Effective and Selective Extraction of Quercetin from Onion (<i>Allium cepa</i> L.) Skin Waste Using Water Dilutions of Acid-Based Deep Eutectic Solvents
Matteo Ciardi,
Federica Ianni,
Roccaldo Sardella,
Stefano Di Bona,
Lina Cossignani,
Raimondo Germani,
Matteo Tiecco,
Catia Clementi
Affiliations
Matteo Ciardi
Department of Chemistry, Biology and Biotecnology, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
Federica Ianni
Department of Pharmaceutical Sciences, University of Perugia, Via Fabretti 48, 06123 Perugia, Italy
Roccaldo Sardella
Department of Pharmaceutical Sciences, University of Perugia, Via Fabretti 48, 06123 Perugia, Italy
Stefano Di Bona
Department of Chemistry, Biology and Biotecnology, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
Lina Cossignani
Department of Pharmaceutical Sciences, University of Perugia, Via Fabretti 48, 06123 Perugia, Italy
Raimondo Germani
Department of Chemistry, Biology and Biotecnology, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
Matteo Tiecco
Department of Chemistry, Biology and Biotecnology, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
Catia Clementi
Department of Chemistry, Biology and Biotecnology, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
Deep Eutectic Solvents (DESs) are experiencing growing interest as substitutes of polluting organic solvents for their low or absent toxicity and volatility. Moreover, they can be formed with natural bioavailable and biodegradable molecules; they are synthesized in absence of hazardous solvents. DESs are, inter alia, successfully used for the extraction/preconcentration of biofunctional molecules from complex vegetal matrices. Onion skin is a highly abundant waste material which represents a reservoir of molecules endowed with valuable biological properties such as quercetin and its glycosylated forms. An efficient extraction of these molecules from dry onion skin from “Dorata di Parma” cultivar was obtained with water dilution of acid-based DESs. Glycolic acid (with betaine 2/1 molar ratio and L-Proline 3/1 molar ratio as counterparts) and of p-toluensulphonic acid (with benzyltrimethylammonium methanesulfonate 1/1 molar ratio)-based DESs exhibited more than 3-fold higher extraction efficiency than methanol (14.79 µg/mL, 18.56 µg/mL, 14.83 µg/mL vs. 5.84 µg/mL, respectively). The extracted quercetin was also recovered efficaciously (81% of recovery) from the original extraction mixture. The proposed extraction protocol revealed to be green, efficacious and selective for the extraction of quercetin from onion skin and it could be useful for the development of other extraction procedures from other biological matrixes.
