Synthesis and biological evaluation of colchicine C-ring analogues tethered with aliphatic linkers suitable for prodrug derivatisation.

Colchicine was modified at the 10-OCH(3) position of the C-ring by reaction with heterocyclic amines or commercially available amines to afford a library of target colchicinoids in high yields (62-99%). Molecular modeling revealed that the incorporation of the linker groups led to a reduction in entropy and therefore binding affinity when compared with colchicine. Some colchicinoids were shown to be equicytotoxic with colchicine when evaluated in the DLD-1 colon cancer cells and retained activity in resistant A2780AD or HeLa cells with mutant Class III β-tubulin. Importantly, unlike colchicine, the analogues in this study are amenable for prodrug derivatisation and with potential for tumor-selective delivery.