Antioxidant Action of Furan Fatty Acids : Reactions with Reactive Oxygen Species

Abstract

As a continuation of the work on the biological roles of naturally occurring furan fatty acids (Furan acids), I studied on their antioxidant activity, especially the ability to scavenge biologically important oxidants, peroxy] radical (ROO・), hydrogen peroxide (H_2O_2), hydroxyl radical (・OH), superoxide (O_2^-) and hypochlorous acid ion (-OCl). Scavenging of t-butylperoxyl radical ((CH_3)_3COO・) was confirmed by electron spin resonance (ESR) spectrometry, using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap. The antioxidant action of furan acids during oxidation of linoleic acid in aqueous dispersion previously reported can thus be explained as primarily due to the ability to scavenge the linoleic acid peroxyl radical (LOO・). These acids effectively react with ・OH, an extremely strong oxidant, with a second-order rate constant of 1.71×10^<10>M^^<-1>s^<-1>, as determined by ESR spectrometry. The ability of Furan acids to scavenge ・OH was compared with that of known ・OH scavengers such as dimethylsulfoxide, mannitol, histidine and ethanol. They are also a strong inhibitor of linoleic acid oxidation initiated by ・OH. They are scavengers of -OCl, being able to protect α_1-antiproteinase from inactivation by -OCl. In contrast, reactions of Furan acids with H_2O_2 and O_^- could not be detected by the methods in this study. Overall, these results show Furan acids to possibly be useful as antioxidants in biological systems.