###### Abstract  
It is known that sunflower (_Helianthus annuus_ L.) calathide enzymatically hydrolyzed extract (SCHE) contributes to the regulation of serum uric acid (UA); however, evidence regarding its bioactive components and mechanism are lacking. We identified two water-soluble components (scopoletin and chlorogenic acid) that are abundant in sunflower calathide, especially evaluated for the inhibition of xanthine oxidase (XO) and the expression levels of uric transporters with SCHE. Molecular docking of a chlorogenic acid-XO complex was more stable than that of the Scopoletin-XO, and its binding pockets, which closed the Mo = S center, was similar to xanthine pockets. Moreover, chlorogenic acid exhibited stronger inhibition than that of the scopoletin below 260 uM, despite the IC\({}_{50}\) of scopoletin (577.7 uM) being lower than that chlorogenic acid (844.7 uM) on the UA generation assessed by a spectrophotometer in vitro. It revealed that chlorogenic acid and scopoletin were competitive inhibitors of XO. In addition, the SCHE (300 ug/mL) and chlorogenic acid (0.75 mM) obviously inhibited urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) expression levels, while scopoletin significantly upregulated the expression of GLUT9. To summarize, chlorogenic acid served a crucial role in UA regulation consistent with the SCHE and functioned as an important ingredient of SCHE. The strategic analysis of SCHE combined with scopoletin and chlorogenic acid may contribute to the development of food supplemental alternatives on UA metabolism and the reduction of agricultural byproduct waste. sunflower calathide; scopoletin; chlorogenic acid; urate transporters; xanthine oxidase inhibitor; molecular docking +
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and natural low-methoxyl pectin, which possesses nutritional effects extracted from the sunflower head, could be used as a potential low-calorie or sugar-free food in the health care industry [7]. Although Chinese researchers have not only found its benefits in the field of hyperuricemia and gout [8], but also revealed the inhibitory effects of sunflower calathide on the expression of urate transporter (URAT1) and the activity of xanthine oxidase (XO) in mice [9], the active components and mechanism of actions still remain unknown. On the one hand, the current animal models regarding hyperuricemia and gout cannot mimic human disease well, because of the presence of uricase in mice [10], even if some employed uricase knockout mice without reliable arguments [11]; on the other hand, human kidneys that developed hyperuricemia were difficult to obtained for further research. Thus, a proper carrier chosen from human-derived cell lines was significant for research on human urate transporters. Accordingly, human embryonic kidney 293T cells expressed URAT1 (SLC22A12) stably [12] and there was a successful exploration involved in glucose transporter 9 (GLUT9) on UA-induced HEK293T cells [13]. Additionally, the protective effect on H\({}_{2}\)O\({}_{2}\)-induced kidney damage was evaluated by HEK293T cells [14], so that it could be employed to detect the oxidative stress involved in UA stimulation. In these cases, we considered 293T cells as a potential experimental model to investigate urate transporters in the human kidney. In this study, the inhibition of XO, which promotes the generation of xanthine and UA [15], was also considered as therapeutic targets. We identified scopoletin and chlorogenic acid through UPLC-Q-Orbitrap [16] and validated the inhibition of xanthine oxidase in vitro as well as employing AutoDock Tools, an efficient molecular docking approach for virtual screening, to predict the protein-ligand binding interactions [17] and the type of inhibition. Especially, the high UA exposed model was established to evaluate the bioactivity of the extract of _Helianthus annuus_ L. calathide combined with scopoletin and chlorogenic acid.