TY - JOUR
T1 - Elucidation of antioxidant activity of α-lipoic acid toward hydroxyl radical
AU - Matsugo, Seiichi
AU - Yan, Liang-Jun
AU - Han, Derick
AU - Trischler, Hans J.
AU - Packer, Lester
PY - 1995/1/1
Y1 - 1995/1/1
N2 - The photosensitive organic hydroperoxidz, NP-III, which produces hydroxyl radicals on illumination by UVA light, was used to examine the antioxidant activity of α-lipoic acid and its derivatives toward hydroxyl radical. Apolipoprotein (apo-B) of human low density lipoprotein (LDL) and bovine serum alubumin (BSA) were irradiated with UVA in the presence of NP-III and α-lipoic acid. The oxidation of BSA and the apo-B protein of LDL by NP-III was completely suppressed by α-lipoic acid. ESR studies using dimethylpyrroline oxide (DMPO) as a spin trapping reagent also revealed that in the presence of α-lipoic acid, the DMPO-OH adduct produced from the irradiation of NP-III and DMPO completely disappeared. DMPO-OH quenching experiments were performed in the presence or absence of desferoxamine but no change in the signal intensity was found. Hence, the quenching activity of α-lipoic acid is not due to its chelating activity toward transition metals (ferrous ions). The results lead us to conclude that α-lipoic acid is an efficient hydroxyl radical quencher owing to the disulfide bond in the dithiolane ring.
AB - The photosensitive organic hydroperoxidz, NP-III, which produces hydroxyl radicals on illumination by UVA light, was used to examine the antioxidant activity of α-lipoic acid and its derivatives toward hydroxyl radical. Apolipoprotein (apo-B) of human low density lipoprotein (LDL) and bovine serum alubumin (BSA) were irradiated with UVA in the presence of NP-III and α-lipoic acid. The oxidation of BSA and the apo-B protein of LDL by NP-III was completely suppressed by α-lipoic acid. ESR studies using dimethylpyrroline oxide (DMPO) as a spin trapping reagent also revealed that in the presence of α-lipoic acid, the DMPO-OH adduct produced from the irradiation of NP-III and DMPO completely disappeared. DMPO-OH quenching experiments were performed in the presence or absence of desferoxamine but no change in the signal intensity was found. Hence, the quenching activity of α-lipoic acid is not due to its chelating activity toward transition metals (ferrous ions). The results lead us to conclude that α-lipoic acid is an efficient hydroxyl radical quencher owing to the disulfide bond in the dithiolane ring.
UR - http://www.scopus.com/inward/record.url?scp=0028930944&partnerID=8YFLogxK
U2 - 10.1006/bbrc.1995.1318
DO - 10.1006/bbrc.1995.1318
M3 - Article
C2 - 7887924
AN - SCOPUS:0028930944
SN - 0006-291X
VL - 208
SP - 161
EP - 167
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 1
ER -