Figure 3.
Promiscuous PPI inhibitory activity of MeBlu. Methylene blue inhibited several protein–protein interactions as assayed here in concentration-dependent manner following typical law of mass action response (i.e., unity Hill slope, nH = 1). In addition to coronavirus spike protein interactions with human ACE2, including SARS-CoV-2, its delta variant of concern, and the cold-causing HCoV-NL63, it also inhibited the PPIs of hepatitis C virus envelope glycoprotein E with CD81 as well as others such as IL-2–IL-2Rα with similar potency. Data (mean ± SD) for each assay as indicated were normalized and fitted with standard inhibition curves; obtained IC50 values are shown at right.