Faculty of Science and Technology, The Technological and Higher Education Institute of Hong Kong, Tsing Yi, Hong Kong.
Abstract: (1026 Views)
5-aminolevulinic acid (5-ALA) is the mitochondria metabolite produced from glycine and succinyl-CoA, which is converted to protoporphyrin IX (PpIX) by the conjugation of eight itself molecules forming the “heme” group in a porphyrin ring (Figure 1) [1]. The PpIX is used as a photosensitizer (PS) with an absorption wavelength of 410 nm, and 5-ALA acts as a precursor or prodrug for PpIX in photodynamic therapy (PDT). Exogenous administration of excessive amounts of 5-ALA increases the production of PpIX during heme biosynthesis. It is eliminated after 24-48 h with a lower risk of long-term photosensitivity [2]. However, 5-ALA PDT has several disadvantages, including the concentration of ALA is affected by its absorption and pharmacokinetics that are not fully covered the treatment area [3-5], as well as the limited depth of tumor penetration and caused pain symptoms [6].