Conformational features of 4-(N)-squalenoyl-gemcitabine in solution: a combined NMR and molecular dynamics investigation

A combination of NMR spectroscopy and molecular modelling techniques has been used to investigate the conformational behaviour in solution of 4-(N)-squalenoyl-gemcitabine (Sq-Gem), a promising anticancer new derivative whose pharmacological and biological properties and its use in the medical applications are heavily influenced by its three-dimensional structure. NMR scalar coupling constants (J-couplings) have been experimentally measured, by mono-and bi-dimensional methods, and, subsequently, compared with the theoretical values estimated, via DFT calculations, on the most representative conformations obtained and optimized by molecular dynamics (MD) simulations in methanol solution. Following this approach, we found a good agreement between calculated and experimental NMR data for the major conformations in which the flexible squalenoyl chain is strongly folded.