Antioxidant and xanthine oxidase inhibitory activities of rosmarinic acid-rich extract from perilla seed meal

Hyperuricemia can lead to various diseases, including diabetes, renal disorders, and gout. Xanthine oxidase (XO), a crucial enzyme, synthesizes uric acid from xanthine; and concurrently generates reactive oxygen species, causing oxidative stress. This study aimed to validate the biological function of perilla seed meal (PSM), a by-product of cold-pressed perilla oil, concerning phytochemical contents, antioxidants, and XO inhibitory activities. PSM extraction employed 70% ethanol, and the solvent partition technique enriched the rosmarinic acid (RA)-rich fraction. Total phenolic and flavonoid contents, along with antioxidant capabilities, were determined. The reducing property of the PSM fraction was confirmed through the FRAP assay, while HPLC quantified RA. In addition, the inhibitory efficiency of the PSM fraction against XO was investigated. The ethyl acetate (EA) fraction exhibited the highest levels of phenolics, flavonoids, and RA. ABTS and DPPH assays revealed the most effective radical scavenging by the EA fraction, with IC50 values of 6.51 +/- 0.11 mu g/l and 20.43 +/- 0.18 mu g/l, respectively. Moreover, the EA fraction demonstrated the highest FRAP value of 3778.05 +/- 6.8 mu M Fe2+/g. The XO inhibition of the EA fraction exhibited significant inhibition compared to the ethanol extract. Mixed-type inhibition of XO was identified in PSM. Our results suggest that PSM exhibits high phytochemical compounds, antioxidant capacities, and XO inhibition, meriting further exploration for clinical applications.