Water-organic Solvent Systems Research Articles

Calendula Flowers (Calendulae officinalis flos): Methods to Obtain Fractions of Biologically Active Substances

INTRODUCTION. The pharmaceutical industry aims at developing sustainable resource-saving technologies for manufacturing medicines. Approaches to the effective use of herbal drugs include applying technologies yielding compounds with various pharmacological effects in one production cycle. To date, no standardised herbal drug processing technology has been designed to produce calendula flower-based medicinal products with various pharmacological effects. The Member States of the Eurasian Economic Union (EAEU) process calendula flowers by extraction methods yielding one fraction of biologically active substances per cycle (either only flavonoids or only carotenoids).AIM. This article aimed to investigate the possibility of stepwise processing of calendula flowers to obtain biologically active substances with different polarities (carotenoids, flavonoids, and polysaccharides) per cycle.MATERIALS AND METHODS. The authors extracted carotenoids using hexane. The study included additional thermal pretreatment of the herbal drug. Carotenoids and flavonoids were quantified by spectrophotometry, and polysaccharides were quantified by gravimetric analysis. After hexane removal, the dry oily residue was dissolved in oil with mechanical stirring to obtain the oil extract. The study included a three-step processing method that comprised hexane extraction (extraction of carotenoids with a low-polarity organic solvent), extraction with a water–organic solvent system (extraction of flavonoids), and aqueous extraction (precipitation of polysaccharides).RESULTS. The lipophilic extracts obtained by single hexane extraction or by single hexane extraction and heat treatment had the maximum carotenoid content (~4%), which was 10 times the carotenoid content in the extracts obtained using a water– organic solvent system. Oil extracts were prepared from the dry residue left after removing hexane by distillation at its boiling point. The content of biologically active substances in the oil extracts was comparable to that in the intact herbal drug. Water–organic solvent extraction yielded 68.5% more flavonoids from the herbal drug extracted with hexane than from the intact herbal drug. In contrast, aqueous extraction applied to the intact herbal drug yielded 1.7 times the amount of flavonoids obtained by aqueous extraction preceded by hexane extraction. The water-soluble polysaccharide fraction extracted from the intact herbal drug had 10 times the flavonoid content observed in the fraction extracted from the processed herbal drug. Each subsequent processing step decreased the total polysaccharide content and the content of individual polysaccharide fractions and increased their purity. The ratio of polysaccharide fractions remained unchanged across all processing methods tested.CONCLUSIONS. Stepwise processing of calendula flowers ensured that one processing cycle provided three fractions containing increased amounts of carotenoids, flavonoids, and polysaccharides. Relative to the intact herbal drug, there was a 3.3-fold increase in the yield of carotenoids, and the yields of flavonoids and polysaccharides increased by 44.8 and 41.3%, respectively. The resulting product had a higher degree of purity than the products obtained by pretreatment and double hexane extraction or by using the intact herbal drug. The stepwise processing method is advisable for the production of medicines that are enriched with a specific group of biologically active substances or contain smaller amounts of impurities.

Highly active and stable Ru–(OH)-based catalysts supported on Ni–manganite for the base-free aerobic oxidation of 5-hydroxymethyl furfural to 2,5-furan dicarboxylic acid in a noble water–organic solvent system

Highly efficient and robust Ru supported on nickel–manganite catalysts for selective conversion of 5-hydroxymethyl furfural into 2,5-furan dicarboxylic acid in a solvent mixture of noble water and acetone with eliminating homogeneous base addition.

Choline Chloride Urea Effect on Liquid–Liquid Equilibria of 5-Hydroxymethylfurfural–Water–Organic Solvent Systems in the Absence and Presence of Sodium Chloride

Deep eutectic solvent (DES) has demonstrated its ability to improve the yield and selectivity in the 5-hydroxymethylfurfural (HMF) production process. Liquid–liquid extraction is a beneficial proce...

Fabrication and Characterization of S-Benzyldithiocarbazate Schiff Base Microcrystals by a Reprecipitation Method for Enhanced Antibacterial Activity

In this study, the microcrystallization of the 2-thiophenecarboxaldehyde Schiff base of S-benzyldithiocarbazate (i.e. benzyl (2E)-2-[(thiophen-2-yl)methylidene]hydrazine-1-carbodithioate [TASBnDTC]) was fabricated by a reprecipitation method in an organic solvent-water system using different crystallization parameters, including temperature and the concentration of the target compound. The size, anisotropy, crystalline phase, and surface morphology of the TASBnDTC microcrystals were characterized by dynamic light scattering and scanning electron microscopy. The stability of the Schiff base microcrystals was also evaluated. Different sizes of surfactant-dispersed TASBnDTC microcrystals (1505, 2194, and 2447 nm) were fabricated from three different concentrations of the Schiff base (0.001 M, 0.002 M, and 0.003 M, respectively) in an acetone-water system. The TASBnDTC microcrystals were also evaluated by X-ray powder diffraction

Liquefaction of bamboo biomass and production of three fractions containing aromatic compounds

Depolymerization of lignin to produce value-added aromatic monomers has attracted increasing attention since these monomers can be used as phenol replacement in production of phenolic resins. Here a one-pot depolymerization of bamboo lignin was investigated to obtain aromatic platforms with low molecular weight using acidic catalyst and ethanol. Three fractions (1#, 2#, and 3#) containing different molecular weight distributions of aromatic compounds could be efficiently extracted using water-organic solvent system via a stepwise fractionation process by gradual removal of solvent. The fractions distribution was found to be primarily dependent on the reaction temperature and time. When the temperature was increased from 160 °C to 200 °C, the yield of fractions containing aromatic products increased significantly from 19.1 wt% to 27 wt%, the same change trend was found by changing the time, and the yield of aromatic products increased from 22.4% to 26.7% with an increase of time from 10 min to 30 min. The bioproducts were characterized by using gas chromatography/mass spectrometry (GC–MS), gel permeation chromatography (GPC) and two-dimensional heteronuclear single-quantum coherence (2D HSQC NMR). As evidenced by GC–MS spectra, the three fractions were mainly comprised of phenolic derivatives, and the relative contents of phenolic compounds took up about 80% of the total area of each fraction. With the similar physiochemical properties of the fractions, aromatic platforms could provide a new paradigm of bamboo lignin utilization for renewable energy and value-added biochemicals.

Natural Nanofiber Shuttles for Transporting Hydrophobic Cargo into Aqueous Solutions.

Hydrophobic biomolecules realize their functions in vivo in aqueous environments, often through a delicate balance of amphiphilicity and chaperones. Introducing exogenous hydrophobic biomolecules into in vivo aqueous systems is a challenge in drug delivery and regenerative medicine, where labile linkers, carriers, and fusions or chimeric molecules are often designed to facilitate such aqueous interfaces. Here, we utilize naturally derived silk nanofiber shuttles with the capacity to transport hydrophobic cargos directly into aqueous solutions. These nanofibers disperse in organic solvents and in aqueous solutions because of their inherent amphiphilicity, with enriched hydrophobicity and strategically interspersed negatively charged groups. Hydrophobic molecules loaded on these shuttles in organic solvent-water systems separated from the solvent after centrifugation. These concentrated hydrophobic molecule-loaded nanofibers could then be dispersed into aqueous solution directly without modification. These shuttle systems were effective for different hydrophobic molecules such as drugs, vitamins, and dyes. Improved biological stability and functions of hydrophobic cargos after loading on these nanofibers suggest potential applications in drug delivery, cosmetology, medical diagnosis, and related health fields, with a relatively facile process.

Thermodynamic aspects of phase equilibrium in binary water–organic solvent mixtures

It is shown that the boundary curves of liquid equilibria in binary systems characterize the temperature–concentration boundary of the existence of homogeneous mixtures whose formation is not accompanied by changes in the Gibbs energy of the system and are a combination of two branches that do not convert into each other but intersect at the temperature of homogenization of a mixture of critical composition. The phase diagrams of a number of water–organic solvent systems are analyzed to determine the thermodynamic particularities of the latter.

Prediction of conversion at equilibrium for lipase esterification in two-phase systems

In this work, a calculation procedure to predict reactant conversion at equilibrium in the case of lipase esterification in two-phase water-organic solvent system has been developed. The method is based on conventional thermodynamics using the UNIFAC predictive model to calculate the value of activity coefficients of compounds. Our approach was validated by comparison with experimental results in the case of the enzymatic esterification of oleic acid by 1-butanol in a two-phase water/n-heptanesystem. In this configuration only 1-butanol partitions significantly between the two phases. With this procedure, it was shown that oleic acid conversion at equilibrium was influenced by the initial mole fraction ratio of reactants, the volume ratio of the organic phase to aqueous phase, as well as the temperature and the nature of the organic solvent. The value of the equilibrium constant of the reaction, which is required for the calculations, was estimated from experiments at 298.15K and found equal to 78±3. The results emphasize the prominent role of the thermodynamic activity of 1-butanol in the reactional mixture. In the case of different investigated solvents, it was shown that the thermodynamic activity of this compound has to be maximized to favor conversion of oleic acid at equilibrium.

Predicting solvent-water partitioning of charged organic species using quantum-chemically estimated Abraham pp-LFER solute parameters

Methods for obtaining accurate predictions of solvent-water partitioning for neutral organic chemicals (e.g., Kow) are well-established. However, methods that provide comparable accuracy are not available for predicting the solvent-water partitioning of ionic species. Previous methods for addressing charge contributions to solvent-water partitioning rely on charged solute descriptors which are obtained from regressions to neutral species descriptors as well as charged descriptors which are specific to unique charge-functionalities and structural moieties. This paper presents a method for obtaining Abraham poly-parameter linear free energy relationship (pp-LFER) descriptors using quantum chemical calculations and molecular structure, only. The method utilizes a large number of solvent-water systems to overcome large errors in individual quantum chemical computations of ionic solvent-water partition coefficients. The result is a single set of quantum-chemically estimated Abraham solute parameters (QCAP) which are solvent-independent, and can be used to predict the solvent-water partitioning of ionic species.Predictions of solvent-water partition coefficients for ionic species using quantum-chemically estimated Abraham parameters (QCAPs) are shown to provide improved accuracy compared over both existing Absolv-estimated Abraham solute parameters (AAP) as well as direct a priori quantum chemical (QC) calculations for partitioning of anionic solutes in 4 organic solvent-water systems (RMS = 0.740, 2.48 and 0.426 for the Absolv, QC and QCAP methods, respectively). For quaternary amine cations in the octanol-water system the RMS errors of the solvent-water partition coefficients were larger and similar between the two Abraham models (RMSE = 0.997 and 1.16, for the AAP and QCAP methods, respectively). Both methods showed significant improvement over direct QC calculations (RMSE = 2.82).

Effect of amphiphilic polysaccharides released from Botryococcus braunii Showa on hydrocarbon recovery

Water-soluble polymers are released from the extracellular matrix of Botryococcus braunii by thermal pretreatment prior to hydrocarbon extraction. In this study, hydrocarbon recovery was reduced by adding polymers to algal slurries from which they were previously washed. The water-soluble polymers are amphiphilic and emulsify the water–organic solvent systems used in hydrocarbon extraction. To obtain >90% hydrocarbon yields from high-concentration slurry, the original 10% water-soluble polymer content of dry algal cells had to be reduced to less than 0.5%. The water-soluble polymers were polysaccharides with a molecular weight greater than 2×106 and mainly comprised of galactose, arabinose, and uronic acid. We suggest that high-molecular-weight water-soluble polymers are desirable as industrial emulsifiers and thickeners.

Biphasic water splitting by osmocene

The photochemical reactivity of osmocene in a biphasic water-organic solvent system has been investigated to probe its water splitting properties. The photoreduction of aqueous protons to hydrogen under anaerobic conditions induced by osmocene dissolved in 1,2-dichloroethane and the subsequent water splitting by the osmocenium metal-metal dimer formed during H(2) production were studied by electrochemical methods, UV-visible spectrometry, gas chromatography, and nuclear magnetic resonance spectroscopy. Density functional theory computations were used to validate the reaction pathways.

Separation through liquid–liquid extraction and spectrophotometric determination of U(VI) with the ortho-aminophenol reagent

The extractive properties of the ortho-aminophenol reagent upon U(VI) were investigated in two solvents: 4-chlor-acetophenone and acetylacetone, in a water-organic solvent system. The method here proposed is based on the complexation reaction of the uranyl ion, UO22+, with ortho-aminophenol dissolved in 4-chlor-acetophenone, at room temperature, over a pH interval = 4–6, followed by spectro-photometry of the organic phase, involving measuring of absorbancy at 569.6 nm. The Beer law is valid over the 1–12 μg U(VI)/mL concentration interval, with molar absorbtivity emax = 4.3 × 105 mol−1 cm2 and Sandell sensitivity = 0.0526 μg cm−2. The structure, stability and solubility of the formed complex was studied by UV–VIS and IR spectrometry, diffractometry and scanning electron microscopy. The mixed complex formed between the uranyl ion and the ortho-aminophenol dissolved in 4-chlor-acetophenone, [UO2.(L)2.(S)4], is characterized by the following parameters: metal/ligand combination ratio: M/L = 1/2, stability constant β = 2.06 × 106, distribution coefficient D = 66.56 (Vorg = Vaq), percentage extraction E% = 98.52, and recovery factor, R%, ranging between 99.48 and 99.85%.

Evaluation of Nonionic Block Polymer Surfactants in Maize Root Proteome Extraction within Water–Organic Solvent Phases

In the present work, six nonionic block copolymer surfactants consisting of poly(ethylene glycol) (PEG), polyethylene (PE), and poly(propylene glycol) (PPG) were exploited to extract total proteins from maize (Zea mays L.) roots within a water–organic solvent system. After the treatment, proteins were partitioned into aqueous phase, interphase, and organic phase. The total yield was increased by up to 30% after adding PE-PEG block polymer surfactant compared with control. Two-dimensional electrophoresis (2-DE) was further used to evaluate proteins in water phase and interphase; the results revealed that the spot numbers and density were all improved, and well-focused electrophoretic patterns were achieved with higher density and without excess Joule heating problem after adding nonionic block polymer surfactants. Among the six investigated block polymers, PE-PEG extracted the largest amount of proteins.

A highly efficient method for the α,β-dehydrogenation of α-amino esters and α-amino-β-diesters

N-monochlorination of N-unprotected α-amino esters and α-amino-β-diesters was efficiently and very simply effected by using inexpensive effervescent sodium dichloroisocyanurate tablets for water disinfection in a biphasic organic solvent-water system. Subsequent dehydrochlorination provided α,β-didehydroaminoacid esters, whose hydrogenation would allow the starting compounds to be easily racemized.

Solute partitioning in polymer–salt ATPS: The Collander equation

The partition coefficients for several solutes (five nitrophenylated-monosaccharides and four proteins) were experimentally determined, at 23 °C, in three different tie-lines of two polymer–salt aqueous two-phase systems (ATPS): UCON-K 2HPO 4 and UCON-NaH 2PO 4. These partition coefficients together with others obtained from the literature for five dinitrophenylated-amino acids were used to investigate the suitability of the Collander equation to correlate partition coefficients in polymer–salt ATPS. This equation was first proposed to describe the linear correlation between partition coefficients of solutes in different water–organic solvent systems. More recently, it was proved that partition coefficients for several biomolecules in polymer–polymer ATPS can also be correlated with this equation. In this work, several correlations were tested: partition coefficients obtained for different tie-lines within the same system and also partition coefficients obtained from different systems. In both cases, a linear relation was observed, despite a less satisfactory correlation was found when different ATPS were compared. Overall, it was demonstrated that the Collander equation can be used to satisfactorily correlate solute partitioning in the studied polymer–salt ATPS.

Volume Reduction of Nonaqueous Media Contaminated with a Highly Halogenated Model Compound Using Superoxide

Highly halogenated organic compounds, which include polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins (PCDDs) formed during the synthesis of pentachlorophenol and chlorophenoxy herbicides, are often found as contaminants in less toxic nonaqueous media, such as waste oil, oily sludges, or biosolids. Superoxide is highly reactive with halogenated compounds when both are dissolved in nonaqueous media; however, superoxide is most economically generated in water, where it is unreactive with most organic compounds. Superoxide reactivity was investigated in organic solvent-water systems as a basis for treating halogenated contaminants in less toxic nonaqueous media. Such a process could potentially render a contaminated oil or sludge nonhazardous, providing a mechanism for waste volume reduction. Increasing amounts of water added to acetone and dimethyl sulfoxide systems decreased the activity of superoxide in the solvent, but enough activity remained for effective treatment. Superoxide was then generated in the aqueous phase of two-phase water-organic solvent systems, and significant superoxide activity was achieved in the organic media with the addition of phase transfer catalysts (PTCs) to transfer superoxide into the nonaqueous phase. The results of this research demonstrate that superoxide, which can be generated in water electrochemically or through the catalytic decomposition of peroxygens, has the potential to be transferred to oils, sludges, and other less toxic nonaqueous media to destroy highly refractory contaminants such as PCBs, PCDDs, and other halogenated contaminants.

Characterization of monoterpene biotransformation in two pseudomonads

To study the metabolic profile of Pseudomonas rhodesiae and Pseudomonas fluorescens in water-organic solvent systems using terpene substrates for both growth and biotransformation processes and to determine the aerobic or anaerobic status of these degradation pathways. Substrates from pinene (alpha-pinene, alpha-pinene oxide, beta-pinene, beta-pinene oxide, turpentine) and limonene (limonene, limonene-1,2-oxide, orange peel oil) families were tested. For the bioconversion, the terpene-grown biomass was concentrated and used either as whole cells or as a crude enzymatic extract. Pseudomonas rhodesiae was the most suitable biocatalyst for the production of isonovalal from alpha-pinene oxide and did not metabolize limonene. Pseudomonas fluorescens was a more versatile micro-organism and metabolized limonene in two different ways. The first (anaerobic, cofactor-independent, noninducible) allowed limonene elimination by synthesizing alpha-terpineol. The second (aerobic, cofactor-dependent) involved limonene-1,2-oxide as an intermediate for energy production through a beta-oxidation process. Enzymatic isomerization of beta- to alpha-pinene was described for the first time for both strains. Alpha-terpineol production by P. fluorescens was very efficient and appeared as a promising alternative for the commercial production of this bioflavour.

Prediction of solubilities of salts, osmotic coefficients and vapor–liquid equilibria for single and mixed solvent electrolyte systems using the LIQUAC model

The electrolyte model LIQUAC has been used up till now to predict osmotic coefficients, mean ion activity coefficients, the vapor–liquid equilibrium (VLE) behavior, the solubility of gases in single and mixed solvent electrolyte systems, and solubilities of salts in aqueous solutions. In this paper, the required expressions for the calculation of salt solubilities not only in aqueous systems, but also in organic solvents and water–solvent electrolyte systems were deduced in detail based on the LIQUAC model with a fixed reference state and thermodynamic relations. Four salts (NaCl, KCl, NH 4Cl and NaF) and two solvent (water and methanol) were selected to test the derived expressions. The results show that the LIQUAC model with a fixed reference state can be used to predict osmotic coefficients, solubilities of salts in aqueous solutions, vapor–liquid equilibria, and the solubilities of salts in water–organic solvent systems with strong electrolytes.

Enzymatic catalysis of 2,6-dimethoxyphenol by laccases and products characterization in organic solutions

2,6-Dimethoxyphenol (DMP) as a substrate was widely used in determination of laccase activity. It is surprising, however, that its catalyzed oxidation products have not been completely determined until now. Studies were thus conducted on Rhus laccase (RL) and immobilized Rhus laccase (IRL)-catalyzed oxidation reactions of 2,6-dimethoxyphenol in water-organic solvent systems. These reactions proceeded well in water-(im)miscible organic solvent systems pre-saturated with water. Only one product, 3,3′,5,5′-tetramethoxy-1,1′biphenyl-4,4′-diol (TMBP), was produced by RL catalysis, and it was thoroughly characterized by FT-IR, NMR, GC-MS, etc. A simple enzymatic mechanism of this reaction is propos

Capillary electrophoretic assay for the stability of tris(8-quinolinolato)gallium(III) in tablet formulations

A capillary electrophoresis (CE) method for testing the stability of a novel oral anticancer metallodrug, tris(8-quinolinolato)gallium(III) (KP46), is proposed. As both the intact drug and its eventual impurity or/and decomposition product, 8-quinolinol, are not charged (at most of the pH range), the micellar-mediated CE mode based on using micellar concentrations of sodium dodecyl sulfate was employed. The running electrolyte conditions were optimized in order to resolve the peak of KP46 from the signal of 8-quinolinol, as well as from these of tablet matrix components. The stability of KP46 in different organic and water-organic solvent systems was studied regarding its limited solubility and the following recovering experiments. The method thus developed was applied to the determination of KP46 in tablet formulations, for which sample preparation method, namely powdering and ultrasound-assisted extraction (with 50% aqueous acetone), was tested and optimized in terms of procedure time (10 min). Different in the content of the active substance (10–30%) batches of tablets stored for two years after preparation were validated and recoveries obtained at the level from 97 to 102% confirmed sufficient drug stability. This principal finding was verified by means of an independent method, gas chromatography coupled with mass spectrometry (GC–MS).