Methods to Detect Nitric Oxide and Reactive Nitrogen Species in Biological Sample

Oxidative stress has been implicated in various human diseases, including cancer, mainly through the generation of reactive nitrogen species (RNS), such as nitric oxide (NO), nitrite, nitroxyl, s-nitrosothiols, and reactive oxygen species (ROS) such as peroxides, superoxide, and hydroxyl radicals. NO being the main player among RNS induced altered cellular molecules and metabolisms, thus making it important to understand and detect the generation of NO in biological samples. There are many methods for direct and indirect detection of NO; out of these most commonly used are spectrophotometric-based Griess assay and fluorescence probe-based assays. In this chapter, we summarize these routinely used methods to detect NO and various challenges associated with these methods.