Structure-Based Design and Discovery of Pyridyl-Bearing Fused Bicyclic HIV-1 Inhibitors: Synthesis, Biological Characterization, and Molecular Modeling Studies

Two series of new pyridyl-bearing fused bicyclic analogues designed to target the dual-tolerant regions of the non-nucleoside reverse transcriptase inhibitor (NNRTI)-binding pocket were synthesized and evaluated for their anti-HIV activities. Several compounds, such as <b>6</b>, <b>14</b>, <b>15</b>, <b>21</b>, <b>30</b>, and <b>33</b>, were found to be potent inhibitors against the wild-type (WT) HIV-1 strain or multiple NNRTI-resistant strains at low nanomolar levels. Detailed structure-activity relationships were obtained by utilizing the variation of moieties within the corresponding pharmacophores. In vitro metabolic stability profiles and some drug-like properties of selected compounds were assessed, furnishing the preliminary structure-metabolic stability relationships. Furthermore, molecular modeling studies elucidated the binding modes of compounds <b>6</b>, <b>15</b>, <b>21</b>, and <b>30</b> in the binding pocket of WT, E138K, K103N, or Y181C HIV-1 RTs. These promising compounds can be used as lead compounds and warrant further structural optimization to yield more active HIV-1 inhibitors.