Pepstatin is widely used as a potent inhibitor of aspartic proteases, such as pepsin, cathepsin D, and renin. It is commonly applied in biochemical research to prevent protein degradation during cell lysis and protein extraction, especially when working with acidic organelles like lysosomes. Due to its specificity, pepstatin is added to protease inhibitor cocktails to preserve the integrity of target proteins. It is also used in studies investigating the role of aspartic proteases in physiological processes, including protein processing, antigen presentation, and disease mechanisms such as neurodegeneration and cancer progression. In addition, pepstatin has been explored for its potential to inhibit viral proteases, including those from HIV, making it a tool compound in antiviral research.