INHIBITION OF XANTHINE OXIDASE-XANTHINE-IRON MEDIATED LIPID-PEROXIDATION BY EUGENOL IN LIPOSOMES

The effect of eugenol on xanthine oxidase (XO) xanthine(X)-Fe+3-ADP me diated lipid peroxidation was studied in liver microsomal lipid liposo mes. Eugenol inhibited the lipid peroxidation in a dose dependent mann er as assessed by formation of thiobarbituric acid reactive substances . When tested for its effect on XO activity per se, (by measuring uric acid formation) eugenol inhibited the enzyme to an extent of 85% at 1 0 mu m concentration and hence formation of O-2-radical-anion also How ever, the concentration of eugenol required for XO inhibition was more in presence of metal chelators such as EDTA, EGTA and DETAPAC, but no t in presence of deferoxamine, ADP and citrate. The antiperoxidative e ffect of eugenol was about 35 times more and inhibition of XO was abou t 5 times higher as compared to the effect of allopurinol. Eugenol did not scavenge O-2-radical-anion generated by phenazine methosulfate an d NAD but inhibited propagation of peroxidation catalyzed by Fe2+ EDTA and lipid hydroperoxide containing liposomes. Eugenol inhibits XO-X-F e3+ ADP mediated peroxidation by inhibiting the XO activity per se in addition to quenching various radical species.