Abstract
FMOs of the HA-CUR complex computed in the gas phase (left) and implicit water (right). Isosurface values 0.01 A.U.
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•Computational investigations of HA-CUR conjugates with larger number of monomeric HA and CUR units.•Computational studies of the effects of other implicit solvents on structure and properties of conjugates.•Studies of reactivity characteristics of such conjugates, energetics of their formation reactions, etc.
In this article, we are reporting the results of the first detailed Density Functional Theory (DFT) study of the structure of the hyaluronic acid-curcumin (HA-CUR) compound. The molecular orbitals (MOs), frontier molecular orbitals (FMOs, i.e., energies of the FMOs and HOMO/LUMO gaps), and molecular electrostatic potential (MEP) of the compound have been investigated using the Gaussian 09 package using the hybrid functional B3LYP with the split-valence polarized 6-311G(d,p) basis set (B3LYP/6-311G(d,p) approach). In addition, the NBO (Natural Bond Orbital) charge analysis and NBO bonding analysis for the HA-CUR complex have been performed. The structures of the HA and CUR moieties inside the HA-CUR complex are found noticeably different from their free molecules, and the LUMO of the HA-CUR complex is noticeably stabilized compared to the HA LUMO and to the CUR LUMO, which leads to the noticeable closure of the HA-CUR HOMO/LUMO gap compared to the HA gaps and CUR water-computed gap. The detailed studies carried out on the HA-CUR complex in different aspects will definitely be useful for the researchers working in the area of the novel drug design and pharmaceutical chemistry.