Superoxide anion scavenging activity of alk(en)yl phenol compounds by using PMS-NADH system

Anacardic acid C15:3 and cardol C15:3 sigmoidally suppressed superoxide anion (O2-) generation using xanthine oxidase. To study this suppression activity, anacardic acids, cardanols and cardols having different numbers of double bonds in alk(en)yl chains were prepared. The O2- scavenging activity and H2O2 formation from O2- using PMS-NADH were examined. Anacardic acids and cardols indicated sigmoidal O2- scavenging activity but cardanols did not. The O2- scavenging activity of anacardic acid C15:3 was weaker than the suppression activity using xanthine oxidase, but the scavenging activity of cardol C15:3 was quite similar to the suppression using xanthine oxidase. The H2O2 formation from O2- decreased by the addition of anacardic acids, cardanols and cardols but increased by the addition of gallic and caffeic acids. From these results, we deduced that the O2- suppression activity of xanthine oxidase reaction with cardols is the O2- scavenging activity and that anacardic acids and cardols are O2- scavengers having low prooxidant property.