Protein hydrolysates and xanthine oxidase inhibitory peptides from sunflower capitulum exert antihyperuricemic effects: a comprehensive study based on serum metabolomics and gut microbiota analysis

Abstract

Hyperuricemia (HUA), which results from an imbalance between uric acid production and excretion, is a major risk for gout and other metabolic disorders. Food-derived bioactive peptides have attracted increasing attention as dietary candidates for HUA management. However, the relative in vivo efficacy of protein hydrolysates and their derived xanthine oxidase inhibitory peptides remains unclear. In this study, sunflower capitulum protein hydrolysate (SCPH) and its derived peptide, Leu-Gly-Asp-Phe (LGDF) were systematically compared by combining in vitro assays, animal experiments, serum metabolomics, and gut microbiota analysis. SCPH was prepared by a two-step enzymatic hydrolysis (IC₅₀ = 20.18 mg mL⁻¹), and LGDF was identified, screened by molecular docking, and further confirmed by in vitro enzymatic assays (IC₅₀ = 9.7 mM). In potassium oxonate/adenine-induced HUA mice, both SCPH (400 mg kg⁻¹) and LGDF (60 mg kg⁻¹) significantly reduced serum uric acid levels, suppressed xanthine oxidase activity, and alleviated renal and liver injury. Notably, only high-dose SCPH significantly decreased adenosine deaminase activity, suggesting a broader regulatory effect on purine metabolism. Serum metabolomics showed that both treatments commonly regulated glycerophospholipid metabolism and reduced gut microbiota-derived aromatic metabolites. SCPH additionally affected taurine and hypotaurine metabolism as well as biotin metabolism. Meanwhile, both treatments increased beneficial genera in HUA mice, while SCPH showed stronger effects on Alloprevotella and Colidextribacter and more effectively suppressed potentially detrimental taxa such as Bacteroides and Parabacteroides. Overall, under the tested dose, SCPH exerted a broader regulatory effect than LGDF, particularly with respect to ADA inhibition and the regulation of serum metabolomic profiles and gut microbiota composition. These results support the value-added utilization of sunflower byproducts as functional dietary ingredients for HUA management.