Countercurrent assisted quantitative recovery of metabolites from plant-associated natural deep eutectic solvents

Abstract

NAtural Deep Eutectic Solvents (NADES) are chemically simple but physiologically important plant constituents that exhibit unique solubilizing properties of other metabolites, including bioactive constituents. The high polarity of NADES introduces a challenge in the ability of conventional solid-support based chromatography to recover potential bioactive metabolites. This complicates the systematic explanation of the NADES’ functions in botanical extracts. The present study utilizes countercurrent separation (CCS) methodology to overcome the recovery challenge. To demonstrate its feasibility, Glucose-Choline chloride-Water (GCWat, 2:5:5, mole/mole) served as a model NADES, and four widely used marker flavonoids with different polarities (rutin, quercetin, kaempferol, and daidzein) were chosen as model target analytes. In order to prepare GCWat with high consistency, a water drying study was performed. The unique capabilities of the recently introduced CherryOne system, offering volumetric phase metering, were used to monitor the CCS operations. The collected fractions were analyzed using UHPLC and NMR/quantitative NMR. CCS was able to recover the analytes from the NADES matrix with quantitative recoveries of 95.7%, 94.6%, 97.0%, and 96.7% for rutin, quercetin, kaempferol, and daidzein respectively. The CCS strategy enables recovery of target metabolites from NADES-containing crude extracts as well as from other chemical mixtures, and moreover offers a means of using NADES as environmentally friendly extraction solvents.

Deep eutectic solvent‐based extraction of polyphenolic antioxidants from onion (Allium cepa L.) peel

“…The mass transfer will occur between the DES droplets (dispersed phase) and the surrounding aprotic solvent. Phenolic compounds will distribute between DES and aprotic solvent, depending on the partition coefficient . Solid–liquid extraction treatment resulted in a very low amount of these flavonoids: quercetin (0.075557 mg g −1 ), kaempferol (0.006019 mg g −1 ), and myricetin (0.013282 mg g −1 ).…”

“…Phenolic compounds will distribute between DES and aprotic solvent, depending on the partition coefficient. 19 Solid-liquid extraction treatment resulted in a very low amount of these flavonoids: quercetin (0.075557 mg g −1 ), kaempferol (0.006019 mg g −1 ), and myricetin (0.013282 mg g −1 ). This is because, during elution of the bed by distilled water, a quantity of flavonoids washes out with DES.…”

Deep Eutectic Solvents as Extraction Media for Valuable Flavonoids from Natural Sources

“…DES can be synthesized via a number of methods . Considering the research listed in this review, predominant methods are often simple, such as stirring at room to high temperatures (80 °C), freeze-dry mixing, or ultrasound-assisted mixtures [7,8]. The synthesis method can be selected with cost in mind (lower temperatures prevail), speed or efficiency (favoring higher temperatures and/or ultrasound assistance) or limited by the properties of the reagents (thermal-sensitive substances might require freeze-drying instead of heating due to thermal instability).…”

Sweet spot matching: A thin-layer chromatography-based countercurrent solvent system selection strategy

“…The selected SS gave an R f values close to 0.5 on the high side and a K value above 7.00. Higher K values were deemed superior to lower K values for effective separations of flavonoids [23]. The flavonoids, isoliquiritin, isoliquiritin apioside, and liquiritin performed well in EAcWat SSs [5].…”