Abstract: In order to investigate the material basis of the uric acid-lowering activity of Gynura procumbens, G. procumbens extracts obtained by hot reflux extraction with different ethanol concentrations (0%, 30% and 70%) were evaluated for bioactive ingredients, xanthine oxidase (XOD) inhibitory activity and antioxidant activity. The extracts were analyzed and identified by non-targeted metabolomics. Meanwhile, the 30% and 70% ethanol extracts, which exhibited high XOD inhibitory activity, was evaluated for uric acid-lowering activity in a mouse model of hyperuricemia induced by hypoxanthine and potassium oxonate. The results showed that the XOD inhibitory activity of the extracts was significantly positively correlated with the total flavonoid and total organic acid contents (P < 0.05 and P < 0.01, respectively), and the superoxide anion scavenging capacity was significantly positively correlated with the total phenol content (P < 0.01). A total of 705 differential metabolites were detected by non-targeted metabolomics. In vitro experiments revealed that naringenin, 1,5-dicaffeoylquinic acid, α-linolenic acid, ferulic acid and diosmetin were the key contributors to the uric acid-lowering activity of G. procumbens. Both 30% and 70% ethanol extracts alleviated hyperuricemia by lowering serum uric acid and inhibiting XOD (P < 0.01), and alleviated hyperuricemia-induced oxidative liver damage. In this study, through in vivo and in vitro experiments, the uric acid lowering activity of G. procumbens was verified, and the basis of the uric acid lowering substance was discussed, which could provide a theoretical basis for the preparation of uric acid-lowering substances from G. procumbens and the development of functional foods with uric acid-lowering activity.

Key words: Gynura procumbens; hyperuricemia; non-targeted metabolomics; xanthine oxidase; uric acid