1H-Pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14(4H,12H)-dione, 4-ethyl-4-hydroxy-, (S)- 20(S)-Camptothecine 21,22-Secocamptothecin-21-oic acid lactone 7689-03-4 CAMPTOTHECIN Camptothecine NSC 100880 NSC94600