pyropheophorbide a

**Pyropheophorbide a** is a semi-synthetic tetrapyrrole-based small molecule derived from the degradation of chlorophyll a. It acts as a second-generation **photosensitizer** widely used in research for **photodynamic therapy (PDT)** of cancer. Upon activation with red to near-infrared light (668 nm), pyropheophorbide a generates **singlet oxygen** and other reactive oxygen species, leading to localized tumor cell destruction. It has a high singlet-oxygen quantum yield (>0.5) and strong absorption in the therapeutic window. Poor tumor selectivity, limited water solubility, and cutaneous photosensitivity are limiting factors, but targeted formulations (e.g., nanoparticle delivery, aptamer conjugates) are under investigation to enhance cancer selectivity and reduce toxicity. The compound is for research use only and not approved for general human use. Clinical derivatives (such as Photochlor) are in trials for PDT in oncology[3][5][8].

Other names

pyropheophorbide apyrophaeophorbide a24533-72-03-(16-ethenyl-11-ethyl-4-hydroxy-12,17,21,26-tetramethyl-7,23,24,25-tetrazahexacyclo[18.2.1.15,8.110,13.115,18.02,6]hexacosa-1,4,6,8(26),9,11,13(25),14,16,18(24),19-undecaen-22-yl)propanoic acid9-ethenyl-14-ethyl-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid