NBD-556 is small molecule mimetic of CD4, NBD-556 recognizes the HIV-1 envelope protein gp120 and induces restructuring of gp120 analogous to CD4 binding. IC50 Value: Target: HIV NBD-556 N-phenyl-N′-(2,2,6,6-tetramethyl-piperidin-4-yl)-oxalamide analogs as a novel class of human immunodeficiency virus type 1 (HIV-1) entry inhibitors that block the gp120–CD4 interaction. Human immunodeficiency virus (HIV-1) interaction with the primary receptor, CD4, induces conformational changes in the viral envelope glycoproteins that allow binding to the CCR5 second receptor and virus entry into the host cell. The small molecule NBD-556 mimics CD4 by binding the gp120 exterior envelope glycoprotein, moderately inhibiting virus entry into CD4-expressing target cells and enhancing CCR5 binding and virus entry into CCR5-expressing cells lacking CD4.