Evaluation of Structurally Different Ionic Liquid-Based Surfactants in a Green Microwave-Assisted Extraction for the Flavonoids Profile Determination of Mangifera sp. and Passiflora sp. Leaves from Canary Islands.

Kristýna Moučková,Juan H Ayala,Idaira Pacheco-Fernández,Verónica Pino,Petra Bajerová

doi:10.3390/molecules25204734

Abstract

Aqueous solutions of ionic liquids (ILs) with surface active properties were used as extraction solvents, taking advantage of their impressive solvation properties, in a green microwave-assisted solid-liquid extraction method (IL-MA-SLE) for the extraction of flavonoids from passion fruit and mango leaves. The extraction method was combined with high-performance liquid chromatography and photodiode-array detection (HPLC-PDA) and optimized by response surface methodology using the Box-Behnken experimental design. Under optimum conditions, the extraction efficiency of six structurally different IL-based surfactants was evaluated. Thus, imidazolium-, guanidinium- and pyridinium-type ILs with different tailorable characteristics, such as side chain length and multicationic core, were assessed. The decylguanidinium chloride ([C10Gu+][Cl–]) IL-based surfactant was selected as key material given its superior performance and its low cytotoxicity, for the determination of flavonoids of several samples of Passiflora sp. and Mangifera sp. leaves from the Canary Islands, and using as target analytes: rutin, quercetin and apigenin. The analysis of 50 mg of plant material only required 525 µL of the low cytotoxic IL-based surfactant solution at 930 mM, 10.5 min of microwave irradiation at 30 °C and 50 W, which involves a simpler, faster, more efficient and greener method in comparison with other strategies reported in the literature for obtaining bioactive compounds profiles from plants.

Highlights

Nowadays, much attention is paid to the incorporation of the Green Chemistry principles in analytical extraction methods [1]
Considering the promising results obtained in our previous study related to the extraction of phenolic compounds from Vitis vinifera leaves by an ionic liquids (ILs)-MA-solid–liquid extraction methods (SLE) method using [C16 C4 Im+ ][Br– ][20], this IL was selected to optimize the extraction procedure in the current study
Three flavonoids were selected as target analytes given their significant presence in passion fruit and mango leaves, as it has been previously reported in the literature [15,16,17,18,25]

Summary

Introduction

Much attention is paid to the incorporation of the Green Chemistry principles in analytical extraction methods [1]. Depending on the number of cation moieties, they divide into two main groups: monocationic and multicationic ILs [2,3] They have gained considerable popularity in analytical sample preparation in recent years for presenting a number of outstanding features for solvent extraction processes, such as great solvation ability, high thermal, chemical and electrochemical stability, nonflammability, and negligible volatility at room temperature, which confers them low toxicity in comparison with conventional solvents [2]. ILs are tunable by selecting the adequate combination of cation and anion, or by incorporating different functional groups in their structures This allows the preparation of ILs with specific properties, since even a simple modification in the IL structure leads to significant changes in their properties. A wide range of ILs derivates have been described, including IL-based surfactants [3,4,5,6,7]

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