Computational studies identifying entry inhibitor scaffolds targeting the Phe43 cavity of HIV-1 gp120

Targeting protein-protein interactions, such as the HIV-1 gp120-CD4 interface, has become a cutting-edge approach in the current drug discovery scenario. Many small molecules have been developed so far as inhibitors of the interaction between CD4 and HIV-1 gp120. However, due to a variety of reasons such as solubility, drug toxicity and drug resistance, these inhibitors have failed to prove clinically useful. As such, the identification of novel compounds that bind to protein-protein interactions is still a research area of considerable interest. Here, a structure-based virtual screening approach was successfully applied with the aim of identifying novel HIV-1 entry inhibitors targeting the Phe43 pocket of HIV-1 gp120. Several compounds able to inhibit viral replication in cell culture were identified, with the best agent endowed with an EC₅₀ value of 0.9μM. Inactivity of all the identified hits toward a mutant (Met475Ile) strain strongly suggests that they interact in the Phe43 cavity of gp120, as intended. Remarkably, all of these small molecules have a chemical scaffold unrelated to any known class of entry inhibitors reported thus far. Overall, our strategy led to the identification of four novel chemical scaffolds that inhibit HIV-1 replication through the destabilization of the HIV-1 gp120-CD4 interface.