protoporphyrin IX

Protoporphyrin IX is an organic compound classified as a porphyrin, specifically a cyclic tetrapyrrole that serves as a critical intermediate in the biosynthesis of heme and chlorophyll. It is the iron-free form of hemin, featuring a highly conjugated ring system that allows it to function as a potent **photosensitizing agent**. In clinical and research contexts, protoporphyrin IX is used primarily as a photosensitizer for **photodynamic therapy (PDT)**—where, when activated by light, it produces reactive oxygen species that can selectively destroy cancer cells. Protoporphyrin IX is also a metabolic precursor in heme biosynthesis pathways and is commonly assessed as a biomarker for various metabolic disorders. It has additional biological activities, including roles in cellular respiration, liver function, and as an inhibitor of p53/MDM2 and p53/MDM4 protein interactions, which contributes to induction of apoptosis in cancer cells.

Other names

protoporphyrinOoporphyrinProtoporpyrin IX