Leucomethylene blue mesylate is widely used in biological and medical research as a reducing agent and stain. It plays a crucial role in histology for staining tissues, particularly in the visualization of cellular structures under a microscope. In neuroscience, it is utilized to study neural activity and map brain functions due to its ability to track neuronal pathways. Additionally, it is employed in diagnostic applications, such as identifying certain types of bacteria or parasites in clinical samples. Its redox properties make it valuable in biochemical assays, where it helps in monitoring enzymatic reactions and oxidative processes. In pharmacology, it is explored for its potential therapeutic effects, including neuroprotective and antioxidant properties, particularly in conditions like Alzheimer’s disease and other neurodegenerative disorders.