Photodynamic Therapy-Induced Anticandidal Effects via Reactive Oxygen Species Generation from Bisdemethoxycurcumin and Potassium Iodide

Objective: This study aimed to evaluate the anticandidal effects of a novel combination of two photosensitizers: bisdemethoxycurcumin (BDMC) and potassium iodide (KI) for antimicrobial Photodynamic therapy on Candida albicans biofilm and investigated reactive oxygen species involvement. Materials and methods: Mature candida biofilms were subjected to BDMC at concentrations of 20, 40, and 80 µM, and to 100 mM KI, using both single and combined treatments, followed by light irradiation (430±10 nm LED, 200 mW/cm²) at different energy densities (0 – 100 J/cm²). Biofilm viability and reactive oxygen species (ROS) generation were assessed using drop plate, and fluorescence measurement with electron paramagnetic resonance spectroscopy, respectively. Statistical analysis employed Shapiro-Wilk, Kruskal-Wallis H, Dunn, with a significance level of p < 0.05, and Spearman rank correlation tests. Results: 80 µM BDMC+100 mM KI-aPDT reduced C. albicans biofilm by 3.68log ₁₀ and enhanced singlet oxygen generation by 60–68%. Hydroxyl radical production was moderately correlated (r=0.413), while singlet oxygen was strongly correlated (r=0.847) with candidal inhibition. Minimal human epithelial cell reduction was observed. Conclusion : BDMC+KI+dental blue LED effectively inhibit C. albicans biofilms via singlet oxygen, comparable to Nystatin. Clinical relevance: Bisdemethoxy curcumin+potassium iodide act as a photosensitizer in PDT to inhibit Candida albicans biofilm.