LAUSR

BACKGROUND The photosensitivity reaction to the photosensitizers which appears after a Photodynamic therapy treatment session is a challenge that needs further investigation. The goal of this research is to evaluate the possibility of using saffron to reduce or control this challenge and to present mathematical modeling of the cell survival curves and their dependency on a saffron concentration. METHODS Red blood cells (RBC) and Staphylococcus aureus Bacteria (STB) were used as targets in this study. The Photosensitivity of Rose Bengali, Methylene Blue, and Photofrin independently and incorporated with saffron was investigated for continued irradiation at different Saffron concentrations. Gompertz's function was used to fit the survival curve parameters. The 50% cell survival rate was fit to an empirical formula based on Saffron concentrations. RESULTS Saffron inhibits the photosensitivity reaction of the three photosensitizers and causes a significant increase in the 50% survival rate time (t50) for RBC`s and STB. Saffron didn't show phototoxicity when incubated alone with RBC`s and STB. The survival curve parameters of the RBCs and STB showed a good fit to the Gompertz function. Saffron concentration is related to the RBC`s t50 based on power dependency of 0.56, 0.38 and 0.31 for Photofrin, Methylene Blue and Rose Bengali respectively and 0.1 on STB for Rose Bengali. CONCLUSION Saffron can efficiently be used to reduce the photosensitivity reaction of Photosensitizers after a PDT treatment session. Gompertz function was found to be an appropriate mathematical model for survival rate curves. The t50 and the saffron concentration are well related through a power dependence empirical formula.