PURPOSE: To investigate the light-induced decomposition of indocyanine green (ICG) and to test the cytotoxicity of light-induced ICG decomposition products. METHODS: ICG in solution was irradiated with laser light, solar light, or surgical endolight. The light-induced decomposition of ICG was analyzed by high-performance liquid chromatography (HPLC) and mass spectrometry. Porcine retinal pigment epithelial (RPE) cells were incubated with the light-induced decomposition products of ICG, and cell viability was measured by trypan blue exclusion assay. RESULTS: Independent of the light source used, singlet oxygen (photodynamic type 2 reaction) is generated by ICG leading to dioxetanes by [2+2]-cycloaddition of singlet oxygen. These dioxetanes thermally decompose into several carbonyl compounds. The decomposition products were identified by mass spectrometry. The decomposition of ICG was inhibited by adding sodium azide, a quencher of singlet oxygen. Incubation with ICG decomposition products significantly reduced the viability of RPE cells in contrast to control cells. CONCLUSIONS: ICG is decomposed by light within a self-sensitized photo oxidation. The decomposition products reduce the viability of RPE cells in vitro. The toxic effects of decomposed ICG should be further investigated under in vivo conditions.
PURPOSE: To investigate the light-induced decomposition of indocyanine green (ICG) and to test the cytotoxicity of light-induced ICG decomposition products. METHODS:ICG in solution was irradiated with laser light, solar light, or surgical endolight. The light-induced decomposition of ICG was analyzed by high-performance liquid chromatography (HPLC) and mass spectrometry. Porcine retinal pigment epithelial (RPE) cells were incubated with the light-induced decomposition products of ICG, and cell viability was measured by trypan blue exclusion assay. RESULTS: Independent of the light source used, singlet oxygen (photodynamic type 2 reaction) is generated by ICG leading to dioxetanes by [2+2]-cycloaddition of singlet oxygen. These dioxetanes thermally decompose into several carbonyl compounds. The decomposition products were identified by mass spectrometry. The decomposition of ICG was inhibited by adding sodium azide, a quencher of singlet oxygen. Incubation with ICG decomposition products significantly reduced the viability of RPE cells in contrast to control cells. CONCLUSIONS:ICG is decomposed by light within a self-sensitized photo oxidation. The decomposition products reduce the viability of RPE cells in vitro. The toxic effects of decomposed ICG should be further investigated under in vivo conditions.
Authors: Julia Parrish-Novak; Kelly Byrnes-Blake; Narine Lalayeva; Stefanie Burleson; Janean Fidel; Rhonda Gilmore; Pamela Gayheart-Walsten; Gregory A Bricker; William J Crumb; K S Tarlo; Stacey Hansen; Valorie Wiss; Errol Malta; William S Dernell; James M Olson; Dennis M Miller Journal: Int J Toxicol Date: 2017-03-17 Impact factor: 2.032
Authors: Gal Shafirstein; Wolfgang Bäumler; Leah J Hennings; Eric R Siegel; Ran Friedman; Mauricio A Moreno; Jessica Webber; Cassie Jackson; Robert J Griffin Journal: Int J Cancer Date: 2011-07-21 Impact factor: 7.396