Comparative analysis of the polyphenolic profile and antioxidant activity of different plant parts of knotweed (Polygonum aviculare L.)

Polygonum aviculare L. (Polygonaceae), commonly known as knotweed, is a widely distributed annual plant with a history of ethnopharmacological use. Despite its traditional applications and reported bioactivities, comprehensive analyses comparing the chemical composition and antioxidant potential of its individual plant parts are lacking. In this study, ethanol extracts were prepared from the aerial parts, leaves, stems, and roots of P. aviculare collected in northern Serbia. Targeted HPLC-MS/MS analysis quantified 31 polyphenols, while qualitative HPLC-DAD-MS analysis enabled the identification of dominant phenolic compounds based on their spectral (UV and MS) characteristics, without confirmation using reference standards. Catechin was most abundant in root and stem extracts, while the leaf extract exhibited the highest concentrations of gallic and chlorogenic acids, as well as flavonol-3-O-glucuronides. Antioxidant activity was assessed using a cell-based assay in U937 cells exposed to AAPH-induced oxidative stress. All extracts demonstrated significant antioxidant capacity, with the leaf extract showing the highest activity (252.8 ± 22.5 mg TE/g dry extract). Principal component analysis (PCA) revealed distinct polyphenolic profiles among the extracts, especially between roots and aerial parts. These findings highlight the differential distribution of bioactive compounds in P. aviculare and support the leaf extract as the most promising antioxidant source, warranting further investigation for therapeutic and nutraceutical applications.