Fused 2‐Thiohydantoin Derivatives: Evaluation as Potential Antioxidants

A series of fused 5,5-diphenyl and 5-arylidene-2-thiohydantoin derivatives were examined for their oxygen free radical inhibitory and radical scavenging properties (RSC) using both an enzymic and non-enzymic biological generators of free radicals. Non-enzymic lipid peroxidation (OH . radicals) was assayed as the amount of malondialdebyde (MDA) that had been formed during incubation of boiled rat liver microsomes in the presence of ascorbic acid and ferric ions. Superoxide anions ( . O 2 anion radicals) were generated enzymatically in the xanthine-xanthine oxidase system. Among the 20 investigated compounds only four fused arylidene 2-thiohydantoin derivatives showed weak antioxidant activity scavenging OH . radicals. There is a relationship between the electrophilic OH . radical scavenging properties (RSC) of the tested molecules and the value of their HOMO energy derived from semiempirical MO calculations.