Loxistatin acid is primarily used as a potent and selective inhibitor of cysteine proteases, particularly cathepsins B, H, L, and calpains. It is widely applied in research settings to study protease-mediated cellular processes such as apoptosis, inflammation, and lysosomal function. Due to its ability to cross cell membranes, it is effective in both in vitro and cellular assays. It has been investigated for its potential in reducing tissue damage in ischemia-reperfusion injury, especially in models of myocardial infarction and stroke, where uncontrolled protease activity contributes to cell death. Loxistatin acid also shows promise in research on neurodegenerative diseases, where calpain overactivation is linked to neuronal damage. Additionally, it is used to suppress antigen processing in immunological studies, helping to dissect the role of proteases in immune responses. Its specificity makes it a valuable tool in developing therapeutic strategies targeting pathological proteolysis.