Multifaceted evaluation of Carduus nutans extract effects on metabolic enzymes and antioxidant capacity overall

Carduus nutans L., a medicinal plant used in folk medicine, has not been sufficiently investigated regarding its potential effects on enzymes associated with diabetes and lipid metabolism. In this study, phytochemical contents (total phenolic, total flavonoid, and total tannin), antioxidant capacities (DPPH radical scavenging activity, metal chelating capacity, and reducing power), and inhibitory activities against α-glucosidase, α-amylase, pancreatic lipase, and pancreatic cholesterol esterase enzymes were evaluated. Antioxidant analysis demonstrated that the DPPH radical scavenging capacity of the aerial part extract at 2 mg/mL (94.15 ± 0.17%) was comparable to that of the reference compound gallic acid (95.58 ± 0.07%). The metal-chelating capacity of the aerial extract (77.63 ± 3.19%) was lower but still considerable compared to EDTA (100.19 ± 0.16%). The evaluation of α-amylase inhibition showed that the aerial extract of C. nutans (IC50: 47.53 ± 1.65 µg/mL) exhibited moderate inhibitory activity, although markedly lower than acarbose (IC50: 0.51 ± 0.02 µg/mL). In contrast, the extracts showed extremely weak inhibition of α-glucosidase. These findings indicate that C. nutans possesses notable antioxidant potential and selectively modulates enzymes involved in carbohydrate metabolism. Although direct inhibition of lipid metabolism-related enzymes was limited, the overall biological activity appears associated with its phenolic-rich phytochemical profile. This study provides the first data on C. nutans's inhibition of α-amylase, pancreatic lipase, and pancreatic cholesterol esterase and offers new insights into its pharmacological potential in metabolic diseases.