Circadian and seasonal variation of endogenous ubiquinone plasma level

• Published in: Chronobiology international Vol. 19; no. 3; pp. 599 - 614
• Main Authors: Reis, F., Hermida, R. C., Souza, I., Maldonado, J., Tavares, P., Fontes-Ribeiro, C. A., Teixeira, H. M., Alcobia, T., Almeida, L., Teixeira, F.
• Format: Journal Article
• Language: English
• Published: Monticello, NY Informa UK Ltd 01.01.2002; Taylor & Francis; Dekker
• Subjects: Adult; African Continental Ancestry Group; Antioxidants - administration & dosage; Antioxidants - metabolism; Biological and medical sciences; Chronobiology; Circadian rhythm; Circadian Rhythm - physiology; Coenzyme Q10; European Continental Ancestry Group; Female; Fundamental and applied biological sciences. Psychology; Gender; Humans; Male; Race; Seasonal variation; Seasons; Sex Characteristics; Ubiquinone; Ubiquinone - administration & dosage; Ubiquinone - blood; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Human; Ubiquinone; Seasonal variation; Variability; Race; Sex; Endogenous substance; Biological rhythm; Concentration; Circadian rhythm; Comparative study; Blood plasma
• ISSN: 0742-0528; 1525-6073
• DOI: 10.1081/CBI-120004544

Coenzyme Q10 (CoQ10) or ubiquinone, a redox component of the mitochondrial electron transport chains, is a powerful antioxidant and membrane stabilizer that may prevent cellular damage during myocardial ischemia and reperfusion therapy. Coenzyme Q10 has been used primarily as an adjuvant therapy for some cardiomyopathies. However, one of the main problems in CoQ10 administration is the high variability of endogenous plasma and tissue levels, which seems to be dependent on several factors. This work explores temporal 24h and seasonal variation as well as gender and racial differences in endogenous plasma ubiquinone concentration. Coenzyme Q10 measurements (quantified by HPLC-UV) of 16 healthy volunteers were done during the daytime hours of activity beginning at 09:00h one day and ending at 09:00h the next day (13 different determinations) in two distinct months, April and October, of the year. A statistically significant circadian rhythm in plasma ubiquinone concentration that includes only the fundamental 24h component was demonstrated both in the April and October data. Furthermore, the time-point means of the ubiquinone concentration in the October study were invariably higher than those obtained in the April study. No statistically significant differences were found in CoQ10 concentration between male and female subjects, both in April and in October. In addition, racial differences were demonstrated; lower plasma ubiquinone levels were found in Caucasian compared to African subjects. However, the latter small group of subjects failed to demonstrate a circadian rhythm, neither in the April nor in the October analysis.