Phytochemical riches and bioactive potential of Onopordum acanthium L. (Asteraceae) from Iran

Onopordum acanthium L. (Asteraceae), a traditionally used medicinal plant, was investigated for its morphological, phytochemical, and biological properties in this comprehensive study. Methanolic and aqueous extracts were prepared from different parts of the plant (root, stem, leaf, flower, and fruit) and analyzed for their phenolic composition, antioxidant, antidiabetic, anticholinesterase, antimicrobial, and genotoxic activities. LC-MS/MS analysis revealed that chlorogenic acid was most abundant in the flower (3045.38 ng/mL) and root (728.53 ng/mL) aqueous extracts, while quinic acid reached 856.27 ng/mL in the root. Quercetin, apigenin, and luteolin were also detected at significant levels. The fruit methanol extract showed the highest total phenolic (100.78 ± 0.0015 µg GAE/mg), flavonoid (603.67 ± 0.0015 µg RE/mg), and tannin (186.22 ± 0.0015 µg TAE/mg) contents. Antioxidant assays demonstrated notable ABTS^•⁺ (38.38 ± 0.0042%) and DPPH^• (28.43 ± 0.0252%) scavenging capacities in the same extract. Regarding enzyme inhibition, the flower aqueous extract showed the strongest α-glucosidase inhibition (45.58%), while the fruit aqueous extract exhibited moderate α-amylase inhibition (26.33%). The stem methanol extract displayed the highest acetylcholinesterase inhibition (19.02%), whereas the root aqueous extract showed the highest butyrylcholinesterase inhibition (10.76%). Antimicrobial assays revealed moderate antifungal activity, particularly against Candida tropicalis (MIC = 312.5 µg/mL), with the flower and fruit methanol extracts being the most effective. Genotoxicity assessment using Ames and Allium tests confirmed biosafety up to 5 mg/plate and 250 mg/L, respectively, except for flower extracts, which showed slight cytogenotoxicity. Overall, this study highlights O. acanthium as a promising natural source of phenolic compounds with therapeutic potential, particularly in managing oxidative stress, diabetes, and neurodegenerative disorders.