camptothecin
dl-10-hydroxycamptothecin
(E)-6-benzylidene-4-ethyl-3,10-dioxo-3,4,6,7,8,10-hexahydro-1H-pyrano[3,4-f]indolizine-5-carboxylic acid
4,11-diethyl-4,9-dihydroxy-1H-pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-3,14 (4H,12H)-dione
4-Ethyl-7,8-dihydro-4-hydroxy-1H-pyrano[3,4-f]indolizine-3,6,10(4H)-trione