Background: Coenzyme Q10 is an endogenous antioxidant as well as a popular dietary supplement. In blood circulation, coenzyme Q10 exists predominantly as its reduced ubiquinol-10 form, which readily oxidizes to ubiquinone-10 ex vivo. Plasma concentrations of coenzyme Q10 reflect net overall metabolic demand, and the ratio of ubiquinol-10:ubiquinone-10 has been established as an important biomarker for oxidative stress. However, the lability of ubiquinol-10 makes accurate determination of both forms of coenzyme Q10 difficult. Ex vivo oxidation of ubiquinol-10 to ubiquinone-10 during sample collection, processing and analysis may obfuscate the in vivo ratio.
Methods: We developed a rapid and sensitive method for the determination of ubiquinol-10 and ubiquinone-10 in human plasma, using coenzyme Q9 analogues as internal standards. Single-step protein precipitation in 1-propanol, a lipophilic and water-soluble alcohol, allowed for rapid extraction.
Results: Analysis by ultra performance liquid chromatography-tandem mass spectrometry provided rapid run-time and high sensitivity, with lower limits of quantitation for ubiquinol-10 and ubiquinone-10 of 5 μg/L and 10 μg/L, respectively.
Conclusions: This method is suitable for clinical studies with coenzyme Q10 supplementation in various disease states where this lipid-antioxidant may be beneficial. We have applied this method to >300 plasma samples from coenzyme Q10 research studies in chronic haemodialysis patients and postsurgical patients.
Keywords: UPLC-MS/MS; oxidized CoQ10; plasma concentrations; reduced Coq10; stability.
© The Author(s) 2015.