Phytochemical composition, antioxidant potential, and enzyme inhibitory activities of Onosma angustissima ethanolic extract: a comparative approach

Natural plant extracts are increasingly explored for their bioactive compounds and therapeutic applications. This study investigated the chemical composition, antioxidant properties, and enzyme inhibitory activities of the ethanolic extract of Onosma angustissima Hausskn. & Bornm. Total phenolic and flavonoid contents were quantified as 39.13 mg GAE/g and 35.96 mg RE/g, respectively. LC–ESI–MS/MS analysis identified chlorogenic acid (7006 µg/g extract), rosmarinic acid (1619 µg/g extract), and luteolin 7-glucoside (1242 µg/g extract) as predominant compounds. The extract exhibited moderate antioxidant activity with EC₅₀ values of 0.62 mg/mL (FRAP), 0.93 mg/mL (CUPRAC-Cupric Reducing Antioxidant Capacity), and 1.01 mg/mL (phosphomolybdenum assays). Radical scavenging assays revealed IC₅₀ values of 1.19 mg/mL [ABTS˙⁺-2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] and 2.94 mg/mL (DPPH˙-2,2-diphenyl-1-picrylhydrazyl), while ferrous ion chelation exhibited an IC₅₀ of 1.63 mg/mL. In enzyme inhibition assays, the extract demonstrated IC₅₀ values of 1.10 mg/mL for acetyl cholinesterase (AChE), 1.70 mg/mL for butyryl cholinesterase (BChE), and 1.10 mg/mL for tyrosinase. For carbohydrate-hydrolyzing enzymes, IC₅₀ values were 3.11 mg/mL for α-amylase and 1.15 mg/mL for α-glucosidase, comparable to the standard acarbose (1.235 mg/mL). These findings suggest that the bioactivity of O. angustissima is linked to its rich phenolic and flavonoid composition, particularly chlorogenic and rosmarinic acids. The extract holds promise for therapeutic applications in oxidative stress-related conditions and metabolic disorders. Further research is recommended to isolate individual bioactive compounds and evaluate their in vivo efficacy and safety profiles to better understand the therapeutic potential of O. angustissima.