TLR7/8 Antagonist 1 (Compound 16c) is the potent antagonist of TLR7/8 with IC 50 s of 3.91 and 2.19 μM, respectively. TLR7/8 Antagonist 1 is an imidazoquinoline derivative compound. Toll-like receptors (TLRs) 7 and 8 are key targets in the development of immunomodulatory drugs for researching infectious disease, cancer , and autoimmune disorders.