Xanthine Oxidase Inhibition by Aqueous Extract of Limonium brasiliense (Plumbaginaceae)

Resumo

Limonium brasiliense (Boiss.) Kuntze is a medicinal plant belonging to the Plumbaginaceae family that is popularly used in the folk medicine and it is believed to have cardioprotective properties.Xanthine oxidase (XO) is a key enzyme that catalyze the oxidation of hypoxanthine and xanthine to uric acid causing hyperuricemia in humans.In this study, we examined XO inhibitory activities of the aqueous fraction of Limonium brasiliense extract, and its polar bioactive constituents, using the enzymatic HX–XO system in vitro.Seven active compounds isolated from the aqueous extract were identified by comparison of their 1H and 13C NMR data with those reported in the literature. Myricetin, apigenin, taxifolin, 3-O-acetyltaxifolin, myricetin-3-O-α-rhamnopyranoside and gallic acid have proved to be strong XO inhibitors.Prodelphinidin B1‐3,3’‐digallate was effective for scavenging superoxide radicals (O2•_), generated enzymatically by a hypoxanthine (HX)/xanthine oxidase (XO) system and/or for inhibiting XO activity. This compound showed the most potent inhibitory activity with an IC50 value of 6,61 µM, comparable to allopurinol, the drug of choice for inhibition of XO in gout patients.For the first time, this study provides a rational basis for the use of aqueous fraction of L. brasiliense against hyperuricemia, displaying potent XO inhibitory activity with an IC50 value of 48.3 µg/ml. This inhibitory effect is compatible with the presence of Prodelphinidin B1‐3,3’‐digallate in this extract.