Ubiquinol-10 is an effective lipid-soluble antioxidant at physiological concentrations.
It is well known that ubiquinone-10 (coenzyme Q10, ubiquinone 50) acts as an electron carrier of the respiratory chain in mitochondria. In this paper we show that ubiquinol-10, the reduced form of ubiquinone-10, also efficiently scavenges free radicals generated chemically within liposomal membranes. Ubiquinol-10 is about as effective in preventing peroxidative damage to lipids as alpha-tocopherol, which is considered the best lipid-soluble antioxidant in humans. The number of radicals scavenged by each molecule of ubiquinol-10 is 1.1 under our experimental conditions. In contrast to alpha-tocopherol, ubiquinol-10 is not recycled by ascorbate. However, it is known that ubiquinol-10 can be recycled by electron transport carriers present in various biomembranes and possibly by some enzymes. We also show that ubiquinol-10 spares alpha-tocopherol when both antioxidants are present in the same liposomal membranes and that ubiquinol-10, like alpha-tocopherol, does not interact with reduced glutathione. Our data together with previous work on the antioxidant function of ubiquinol reported in the literature strongly suggest that ubiquinol-10 is an important physiological lipid-soluble antioxidant.
Frei
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B
Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
Kim
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MC
Ames
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BN
D007700:Kinetics; D015227:Lipid Peroxidation; D008081:Liposomes; D010713:Phosphatidylcholines; D012995:Solubility; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D014810:Vitamin E
D008081:Liposomes; D010713:Phosphatidylcholines; D014451:Ubiquinone; D014810:Vitamin E; C026663:ubiquinol-10; C025204:Ubiquinone Q2; C003741:ubiquinol