BioFactors 25 (2005) 73–86 73 IOS Press Life-long supplementation with a low dosage of coenzyme Q 10 in the rat: Effects on antioxidant status and DNA damage Jos´ e L. Quiles a,∗ , Julio J. Ochoa a , Maurizio Battino b , Purificaci´ on Gutierrez-Rios a , Eduardo A. Nepomuceno a , Magdalena L ´ opez Fr´ ıas a , Jes ´ us R. Huertas a and Jos´ e Mataix a a Institute of Nutrition and Food Technology, Department of Physiology, University of Granada, Spain b Institute of Biochemistry, Faculty of Medicine, Polytechnic University of Marche, Ancona, Italy Abstract. Life-long low-dosage supplementation of coenzyme Q10 (CoQ10) is studied in relation to the antioxidant status and DNA damage. Thirty-two male rats were assigned into two experimental groups differing in the supplementation or not with 0.7 mg/kg/day of CoQ10 . Eight rats per group were killed at 6 and 24 months. Plasma retinol, α-tocopherol, coenzyme Q, total antioxidant capacity and fatty acids were analysed. DNA strand breaks were studied in peripheral blood lymphocytes. Aging and supplementation led to significantly higher values for CoQ homologues, retinol and α-tocopherol. No difference in total antioxidant capacity was detected at 6 months but significantly lower values were found in aged control animals. Similar DNA strand breaks levels were found at 6 months. Aging led to significantly higher DNA strand breaks levels in both groups but animals supplemented with CoQ10 led to a significantly lower increase in that marker. Aged rats showed significantly higher polyunsaturated fatty acids. This study demonstrates that lifelong intake of a low dosage of CoQ 10 enhances plasma levels of CoQ9, CoQ10, α-tocopherol and retinol. In addition, CoQ10 supplementation attenuates the age-related fall in total antioxidant capacity of plasma and the increase in DNA damage in peripheral blood lymphocytes. Keywords: Comet assay, DNA strand breaks, ubiquinone, coenzyme Q 9, α-tocopherol, retinol, fatty acids, total antioxidant capacity 1. Introduction The particular chemical properties of ubiquinone or coenzyme Q 10 (CoQ 10 ) give this molecule multi- ple biological functions, including the long-known role in mitochondrial bioenergetics [32], antioxidant properties [6], nitrite reductase activity [28], proton-gated redox activity in lysosomes [41], extramito- chondrial electron transfer, e.g. plasma membrane oxidoreductase activity [58], and as a cofactor for uncoupling proteins in brown adipose tissue [13]. Also, CoQ 10 has been studied as a therapeutic drug for conditions such as congestive heart failure, angina, hypertension [55], and neurodegenerative dis- eases [3]. Its use has also been proposed in the management of certain aspects of cancer [17,44] and atherosclerosis [59]. Aging, which has multi-faceted social as well as scientific implications, is usually defined as the progressive loss of function accompanied by decreasing fertility and increasing mortality [27]. According * Address for correspondence: Dr. Jos´ e L. Quiles, Institute of Nutrition and Food Technology, C/ Ram´ on y Cajal 4, 18071 Granada, Spain. Tel.: +34 958248324; Fax: +34 958248326; E-mail: jlquiles@ugr.es. 0951-6433/05/$17.00  2005 – IOS Press and the authors. All rights reserved