Targeted Quantitative Phenolic Profiling and In Vitro Biological Activities of Onosma erecta Sm. Extracts Obtained by Ultrasound-Assisted Extraction

Onosma erecta remains insufficiently characterized in terms of quantitative phenolic composition and solvent-dependent bioactivity. This study compared ultrasound-assisted water and methanol extracts of its aerial parts using targeted liquid chromatography–tandem mass spectrometry (LC–MS/MS), antioxidant assays, enzyme inhibition tests, and the water-soluble tetrazolium-1 (WST-1) cell viability assay in A549 human lung carcinoma cells. Of 30 targeted phenolic compounds, 21 were quantified. The methanol extract was enriched in chlorogenic acid (16,430 µg/g extract) and rosmarinic acid (2474 µg/g extract), whereas selected hydroxybenzoic acids and flavonoid aglycones were more abundant in the water extract. The methanol extract exhibited higher total phenolic and flavonoid contents and stronger responses in four of six antioxidant assays. It also showed lower half-maximal inhibitory concentrations (IC50) against all five tested enzymes. Notably, its α-glucosidase IC50 (1.12 mg/mL) was lower than that of acarbose (1.26 mg/mL) under the assay conditions. Both extracts produced elevated WST-1 signals at intermediate concentrations, which do not establish enhanced proliferation or safety. As results derive from technical triplicates of single extract preparations, further independent replication and mechanistic and toxicological validation are warranted.