ANTIOXIDANT ACTIVITY OF QUERCETIN AGAINST METMYOGLOBIN-INDUCED OXIDATION OF FISH-OIL BILE-SALT EMULSION

The antioxidative effect of quercetin was examined in metmyoglobin-ind uced oxidation of a fish oil-bile salt emulsion (average diameter of p articles; 20 mu m) to evaluate its effectiveness during the digestion of highly oxidizable oils. The activity of quercetin increased with th e lowering of the initial peroxide value (PV) of the oil and its effec tiveness was superior to that of alpha-tocopherol. A synergistic antio xidant effect was observed upon the addition of quercetin and alpha-to copherol irrespective of the initial PV of the oils, and quercetin was consumed faster than alpha-tocopherol. The loss of quercetin was larg er than that of alpha-tocopherol when cumene hydroperoxide and metmyog lobin were mixed in a trimyristin-bile salt emulsion. In an ultrafiltr ation experiment on emulsified oil with a membrane filter of 100nm por e size, the recovery of quercetin in the filtrate was higher than that of alpha-tocopherol. These data suggest that quercetin was an antioxi dant in the digestion of fish oil. The effectiveness seems to come fro m its distribution in the emulsified oil, different from that of alpha -tocopherol, and its ability to scavenge radicals generated from the r eaction of lipid hydroperoxides with metmyoglobin.