Abstract: This study analyzed the differences in polyphenol metabolite profiles, antioxidant activities and DNA protective effects between the stems plus leaves and the seeds of Agriophyllum squarrosum (L.) Moq. (ASLM). Using widely targeted metabolomics, 1 138 polyphenolic metabolites were preliminarily identified, flavonoid compounds being the major ones (accounting for 60.07% of the total). The absolute quantification of the major flavonoid compounds was carried out, and the top five most abundant monomers in the seeds were rutin (365.82 nmol/g), narcissin (261.24 nmol/g), kaempferol-3-O-rutinoside (29.50 nmol/g), (-)-epicatechin (26.12 nmol/g), and (-)-catechin (5.61 nmol/g). In contrast, isorhamnetin-3-O-glucoside (793.96 nmol/g), narcissus glycoside (754.79 nmol/g), isorhamnetin (344.07 nmol/g), rutin (280.89 nmol/g), and hyperoside (242.28 nmol/g) were identified as the top five most abundant monomers in the stems plus leaves. The total phenol contents in the stems plus leaves, as determined by the Folin-Ciocalteu method, were significantly higher than that in the seeds. The antioxidant activities of the polyphenol extracts from the stems plus leaves were significantly more potent than that of the seeds (P < 0.05). Within the concentration range of 10–50 μg/mL, the polyphenol extract from the seeds generally demonstrated superior DNA protective effects compared with the polyphenol extracts from the stems plus leaves, and it even exceeded the positive control Trolox in protection against hydroxyl radical-mediated DNA damage. Correlation analysis indicated that isorhamnetin-3-O-glucoside and isorhamnetin were the core contributors to the antioxidant activity. The DNA protective effect was associated with the synergistic action of rutin with other phenolic constituents. In summary, ASLM is rich in phenolic compounds, with the stems plus leaves serving as an excellent natural source of antioxidants, while the seeds exhibit unique potential in protecting against DNA oxidative damage. This study provides a theoretical basis for further research into the functional activities and comprehensive utilization of ASLM.

Key words: Agriophyllum squarrosum (L.) Moq.; polyphenols; antioxidant activity; DNA protection