Studies on the antioxidant activity of some thiazolidinedione, imidazolidinedione and rhodanine derivatives having a flavone core

A series of flavonyl-2,4-thiazolidinedione, imidazolidinedione and rhodanine derivatives were tested for their antioxidant activity as scavengers of oxygen free radicals. Free radical scavenging activities, including superoxide anion radical (O-2((center dot) over bar)), hydroxyl radical (HO center dot) and 2,2'-diphenyl-1-picrylhydrazyl free radical have been evaluated using chemiluminescence, electron paramagnetic resonance and spin trapping with 5,5-dimethyl-1-pyrroline-1-oxide as a spin trap. Potassium superoxide in dimethylsulfoxide and 18-crown-6 ether were used for the production of O-2((-) over bar). Hydroxyl radical was generated using the Fenton reaction. Ten of the eleven examined compounds exhibited decrease in chemiluminescence, but there were large differences in the decrease, ranging from 16% to 89%; also, two of these compounds increased light emission by about 200%. On the contrary, all compounds tested exhibited 30-68% scavenging HO center dot and 25-96% scavenging the DPPH center dot radical respectively. Possible mechanisms are proposed to explain the results. Copyright (C) 2014 John Wiley & Sons, Ltd.