Computational study of Actinonin@Cucurbit[8]uril supramolecular complexes for colorectal cancer therapy

The formation of host-guest complexes with Cucurbit[∗n∗]urils can significantly enhance the solubility and stability of pharmaceutical compounds, improving their efficacy and reliability in therapeutic applications. This study investigates the complexation between the drug Actinonin and the macrocyclic host Cucurbit[8]uril, examining two distinct binding orientations using density functional theory (DFT) at the B3LYP-D3/TPZ level of theory. A comprehensive computational analysis including Fukui indices, binding energies, frontier molecular orbitals, and global chemical reactivity descriptors was employed to characterize the system's reactivity and identify susceptible sites for electrophilic and nucleophilic attacks. Further examination through natural bond orbital (NBO) analysis revealed significant orbital delocalization between the host and guest, while the quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis, based on the reduced density gradient (RDG), provided detailed insight into intermolecular forces, including hydrogen bonds and van der Waals interactions. Our results confirm that the complex with orientation B exhibits superior stability compared to orientation A, establishing it as the most favorable configuration. Molecular docking studies demonstrated that Actinonin binds strongly to the peptide deformylase target (PDB ID: 4H8E), with a MolDock score of -158.277 kcal/mol and significant hydrogen bonding, underscoring its potential as an inhibitor for colorectal cancer treatment. Virtual screening of 2576 compounds identified over 20 promising candidates with comparable binding affinities, and molecular dynamics simulations verified the stability of the protein-ligand complex, reinforcing the potential of these interactions for future therapeutic development.