Substituted analogues of camptothecin possessing cytotoxic activity towards cancer cells, of the general structure: ##STR1## wherein E is H, CO.sub.2 R, CONH.sub.2, CONHR, CONR.sub.2, acyl, or CN; X is H, OH, or OR; R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are independently the same or different and are H, or a linear or branched chain alkyl, alkylaryl, or hydroxyalkyl group, or an aryl group; R.sup.5, R.sup.6, R.sup.7, R.sup.8, and R.sup.9 are independently the same or different and are H, or a linear or branched chain alkyl, alkylaryl, alkoxy, hydroxyalkyl, or aminoalkoxy group, or an aryl or aryloxy group, or a C-glycal, or CO.sub.2 R, nitro, cyano, Cl, F, Br, I, SR.sup.10, NR.sup.11 R.sup.12, OR.sup.13 ; R is H, or a linear or branched chain alkyl, alkylaryl, or hydroxyalkyl group, or an aryl group; R.sup.10, R.sup.11 and R.sup.12 are independently the same or different and are H, or a linear or branched chain alkyl, alkylaryl, hydroxyalkyl, or acyl group, or an aryl group; R.sup.13 is glycosyl; n is 0 or 1; with the proviso that when R.sup.1 is ethyl, and n is 0, E, R.sup.2, R.sup.3, and R.sup.4 are not all H. Intermediate compounds leading to the camptothecin analogues comprise substituted tricyclic compounds which consist of rings C, D, and E fused together. Methods for preparing the analogues involve condensation of such intermediates with variably substituted protected .alpha.-aminobenzaldehydes.