Efficacy of erythrosine and cyanidin-3-glucoside mediated photodynamic therapy on Porphyromonas gingivalis biofilms using green light laser

Abstract

© 2017 Elsevier B.V. Background The purpose of this in vitro study was to evaluate the efficacy of erythrosine and cyanidin-3-glucoside as photosensitizers in PDT for the elimination of Porphyromonas gingivalis (P. gingivalis) biofilms. Methods P. gingivalis biofilms were prepared from a chronic periodontitis subject. Erythrosine and cyanidin-3-glucoside were prepared and randomly allocated as follows: 110, 220, 330, and 440 μM erythrosine; 101, 202, 303, and 404 μM anthocyanin; and 440 μM erythrosine + 404 μM cyanidin-3-glucoside. There were 18 PDT experimental groups (non-irradiated/irradiated with a 532-nm green light diode laser at 1.29 J/cm2 for 60 s). The 3 controls were grouped as follows: biofilms exposed to the photosensitizers alone, biofilms exposed to the laser alone, and biofilms exposed to 0.12% chlorhexidine. All sample groups were cultured at 1, 3 and 6 h after PDT and incubated in an anaerobic chamber at 37 °C for 4 days. The surviving fraction was calculated from the log10 CFU/ml. The 330 and 440 μM erythrosine and the 440 μM erythrosine + 404 μM cyanidin-3-glucoside were mixed with spin traps (TEMPO, DMPO), and the electron spin resonance spectra were evaluated. Results The log10 CFU/ml measurements showed that the PDT groups with 330 μM or 440 μM erythrosine and 440 μM erythrosine + 404 μM cyanidin-3-glucoside had statistically significant differences from the other groups (one-way ANOVA and Bonferroni's multiple comparison test, p- value ≤ 0.05). Conclusions PDT using 330 μM erythrosine, 440 μM erythrosine or 440 μM erythrosine + 404 μM cyanidin-3-glucoside irradiated with the laser more effectively inhibited P. gingivalis in biofilms.