Effect of intermittency factor on singlet oxygen and PGE 2 formation in azulene-mediated photodynamic therapy: A preliminary study

• Published in: Biochemistry and biophysics reports Vol. 31; p. 101290
• Main Authors: Damrongrungruang, Teerasak, Phiphitaporn, Sujaree, Salacheep, Nuttakul, Sritragool, Chonlada, Teerakapong, Aroon, Meesawat, Kittipitch, Kruesubthaworn, Anan, Ruangsuwan, Chaiyapong, Weera-Archakul, Wilawan
• Format: Journal Article
• Language: English
• Published: Netherlands 01-09-2022
• Subjects: Intermittency factor; Photodynamic therapy; Singlet oxygen; Inflammation; Azulene; Pulse mode
• ISSN: 2405-5808

In photodynamic therapy, intermittent irradiation modes that incorporate an interval between pulses are believed to decrease the effect of hypoxia by permitting an interval of re-oxygenation. The effect of the irradiation intermittency factor (the ratio of the irradiation pulse time to the total irradiation time) on singlet oxygen formation and inflammatory cytokine production was examined using azulene as a photosensitizer. Effects of difference intermittency factor on singlet oxygen formation and inflammatory cytokine were examined. Azulene solutions (1/10 μM) were irradiated with a 638-nm 500 mW diode laser in fractionation (intermittency factor of 5 or 9) or continuous mode using 50 mW/cm
at 4 or 8 J/cm
. Singlet oxygen measurement was performed using a dimethyl anthracene probe. Peripheral blood mononuclear cells (PBMC) were stimulated by 10 ng/ml rhTNF-α for 6 h, before addition of 1 and 10 μM azulene solutions and irradiation. PGE
measurement was undertaken using a human PGE
ELISA kit. Kruskal-Wallis with Dunn Bonferroni test was used for statistical analyses at p < 0.05.Irradiation of 1 μM azulene+4 J/cm
+intermittency factor of 9 increased singlet oxygen 3-fold (p < 0.0001). Irradiation of 10 μM azulene at either 4 J/cm
+intermittency of 9 or 8 J/cm
+intermittency factor of 5 reduced PGE
expression in PBMCs to non-inflamed levels. Thus, at 50 mW/cm
, 10 μM azulene-mediated photodynamic therapy with a high intermittency factor and a low energy density generated sufficient singlet oxygen to suppress PGE
in Inflamed PBMCs.