ChEBI: Picrotoxinin is a picrotoxane sesquiterpenoid that is 3a,4,5,6,7,7a-hexahydro-1H-indene-3,7-dicarboxylic acid which is substituted at positions 3a, 6, and 7a by methyl, isopropenyl, and hydroxy groups, respectively; in which the double bond at position 2-3 has been epoxidised; and in which the carboxy groups at positions 3 and 7 have undergone gamma-lactone formation by O-alkylation to positions 4 and 5, respectively. A component of picrotoxin. It has a role as a plant metabolite, a GABA antagonist and a serotonergic antagonist. It is an organic heteropentacyclic compound, an epoxide, a tertiary alcohol, a gamma-lactone and a picrotoxane sesquiterpenoid.