Reaction of endogenous Coenzyme Q₁₀ with nitrogen monoxide and its metabolite nitrogen dioxide

ABSTRACT

Objectives: Coenzyme Q₁₀, incorporated in DOPC lyposomes or naturally present in liver bovine mitochondria or in human blood plasma, was reacted with nitrogen dioxide ^•NO₂ or with a ^•NO/^•NO₂ mixture.

Methods and Results: The reaction course was monitored by Electron Paramagnetic Resonance (EPR) spectroscopy and in all cases the formation of a di-tert-alkyl nitroxide was observed, deriving from the addition of ^•NO₂ to one of the double bonds, most likely the terminal one, of the isoprenic chain. The rate constant for nitroxide formation was also determined by EPR spectroscopy and an initial rate of ca. 7 × 10⁻⁸M s⁻¹ was obtained.

KEYWORDS:

• Coenzyme Q₁₀
• nitrogen dioxide
• nitroxide
• isoprenic chain
• addition reaction
• mitochondria
• liposomes
• plasma

Acknowledgements

The authors wish to thank Università Politecnica delle Marche for financial support and Dr. Giovanna Mobbili for liposomes preparation.

Disclosure statement

No potential conflict of interest was reported by the authors.