A rational design of bioactive taxanes with side chains situated elsewhere than on C-13.

The structure of alphabeta-tubulin was refined and used in the docking study for taxuspine D, paclitaxel and their analogues. The conformational space in the binding site was explored by molecular dynamics. The interaction energy was calculated by minimization in the active site of beta-tubulin. The C-5 cinnamoyl side chain in taxuspine D is found to mimic the C-13 side chain of paclitaxel. A virtual taxane with a new C-5 side chain is predicted to be more active than taxuspine D. The C-13 side chain could be replaced with a novel C-5 side chain if the conformation of the core skeleton is modified.