A Green Extraction Process for Polyphenols from Elderberry (Sambucus nigra) Flowers Using Deep Eutectic Solvent and Ultrasound-Assisted Pretreatment

Abstract

Sambucus nigra flowers, known as elderberry flowers (EBF), are a plant tissue rich in polyphenolic phytochemicals with important bioactivities. However, there are few studies dealing with the production of polyphenol-containing EBF extracts. The objective of the investigation presented herein was the development of a high-performance green extraction methodology, to generate EBF extracts enriched in polyphenolic substances, using an efficient deep eutectic solvent, combined with ultrasonication pretreatment. The DES was composed of L-lactic acid (hydrogen bond donor—HBD) and glycine (hydrogen bond acceptor—HBA) and, after an initial screening to properly regulate HBD/HBA ratio, the extraction was optimized by deploying response surface methodology. Under the optimized conditions, which were DES/water (85% w/v), liquid-to-solid ratio 60 mL g−1, and stirring speed 200 rounds per minute, the extraction yield in total polyphenols amounted to 121.24 ± 8.77 mg gallic acid equivalents per g dry matter. The integration of ultrasonication prior to the batch stirred-tank extraction boosted polyphenol recovery of up to 174.73 ± 2.62 mg gallic acid equivalents per g dry matter. Liquid chromatography–mass spectrometry analysis showed that the richest EBF extract obtained was dominated by rutin, a di-p-coumaroylquic acid and chlorogenic acid.

Choline Chloride Based Natural Deep Eutectic Solvents as Extraction Media for Extracting Phenolic Compounds from Chokeberry (Aronia melanocarpa)

“…DESs have already shown applications in various fields, including organic synthesis [25], preparation of inorganic materials [26], and biochemistry [27]. Currently, the use of DESs/NADESs in separation processes is rapidly increasing, especially in the extraction of phenolic compounds from plants [28][29][30][31][32][33][34]. DESs/NADESs have important advantages over conventionally used organic solvents, such as no or low toxicity, biodegradability, low cost and easy preparation [24].…”

Batch Stirred-Tank Green Extraction of Salvia fruticosa Mill. Polyphenols Using Newly Designed Citrate-Based Deep Eutectic Solvents and Ultrasonication Pretreatment

“…The linear regression gave R 2 = 0.67 (p = 0.0003), revealing a trend that should not be overlooked, which evidenced higher extraction efficiency for DES with lower pH. Although previous studies on polyphenol extraction with DES stressed emphatically the importance of R mol D/A on the extraction yield [16,[21][22][23][24], a correlation of yield with pH is heretofore unreported. As also reported for classical solvents, pH is critical for DES extraction efficiency.…”

“…Total polyphenol concentration was determined with the Folin-Ciocalteu methodology and yield in total polyphenols was expressed as mg gallic acid equivalents (GAE) per g dry mass [20]. Total flavonoid determination was carried out with the aluminum chloride reagent and results were expressed as mg rutin equivalents (RtE) per g dry mass [21]. The antiradical activity (A AR ) was estimated with a stoichiometric methodology [16], using DPPH as the radical probe.…”

Determination of Ferulic Acid in Angelica sinensis by Temperature-Controlled Hydrophobic Ionic Liquids-Based Ultrasound/Heating-Assisted Extraction Coupled with High Performance Liquid Chromatography

“…Therefore, instrumental assisted extraction methods of FA such as ultrasonic-assisted extraction (UAE) [10], high hydrostatic pressure extraction (HHPE) [11], supercritical fluid extraction [12] and pressurized liquid extraction (PLE) [2] were attracting more and more attentions due to their advantages of easy operation, time and solvent saving. Over the past few years, UAE has become increasingly popular and proven to be very practical owing to its low cost, easy operation and high extraction efficiency characteristics [13][14][15]. The ultrasonic would induce cavitation and shockwaves, leading to increasing solid-liquid extraction yield [16].…”