RESUMO
Acquired immunodeficiency syndrome (AIDS), one of the deadliest global diseases, is caused by the Human Immunodeficiency Virus (HIV). To date, there are no known conventional drugs that can cure HIV/AIDS, and this has prompted continuous scientific efforts in the search for novel and potent anti-HIV therapies. In this study, molecular dynamics simulation (MDS) and computational techniques were employed to investigate the inhibitory potential of bioactive compounds from selected South African indigenous plants against HIV-1 subtype C protease (HIVpro). Of the eight compounds (CMG, MA, UA, CA, BA, UAA, OAA and OA) evaluated, only six (CMG (-9.9 kcal/mol), MA (-9.3 kcal/mol), CA (-9.0 kcal/mol), BA (-8.3 kcal/mol), UAA (-8.5 kcal/mol), and OA (-8.6 kcal/mol)) showed favourable activities against HIVpro and binding landscapes like the reference FDA-approved drugs, Lopinavir (LPV) and Darunavir (DRV), with CMG and MA having the highest binding affinities. Using the structural analysis (root-mean-square deviation (RMSD), fluctuation (RMSF), and radius of gyration (RoG) of the bound complexes with HIVpro after 350 ns, structural evidence was observed, indicating that the six compounds are potential lead candidates for inhibiting HIVpro. This finding was further corroborated by the structural analysis of the enzyme-ligand complexe systems, where structural mechanisms of stability, flexibility, and compactness of the study metabolites were established following binding with HIVpro. Furthermore, the ligand interaction plots revealed that the metabolites interacted hydrophobically with the active site amino residues, with identification of other key residues implicated in HIVpro inhibition for drug design. Overall, this is the first computational report on the anti-HIV-1 activities of CMG and MA, with efforts on their in vitro and in vivo evaluations underway. Judging by the binding affinity, the degree of stability, and compactness of the lead metabolites (CMG, MA, CA, BA, OA, and UAA), they could be concomitantly explored with conventional HIVpro inhibitors in enhancing their therapeutic activities against the HIV-1 serotype.
RESUMO
BACKGROUND: HIV-1 subtype C protease is a strategic target for antiretroviral treatment. However, resistance to protease inhibitors appears after months of treatment. Chromones and 2- biscoumarin derivatives show potential for inhibition of the HIV- subtype C protease. OBJECTIVE: Different heterocyclic structures from the ZINC database were docked against Human Immunodeficiency Virus-1 (HIV) subtype C protease crystal structure 2R5Q and 2R5P. The 5 best molecules were selected to be docked against 62 homology models based on HIV-protease sequences from infants failing antiretroviral protease treatment. This experimentation was performed with two molecular docking programs: Autodock and Autodock Vina. These molecules were modified by substituting protons with different moieties, and the derivatives were docked against the same targets. Ligand-protein interactions, physical/chemical proprieties of the molecules, and dynamics simulations were analyzed. METHODS: Docking of all of the molecules was performed to find out the binding sites of HIV-1 subtype C proteases. An in-house script was made to substitute protons of molecules with different moieties. According to the Lipinski rule of five, physical and chemical properties were determined. Complexes of certain ligands-protease were compared to the protein alone in molecular dynamics simulations. RESULTS: From the first docking results, the 5 best (lowest energy) ligands (dibenz[a,h]acridine, dibenz[a, i]acridine, NSC114903, dibenz[c,h]acridine, benzo[a]acridine) were selected. The binding energy of the modified ligands increased, including the poorest-performing molecules. A correlation between nature, the position, and the resulting binding energy was observed. According to the Lipinski rules, the physico-chemical characteristics of the five best-modified ligands are ideal for oral bioavailability. Molecular dynamics simulations show that some lead-protease complexes were stable. CONCLUSION: Dibenz[a,h]acridine, dibenz[a, i]acridine, NSC114903, dibenz[c,h]acridine, benzo[ a]acridine and their derivatives might be considered as promising HIV-1 subtype C protease inhibitors. This could be confirmed through synthesis and subsequent in vitro assays.