Bicuculline is a benzylisoquinoline alkaloid that is 6-methyl-5,6,7,8-tetrahydro[1,3]dioxolo[4,5-g]isoquinoline which is substituted at the 5-pro-S position by a (6R)-8-oxo-6,8-dihydrofuro[3,4-e][1,3]benzodioxol-6-yl group. A light-sensitive competitive antagonist of GABAA receptors. It was originally identified in 1932 in plant alkaloid extracts and has been isolated from Dicentra cucullaria, Adlumia fungosa, Fumariaceae, and several Corydalis species. It has a role as a GABAA receptor antagonist, an agrochemical, a central nervous system stimulant, a GABA-gated chloride channel antagonist and a neurotoxin. It is a benzylisoquinoline alkaloid, an isoquinoline alkaloid and a member of isoquinolines.