Methyl-5-amino-4-oxopentanoate

Methyl ester of 5-aminolevulinic acid. The substance is used in medicine as a photosensitizer in photodynamic therapy procedures. See below photodynamic therapy, see below photodynamic daylight therapy

MAOP accumulates preferentially in tumour cells. As a prodrug, the substance is metabolised by esterases in the cells to 5-aminolevulinic acid (5-ALA). Compared to 5-ALA, MAOP is more selective, causes less pain and penetrates the tissue better due to its higher lipophilicity. Intracellularly, the catalytic action of delta-aminolevulinic acid dehydratase initially produces porphobilinogen (PBG) from two molecules of 5-ALA. From 4 molecules of porphobilinogen, protoporphyrin IX is then formed via 3 further intermediate stages. protoporphyrin IX is the actually effective photosensitizer used for photodynamic therapy.

Protoporphyrin IX induces photosensitivity. Irradiation with a light source (wavelength of approx. 630 nm) generates free radicals and reactive oxygen species, which convert the degenerated cells into apoptosis.