Propidium is a fluorescent intercalating agent that can be used to stain cells and nucleic acids. Also aninhibitor of cholinesterases. Has red fluorescence at 488 nm. Has the following spectral properties: extinction coefficient: 5,900 M -1 cm -1 (493 nm); 55,700 M -1 cm -1 (287 nm) 13,800 M -1 cm -1 (252.5 nm); excitation maximum: 536 nm; emission maximum: 617 nm. Used as building blocks of Multi-target drug ligand MTDL