a wide spectrum of beneficial properties such as anti-convulsion, neuro-protection and reducing anxiety
