Recent advances in the chemical biology of nitroxyl (HNO) detection and generation

• New fluorescent, mass spectrometric and electrochemical HNO detection.
• New structurally varied HNO donors.
• Endogenous HNO formation from NO and H2S “cross-talk”.
• Better defined roles for HNO in specific biological processes.

Nitroxyl or azanone (HNO) represents the redox-related (one electron reduced and protonated) relative of the well-known biological signaling molecule nitric oxide (NO). Despite the close structural similarity to NO, defined biological roles and endogenous formation of HNO remain unclear due to the high reactivity of HNO with itself, soft nucleophiles and transition metals. While significant work has been accomplished in terms of the physiology, biology and chemistry of HNO, important and clarifying work regarding HNO detection and formation has occurred within the last 10 years. This review summarizes advances in the areas of HNO detection and donation and their application to normal and pathological biology. Such chemical biological tools allow a deeper understanding of biological HNO formation and the role that HNO plays in a variety of physiological systems.