This work aimed at evaluating eutectic mixtures as green and designer solvents to extract bioactive compounds from Eugenia pyriformis Cambess (EPC) leaves. First, it was defined through the Folin–Ciocalteu (F–C) reducing capacity and antioxidant activity the optimized conditions of solid–liquid extraction (SLE). Consecutively, this condition (65 °C, 1:30 (m/v) solid–liquid ratio, and 150 min of process) was applied to evaluate the effect of the eutectic mixture-forming compounds in the SLE. The results showed that the lactic acid-based eutectic mixture was the most suitable solvent to preserve bioactive compounds from EPC leaves. Moreover, according to F–C analysis, the lactic acid-based eutectic mixtures boosted the SLE (163.14 ± 5.81 mg gallic acid/g sample). Regarding the phenolic profile, the EPC leaves showed the presence of quercetin, naringin, rutin, catechin, and gallic acid. These findings proved the eutectic mixtures and their forming compounds designer ability to extract valuable biocompounds from EPC leaves.

Aqueous biphasic systems (ABS) have positive aspects associated with the low cost, eco-friendly system, biomolecule separation ability, and high extraction yield. The presence of quaternary ammonium salts on the ABS, e.g., cholinium chloride ([N 111(2OH) ]Cl), confers to these systems unusual characteristics for biomolecule separation and purification. In this work, PEG-based ABS employing cholinium chloride combined with inorganic and organic salts, to obtain ions at equivalent concentrations, were evaluated. In general, it was observed that the presence of cholinium chloride decreases the biphasic region compared to the ternary system. For all systems, the top phase is richer in polymer, and the bottom phase is richer in salt, regardless of the cholinium chloride presence. Furthermore, the influence of cholinium chloride through the partition coefficient of different kinds of biomolecules (alkaloids, amino acids, and phenolic compounds) was estimated. The cholinium chloride presence demonstrated to be able to tune the partition behavior due to its affinity with the evaluated biomolecules.

Raw coffee beans are seen as valuable sources of bioactive compounds, such as alkaloids and chlorogenic acids. In this study, an efficient and eco-friendly method for the simultaneous extraction of caffeine, trigonelline, and chlorogenic acids from raw beans of two coffee species was developed, using green solvents and an unconventional method of extraction (assisted by ultrafast rotary disintegrator/homogenizer (UT-AE)). The experimental extraction conditions were optimized according to a completely randomized design (CRD), considering the following variables: solvent type (four deep eutectic solvents (DESs), water, and aqueous choline chloride solution (50 wt.%); temperature (25, 45, and 65 °C); and extraction technique (solid-liquid extraction with agitated heating and assisted by ultrafast rotary disintegrator/homogenizer). The extract obtained with choline chloride solution (50 wt.%) exhibited high total phenolic compounds and the highest antioxidant capacity. An analysis using high-performance liquid chromatography with a diode array detector (HPLC-DAD) indicated the presence of chlorogenic acids, caffeine, and trigonelline in all the extracts, in different amounts. The results obtained by the analysis of phenolic compounds and HPLC indicated that the aqueous solution of choline chloride (50% wt.%) was the most suitable solvent for the extraction of chlorogenic acids, while the water-based extracts showed high values of caffeine and trigonelline. DESs, in turn, seems to promote a protective effect on the antioxidant activity of biomolecules.

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