Studies On Extraction And Effects On Hyperuricemia Of Quercetin From Bud Of Sophora Japonica L.

Xanthine oxidase (XO) can catalyze the oxidation of xanthine and hypoxanthine to generate uric acid. If the uric acid was excessively accumulated in the human body, hyperuricemia and gout can be caused. Therefore, it is an effective means to prevent and treat gout that inhibiting the activity of XO. This paper aimed to investigate the inhibitory effect of a variety of flavonoids on XO activity and hyperuricemic mice, and defined the best xanthine oxidase inhibition (XOI)-quercetin, then extracted quercetin from the flower bud of Sophora japonica L. and verified the hypouricemic effect of the extract from the flower bud of Sophora japonica L.. The main conclusions are as follows1. Nine highly representative standard flavonoids inhibiting the XO activity in vitro was determined by HPLC. The XO activity was inhibited to varying degrees by nine standard flavonoids in vitro. Quercetin with an IC50value of3.67μg/mL is the best XOI of the nine standard flavonoids, then luteolin(IC506.12μg/mL)and apigenin(IC508.52μg/mL). According to the structure-activity relationship, the hydroxyl groups at C-3, C-5and C-7and the double bond between C-2and C-3were essential for a high inhibitory activity on xanthine oxidase. The results of study in vivo demonstrated that the hypouricemic action of standard quercetin could be explained, to some extent, by inhibiting XO activities.2. Quercetin in the bud of Sophora japonica L.was extracted by dissolving in alkali liquid and sinking in sour liquid, followed by hydrolyzing in sour liquid. The best extraction condition was confirmed by single-factor experiment and orthogonal experiment, which is rutin precipitation of pH4.0, sulfuric acid-liquid ratiol:80(1g rutin need80mL,2%H2SO4),2h of hydrolysis time. Polyamide resin was chose to purify the extract mentioned above. Before and after purification, the purity of quercetin is respectively75.12%and90.89%.3. This study aimed to investigate the effect of the extract from the flower bud of Sophora japonica L.-quercetin on the xanthine oxidase (XO) activity and the hyperuricemic mice. The XO activity was inhibited significantly by the extract in vitro with an IC50value of15.63μg/mL. Mice were treated with the extract for7days and then hyperuricemia was induced by intraperitoneal injection of the uricase inhibitor potassium oxonate. The results demonstrated that the hypouricemic action of the extract from the bud of Sophora japonica L. could be explained, to some extent, by inhibiting XO activities. And the extract had no injury about kidney function of hyperuricemic mice.The extract from the bud of Sophora japonica L. would be promising as a natural product with hypouricemic effect, and the hypouricemic effect of the extract is safe.