Phytochemical variability and bioactive potential of Sambucus nigra L. flower extracts: A comparative study across four ecological regions from Romania

Sambucus nigra L. flowers (elderflowers) are traditionally used for their therapeutic properties, yet their phytochemical composition and bioactivity may vary depending on environmental and technological factors. In this regard, this study aimed to investigate the influence of extraction method (infusion, maceration, and ultrasound-assisted extraction [UAE]), solvent (water or 70 % ethanol), and geographical origin (Beclean, Bidiu, Mărișel, and Târgu-Mureș, Romania) on the phytochemical profile and biological activities of elderflower extracts (n = 16). Following extraction, total phenolic content (TPC) ranged from 82.41 to 157.29 mg GAE/g extract, while total flavonoid content (TFC) varied between 34.67 and 84.03 mg QE/g extract. Extraction method/solvent and collection site influenced the phytochemical profile, thus ethanol-based UAE consistently had the highest levels of phenolic compounds, particularly in the Mărișel sample (UESM1), which also showed the strongest antioxidant capacity (DPPH: 410.82 mg TE/g; FRAP: 356.50 mg TE/g). HPLC-DAD-MS analysis identified 14 major phenolics, with 5-caffeoylquinic acid (up to 111.66 µg/g) and rutin (up to 125.25 µg/g) as dominant compounds. Enzyme inhibition was most pronounced against α-amylase (IC 50 = 773.90 µg/mL) and acetylcholinesterase (IC 50 = 922.83 µg/mL) in ethanol-based UAE extracts, whereas lipase and tyrosinase were not significantly inhibited. Overall, extraction method, solvent type, and geographical origin critically shaped the phytochemical composition and bioactivities of elderflower extracts, with ethanol-based UAE from high-altitude samples offering the most favorable profile. These findings support the potential of elderflower extracts as candidates for standardized nutraceutical at managing oxidative stress and metabolic disorders. • Ethanol-UAE extracts had the highest phenolic and flavonoid content. • Mărișel-derived samples showed superior bioactive compound levels. • UESM1 extract showed strongest antioxidant and enzyme inhibition activity. • Phenolic profile was dominated by 5-CQA, rutin, and kaempferol-diglucoside. • Extraction method/solvent and collection site influenced the phytochemical profile.