Microcystin-LY is a toxic cyanobacterial compound primarily known for its hepatotoxic effects. It is produced during algal blooms in freshwater systems and poses a significant environmental and public health risk. Its main application relevance lies in environmental monitoring, where it serves as a biomarker for water contamination by harmful cyanobacteria. Detection of Microcystin-LY in water supplies triggers public health advisories and guides water treatment protocols to prevent human and animal exposure. Due to its potent inhibition of protein phosphatases, it is also used in scientific research to study cellular signaling pathways, particularly those involving phosphorylation in liver cells. However, it has no commercial or therapeutic applications because of its high toxicity.