Direct Violet 1, an azo dye, is a textile dye. Direct Violet 1 is also the protein-protein interaction (PPI) between the SARS-CoV-2 spike protein and ACE2 inhibitor with IC50s of 1.47-2.63 µM[1][2].
Direct Violet 1 inhibits SARS-CoV-2-S-RBD binding to human ACE2, inhibits SARS-CoV-S1S2 binding to ACE2, and inhibits TNF-R1 binding to TNFα with IC50 values of 1.47 µM, 2.63 µM, and 2.11 µM, respectively[1]. Direct Violet 1 inhibits SARS-CoV-2 pseudovirus entry into hACE2 expressing host cells in a concentration-dependent manner with an IC50 of 35.8 µM[1].
[1]. Damir Bojadzic, et al. Small-Molecule In Vitro Inhibitors of the Coronavirus Spike-ACE2 Protein-Protein Interaction as Blockers of Viral Attachment and Entry for SARS-CoV-2. bioRxiv, 2020 Oct 22. [2]. Wafaa M Abd El-Rahim, et al. Genotoxicity studies on the removal of a direct textile dye by a fungal strain, in vivo, using micronucleus and RAPD-PCR techniques on male rats. J Appl Toxicol. 2008 May;28(4):484-90.