title: Alpha lipoic acid (ALA) protects proteins against the hydroxyl free radical-induced alterations: rationale for its geriatric topical application.
abstract: The well known OH* free radical scavenging properties of alpha-lipoic acid (ALA) cannot be easily utilized for biological experiments, because the compound is practically insoluble in water. We elaborated a simple method of preparing its Na-salt (Na-ALA) which proved to be water soluble. It has been demonstrated by ESR spin trapping experiments with DMPO, using the Fenton reaction as the source of OH* free radicals that Na-ALA maintains its OH* free radical scavenging ability: it reacts nearly an order of magnitude faster with these radicals than the spin trap itself. It was tested in two different systems to determine whether Na-ALA was able to protect bovine serum albumin (BSA) against the OH* free radical-induced polymerization and protein oxidation. (i) OH* free radicals were generated by Fenton reaction in the presence of BSA. This protein is polymerized by these radicals shown by the loss of its water solubility; Na-ALA exerted a considerable protective effect against this type of protein damage. (ii) BSA oxidation was induced by Co-gamma irradiation of 80 krad, resulting in a strong increase in the protein carbonyl content. Na-ALA inhibited this carbonyl formation very efficiently. The data suggest that the interaction of the OH radical with Na-ALA takes place on the disulfide group, yielding thiosulfinate or thiosulfonate. The results indicate that the geriatric topical application of Na-ALA may have an established rationale.
authors.affiliation: Department of Dermatology, Yale School of Medicine, New Haven, CT, USA.
authors.forename: N
authors.initials: N
authors.lastname: Perricone
authors.forename: K
authors.initials: K
authors.lastname: Nagy
authors.forename: F
authors.initials: F
authors.lastname: Horváth
authors.forename: G
authors.initials: G
authors.lastname: Dajkó
authors.forename: I
authors.initials: I
authors.lastname: Uray
authors.forename: I
authors.initials: I
authors.lastname: Zs -Nagy