Viticulture and wine production are important agro-economic activities worldwide, with the consumption of the grapes being the main route of exploitation in this field. These processes also generate huge amounts of residues leading to an increasing demand in valorization and reuse of Vitis vinifera by-products. In this sense, grapevine leaves are chiefly characterized by phenolic compounds which can be exploit for numerous applications within pharmaceutical and cosmetic sectors [1,2]. Different approaches have been developed for the extraction of these natural compounds from Vitis vinifera by-products. These methods normally require numerous steps and large amounts of organic solvents. In this regard, this study proposes a new sustainable and simple strategy for the micro-scale extraction of phenolic compounds from grapevine leaves with analytical purpose. The method is based on a microwave-assisted solid-liquid extraction approach (MA-SLE), using an aqueous solution of an ionic liquid (IL)-based surfactant as extraction phase. ILs are a well-known alternative to conventional organic solvents due to their lower toxicity and impressive synthetic tunability. Two IL-based surfactants were evaluated, and the method was optimized by using experimental designs, resulting in the use of small amounts of sample (100 mg) and extraction phase (2.25 mL), low concentrations of the selected 1-hexadecyl-3-butyl imidazolium bromide IL (0.1 mM), and 30 min of extraction time. The method does not require organic solvents, nor any clean-up step, apart from filtration prior to the injection in the analytical system. The proposed methodology was then applied for the determination of the polyphenolic pattern of six different varieties of Vitis vinifera leaves from the Canary Islands, using HPLC and UV detection for the quantification of the compounds. The proposed MA-SLE approach is greener, simpler, and more effective than other methods, while the results from the analysis of the leaves samples demonstrate that these by-products can be exploited as a source of natural compounds for many applications [3]. References: [1] M.A Nunes, F. Rodrigues, M.B.P.P Oliveira, “Handbook of Grape Processing By-Products: Sustainable Solutions” Galanakis, C.M., Ed.; Elsevier: Cambridge, MA, USA, 2017, pp. 267–292. [2] S. Acquadro, S. Appleton, A. Marengo, C. Bicchi, B. Sgorbini, M. Mandrone, F. Gai, P.G. Peiretti, C. Cagliero, P. Rubiolo, Molecules 25, 464 (2020) [3] G. Mastellone, I. Pacheco-Fernández, P. Rubiolo, V. Pino, C. Cagliero, Molecules 25, 3072 (2020)
SUSTAINABLE MICRO-SCALE EXTRACTION OF BIOACTIVE PHENOLIC COMPOUNDS FROM VITIS VINIFERA LEAVES WITH IONIC LIQUID-BASED SURFACTANTS
Giulia Mastellone;Patrizia Rubiolo;Cecilia Cagliero
2021-01-01
Abstract
Viticulture and wine production are important agro-economic activities worldwide, with the consumption of the grapes being the main route of exploitation in this field. These processes also generate huge amounts of residues leading to an increasing demand in valorization and reuse of Vitis vinifera by-products. In this sense, grapevine leaves are chiefly characterized by phenolic compounds which can be exploit for numerous applications within pharmaceutical and cosmetic sectors [1,2]. Different approaches have been developed for the extraction of these natural compounds from Vitis vinifera by-products. These methods normally require numerous steps and large amounts of organic solvents. In this regard, this study proposes a new sustainable and simple strategy for the micro-scale extraction of phenolic compounds from grapevine leaves with analytical purpose. The method is based on a microwave-assisted solid-liquid extraction approach (MA-SLE), using an aqueous solution of an ionic liquid (IL)-based surfactant as extraction phase. ILs are a well-known alternative to conventional organic solvents due to their lower toxicity and impressive synthetic tunability. Two IL-based surfactants were evaluated, and the method was optimized by using experimental designs, resulting in the use of small amounts of sample (100 mg) and extraction phase (2.25 mL), low concentrations of the selected 1-hexadecyl-3-butyl imidazolium bromide IL (0.1 mM), and 30 min of extraction time. The method does not require organic solvents, nor any clean-up step, apart from filtration prior to the injection in the analytical system. The proposed methodology was then applied for the determination of the polyphenolic pattern of six different varieties of Vitis vinifera leaves from the Canary Islands, using HPLC and UV detection for the quantification of the compounds. The proposed MA-SLE approach is greener, simpler, and more effective than other methods, while the results from the analysis of the leaves samples demonstrate that these by-products can be exploited as a source of natural compounds for many applications [3]. References: [1] M.A Nunes, F. Rodrigues, M.B.P.P Oliveira, “Handbook of Grape Processing By-Products: Sustainable Solutions” Galanakis, C.M., Ed.; Elsevier: Cambridge, MA, USA, 2017, pp. 267–292. [2] S. Acquadro, S. Appleton, A. Marengo, C. Bicchi, B. Sgorbini, M. Mandrone, F. Gai, P.G. Peiretti, C. Cagliero, P. Rubiolo, Molecules 25, 464 (2020) [3] G. Mastellone, I. Pacheco-Fernández, P. Rubiolo, V. Pino, C. Cagliero, Molecules 25, 3072 (2020)
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