The Effect of Curcumin in Antitumor Photodynamic Therapy: in vitro experiments with Caco-2 and PC-3 Cancer Lines.

•Caco-2 and PC-3 cell cultures were used as PDT resistant and non-resistant in vitro cancer models, respectively.•The dose-dependent cytotoxicity of 5-ALA mediated PDT and Curcumin were investigated on the cell lines.•Adding Curcumin to 5-ALA mediated PDT significantly reduced resistance to PDT in Caco-2 cells.•Possible mechanism such as Nitric Oxide inhibition are discussed for future study.