Gallocyanine as a Fluorogen for the Identification of NADPH-Dependent Production of Superoxide Anion Radical by Blood Cells

The interaction of the oxazine dye gallocyanine with reactive oxygen ( $$^{\centerdot }{\text{O}}_{2}^{ - },$$ Н2О2) and halogen (HOCl) species has been studied by spectrophotometry, mass spectrometry, and spectrofluorimetry. It has been shown that gallocyanine reacts with HOCl and $$^{\centerdot }{\text{O}}_{2}^{ - }$$ (but not with Н2О2) to form fluorescent products. It has been found using the inhibition assay that, both in the xanthine/xanthine oxidase system and in activated human blood neutrophils, the main contribution to the conversion of gallocyanine to a fluorophore comes from its reaction with $$^{\centerdot }{\text{O}}_{2}^{ - }{\text{.}}$$ The results obtained suggest that gallocyanine can act as a fluorogenic chemosensor and be used for estimating the activation of neutrophils and the NADPH-dependent production of superoxide anion radical by neutrophils and other blood cells, as well as for testing antioxidant drugs designed with the aim to correct diseases associated with oxidative stress.