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.