Increasing photodynamic therapy efficacy by the natural compound curcumin

Photodynamic therapy (PDT) is a cancer treatment in which an injected or applied photosensitizing agent is activated by light of a specific wavelength which causes a sequence of photochemical and photobiological processes resulting in irreversible selective damage to the target tissue. PDT is a promising antitumor treatment method for its high selectivity, non-invasiveness and minimal side effects. However, due to the resistance of some cancer cell lines to PDT, it exhibits results with low efficiency. Therefore, there is an urgent need to overcome this resistance to increase the PDT's efficiency, making PDT more widely applicable. Thus, this M.Sc. study introduces the usage of Curcumin, which is a non-toxic natural compound that has antitumor characteristics, with 5-ALA-PDT to increase PDT's efficacy. First, 5-ALA mediated PDT and Curcumin antitumor characteristics were evaluated on two cell lines, PC-3 and Caco-2. Then, the determined PDT doses were applied to the cell lines together with two different Curcumin concentrations. Illumination was performed using 635-nm diode laser after 6-hr incubation of 5-ALA and Curcumin. The outcomes of this study prove the success of the proposed combination on the highly resistive colon cancer (Caco-2 cell line) with 62.4% decrease in cell viability.