Onosma obtusifolia extracts: Antioxidant potential and molecular docking insights into acetylcholinesterase, α-amylase, and tyrosinase inhibition

Natural products provide bioactive compounds against oxidative stress and enzyme-related disorders. This study investigates the chemical composition, antioxidant properties, and enzyme inhibitory activities of Onosma obtusifolia extracts obtained via maceration (MAC-ME), ultrasound-assisted extraction (UAE-ME), and Soxhlet extraction (SOE-ME). Molecular docking was employed to evaluate interactions of major phytochemicals with target enzymes. Among the extracts, SOE-ME exhibited the highest total phenolic (36.42 mg GAEs/g) and flavonoid (34.85 mg REs/g) contents. Chlorogenic acid was the most abundant phenolic compound (8355 μg/g in MAC-ME), followed by rosmarinic acid and luteolin 7-glucoside. SOE-ME showed the strongest antioxidant activity, with IC₅₀ values of 1.29 mg/mL (DPPH) and 1.18 mg/mL (ABTS), as well as the most potent inhibition of acetylcholinesterase (IC₅₀: 1.25 mg/mL) and tyrosinase (IC₅₀: 1.82 mg/mL). Molecular docking highlighted rosmarinic acid as a key ligand, exhibiting strong binding affinities with acetylcholinesterase (ΔG: –9.48 kcal/mol), α-amylase (ΔG: –8.72 kcal/mol), and tyrosinase (ΔG: –8.12 kcal/mol). These findings indicate that O. obtusifolia, especially SOE-ME, may serve as a valuable source of antioxidant and enzyme-inhibitory agents. Further in vivo studies are encouraged to validate its pharmacological potential.