Dicaffeoylquinic acid inhibitors of human immunodeficiency virus integrase: inhibition of the core catalytic domain of human immunodeficiency virus integrase

Integration of a cDNA copy of the human immunodeficiency virus (HIV) genome is mediated by an HIV-1-encoded enzyme, integrase (IN), and is required for productive infection of CD4+ lymphocytes. It had been shown that 3,5-dicaffeoylquinic acid and two analogues were potent and selective inhibitors of HIV-1 IN in vitro. To determine whether the inhibition of IN by dicaffeoylquinic acids was limited to the 3,5 substitution, 3,4-, 4,5-, and 1,5-dicaffeoylquinic acids were tested for inhibition of HIV-1 replication in tissue culture and inhibition of HIV-1 IN in vitro. All of the dicaffeoylquinic acids were found to inhibit HIV-1 replication at concentrations ranging from 1 to 6 microM in T cell lines, whereas their toxic concentrations in the same cell lines were > 120 microM. In addition, the compounds inhibited HIV-1 IN in vitro at submicromolar concentrations. Molecular modeling of these ligands with the core catalytic domain of IN indicated an energetically favorable reaction, with the most potent inhibitors filling a groove within the predicted catalytic site of IN. The calculated change in internal free energy of the ligand/IN complex correlated with the ability of the compounds to inhibit HIV-1 IN in vitro. These results indicate that the dicaffeoylquinic acids as a class are potent and selective inhibitors of HIV-1 IN and form important lead compounds for HIV drug discovery.