Prediction of pH Value of Aqueous Acidic and Basic Deep Eutectic Solvent Using COSMO-RS σ Profiles' Molecular Descriptors

The aim of this work was to develop a simple and easy-to-apply model to predict the pH values of deep eutectic solvents (DESs) over a wide range of pH values that can be used in daily work. For this purpose, the pH values of 38 different DESs were measured (ranging from 0.36 to 9.31) and mathematically interpreted. To develop mathematical models, DESs were first numerically described using σ profiles generated with the COSMOtherm software. After the DESs’ description, the following models were used: (i) multiple linear regression (MLR), (ii) piecewise linear regression (PLR), and (iii) artificial neural networks (ANNs) to link the experimental values with the descriptors. Both PLR and ANN were found to be applicable to predict the pH values of DESs with a very high goodness of fit (R2independent validation > 0.8600). Due to the good mathematical correlation of the experimental and predicted values, the σ profile generated with COSMOtherm could be used as a DES molecular descriptor for the prediction of their pH values.

Development of ANN models based on combined UV-vis-NIR spectra for rapid quantification of physical and chemical properties of industrial hemp extracts

OBJECTIVES

The aim of this study was to develop artificial neural network (ANNs) models for prediction of physical (total dissolved solids, extraction yield) and chemical (total polyphenolic content, antioxidant activity) properties of industrial hemp extracts, prepared by two different extraction methods (solid-liquid extraction and microwave-assisted extraction) based on combined UV-VIS-NIR spectra. Spectral data were gathered for 46 samples per extraction method.

RESULTS

The PCA analysis ensured efficient separation of the samples based on the amount of ethanol in extraction solvent using NIR spectra for both conventional and microwave-assisted extraction.

CONCLUSIONS

Results showed that reliable ANN models (R² >0.7000) for describing physical, chemical, and simultaneously physical and chemical characteristics can be developed based on combined UV-VIS-NIR spectra of industrial hemp extracts without spectra pre-processing.

Natural deep eutectic solvent as a unique solvent for valorisation of orange peel waste by the integrated biorefinery approach

This research investigates the use of seven natural deep eutectic solvents (NADESs) for valorisation of orange peel waste, with the final goal to propose a unique NADES for integrated biorefinery. Initial screening of NADESs revealed the excellent ability of cholinium-based NADES with ethylene glycol as hydrogen bond donor (ChEg50) to serve as a medium for orange peel-catalysed kinetic resolution (hydrolysis) of (R,S)-1-phenylethyl acetate with high enantioselectivity (ee = 83.2%, X  = 35%), as well as it's stabilizing effect on the hydrolytic enzymes (hydrolytic enzymes within ChEg50 peel extract were stabile during 20 days at 4 °C). The ChEg50 also showed a satisfactory capacity to extract D-limonene (0.5 mg g_FW^-1), and excellent capacity to extract polyphenols (45.7 mg g_FW^-1), and proteins (7.7 mg g_FW^-1) from the peel. Based on the obtained results, the integrated biorefinery of orange peel waste using ChEg50 in a multistep process was performed. Firstly, enantioselective kinetic resolution was performed (step I; ee = 83.2%, X  = 35%), followed by isolation of the product 1-phenylethanol (step II; h = 82.2%) and extraction of polyphenols (step III; h = 86.8%) from impoverished medium. Finally, the residual orange peel was analysed for sugar and lignin content, and results revealed the potential of waste peel for the anaerobic co-digestion process. The main bottlenecks and futures perspective of NADES-assisted integrated biorefinery of orange peel waste were outlined through SWOT analysis.

Biological Potential of Flaxseed Protein Hydrolysates Obtained by Different Proteases

Flaxseed meal, a byproduct of flaxseed oil extraction, was treated as low-value agrowaste for a long time despite its high protein content. Flaxseed meal has recently garnered increasing interest as a source of proteins and other bioactive compounds with positive impacts on human health. The aim of this study was to investigate the in vitro biological potential of flaxseed protein hydrolysates (FPH). Three FPHs were prepared using three hydrolytic enzymes: Alcalase, Neutrase and Protamex. The molecular weight profile of peptides contained in the hydrolysates was determined by size exclusion chromatography (SEC). The oxygen radical absorbance capacity (ORAC) assay was used to determine the peptide antioxidant capacity, while proliferative effects were studied in two cell lines: HeLa and HaCaT. The latter was also used to determine the protective effect of the FPH during induced oxidative stress. Alcalase showed the highest proteolytic activity, while the produced flaxseed protein hydrolysate (FPH-A) exhibited the strongest antioxidant potential. FPH-A had cytotoxic effects at 10 mg/mL in HeLa cells, but it stimulated HaCaT cell growth. Moreover, a mild protective effect of FPH-A was detected in HaCaT cells after induction of oxidative stress. Flaxseed protein hydrolysates obtained by Neutrase (FPH-N) and Protamex (FPH-P) have less pronounced or no potential at all, with respect to their antioxidative or antiproliferative activity. Therefore, to increase value-added utilization of flaxseed meal we suggest further research on hydrolysate obtained by Alcalase.

Enabling technologies for the extraction of grape-pomace anthocyanins using natural deep eutectic solvents in up-to-half-litre batches extraction of grape-pomace anthocyanins using NADES

Bioactive compounds should be extracted using alternative solvents and enabling technologies, in accordance with green extraction principles. The aim of this study is to develop an eco-friendly extraction method for grape-pomace anthocyanins on a larger scale. From a preliminary screening of 8 different natural deep eutectic solvents (NADES), a combination of choline chloride:citric acid was selected because of its price, physicochemical properties, and anthocyanin recovery and stability. The effects of multimode-microwave (MW), and low-frequency-ultrasound (US) irradiation (used alone or simultaneously), as well as that of process parameters on extraction efficiency have been investigated in order to maximise anthocyanin extraction yield. The best conditions were found to be: simultaneous ultrasound/microwave-assisted extraction (UMAE) (MW power at 300 W, US power 50 W), for 10 min with 30% (v/v) of water. This gave 1.77 mg g_dw^-1 of anthocyanins. Anthocyanins were efficiently recovered from NADES, which were recycled. The optimised procedure was scaled up to a half-litre batch.

Physicochemical Properties, Cytotoxicity, and Antioxidative Activity of Natural Deep Eutectic Solvents Containing Organic Acid

Natural deep eutectic solvents (NADES) may be considered ‘designer solvents’ due to their numerous structural variations and the possibility of tailoring their physicochemical properties. Prior to their industrial application, characterization of NADES is essential, including determination of their physicochemical properties, cytotoxicity, and antioxidative activity. The most important physicochemical properties of eight prepared NADES (choline chloride:malic acid, proline:malic acid, choline chloride:proline:malic acid, betaine:malic acid, malic acid:glucose, malic acid:glucose:glycerol, choline chloride:citric acid, and betaine:citric acid) were measured as functions of temperature and water content. In general, the structure of prepared NADES greatly influences their physical properties, which could be successfully modified and adjusted by addition of water. All tested NADES were absolutely benign and noncorrosive for investigated steel X6CrNiTi18-10. Furthermore, cytotoxicity of prepared solvents was assessed toward three human cell lines (HEK-293T, HeLa, and MCF-7 cells), and antioxidative activity was measured by the Oxygen Radical Absorbance Capacity (ORAC) method. With regard to cell viability, all tested NADES containing carboxylic acid could be classified as practically harmless and considered environmentally safe. The ORAC values indicated that the tested NADES displayed antioxidative activity.

Ready-to-use green polyphenolic extracts from food by-products

To establish environmentally friendly polyphenolic extracts from grape and olive pomace, natural deep eutectic solvents (NADES) were used coupled with alternative energy sources - ultrasound and microwave irradiation. Obtained extracts were characterized by HPLC analysis, while antioxidant capacity was determined by ORAC method. Furthermore, in vitro cytotoxicity of prepared extracts was assessed by antiproliferation assay on two tumour cell lines, whereas for investigation of type of cell death or cell cycle arrest a flow cytometric analysis was applied. In addition, a detection of compounds with DNA/RNA-bindingaffinity in extracts was investigated by UV/Vis and circular dichroism spectroscopy. Grape pomace extract in NADES showed to be the best of all extracts tested, with regard to extraction of total polyphenolic compounds (p < 0.05) and related biological activities such as antioxidant and antiproliferative activity. Prepared polyphenolic extracts in NADES could be considered as ready-to-use in food and pharmaceutical industry without demanding and expensive downstream purification steps.

Cyclic AMP in the cerebrospinal fluid of patients with recent cerebral infarction

The concentrations of cyclic adenosine 3',5'-monophosphate (c-AMP) and glucose were measured in cerebrospinal fluid (CSF) of 43 patients with recent cerebral infarction divided into five groups in respect to the time (up to 24 h) elapsed between cerebrovascular insult and CSF sampling. 10 of the additionally studied subjects were (control group) neurologically normal. None of the investigated subjects was under therapy at the time of CSF sampling. The levels of c-AMP and glucose in patients with cerebral infarction were found not to be related to the degree of neurological deficit but to the duration of ischemia. CSF c-AMP was elevated (p less than 0.001) for 8-12 h following the cerebrovascular insult and subsequently reached the level of controls. The CSF glucose level was elevated during the whole period of observation.