Redox-Based Theranostics of Gastric Ulcers Using Nitroxyl Radicals

Redox-based theranostics involves redox monitoring and therapeutics that normalize redox imbalance. It may be a promising approach to markedly improve a patient's quality of life through streamlined treatment. Nitroxyl radicals are useful for both redox monitoring and treating gastric ulcers in rodents. Redox monitoring using in vivo electron paramagnetic resonance (EPR) spectroscopy in a gastric ulcer rat model showed the production of reactive oxygen species in the whole stomach. A combination of Overhauser-enhanced magnetic resonance imaging (MRI) and nitroxyl radicals provided high-resolution images of redox imbalance in the stomach of rats with a gastric ulcer. Treatment with nitroxyl radicals was effective to treat ulcers that were formed using model experiments of Helicobacter pylori and mental stress as well as nonsteroidal anti-inflammatory drugs. For redox monitoring using Overhauser-enhanced MRI, the EPR irradiation power that is delivered to subjects must be within the range of the specific absorption rate regulation to protect against microwave damage regardless of a decrease in image contrast. The effect of long-term treatment with a nitroxyl radical in patients with a gastric ulcer remains unclear. Further research on redox-based theranostics in redox-related diseases, including gastric ulcers, would be accelerated by improving the redox imager and by developing functional nitroxyl radicals that localize in the target organ, tissue, or cell and that have specific reactivity for the redox-related biomolecule.