effectiveness of 5-aminolevulinic acid-mediated photodynamic therapy combined with curcumin

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 the 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, ala/pdt has several disadvantages. for instance, the concentration of ala is affected by its absorption and pharmacokinetics that do not fully cover the treatment area [3-5]. it also limits the depth of tumor penetration and causes pain [6].