GRL-0617 is primarily used as a potent inhibitor of the papain-like protease (PLpro) enzyme in coronaviruses, including SARS-CoV-2. It blocks viral replication by interfering with the protease activity necessary for processing viral polyproteins, making it a valuable tool in antiviral research. Due to its ability to selectively target PLpro without affecting host cell proteases significantly, GRL-0617 serves as a lead compound for developing therapeutics against coronavirus infections. It is widely used in biochemical assays and cell-based studies to investigate protease function and evaluate antiviral efficacy. Its application extends to structure-activity relationship (SAR) studies aimed at optimizing inhibitor potency and drug-like properties.