5-aminolevulinic acid (5-ALA)

5-aminolevulinic acid (5-ALA) is an endogenous, non-proteinogenic delta-amino acid that serves as the primary precursor in the heme biosynthetic pathway [1, 3]. Synthesized from glycine and succinyl-CoA in the mitochondria, it is subsequently converted through a series of enzymatic steps into protoporphyrin IX (PpIX) and finally into heme [1, 13]. In clinical practice, 5-ALA is utilized as a prodrug for photodynamic therapy (PDT) and fluorescence-guided surgery (FGS), particularly in the treatment of actinic keratosis and the visualization of malignant gliomas [3, 5, 13]. Its therapeutic utility stems from the preferential accumulation of PpIX in neoplastic cells, which, upon exposure to specific wavelengths of light, generates cytotoxic reactive oxygen species or emits red fluorescence [1, 5]. Beyond its role in oncology, 5-ALA is being investigated for its potential in managing metabolic disorders and modulating immune responses through the induction of heme oxygenase-1 (HO-1) [6, 9]. Although 5-ALA is a key component of therapeutic interventions, it is classified as a metabolite and prodrug rather than a traditional protein target like a receptor or enzyme [1, 3]. Commonly used formulations include Levulan and Gleolan, which are associated with transient photosensitivity and require patients to avoid bright light post-administration [1, 19].

Other names

delta-aminolevulinic acidd-ALAALA5-amino-4-oxopentanoic acid

Acts as a metabolic prodrug converted to Protoporphyrin IX (PpIX), which generates reactive oxygen species upon light activation or emits fluorescence.