Hydroxyl radical-scavenging property of indomethacin.

The ability of indomethacin to scavenge hydroxyl radical (.OH) using high pressure liquid chromatography (HPLC) was investigated. .OH radical was generated by photolysis of H2O2 (1.5-10 mmoles/L) with UV light and was trapped with salicyclic acid (500 nmoles). H2O2 produced .OH in a concentration-dependent manner as estimated by .OH adduct products 2,3- and 2,5-dihydroxybenzoic acid (DHBA). Indomethacin in increasing concentrations (5-600 mumoles/L) produced increasing inhibition of generation of 2,3-DHBA (7-67%) and of 2,5-DHBA (7-77%). The results indicate that indomethacin scavenges .OH in a concentration-dependent manner.