Extraction of bioactive components from elderberry (Sambucus nigra L.) with deep eutectic solvents and characterization of components

In this study, extracts were obtained from dried fruits of elderberry (Sambucus nigra L.), which is both an edible and medicinal plant, by ultrasound-assisted extraction (UAE) using deep eutectic solvents (DESs) from green solvents. DESs were synthesized with choline chloride as the hydrogen bond acceptor and 6 different hydrogen bond donors (citric acid, L-ascorbic acid, fructose, sucrose, ethylene glycol, and glycerol). DES extracts were compared with extracts obtained from conventional organic solvents (ethanol and methanol solvents). Antioxidant activities (DPPH and ABTS), total monomeric anthocyanin substance content (pH differential method), and total phenolic substance content (Folin-Ciocalteu) were analyzed. In addition, phenolic substance composition and amounts were examined by LC-MS/MS method. According to the results obtained, glycerol-based deep eutectic solvent, ChCl:GLY:Water (1:1:2), gave better results than ethanol solvent in the analysis of antioxidant activities, total monomeric anthocyanin, and phenolic substance content. For example; in the analysis of total phenolic content (Folin-Ciocalteu), ChCl:GLY:Water (1:1:2) DES was 4,216 mg GAE/g DM, while 50% ethanol-water solution was 3,635 mg GAE/g DM and methanol solution was 5,014 mg GAE/g DM. With the LC-MS/MS method, it was observed that glycerol-based DES (14 phenolic substances) extracted more phenolic substances than methanol (8 phenolic substances), extracted more phenolic substance amounts in 9 phenolic compounds than ethanol, and showed better performance. Anthocyanins (cyanidin-3-rutinoside chloride and cyanidin-3-O-glucoside), flavonoids (hesperidin), and phenolic acids (chlorogenic acid and fumaric acid) were found abundantly in elderberry extracts obtained by DES. Glycerol-based DES has shown that green solvents can be a good alternative to ethanol and methanol from organic solvents that are harmful to the environment and human health. It is necessary to popularize environmentally friendly products for climate change, environmental pollution, and sustainable life.