An HIV-1 attachment inhibitor; binds to non-ligand bound HIV-1 gp120 to inhibit HIV-1 interaction with host CD4+ T cells; reduces infectivity of laboratory strains and clinical isolates of HIV-1 (EC50s = 0.4-2,000 and 25-2,000 nM, respectively); not cytotoxic in a panel of mammalian cells (CC50s = >100 μM)