The Quality Control Assessment of Commercially Available Coenzyme Q10-Containing Dietary and Health Supplements in Japan

Coenzyme Q10 (CoQ10) has been widely commercially available in Japan as a dietary and health supplement since 2001 and is used for the prevention of lifestyle-related diseases induced by free radicals and aging. We evaluated CoQ10 supplements to ensure that these supplements can be used effectively and safely. Commercially available products were selected and assessed by the quality control tests specified in the Japanese Pharmacopoeia XV. When the disintegration time of CoQ10 supplements was measured, a few tested supplements did not completely disintegrate even after incubation in water for an hour at 37°C. In the content test, many samples were well controlled. However, a few supplements showed low recovery rates of CoQ10 as compared to manufacturer’s indicated contents. Among soft capsule and liquid supplements, the reduced form of CoQ10 (H2CoQ10), as well as the oxidized form, was detected by HPLC with electrochemical detector. The results for experimental formulated CoQ10 supplements demonstrated that H2CoQ10 was produced by the interaction of CoQ10 with vitamins E and/or C. From these results, we concluded that quality varied considerably among the many supplement brands containing CoQ10. Additionally, we also demonstrated that H2CoQ10 can be detected in some foods as well as in CoQ10 supplements

Formation of Superoxide Anion during Ferrous Ion-Induced Decomposition of Linoleic Acid Hydroperoxide under Aerobic Conditions

金沢大学医薬保健研究域医学系We studied the mechanism of formation of oxygen radicals during ferrous ion-induced decomposition of linoleic acid hydroperoxide using the spin trapping and chemiluminescence methods. The formation of the superoxide anion (O2.-) was verified in the present study. The hydroxyl radical is also generated through Fenton type decomposition of hydrogen peroxide produced on disproportionation of O2.-. A carbon-centered radical was detected using 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO) as a spin trap. Alkoxyl radical formation is essential for the conversion of linoleic acid hydroperoxide into the peroxyl radical by ferrous ion. It is likely that the alkoxyl radical [R1CH(O.)R2] is converted into the hydroxylcarbon radical [R1C.(OH)R2] in water, and that this carbon radical reacts with oxygen to give the α-hydroxyperoxyl radical [R1R2C(OH)OO.], which decomposes into the carbocation [R1C+(OH)R 2] and O2.-

Saposin B Is a Human Coenzyme Q10-Binding/Transfer Protein

Coenzyme Q10 (CoQ10) is essential for ATP production in the mitochondria, and is an important antioxidant in every biomembrane and lipoprotein. Due to its hydrophobicity, a binding and transfer protein for CoQ10 is plausible, but none have yet been isolated and characterized. Here we purified a CoQ10-binding protein from human urine and identified it to be saposin B, a housekeeping protein necessary for sphingolipid hydrolysis in lysosomes. We confirmed that cellular saposin B binds CoQ10 in human sperm and the hepatoma cell line HepG2 by using saposin B monoclonal antibody. The molar ratios of CoQ10 to saposin B were estimated to be 0.22 in urine, 0.003 in HepG2, and 0.12 in sperm. We then confirmed that aqueous saposin B extracts CoQ10 from hexane to form a saposin B-CoQ10 complex. Lipid binding affinity to saposin B decreased in the following order: CoQ10>CoQ9>CoQ7>>α-tocopherol>>cholesterol (no binding). The CoQ10-binding affinity to saposin B increased with pH, with maximal binding seen at pH 7.4. On the other hand, the CoQ10-donating activity of the saposin B-CoQ10 complex to erythrocyte ghost membranes increased with decreasing pH. These results suggest that saposin B binds and transports CoQ10 in human cells