Potassium oxonate

Curcumin, adenine, and potassium oxonate were purchased from Beijing Solarbio Science & Technology Co., Ltd. (Beijing, China). Antibody against ZO-1, occluding, and claudin-1 were purchased from Abcam (Cambridge, MA, USA).

The herb of P. capitatum was collected from Qianxi county, Guizhou province, China and was identified by Qingde Long (Guizhou Medical University) as the whole plant of Polygonum capitatum Buch.-Ham. ex D. Don. The voucher specimen of P. capitatum (No.: PC20201103) was deposited in the Herbarium of Guizhou Medical University.
The reference standards of gallic acid, protocatechuic acid, (+)-catechin, rutin, quercitrin, quercetin and emodin were purchased from Chengdu Chroma-Biotechnology Co., Ltd. (Chengdu, China). The pure materials of myricitrin, quercetin-3-O-(2″-O-galloyl)-β-d-glucopyranoside, quercetin-3-O-β-d-glucopyranoside, cis-N-caffeoyltyramine and 3″-O-galloylquercitrin were obtained in our laboratory. The purities of the reference standards were determined to be more than 98% by HPLC (-DAD. Hypoxanthine and potassium oxonate were purchased from the Beijing Solarbio Science and Technology Co., Ltd. (Beijing, China). Urate assay kits were purchased from Nanjing Jiancheng Bioengineering Institute (Nanjing, China).
HPLC-grade methanol and acetonitrile were acquired from Honeywell Burdick & Jackson Company (Morristown, NJ, USA). Formic acid (MS grade) was obtained from Fisher Scientific (Madrid, Spain). Deionized water for HPLC analysis was prepared using a Milli-Q water purification system (Millipore, Milford, MA, USA). All other reagents were of analytical grade.