Influence of carboxymethyl chitosan chain length on its interaction with vitamin C and curcumin: molecular docking...

The molecular understanding of the interaction between carboxymethyl chitosan (CMCs) with the encapsulated drug (vitamin C and curcumin) has not been clearly understood yet. This study seeks to ascertain how the polymer length affects the molecular weight of CMCs as a matrix by using molecular dynamics and molecular docking. We have used pentamer (N-CMCs-5), decamer (N-CMCs-10), and pentadecamer(N-CMCs-15). Molecular docking and dynamic simulations showcase diverse interaction strengths, revealing medium-to-weak hydrogen bonds and hydrophobic interactions within the N-CMCs…vitamin C and N-CMCs…curcumin complexes. Notably, N-CMCs-5…vitamin C (- 17.23 kJ/mol) and N-CMCs-10…curcumin (- 19.74 kJ/mol) exhibit the most robust interactions. RMSD analysis underscores the superior stability of N-CMCs-5…vitamin C (6.70 ± 1.68) and N-CMCs-5…curcumin (8.62 ± 2.47), particularly in comparison to other complexes. Stability in the solid phase relies on medium hydrogen bonds, while solution-phase stability hinges on hydrophobic interactions. Intriguingly, distance analysis highlights the exceptional stability of N-CMCs-5…vitamin C and N-CMCs-15…curcumin, maintaining distances below 3.2 Å during a 100 ns simulation, indicating robust complex stability. The binding constant of N-CMCs-5…vitamin C and N-CMCs-15…curcumin respectively 0.96 mM and 0.39 mM. The findings emphasize the influential role of longer polymer conformations in regulating drug release. Sequential docking studies revealed that curcumin has the capacity to stabilize the complexes, whereas vitamin C tends to destabilize them.

The molecular docking method was carried out in grid boxes measuring 10 × 10 × 10 Å using the YASARA software. Docking was performed at a temperature of 298.15 K using the VINA algorithm. Molecular docking generates conformation of the receptor-ligand complex, binding site between ligand and receptor, and the energy of complex interactions. Molecular dynamics simulations have been simulated using the same software but utilizing the AMBER14 force field for 100 ns at 298.15 K through many steps of solvation, neutralization, minimization, equilibrium, production, and trajectory analysis. Molecular dynamics are simulated by solvating in a 10 × 10 × 10 Å periodic boundary box. The solvation procedure employs a TIP3P (Transferable Intermolecular Potential 3-Point) water solvent system with a pH of 7.4 and a density of 0.997 g/L.