Hydroxyl radical scavenging activity of naturally occurring furan fatty acids

As a part of our work on the antioxidant properties of naturally occurring furan fatty acids (F acids), we evaluated their hydroxyl radical (HO.) scavenging activity by an electron spin resonance (ESR) spin trapping technique with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). The additions of F acids to the incubation mixture of Fe2(+)-diethylenetriaminepentaacetic acid complex, H2O2 and DMPO decreased the intensity of the DMPO-OH adduct signal in a dose-dependent way. This decrease was not attributed to the destruction of DMPO-OH adduct by F acids. Kinetic competition studies indicated that the decrease in DMPO-OH signal intensity was mainly due to the competition of F acids with DMPO for HO., and not to the inhibition of the HO. generation system itself. F acids were found to react rapidly with HO. at approximately a diffusion-controlled rate (1.7 x 10(10)M-1 s-1). Comparison with the common HO. scavengers indicated that the rate constant of F acids is higher than those of mannitol and ethanol, and is compatible with those of histidine and dimethylsulfoxide, demonstrating that F acids are a potent HO. scavenger. It is suggested that F acids may serve as antioxidants in biological systems through their ability to scavenge HO..