Method: Standardized suspensions of C. albicans were treated with 2.5 mM Cur and exposed to blue LED light at a fluence of 37.5 J/cm2 (450nm) (P + L + group). The effect of PS or light only was also evaluated (P+L- and P-L+, respectively). The negative control did not receive any PS or light (P-L-). Additionally, a group treated with hydrogen peroxide (H2O2) at a concentration of 10mM was performed as a positive control group for comparing DNA damage in yeast cells. After the treatment, slides of each group were prepared and DNA damage of cells was analyzed with the comet assay. For visualization of DNA, slides were stained with GelRedTM and 20 representative images of each group were viewed at 400 × magnification using a fluorescent microscope (Leica Microsystems DM). The images were analyzed by the free edition of the CometScoreTM software and the analytic parameter tail length (μm) was chosen as the unit of DNA damage. Data were analyzed by ANOVA test and Tukey post-hoc (p<0.05).
Result: The results demonstrated that Cur-mediated PDT (P+L+) and the application of blue LED light alone (P-L+) were able to promote significantly DNA damage in C. albicans cells when compared to the negative control group (P-L-) (p <0,05 ). The application of Cur alone (P+L-) did not cause genotoxic effect on yeast cells. Comet tail length in the groups P+L+ and P-L+ increased significantly when compared to the group H2O2 (p <0,05 ).
Conclusion: The results of this study showed that the association of Cur and blue LED light in PDT caused genotoxic effect on C. albicans cells.