BMS-378806 S2632

BMS-806, a 7-azaindole derivative, binds gp120 and interferes with the interaction of HIV surface protein gp120 with the host cell receptor CD4. BMS-806 inhibits a panel of macrophage- and T cell-tropic HIV-1 strains, which are laboratory strains that use either CCR5 (M-tropic) or CXR4 (T-tropic) co-receptors to enter cells and are classified as B subtypes. The aqueous solubility from the crystalline form of BMS-806 (BMS 378806) is 170 μg/mL. The solubility of BMS-806 is 1.3 mg/mL at pH=2.1 and 3.3 mg/mL at pH=11, a solubility profile that reveals the amphoteric nature of BMS-806 and estimates the pK_a of the protonated form as 2.9 while that of the free base is approximately 9.6. BMS-806 competes with soluble CD4 binding to a monomeric form of gp120 in an ELISA assay with IC50 = ~ 100 nM. BMS-806 is specific towards HIV-1, with no significant inhibitory activity against HIV-2, SIV, MuLV, RSV, HCMV, BVDV, VSV, and influenza virus observed at concentrations ranging from 10 to 30 μM and no overt cytotoxicity toward host cells, CC50 values > 225 μM. ^[1] BMS-806 binds directly to gp120 at a stoichiometry of approximately 1:1, with a binding affinity similar to that of soluble CD4. The potential BMS-806 target site is localized to a specific region within the CD4 binding pocket of gp120 by using HIV-1 gp120 variants carrying either compound-selected resistant substitutions or gp120-CD4 contact site mutations. ^[2]