Abstract: (20S) esters of camptothecin analogs are provided. The compounds are (20S) esters of an aminoalkanoic acid or an imidoalkanoic acid and camptothecin, which is optionally substituted at the 7, 9, 10, 11, and 12 positions of the camptothecin ring. The compounds are useful for treating cancer.

Abstract: Certain N-deacetylcolchicine and N-deacetylthiocolchine derivatives are described wherein the 7-N position on the B ring is substituted with the group —C(O)—(CHR4)m—AR, wherein m is an integer of 0-10, A is S, O, N or a covalent bond; R1 is substituted phenyl or substituted benzoyl; optionally substituted cycloalkyl of 3-7 carbons; optionally substituted naphtyl; an optionally substituted imide ring; an optionally substituted 5 or 6 member heterocycle with at least one N, S, or O in the ring; or an optionally substituted fused heterocyclic or fused carboxyclic ring system; R2 (at the 2-position of the A ring) is methoxy, hydroxy, or methylenedioxy when taken together with R3; R3 (at the 3-position of the A ring) is methoxy, hydroxy, a monosaccharide radical, or is methylenedioxy when taken together with R2; and R4 is H or is H or methyl when m is 1. Also dimers of such compounds are disclosed.