Scavenging ability on ROS of alpha-lipoic acid (ALA)

The scavenging ability of alpha-lipoic acid (ALA) towards superoxide anions, hydroxyl radicals and hydrogen peroxide was evaluated by means of chemiluminescence (CL). In neutral or acid conditions, ALA could scavenge superoxide anions and its scavenging efficiency depended on its concentration. In neutral or alkaline conditions, the CL intensity of the reaction of ALA with hydroxyl radical (OH. radicals) decreased after the first 10 min and then increased with time, suggesting that ALA could scavenge OH. radicals at the beginning, but yielded unknown intermediate products that could lead to the increase of CL intensity at later stages. The increase of CL intensity in the reaction of hydrogen peroxide with ALA may also be due to these products. (C) 2003 Elsevier Ltd. All rights reserved.