title: Interactions of lipoic acid radical cations with vitamins C and E analogue and hydroxycinnamic acid derivatives.
abstract: As a powerful natural antioxidant, lipoic acid exerts significant antioxidant activities in vivo and in vitro by deactivation of reactive oxygen and nitrogen species. In this study we present a novel synergistic interaction of lipoic acid with other endogenous or exogenous antioxidants. Antioxidants vitamins C and E analogue (Trolox C) and hydroxycinnamic acid derivatives were found to recycle lipoic acid by donating electrons to lipoic acid radical cations, thereby increasing the antioxidant capacity of lipoic acid in vivo and in vitro. The rate constant of the electron transfer is in the order 10(9)dm(3)mol(-1)s(-1), close to the diffusion-controlled limit, and transfer quantum yield is above 95%.
authors.affiliation: Lehrstuhl für Organische Chemie II der Ruhr-Universität, Bochum, Germany. changyuan.lu@ruhr-uni-bochum.de
authors.forename: Changyuan
authors.initials: C
authors.lastname: Lu
authors.forename: Yanyun
authors.initials: Y
authors.lastname: Liu
mesh_terms: D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000528:radiation effects; D002109:Caffeic Acids / Q000737:chemistry / Q000528:radiation effects; D002726:Chlorogenic Acid / Q000737:chemistry / Q000528:radiation effects; D003373:Coumaric Acids / Q000737:chemistry / Q000528:radiation effects; D005609:Free Radicals / Q000737:chemistry; D007700:Kinetics; D015394:Molecular Structure; D010315:Particle Accelerators; D013329:Structure-Activity Relationship; D008063:Thioctic Acid / Q000737:chemistry* / Q000528:radiation effects; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D002109:Caffeic Acids; D003373:Coumaric Acids; D005609:Free Radicals; D014810:Vitamin E; D002726:Chlorogenic Acid; C073734:sinapinic acid; D008063:Thioctic Acid; C004999:ferulic acid; D001205:Ascorbic Acid; C040048:caffeic acid