RESUMO
BACKGROUND: We aimed to investigate the effect of azulene on peripheral blood mononuclear cells (PBMCs) viability and singlet oxygen formation. METHODS: 1 × 105 PBMCs were cultured in a 96-well plate in RPMI-1640 supplemented with 10% FBS (37 °C, 5% CO2) for 24 h. Each well was treated for 30 min with each azulene concentration between 0-500 µM and activated by a 625 ± 5 nm light emitting diode (power 20-23 mW) at energy densities of 0-200 J/cm2. MTT cell viability was recorded using a spectrophotometer at a 570 nm. 9,10-Dimethylanthracene (DMA) was utilized for the measurement of singlet oxygen, using a fluorescence spectrophotometer at 375 and 436 nm as the excitation and emission wavelengths, respectively. Optical density,ãrelative fluorescence units were compared using one-way ANOVA and a post-hoc test. The correlation between the cell number and singlet oxygen amount was analyzed by the Spearman correlation test. RESUTS: Azulene at all concentrations with 4.2 J/cm2 light significantly induced singlet oxygen formation. 15 µM azulene with 4.2, 100, or 200 J/cm2 light significantly reduced PBMC viability. The inverse relationship between the cell viability and singlet oxygen amount was observed. CONCLUSIONS: An optimum azulene concentration + red light energy density decreased PBMC viability via singlet oxygen formation.