Higher-Affinity Agonists of 5‑HT_1AR Discovered through Tuning the Binding-Site Flexibility

Discovery of high-affinity and high-selectivity agonists of 5-HT_1AR has become very attractive due to their potential therapeutic effects on multiple 5-HT_1AR-related psychological and neurological problems. On the basis of our previously designed lead compound <b>FW01</b> (<i>K</i>_i = 51.9 nM, denoted as <b>9a</b> in the present study), we performed large-scale molecular dynamics simulations and molecular docking operations on 5-HT_1AR-<b>9a</b> binding. We found the flip-packing events for the headgroup of <b>9a</b>, and we also found that its tail group could bind flexibly at the agonist-binding site of 5-HT_1AR. By finely tuning the flip-packing phenomenon of the <b>9a</b> headgroup and tuning the binding flexibility of <b>9a</b> tail group, we virtually designed a series of new <b>9a</b> derivatives through molecular docking operations and first-principles calculations and predicted that these newly designed <b>9a</b> derivatives should be higher-affinity agonists of 5-HT_1AR. The computational predictions on the new <b>9a</b> derivatives have been confirmed by our wet-experimental studies as chemical synthesis, binding affinity assays, and agonistic-function assays. The consistency between our computational design and wet-experimental measurements has led to our discovery of higher-affinity agonists of 5-HT_1AR, with ∼50-fold increase in receptor-binding affinity and ∼25-fold improvements in agonistic function. In addition, our newly designed 5-HT_1AR agonists showed very high selectivity of 5-HT_1AR over subtype 5-HT_2AR and also over three subtypes of dopamine receptors (D₁, D₂, and D₃)