Phenolic Profile and Antioxidant Potential of Selected European Astragalus Species: Comparative UHPLC–DAD–ESI/TOF–MS and In Vitro Study

Plants of the genus Astragalus are recognized as rich sources of bioactive compounds with antioxidant and therapeutic potential; however, European species remain less explored than the well-known Astragalus membranaceus (Fisch.) Bunge. The aim of this study was to compare the phytochemical composition and in vitro biological activity of selected Astragalus species occurring in Poland (A. cicer L., A. glycyphyllos L., A. membranaceus). Phenolic compounds in methanolic extracts obtained from the roots and aerial parts were analyzed using spectrophotometric methods and UHPLC–DAD–ESI/TOF–MS. Antioxidant activity was evaluated using DPPH, ABTS, FRAP, CUPRAC, metal chelation, superoxide radical scavenging, and lipid peroxidation (TBARS) assays. Additionally, enzyme inhibition toward α-amylase, lipase, hyaluronidase, tyrosinase, and butyrylcholinesterase was assessed. The root of A. membranaceus exhibited the highest total phenolic content (199.84 ± 3.64 mg GAE/g extract) and the strongest antioxidant activity (DPPH IC50 = 36.53 ± 1.22 µg/mL; ABTS IC50 = 26.31 ± 0.03 µg/mL), as well as the most pronounced α-amylase inhibition (IC50 = 17.78 ± 1.16 µg/mL). It also demonstrated moderate protective effects against AAPH-induced lipid peroxidation. The herb of A. cicer showed moderate radical scavenging capacity and the most effective inhibition of lipid peroxidation at higher concentrations. Extracts of A. glycyphyllos displayed weaker radical scavenging but notable metal-chelating properties. Selected extracts also exhibited moderate inhibitory activity against tyrosinase and butyrylcholinesterase. A. membranaceus remains the most potent source of phenolic compounds and antioxidant activity; European species such as A. cicer and A. glycyphyllos represent promising, locally available alternatives and may be used in phytotherapy and functional products.