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, or CN; R.sup.0 and R.sup.1 are independently the same or different and are H, or a linear or branched alkyl, linear or branched alkylaryl, hydroxyalkyl or aryl group; R.sup.2, R.sup.3 and R.sup.4 are independently the same or different and are H, or a linear or branched alkyl, linear or branched alkylaryl, hydroxyalkyl or 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 alkyl, linear or branched alkylaryl or aryl group, or an alkoxy, aryloxy, hydroxyalkyl, C-glycal, nitro, cyano or aminoalkoxy group, or CO.sub.2 R, Cl, F, Br, I, SR.sup.10, NR.sup.11 R.sup.12 or OR.sup.13 ; R is H, an alkyl, aryl, alkylaryl or hydroxyalkyl group; R.sup.10, R.sup.11 and R.sup.12 are independently the same or different and are H, an alkyl, aryl, alkylaryl or acyl group; R.sup.13 is glycosyl; and n is 0 or 1. Also provided are compositions comprising the analogues and methods of treating tumors as well as methods for preparing the analogues.