5,6,17,18-tetramethoxy-1,13-dimethyl-2,3,12a,13,14,15,24,24a-octahydro-1H,12H-8,11:20,23-dietheno[1,10]dioxacyclooctadecino[13,12,11-ij:4,3,2-i'j']diisoquinoline 1-oxide