Autoxidation and antioxidant activity of ubiquinol homologues in large unilamellar vesicles

✍ Scribed by Marta Cipollone; Diana Fiorentini; Maria Cristina Galli; Anna Maria Sechi; Laura Landi

• Book ID: 103037089
• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 585 KB
• Volume: 69
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(94)90030-2

✦ Synopsis

The antioxidant activity of ubiquinol homologues with different side-chain length such as ubiquinol-3 and ubiquinol-7 was compared with that of a-tocopherol when peroxidation was induced by the water-soluble initiator 2,2 '-azobis-(2amidinopropane hydrochloride). In large unilamellar vesicles containing equal amounts of a-tocopherol, ubiquinol-3 and ubiquinol-7 the rates of inhibition were very similar but the stoichiometric factor of quinols was -I. To explain this low value, which is one-half of that found when the autoxidation was performed in apolar solvents (Chem. Phys. Lipids (1992) 61, 121-130), the oxidation of t~-tocopherol and ubiquinol-3 initiated by the azocompound was studied both in methanol and in dimiristoyl-lecithin vesicles. The results obtained show that the ubiquinol homologues undergo a radical chain reaction taking place at the polar interface and suggest that the average preferred location of both quinol headgroups is near to the outer surface of the bilayer.