The Utilization of an Aloe Vera Rind By-Product: Deep Eutectic Solvents as Eco-Friendly and Recyclable Extraction Media of Polyphenolic Compounds.

In this study, an optimized environmentally friendly procedure was employed to enhance the sustainable utilization of phenolic antioxidants derived from aloe vera rind by-products. The procedure involved the application of ultrasound-assisted extraction (UAE) in combination with deep eutectic solvents (DESs). Eleven different DESs and three conventional solvents were employed as extraction media for polyphenolic compounds. Choline chloride-citric acid (ChCl-CA) was selected as the most suitable extractant, considering its extraction efficiency in relation to the total phenolic content. The operating conditions of UAE were optimized and modeled by the use of response surface methodology in order to maximize the yield of total phenolics and antioxidant capacity. The optimal operational parameters for the UAE procedure were determined to be 16.5 min, 74% (v/v) DES in water, and a solvent-to-solid ratio equal to 192. HPLC analysis, which was performed on the optimum extract, revealed significant levels of phenolics present in the aloe rind. Efficient recovery of the extracted antioxidants was obtained by the use of solid-phase extraction (SPE) and polyamide cartridges. The ChCl-CA DES exhibited excellent recycling capability with a yield of over 90% through SPE. Finally, the greenness of the method was evaluated using the green AGREE and AGREEprep metrics. The results highlighted the sustainability and the greenness of the proposed extraction procedure for the aloe by-product.

Novel supramolecular deep eutectic solvent (SUPRADES) as a sole chiral selector in capillary electrophoresis for the enantiomeric separation of fluorine-substituted amphetamine analogs.

In this study, a novel supramolecular deep eutectic solvent consisting of sulfated-ß-CD and citric acid (S-ß-CD-CA) is reported for the first time. This innovative system was evaluated as a sole chiral selector in capillary electrophoresis for the enantioseparation of six fluorine-substituted amphetamine analogs, yielding remarkable outcomes. Baseline separations of all amphetamine analogs under study were achieved in less than 21.00 min using the S-ß-CD-CA as the chiral selector. It was observed that the addition of 0.050 % v/v S-ß-CD-CA into the background electrolyte resulted in the baseline separation of five out of the six fluorine-substituted amphetamine analogs, while in the case of the para-substituted amphetamine analog, 4-fluoramphetamine (4-FA), a higher percentage (0.15 % v/v) was required to achieve baseline enantioseparation. These findings emphasized the potential of this new supramolecular system in providing a class of solvents with promising chiral recognition properties.

Stereoselective separation of psychoactive substances: Multivariate optimization and validation of a capillary electrophoresis method using carboxymethyl-ß-CD/deep eutectic solvent dual system.

A comprehensive study was performed to determine an optimum enantioseparation method for fluorine-substituted amphetamine and cathinone derivatives (fluor-amphetamine and fluor-cathinone derivatives), using a binary system consisting of carboxymethyl-ß-CD (CM-ß-CD) and a deep eutectic solvent (DES), namely choline chloride-ethylene glycol (ChCl-EG). Under this framework, the optimization and modeling of the separation conditions in a binary system were performed with the objective of maximizing resolution and minimizing analysis time. This was achieved through the application of response surface methodology. In particular, the effect of chiral selector concentration and percentage of DES on resolution and analysis time were investigated and optimized using a complete experimental design. The optimum enantioseparation conditions were determined to be 13.84 mM CM-ß-CD and 0.15% v/v ChCl-EG for fluorine-substituted amphetamine derivatives and 14.36 mM and 0.75% v/v ChCl-EG for fluorine-substituted cathinone derivatives, respectively. This combination resulted in a baseline separation for eight out of the nine analytes studied. Overall, the results demonstrated the synergistic effect of the CM-ß-CD/DES dual system and highlighted the significance of DESs as additives in capillary electrophoresis.

The potential of the use of deep eutectic solvents and amino acid-based ionic liquids to enhance the chiral discrimination ability of different chiral selectors in capillary electrophoresis.

The effect of the combined use of amino acid-based ionic liquids (AAILs) and deep eutectic solvents (DESs) with either cyclodextrin- (CD) or cyclofructan- (CF) based chiral selectors for the chiral separation of amphetamine derivatives was investigated in the present study. A non-significant improvement in enantiomeric separation of target analytes was observed when AAILs were combined with either CF or CD. On the other side, a markedly improved chiral separation of enantiomers was obtained using the dual carboxymethyl-ß-cyclodextrin/DES system, highlighting the existence of a synergistic effect. After the addition of 0.5% v/v of choline chloride-ethylene glycol, the resolution of the enantiomers of amphetamine, methamphetamine and 3-fluorethamphetamine, increased from 1.4, 1.1, 1.0 to 1.8, 1.8, and 1.5 min, and the analysis times increased from 19.54, 20.48, 18.71 to 35.71, 35.78 and 32.90 min, respectively. This was not the case for the CF/DES dual system, in which the separation of amphetamines worsened, indicating an antagonistic effect. In conclusion, DESs are a very promising additive in capillary electrophoresis that can improve the separation of chiral molecules in combination with CDs but not CFs.

Phenolic Profile, Antioxidant Activity, and Chemometric Classification of Carob Pulp and Products.

In recent years, carob and its derived products have gained wide attention due to their health-promoting effects, which are mainly attributed to their phenolic compounds. Carob samples (carob pulps, powders, and syrups) were analyzed to investigate their phenolic profile using high-performance liquid chromatography (HPLC), with gallic acid and rutin being the most abundant compounds. Moreover, the antioxidant capacity and total phenolic content of the samples were estimated through DPPH (IC50 98.83-488.47 mg extract/mL), FRAP (48.58-144.32 µmol TE/g product), and Folin-Ciocalteu (7.20-23.18 mg GAE/g product) spectrophotometric assays. The effect of thermal treatment and geographical origin of carobs and carob-derived products on their phenolic composition was assessed. Both factors significantly affect the concentrations of secondary metabolites and, therefore, samples' antioxidant activity (p-value < 10-7). The obtained results (antioxidant activity and phenolic profile) were evaluated via chemometrics, through a preliminary principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA). The OPLS-DA model performed satisfactorily, differentiating all samples according to their matrix. Our results indicate that polyphenols and antioxidant capacity can be chemical markers for the classification of carob and its derived products.

Evaluation of cyclodextrin- and cyclofructan-based chiral selectors for the enantioseparation of psychoactive substances in capillary electrophoresis.

During this study, a simple and easy-to-prepare electrophoretic method was developed for the enantioseparation of amphetamine and cathinone derivatives. Different types of ß-cyclodextrin and cyclofructan-based chiral selectors (CSs), both native and derivatized, were utilized, and the most effective ones, in terms of resolution and analysis time, were identified. In addition, several electrophoretic parameters, such as background electrolyte concentration and pH, and CS concentration, were examined to optimize the separation conditions. Under the optimal electrophoretic conditions, 10 psychoactive substances were enantiomerically separated using 1 mM sulfated cyclofructan-6 (SCF-6) for the amphetamine derivatives and 1 mM sulfated cyclofructan-7 (SCF-7) for the cathinone derivatives dissolved in an aqueous solution of 20-mM monobasic sodium phosphate at pH 2.5, a temperature of 25°C, and an applied voltage of 25 kV. In addition, the method was validated by estimating the intra- and interday precision.

Comparison of cyclofructan-, cyclodextrin-, and polysaccharide-based chiral stationary phases for the separation of pharmaceuticals.

In this study, cyclofructan (CF)-, cyclodextrin (CD)-, and polysaccharide-based chiral stationary phases (CSPs) were exploited in high-performance liquid chromatography (HPLC) for the chiral separations of different clinically and pharmaceutically important compounds. In particular, R-naphthylethyl carbamate CF6 (RN-CF6), 3,5-dimethylphenyl carbamate CF7 (DMP-CF7), neutral beta cyclodextrin (ß-CD), 3,5-dimethylphenyl carbamate ß-CD (DMP-ß-CD), and cellulose tris-(3,5-dimethylphenylcarbamate) (Cellulose-Tris DMP) columns were utilized under isocratic elution. The performance of these CSPs as chiral separation media was evaluated by use of nine analytes: acidic, basic, and amphiprotic. A possible correlation between the functional groups of these analytes and the chiral-recognition ability of each chiral column was also examined. The enantioseparations were optimized by varying different parameters, such as mobile phase additives, column temperature, and flow rate. Finally, a comparison was made between all CSPs, and it was expressed in terms of resolution (RS), efficiency (N), selectivity (α), retention factors (k1', k2') and analysis time (tR1, tR2). It was observed that RN-CF6 was the most suitable and efficient CSP for the chiral separation of various types of analytes, including acids, primary and tertiary amines, alcohols, and many neutral compounds. It was the only CSP that provided baseline enantioseparation of thyroxine (RS = 1.6) and cetirizine (RS = 2.0).

Anti-Cancer Activity and Phenolic Content of Extracts Derived from Cypriot Carob (Ceratonia siliqua L.) Pods Using Different Solvents.

Extracts derived from the Ceratonia siliqua L. (carob) tree have been widely studied for their ability to prevent many diseases mainly due to the presence of polyphenolic compounds. In this study, we explored, for the first time, the anti-cancer properties of Cypriot carobs. We produced extracts from ripe and unripe whole carobs, pulp and seeds using solvents with different polarities. We measured the ability of the extracts to inhibit proliferation and induce apoptosis in cancer and normal immortalized breast cells, using the MTT assay, cell cycle analysis and Western Blotting. The extracts' total polyphenol content and anti-oxidant action was evaluated using the Folin-Ciocalteu method and the DPPH assay. Finally, we used LC-MS analysis to identify and quantify polyphenols in the most effective extracts. Our results demonstrate that the anti-proliferative capacity of carob extracts varied with the stage of carob maturity and the extraction solvent. The Diethyl-ether and Ethyl acetate extracts derived from the ripe whole fruit had high Myricetin content and also displayed specific activity against cancer cells. Their mechanism of action involved caspase-dependent and independent apoptosis. Our results indicate that extracts from Cypriot carobs may have potential uses in the development of nutritional supplements and pharmaceuticals.

Combined use of ß-cyclodextrin and ionic liquid as electrolyte additives in EKC for separation and determination of carob's phenolics-A study of the synergistic effect.

In this work, a simple, reliable, and fast capillary electrophoretic method was developed and validated for the simultaneous determination of 12 polyphenolic compounds, the most frequently found in carob's pulp and seeds. The present work deals with the development of a novel dual electrophoretic system based on the combined use of ß-CD and ionic liquid (IL) as buffer additives. A baseline separation of the target analytes was achieved in less than 10 min by using a BGE consisting of 35 mM borate along with 15 mM ß-CD and 3 mM l-alanine tert butyl ester lactate (l-AlaC4 Lac) IL as buffer additives at pH 9.5, a temperature of 25°C, and an applied voltage of 30 kV. The application of the developed electrophoretic method to real samples enabled the identification and quantification of the main phenolic constituents of both ripe and unripe carob pulp extracts. The results revealed the predominance of gallic acid in both ripe (183.92 µg/g carob pulp) and unripe (205.10 µg/g carob pulp) carob pulp and highlighted the great influence of the ripening stage on carobs polyphenolic composition, with unripe pods being more enriched in polyphenols (total phenolics detected: 912.58 and 283.13 µg/g unripe and ripe carob pulp).

Continuous and pulsed ultrasound-assisted extraction of carob's antioxidants: Processing parameters optimization and identification of polyphenolic composition.

Polyphenols in carobs have recently attracted great attention due to their wide range of biological and health promoting effects. A comprehensive study was conducted to find an optimum method for the extraction, purification and characterization of these valuable bioactive substances. Under this framework, the ultrasound-assisted extraction (UAE) of polyphenols from carob pulp was optimized by the maximization of the yield in total phenolics using response surface methodology. In particular, the effects of solid-solvent ratio, solvent concentration, extraction time, sonication amplitude, and sonication mode were investigated and optimized using a complete experimental design. In comparison to conventional extraction techniques, UAE offered a higher yield of antioxidants and a shorter processing time. Solid-phase extraction was evaluated as a clean-up strategy prior to the electrophoretic analysis of extracts. The results from the analysis of real samples revealed the predominance of gallic acid and highlighted the great influence of the ripening stage on carobs composition.

Analysis of cannabinoids in conventional and alternative biological matrices by liquid chromatography: Applications and challenges.

Cannabis is by far the most widely abused illicit drug globe wide. The analysis of its main psychoactive components in conventional and non-conventional biological matrices has recently gained a great attention in forensic toxicology. Literature states that its abuse causes neurocognitive impairment in the domains of attention and memory, possible macrostructural brain alterations and abnormalities of neural functioning. This suggests the necessity for the development of a sensitive and a reliable analytical method for the detection and quantification of cannabinoids in human biological specimens. In this review, we focus on a number of analytical methods that have, so far, been developed and validated, with particular attention to the new "golden standard" method of forensic analysis, liquid chromatography mass spectrometry or tandem mass spectrometry. In addition, this review provides an overview of the effective and selective methods used for the extraction and isolation of cannabinoids from (i) conventional matrices, such as blood, urine and oral fluid and (ii) alternative biological matrices, such as hair, cerumen and meconium.

Application of an ultra-performance liquid chromatography-tandem mass spectrometric method for the detection and quantification of cannabis in cerumen samples.

In this study, cerumen, a non-conventional biological secretion, was examined as an alternative matrix for forensic analyzis. A fully validated analytical UPLC-MS/MS method was developed for the detection and quantification of the most prevalent psychoactive illicit drug globe wide, Δ9-tethrahydrocannabinol, commonly known as THC, and four major cannabinoids found in cannabis Sativa. The method was validated, and standard external calibration curves were established with correlation coefficients > 0.99. A validated experimental procedure, along with a direct extraction of cannabinoids with acidified acetonitrile resulted in a short total analyzis time and a good extraction efficiency for all the analytes under study. LOD and LOQ values were determined to be 0.01-0.08 pg/mg and 0.04-0.23 pg/mg, respectively. To prove applicability of the proposed assay, volunteers were selected, and cerumen samples were examined for cannabis. The analyzis by use of UPLC-MS/MS indicated that all samples were positive, reporting recent cannabis abuse. Surprisingly, both THC and Cannabinol (CBN) were detected, and quantification was possible in 75% of the cases.

An extensive case study on the dispersion parameters of HI-assisted reduced graphene oxide and its graphene oxide precursor.

The formation of highly concentrated and stable graphene derivatives dispersions remains a challenge towards their exploitation in various applications, including flexible optoelectronics, photovoltaics, 3D-printing, and biomedicine. Here, we demonstrate our extensive investigation on the dispersibility of graphene oxide (GO) and reduced graphene oxide (RGO) in 25 different solvents, without the use of any surfactant or stabilizer. Although there is a significant amount of work covering the general field, this is the first report on the dispersibility of: a) RGO prepared by a HI/AcOH assisted reduction process, the method which yields RGO of higher graphitization degree than the other well-known reductants met in the literature, b) both GO and RGO, explored in such a great range of solvents, with some of them not previously reported. In addition, through calculation of their Hansen Solubility Parameters (HSP), we confirmed their dispersibility behavior in each solvent, while we indirectly validated the most advanced graphitization degree of the studied RGO compared to other reported RGOs, since its HSPs exhibit the highest similarity with the respective ones of pure graphene. Finally, high concentrations of up to 189 µg mL-1 for GO and ~ 87.5 µg mL-1 for RGO were achieved, in deionized water and o-Dichlorobenzene respectively, followed by flakes size distribution and polydispersity indices estimation, through dynamic light scattering as a quality control of the effect of a solvent's nature on the dispersion behavior of these graphene-based materials.

Synergistic enantioseparation systems with either cyclodextrins or cyclofructans and L-alanine Tert butyl ester lactate.

The combined use of chiral ionic liquids (CILs) and conventional chiral selectors (CSs) in CE, to establish a synergistic system, has proven to be an effective approach for the separation of enantiomeric pairs. In this study, a new CE method was developed, employing a binary system of a CS, either a cyclodextrin (CD) or a cyclofructan (CF), and a chiral amino acid ester-based ionic liquid (AAIL), for the chiral separation of four basic, acidic and zwitterionic drug compounds. In particular, the enantioseparation of two anticoagulants, warfarin (WAR) and coumachlor (COU), a non-opioid analgesic, nefopam (NEF) and a third-generation antihistamine, fexofenadine (FXD), was examined, by supporting the BGE with a CS and the chiral AAIL L-alanine tert butyl ester lactate (L-AlaC4 Lac). Parameters, such as the type of the CS, the concentration of both the CS and L-AlaC4 Lac, and the BGE pH, were methodically examined in order to optimize the chiral separation of each analyte. It was observed that, in some cases, the addition of the AAIL into the BGE improved both resolution (Rs ) and efficiency (N) significantly. In other cases, the synergistic effect enabled baseline separation of analyte enantiomers, at a much lower concentration of the CS. Finally, after optimization of separation conditions, baseline separations (Rs >1.5) of all four analytes were achieved in less than 5 min.

Polyphenols in carobs: A review on their composition, antioxidant capacity and cytotoxic effects, and health impact.

Carob (Ceratonia Siliqua L., tree of the pea family Fabaceae) and its products have recently attracted great interest due to their polyphenolic composition. This review summarizes the polyphenolic compounds that are contained in different carob parts (leaves, pod, seeds, barks) and products (syrup, flour, fiber). It also states the main differences of polyphenolic composition due to environmental and natural reasons, such as region, variety, and gender, and due to the processes used for preparation, extraction and analysis. The gender, along with the extraction procedure, proved to be the most important factors affecting the polyphenolic composition. Supercritical fluid extraction is the most efficient technique used because it protects polyphenols from decomposition. Due to the relatively low number of publications, it is concluded that further development of optimum methods for extraction, analysis and isolation of polyphenols should be carried over to assess their antioxidant capacity and their food technological and pharmaceutical industry.

Chiral selectors in CE: Recent development and applications (mid-2014 to mid-2016).

This report, which is a sequence of a series of reviews, records the most important chiral selectors (CSs) applied in CE. It highlights the CSs that were used during the period 2014 to mid-2016. In this review, method developments, validations, and pharmaceutical along with biomedical applications are presented. The different CSs include CDs, antibiotics, cyclofructants, linear and branched oligo- and polysaccharides, and polymeric surfactants. In addition, the advantages of these CSs, along with their chiral recognition mechanisms, and their performance, are discussed.

Enantioseparations in open-tubular capillary electrochromatography: Recent advances and applications.

This review highlights recent advances and applications in open-tubular capillary electrochromatography (OT-CEC) for enantioseparations during the last decade. Although extensive research has been conducted in the area of separations by use of CEC, and a big number of reviews have been published, there is not a review on exclusively the use of chiral stationary phases (CSPs) in OT-CEC for enantioseparations. Therefore, in this review, the design and synthesis of different CSPs are presented, and their potential applications in OT-CEC for enantioseparations are discussed. The different approaches to CSP development include chiral nanomaterials, porous layers, molecular imprinting, sol-gel technique, polyelectrolyte multilayer coating, polymeric coating and others.

Combined use of cyclofructans and an amino acid ester-based ionic liquid for the enantioseparation of huperzine A and coumarin derivatives in CE.

Cyclofructans (CFs) and their derivatives have recently been proven to be efficient chiral selectors (CSs) for the enantioseparation of several analytes in CE, HPLC, and GC. In this study, the chiral separation ability of a number of native and derivatized CFs was examined in CE. Particularly, six different CFs, with different derivatization groups and cavity sizes [native CF-6 and CF-7, isopropyl cyclofructan-6 (IPCF-6), IPCF-7, sulfated cyclofructan-6 (SCF-6), and SCF-7] were used as CSs for the enantioseparation of huperzine A, warfarin, and coumachlor. Almost all of the examined CFs, except from SCF-6 & -7, demonstrated relatively low and sometimes no chiral separation ability for huperzine A. In an effort to improve both resolution and efficiency, the chiral ionic liquid D-Alanine tert butyl ester lactate (D-AlaC4Lac) was added into the BGE. In most of the cases, the combination of CF with D-AlaC4Lac resulted in an improvement in peak efficiency and/or resolution. When CF-6 was utilized with D-AlaC4Lac, a resolution of 1.4 was obtained, while the use of IPCF-6/D-AlaC4Lac provided a baseline enantioseparation. Although the combination of SCF-7 and 40 mM D-AlaC4Lac did not affect resolution, it dramatically increased peak efficiency from 24,000 to 117,000. In the case of warfarin and coumachlor, IPCF-6 and IPCF-7 proved to be the most effective CSs. It is, therefore, concluded that the size of the cavity and the CF derivatization are the key parameters for the chiral separation capability. It is also clear from this study that D-AlaC4Lac is necessary for improved peak efficiencies and resolutions.

Chiral selectors in CE: recent developments and applications (2012-mid 2014).

There is a large number of chiral selectors (CSs) that have, over the years, been synthesized and used in electrophoretic enantioseparations. This report highlights the most important CSs applied in CE during the period 2012 to mid-2014. It is mainly focused on method developments and validations, along with pharmaceutical and biomedical applications. Even though numerous publications have, through the years, reported the utilization of CSs in enantioseparations, only the ones applied in electrophoretic techniques the last approximately three years are demonstrated in this review article. In particular, cyclodextrins, cyclofructants, linear and branched oligo- and polysaccharides, antibiotics, and polymeric surfactants are presented, and their advantages, their chiral recognition mechanisms, and their performance are discussed.

Chiral ionic liquids in chromatographic and electrophoretic separations.

This report provides an overview of the application of chiral ionic liquids (CILs) in separation technology, and particularly in capillary electrophoresis and both gas and liquid chromatography. There is a large number of CILs that have been synthesized and designed as chiral agents. However, only a few have successfully been applied in separation technology. Even though this application of CILs is still in its early stages, the scientific interest is increasing dramatically. This article is focused on the use of CILs as chiral selectors, background electrolyte additives, chiral ligands and chiral stationary phases in electrophoretic and chromatographic techniques. Different examples of CILs, which contain either a chiral cation, a chiral anion or both, are presented in this review article, and their major advantages along with their potential applications in chiral electrophoretic and chromatographic recognition are discussed.