MSI_000052628

Ubiquinol 8 is a ubiquinol in which the polyprenyl substituent is octaprenyl. Ubiquinol-8 is the reduced form of ubiquinone-8. Ubiquinone (also known as coenzyme Q) is an isoprenoid quinone that functions as an electron carrier in membranes. In eukaryotes, ubiquinone is found mostly within the inner mitochondrial membrane where it functions in respiratory electron transport, transferring two electrons from either complex I (NADH dehydrogenase) or complex II (succinate-ubiquinone reductase) to complex III (bc1 complex). The quinone nucleus of ubiquinone is derived directly from 4-hydroxybenzoate, while the isoprenoid subunits of the polyisoprenoid tail are synthesized via the methylerythritol phosphate pathway, which feeds isoprene units into the polyprenyl biosynthesis pathways. The number of isoprenoid subunits in the ubiquinone side chain varies in different species. For example, Saccharomyces cerevisiae has 6 such subunits, Escherichia coli K-12 has 8, rat and mouse have 9, and Homo sapiens has 10. Ubiquinol-8 is effective as an anti-oxidant. By donating one of its hydrogen atoms to become the free-radical semiquinone (.Q-), it can neutralize a lipid peroxyl radical. The free-radical semiquinone is then restored to a non-free-radical state by the respiratory chain Q cycle. Ubiquinol or the free-radical semiquinone can also regenerate the Vitamin E tocopheroxyl radical by electron donation (http://www.benbest.com/nutrceut/CoEnzymeQ.html).