Rational design of 9-vinyl-phenyl noscapine as potent tubulin binding anticancer agent and evaluation of the effects of its combination on Docetaxel

Docetaxel (DOX) based combination therapy is a novel therapeutic strategy that attracts great interest in breast cancer treatment but its clinical utility got limited due to side effects. In contrast, noscapine, an antitussive drug showed antitumor activity against many cancers without any side effects that targets microtubules and attenuates its dynamic instability. In the quest for an increase in the anticancer activity of noscapine, we strategically designed a novel derivative, 9-vinyl phenyl noscapine (VPN), based on ourin silicomolecular docking and molecular dynamics simulation effort. Molecular docking of VPN and DOX onto microtubule revealed a docking score of -4.82 kcal/mol and -6.67 kcal/mol respectively, while the docking score of VPN was changed to -3.23 kcal/mol when it was docked onto the co-complex of tubulin-DOX. Further, the binding free energy (Delta G(bind,PBSA)) of VPN and DOX with tubulin showed -24.04 and -18.65 kcal/mol respectively, while the binding free energy of DOX was increased further in combination with VPN (Delta G(bind, PBSA)was reduced to -21.41 kcal/mol), denoting combination effect of both ligands. The IC(50)value amounted to 30.17 mu M and 19.92 mu M for VPN and 0.621 mu M and 0.193 mu M for DOX, respectively for 48 h and 72 h. The dose dependent cytotoxicity of DOX has been reduced considerably with the combination dose regimen of VPN. Further, the combine effect of both the agents improved the apoptotic cell death 28.5% compared to single agent treatment 5.71% and 10.5% for VPN and DOX, respectively. Both agents bind effectively to tubulin in single and in combination to interfere with cell cycle progression in G2/M transition. This study provides novel concept of combination treatment of DOX and VPN to amend efficiency in breast cancer treatment. Communicated by Ramaswamy H. Sarma