Identification of Scopoletin and Chlorogenic Acid as Potential Active Components in Sunflower Calathide Enzymatically Hydrolyzed Extract towards Hyperuricemia

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 urate 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 μM, despite the IC50 of scopoletin (577.7 μM) being lower than that chlorogenic acid (844.7 μM) 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 μg/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.