Inhibitory Effect of Ruta graveolens L. Extract on Guinea Pig Liver and Bovine Milk Xanthine Oxidase

Flavonoids could serve as potent inhibitors of xanthine oxidase (xo). in the presentstudy, the effects of ruta graveolens l. extract and its major isolated flavonoids,quercetin and rutin, on guinea pig liver xo have been investigated. the inhibitoryeffects of r. graveolens, quercetin and its glycoside form, rutin, were assayedspectrophotometrically. r. graveolens extract showed moderate inhibition on xoactivity. interestingly, bovine milk and guinea pig liver xo were inhibited significantlyat different ranges by either the extract or its flavonoids, whereas allopurinol actedwith almost the same potency on both enzymes. rutin inhibited the enzymes in acompetitive manner, while quercetin was found to be a competitive and mixedinhibitor of guinea pig liver and bovine milk xo, respectively. in conclusion, r.graveolens extract can act as a good inhibitor of xo. interestingly, it was shownthat the inhibitory effects of flavonoids on xo could be species dependent.