Superoxide, hydroxyl and fatty acid radical scavenging by aminosalicylates. Direct evaluation with electron spin resonance spectroscopy.

Reactive oxygen radicals such as superoxide and hydroxyl radicals, as well as intermediate unsaturated fatty acid radicals, have been proposed as playing an important role in various diseases including inflammatory bowel disease (IBD). In this study we evaluated radical scavenger properties of aminosalicylates used in the therapy of IBD using spin trapped electron spin resonance spectroscopy. 5-Aminosalicylic acid (5-ASA), 4-aminosalicylic acid and olsalazine had superoxide radical scavenger properties (IC50 = 0.4, 0.4 and 1.0 mM, respectively). 5-ASA and benzalazine also inhibited hydroxyl radicals (IC50 = 6.5 mM). Fatty acid radicals were not inhibited by aminosalicylates. Our results support the hypothesis that therapeutically active compounds may be oxygen radical scavengers and that fatty acid radical scavenging has to be performed by drugs other than aminosalicylates.