Experimental and COSMO-RS theoretical exploration of rutin formulations in natural deep eutectic solvents: Solubility, stability, antioxidant activity, and bioaccessibility

Green and efficient method to acquire high-value phycobiliprotein from microalgal biomass involving deep eutectic solvent-based ultrasound-assisted extraction

Phycoerythrin (PE) is a phycobiliprotein holding great potential as a high-value food colorant and medicine. Deep eutectic solvent (DES)-based ultrasound-assisted extraction (UAE) was applied to extract B-PE by disrupting the resistant polysaccharide cell wall of Porphyridium purpureum. The solubility of cell wall monomers in 31 DESs was predicted using COSMO-RS. Five glycerol-based DESs were tested for extraction, all of which showed significantly higher B-PE yields by up to 13.5 folds than water. The DES-dependent B-PE extraction efficiencies were proposedly associated with different cell disrupting capabilities and protein stabilizing effects of DESs. The DES-based UAE method could be considered green according to a metric assessment tool, AGREEprep. The crude extract containing DES was further subjected to aqueous two-phase system, two-step ammonium sulfate precipitation, and ultrafiltration processes. The final purified B-PE had a PE purity ratio of 3.60 and a PC purity ratio of 0.08, comparable to the purity of commercial products.

Comparison of green solvents for the revalorization of orange by-products: Carotenoid extraction and in vitro antioxidant activity

Orange peels contain a considerable number of bioactive compounds such as carotenoids, that can be used as ingredients in high-value products. The aim of this study was to compare orange peel extracts obtained with different green solvents (vegetable oils, fatty acids, and deep eutectic solvents (DES)). In addition, the chemical characterization of a new hydrophobic DES formed by octanoic acid and l-proline (C8:Pro) was performed. The extracts were compared in terms of carotenoid extraction, antioxidant activity by three methods, color, and environmental impact. The results confirmed that the mixture of C8:Pro is a DES and showed the highest carotenoid extraction (46.01 µg/g) compared to hexane (39.28 µg/g). The antioxidant activity was also the highest in C8:Pro (2438.8 µM TE/mL). Finally, two assessment models were used to evaluate the greenness and sustainability of the proposed extractions. These results demonstrated the potential use of orange peels in the circular economy and industry.

Potential application of green extracts rich in phenolics for innovative functional foods: natural deep eutectic solvents as media for isolation of biocompounds from berries

The health-promoting effects of berries have attracted attention due to the possible application of their extracts as functional ingredients in food products. Natural deep eutectic solvents (NADESs) are a new generation of environmentally friendly solvents for the extraction of natural products, and they are green alternatives to organic solvents, and they can improve the solubility, stability, and bioavailability of isolated biocompounds. In this study, an efficient eco-friendly method was used for the extraction of phenolic compounds from different berries: chokeberries, blueberries, and black goji berries with a range of eutectic solvents consisting of hydrogen bond acceptors (HBAs) such as choline chloride, L-proline, L-glycine, and L-lysine and hydrogen bond donors (HBDs) such as malic, citric, tartaric, lactic and succinic acids, glucose and glycerol. The obtained results indicated the ability of NADESs towards selective extraction of phenolics; the eutectic system choline chloride : malic acid showed selective extraction of anthocyanins, while choline chloride : glycerol and choline chloride : urea showed selectivity towards flavonoids and phenolic acids. The methodology for screening of the NADES extraction performance, which included chromatographic profiling via high-performance thin layer chromatography combined with chemometrics and spectrophotometric essays, allowed effective assessment of optimal eutectic solvents for isolation of different groups of phenolics. Great antioxidant and antimicrobial activities of extracts, along with the green nature of eutectic solvents, enable NADES berry extracts to be used as "green-labelled" functional foods or ingredients.

Determination of bioactive flavonoids using β-cyclodextrin combined with chitosan-modified magnetic nanoparticles

To accurately determine flavonoids (rutin, quercetin or kaempferol), it is necessary to extract them from complex matrices. The ultrasound-assisted magnetic dispersion microsolid phase extraction technique has been predominantly used for separation and enrichment of the target analytes. The combination of magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent (DESP) is likely to enhance the efficiency of flavonoid extraction from food. In this study, adsorbents were prepared by modifying chitosan with magnetic nanoparticles, and the eluent was a DESP derived from β-cyclodextrin and an organic acid. The successful preparation of these materials was confirmed by FTIR, XRD, FE-SEM and 1H NMR. The extraction recovery rates exceeded 93 %, with limits of detection and quantitation ranging from 0.9 to 2.4 μg/L and 2.7 to 7.2 μg/L, respectively, and the flavonoid clearance rates for ABTS and DPPH radicals reached 100 %. Therefore, the integration of magnetic chitosan nanoparticles with the DESP provides a new and efficient method for the extraction of flavonoids while also presenting a potential application of the DESP in separations.

Natural deep eutectic ready to use extract of astilbin: Super high in vitro bioaccessibility, α-amylase and α-glucosidase enzyme inhibition kinetics

Astilbin, a natural flavonoid, possesses multiple functionalities, while the poor bioavailability seriously restricts its application in functional food and medicine. Therefore, in this study, a natural deep eutectic solvent (NaDES) with choline chloride: lactic acid (CHCL-LAC) is selected to deliver astilbin by evaluating the bioaccessibility and antioxidant capacity during in vitro gastrointestinal digestion, and the inhibitory effect with underlying mechanism of astilbin-CHCL-LAC against α-amylase/α-glucosidase were investigated. The CHCL-LAC showed significant high astilbin bioaccessibility (84.1% bioaccessible) and DPPH and ORAC antioxidant capacity with 75.7% and 57.7% respectively after 3 h in vitro digestion, which may be attributed by hydrogen bond based supramolecule formed between astilbin and CHCL-LAC. Moreover, significant inhibitions of astilbin-CHCL-LAC on α-amylase (IC50 of 0.67 g/L) and α-glucosidase (IC50 of 0.64 g/L) were observed in mixed competitive and non-competitive manners. The dominant binding force between enzymes and astilbin were the hydrogen and hydrophobic interaction. This is the first time that the underlying mechanisms for astilbin delivered by NaDESs were revealed, suggesting that CHCL-LAC-based NaDESs are promising ready-to-use vehicles of natural inhibitors for carbohydrate-hydrolyzing enzymes.