Mixture Of Methanol Research Articles

Solubility study, model correlation and thermodynamics of 3-acetyl-4-hydroxy-2H-chromen-2-one and its chlorinated derivatives in binary solvent mixtures at temperatures from 293.15 to 313.15 K

The solubility of 3-acetyl-4-hydroxy-2H-chromen-2-one (GK-1), 3-acetyl-6-chloro-4-hydroxy-2H-chromen-2-one (GK-2), and 3-acetyl-7-chloro-4-hydroxy-2H-chromen-2-one (GK-3) in binary solvent mixtures of methanol and ethanol was investigated using the gravimetric method over a temperature range of 293.15 K to 313.15 K under atmospheric pressure. Experimental results showed that the mole fraction solubility of GK-1, GK-2, and GK-3 increased with rising temperature and higher co-solvent proportions (0.10 to 0.90 mol fraction). Theoretical mole fraction solubility predictions were made using the Apelblat, Van’t Hoff, Yaws, CNIBS/R-K, and modified Jouyban-Acree models, all of which showed good agreement with the experimental data. Additionally, apparent thermodynamic modeling of GK-1, GK-2, and GK-3 was conducted using the Van’t Hoff equation. The solubility and thermodynamic data obtained are valuable for the processes of production, isolation, separation, and crystallization of these compounds.

Optimizing the Precipitation of Bioactive Compounds From Extracted Curcuma longa Linn. Using Gas Anti‐Solvent Process

ABSTRACTTurmeric is a medicinal herb that can be used in a wide range of applications, such as food ingredients, cosmetics, and traditional medicine. The active ingredients found in turmeric are curcumin (CUR), desmethoxycurcumin (DMC), and bisdesmethoxycurcumin (BMDC). The aim of this research was to precipitate the active ingredients from a turmeric extract using the gas anti‐solvent process with carbon dioxide as the anti‐solvent. The effects of solvent type (ethanol, methanol, and acetonitrile), precipitation temperature (25°C–45°C), and CO2 flow rate (4–12 mL/min) on the amount of precipitates were investigated using the Box–Behnken design of experiments. The precipitates were analyzed for curcuminoids and CUR content using HPLC and were tested for antioxidant activity. It was found that solvent type and temperature were significant variables at a 5% significance level on the amount of precipitates. Using a mixture of ethanol and methanol (77.5% v/v ethanol) with a polarity index of 4.48 as the solvent, a precipitation temperature of 25.40°C, and a CO2 flow rate of 7.56 mL/min was found to be the optimal conditions for achieving the highest amount of precipitates. At the optimal conditions, the amounts of curcuminoids and CUR precipitates were found to be 27.33 ± 0.23 and 13.30 ± 0.12 mg/5 mL of extracted solution, respectively. In the antioxidant studies, the Trolox equivalents found in the products at the optimal conditions using DPPH and ABTS assays were 38.19 ± 0.17 and 65.96 ± 2.36 mg/5 mL of extracted solution, respectively. The total phenolic content was found to be 30.84 ± 1.80 mg/5 mL of extracted solution.

A Fast and Cost-Effective Electronic Nose Model for Methanol Detection Using Ensemble Learning

Methanol, commonly used to cut costs in the production of counterfeit alcohol, is extremely harmful to human health, potentially leading to severe outcomes, including death. In this study, an electronic nose system was designed using 11 inexpensive gas sensors to detect the proportion of methanol in an alcohol mixture. A total of 168 odor samples were taken and analyzed from eight types of ethanol–methanol mixtures prepared at different concentrations. Only 4 features out of 264 were selected using the feature selection method based on feature importance. These four features were extracted from the data of MQ-3, MQ-4, and MQ-137 sensors, and the classification process was carried out using the data of these sensors. A Voting Classifier, an ensemble model, was used with Linear Discriminant Analysis, Support Vector Machines, and Extra Trees algorithms. The Voting Classifier achieved 85.88% classification accuracy before and 81.85% after feature selection. With its cost effectiveness, fast processing time, and practicality, the recommended system shows great potential for detecting methanol, which threatens human health in counterfeit drink production.

Electrical conductance study of Schiff base in different solvents and temperatures: DFT calculation

The electrical conductivities of the N-(2-chlorobenzylidene)benzylamine (NCB) as Schiff bases (SB) compound in water and methanol were studied in different temperatures, the mixtures of methanol and water studied in various percentages of methanol at 298 K. Initially, the relationship between equivalent conductivity and the square root of molar concentration was plotted to find electrolyte types using Kohlrausch equations. The plot indicates that NCB was weakly associated with water, methanol, and mixtures. Lee-Wheaton equation treated the experimental results of symmetrical electrolytes (1:1) to calculate the conductivity confines: equivalent conductance at infinite dilution Λₒ, association constant KA, and the main distance between ions in solution (R) at best-fit values of (ϬΛ). Thermodynamic quantities for the ion association reaction (∆Go, ∆Ho and ∆So) have been measured. Also, the theoretical calculation was used to optimize the energy of the molecule in the gas phase then measured many descriptors by using (AM1, PM3) then DFT. In addition, recalculated the optimization energy in water, and methanol. After theoretical calculation and analysis, it was found that the Λₒ value is related to the molecular volume of the system (molecules assembled in the solvent). As the molecular volume increases, the Λₒ value decreases due to association. KEY WORDS: Schiff bases, Electrical conductivities, Lee-Wheaton equation, Thermodynamic parameter, DFT Bull. Chem. Soc. Ethiop. 2025, 39(1), 177-187. DOI: https://dx.doi.org/10.4314/bcse.v39i1.15

A Study of Heat Recovery and Hydrogen Generation Systems for Methanol Engines

Biofuels are the most essential types of alternative fuels, which currently have significant potential to reduce CO2 emissions compared to fossil fuels. Methanol is a more efficient fuel than petrol due to its physicochemical properties, such as a higher latent heat of vaporization, research octane number, and heat of combustion of the fuel–air mixture. Also, biomethanol is cheaper than traditional petrol and diesel fuel for agricultural countries. The authors have proposed a new approach to improve the characteristics and efficiency of methanol diesel engines by using biomethanol mixed with hydrogen instead of pure biomethanol. Using a hydrogen–biomethanol mixture in modern engines is an effective method because hydrogen is a carbon-free, low-ignition, highest-flame-rate, high-octane fuel. A small quantity of hydrogen added to biomethanol and its combustion in an engine with a heat exchanger increases the combustion temperature and heat release, increases engine power, and reduces fuel consumption. This article presents experimental results of methanol combustion and a hydrogen-in-methanol mixture if hydrogen was retained due to the utilization of the heat of the exhaust gases. The tests were carried on a single-cylinder experimental engine with an injection of liquid methanol and gaseous hydrogen mixtures. The experiments showed that green hydrogen generated onboard the car due to the utilization of heat significantly reduced fuel costs of engines of vehicles and technological installations. It was established a hydrogen gaseous mixture addition of up to 5% by mass to methanol requires a corresponding change in the coefficient of excess air to λ = 1.25. Also, using an additional hydrogen mixture requires adjustment at the ignition moment in the direction of its decrease by 4–5 degrees of the engine crankshaft. Hydrogen gas mixture addition reduced methanol consumption, reaching a maximum reduction of 24%. The maximum increase in power was 30.5% based on experimental data. The reduction in the specified fuel consumption, obtained after experimental tests of the methanol research engine on the stand, can be implemented on the vehicle engines and technological installations equipped with an onboard heat recovery system. Such a system, due to the utilization of heat and the supply of additional hydrogen, can be implemented for engines that work on any alternative or traditional fuels.

Effect of the extraction method on the lipid composition of purslane (Portulaca oleracea L.) seed oil

Purslane (Portulaca oleracea L.) is a widespread weed plant used since ancient times as remedy and as food. Its seed oil possesses significant bioactive potential due to the high content of important phytonutrients, mainly essential fatty acids and phytosterols. Although the total fatty acid composition of oil is well documented, till now there is no data published about individual lipid classes. The information on sterols is scarce as well. Therefore, the aim of this work was to characterize in details for the first time the individual lipid classes and their fatty acid composition, sterols, as well as the oxidative stability of the oil, depending on the extraction method by either hexane, chloroform–methanol mixtures or super-critical CO2. The results revealed no significant effect of extraction method on the individual lipid classes (monoacylglycerols, diacylglycerols, free fatty acids, free sterols, triacylglycerols, sterol esters, wax esters and hydrocarbons), including the fatty acid composition of saponifiables, and quite weak effect on the oxidative stability of the oil regarding super-critical CO2 vs. organic solvents. Detailed analyses of lipid composition confirmed the potential of purslane seed oil as a cheap and highly valuable source of phytonutrients as essential fatty acids and phytosterols, for application in food, pharmaceutical and cosmetic industries.

A Liquid Chromatography‐Tandem Mass Spectrometry Bioanalytical Method Development and Validation for the Determination of Pacritinib in Plasma

ABSTRACTThe primary objective of the current work is to establish and verify an accurate and linear liquid chromatography‐electrospray ionization‐tandem mass spectrometry procedure for quantifying Pacritinib. An effective chromatographic resolution was obtained using the Hypersil Gold (50 × 4.6 mm, 2.1 µm) C18 column. The mobile phase is a mixture of methanol, 0.1% formic acid, and acetonitrile in the proportion of 20:15:65 (%v/v/v). The procedure involved closely monitoring executed ionic transitions of m/z 473.1/376.2 for Pacritinib and 584.26/101.1 for Brigatinib internal standard in multiple reaction monitoring mode. A strong correlation value (r2) of 0.9997 is associated with the linear plot regression line, which can be represented as y = 0.0001x − 0.0008. The relative standard deviation (RSD) results for the matrix effect were 3.63% and 3.57%, respectively, when the quality control (QC) level was low and high, respectively. Over the course of the study, the percentage average recoveries for Pacritinib were found to be 103.27% in high QC, 97.59% in medium QC, and 94.28% in low QC, respectively. The values that were obtained for the QC samples (0.378, 1.058, 7.56, and 11.34 µg/mL) varied from 2.00% to 4.03%. The developed method was useful for evaluating Pacritinib in biological samples for the purposes of QC, forensics, and bioavailability investigations for individuals.

Evaluation of selenocysteine contents in Se-enriched yogurt by Utilizing online post column derivative − High-Performance liquid chromatography

This study demonstrated a novel method using online post-column derivatization high-performance liquid chromatography (PCD-HPLC) to evaluate selenocysteine (SeC) in Se-enriched yogurt. The liquid chromatography process utilized a C18 column. The mobile phase A was composed of 4.0 mM borate buffer adjusted to pH 5.0, while mobile phase B was a 50:50 (v/v) mixture of methanol and acetonitrile. The mobile phases were combined at a ratio of 70:30, with a flow rate of 1 mL min−1. SeC was derivatized to bis-Fmoc selenocystine after separation, using a PCD solution (0.03 mM Fmoc, pH 10, 20 mM borate buffer, and 1.0 mL min−1 flow rate) and detected with a photodiode array detector (DAD) for sensitivity enhancement. The method exhibited excellent linearity (0.023 to 0.20 mg L-1, r2 = 0.9996), with a low LOD and LOQ of 0.018 mg L-1 and of 0.040 mg L-1, respectively. Repeatability and reproducibility were satisfactory, with recoveries of 95.50 % ± 1.49 % (the proposed PCD-HPLC) and 94.33 % ± 0.44 % (sample preparation). This method effectively analyzed the conversion of selenite ions (SeO32-) to SeC by lactic acid bacteria in yogurt, highlighting Se-enriched yogurt as a valuable dietary source of SeC. However, the synthesis efficiency of SeC decreased at inorganic Se supplementation levels above 1.0 mg Se L-1, potentially leading to the formation of less toxic elemental Se (Se0). Therefore, the proposed online PCD-HPLC method proves reliable for SeC analysis in Se-enriched yogurt, providing insights into Se speciation and optimizing Se enrichment processes.

A-317 Development of a patient-focused volumetric absorptive microsampling strategy to assess urinary amino acid excretion

Abstract Background Biochemical determinations of urinary amino acid excretion patterns can diagnose specific inborn errors of metabolism (IEM). Clinical management of these genetic metabolic patients may require frequent urine amino acid tests. A simplified process for transporting home collected urine specimens would benefit the IEM community. Volumetric absorptive microsampling (VAMS) is an emergent alternative sampling technique for the collection of dried biological specimens. We describe the development and preliminary validation results of a VAMS strategy for the analysis of creatinine and amino acids (N=22) from microsampled dried urine. Methods Urine creatinine and amino acids were respectively measured in a clinical laboratory setting using established assays on a CobasPro (Roche) and a MassTrak ultra-performance liquid chromatography (UPLC) amino acid analysis (AAA) solution (Waters). Two 30 µL VAMS tips from a Mitra device (Neoteryx) were used to sample each random urine specimen. An ultrasonication-based solvent extraction procedure was optimized to extract the amino acids and creatinine from the VAMS tips. Solvent extracts were subsequently dried by centrifugal evaporation. Extract from one tip was re-dissolved in water and tested for creatinine using an enzymatic method. The other extract was re-dissolved in 0.02 N sodium hydroxide and tested according to the MassTrak AAA procedure, which deploys pre-column AccQTag derivatization with reversed-phase UPLC on a C18 column (2.1 × 150 mm; 1.7 µm) and UV detection at 260 nm. Accuracy, within-batch precision and short-term stability of the optimized VAMS protocol were determined. Results Extraction solvent with a 60:40 (v/v) water:methanol mixture provided the highest average amino acid recovery. This extraction solvent produced higher average amino acid recoveries at pH 11 (89±13%), than pH 3 (82±10%) or pH 7 (72±11%). Creatinine measured from the VAMS tips (N=44) had a consistent negative bias of 20% relative to neat urine (R=0.9905, slope=0.802, intercept=0.02). The creatinine corrected urine amino acid results from the Mitra device were corrected for this observed concentration bias. The accuracy of the amino acid results derived from the VAMS tip vs neat urine was 104 ± 14%. The average within-batch precision (CV%) of the amino acids was 9.8% (range=6.7% (cystine) to 17.6% (arginine)) and 6.2% for creatinine. The average 1 week storage stability at ambient temperature was 91% (range=73% (ornithine) to 107% (glycine)) for the amino acids and 107% for creatinine. The devised VAMS strategy was applied to the analysis of microsampled dried urine from a patient with cystinuria (OMIM no. 220100). Marked elevations in arginine, cystine, lysine and ornithine were respectively observed and are consistent with the biochemical diagnosis of the patient. Conclusions Creatinine corrected amino acid results from the devised VAMS strategy exhibit good precision and accuracy when compared to tradition analyses of neat urine. The potential use of microsampled dried urine for the diagnosis and monitoring of selected IEM has been demonstrated. The analytical and clinical performance of this VAMS protocol must be further validated, including the use of microsampled dried urine from home specimen collections.

Photopolymerization of Imprinted Polymer with Dummy Template for the Recognition of Hydroquinone in Aqueous Medium

This study' purposes are to synthesize molecularly imprinted polymer (MIP) with hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) using p-xylene under ultraviolet curing at 405 nm for the recognition of hydroquinone (HQ) in aqueous medium. The template was extracted from the polymer with a mixture of methanol and acetic acid (9:1) by volume (v/v). The Fourier transform infrared (FTIR) spectrum of MIP (after wash) showed the absence of peak at the range of 840–860 cm−1, which represented the stretching outside the aromatic plane C–H at the para position (p-xylene). Field emission scanning electron microscope (FESEM) micrograph showed that the MIP had cavities compared to non-imprinted polymer (NIP). The MIP (MIP-Pxy) with ratio (monomer:crosslinker) 0.25 and 1.00% template gave the highest uptake of hydroquinone (HQ) in aqueous solution, which implied more specific recognition (highest KD value). The rebinding of HQ onto MIP-Pxy was best described by both isotherm (Langmuir and Freundlich) and kinetic model (pseudo-first and -second). The MIP was successfully synthesized using p-xylene, able to recognize HQ and was very selective to p-CP. Implication of the study, the synthesized MIP can be used for recognition and sensing materials for HQ and any similar molecules.

Investigating intermolecular interactions of surfactant solutions using femtosecond thermal lens spectroscopy

In this study, we examined the impact of various surfactants (oleic acid, butyric acid, Span-20, and CTAB) on the thermophysical properties of methanol (MeOH) using a femtosecond laser-induced thermal lens (TL) spectroscopic technique. Methanol was chosen for its unique convective properties under intense localized heating, making it a promising candidate for studying photothermal responses. We discovered that the TL characteristics of both pure methanol and methanol-surfactant mixtures are significantly influenced by the molecular interactions and physical properties of the components. Our experimental results indicate that the addition of surfactants notably alters the heat transfer dynamics of the solvent by restricting natural molecular movement and modifying thermal properties, which in turn affect the TL signatures. Beyond the surfactant concentration, we observed that the extent of variation in steady-state TL signals, inflection points, and heat transfer mechanisms depends on the molecular properties of the surfactants, such as chain length, the number of active (hydrophilic) groups per molecule, thermal conductivity, viscosity, and intermolecular interactions. Our TL findings provide a detailed investigation into the effect of surfactants on the photothermal response and heat transfer process of a solvent for the first time.

Novel endophytic fungal species Pithoascus kurdistanensis producing morphine compounds

Papaver genus, commonly known as popies, is a valuable source of alkaloids used in medicine, including papaverine, morphine, codeine, and thebaine. We isolated six endophytic fungal isolates producing morphinan alkaloids from four Papaver species growing in Kurdistan Province, Iran. To do this, a 1:1 mixture of methanol and chloroform was used to extract fungal cultures. The contents of morphinan alkaloids in the extracts were subsequently determined using phase high-performance liquid chromatography. Among the morphinan alkaloid-producing fungal isolates, IRAN 4653C had the highest yield giving 23.06 (mg/g) morphine and 2.03 (mg/g) codeine when grown in potato dextrose liquid medium. The identity of this isolate was examined and recognized as a new fungal species named as Pithoascus kurdistanesis sp. nov. based on multi-gene phylogenetic analyses of ITS, TEF-1α, and TUB2 sequences data and morphological features. The morphinan-producing endophytic fungus and the isolated Pithoascus species from Papaver are being reported for the first time. Accordingly, this fungus shows promise as a new source of valuable compounds which is illustrated and introduced here as a new Microascaceae member belonging to Pithoascus from Kurdistan Province, Iran. Moreover, the morphinan productivity of P. kurdistanesis was further validated by gas chromatography-mass spectrometry (GC–MS).

A detailed chemical kinetic model for methanol and ammonia co-oxidation under hydrothermal flames: Reaction mechanism and flame characteristics

A detailed chemical kinetic model for ammonia and methanol co-oxidation under hydrothermal flames was established with pressure and thermodynamic corrections. Simulation model was validated by comparing with experimental temperature rise, and methanol and ammonia removal efficiencies. Species evolutions, reaction paths, and reaction sensitivities for pure ammonia combustion, and ammonia and methanol co-oxidation under hydrothermal flames were analyzed. Ammonia concentration begins to decrease only when methanol is consumed in a certain amount in the ammonia and methanol co-oxidation under hydrothermal flames, indicating the addition of methanol promotes the degradation of ammonia. Moreover, reaction heat is more conductive to ignition and the conversion of ammonia to nitrogen than active free radicals provided from methanol. The ignition delay time presents a minimum as a function of ammonia/methanol concentration ratio, with the minimum values of ignition delay time present at approximately ωNH3/ωCH3OH = 1 for different methanol concentrations. Higher preheating temperatures favor more NOX but less N2O formation, while higher ammonia concentrations favor both NOX and N2O formations. The presence of ammonia increases the laminar flame speed and permits a lower extinction temperature, indicating the mixture of methanol and ammonia can improve the stability of hydrothermal flames.

Study of molecular interaction between benzaldehyde and methanol using microwave dielectric relaxation spectroscopy and radial distribution function

A microwave dielectric relaxation study was conducted for mixtures of benzaldehyde (BZ) and methanol (MeOH) over a frequency range of 200 MHz to 20 GHz at seven different temperatures, ranging from 293.15 K to 323.15 K. The dielectric relaxation parameters, obtained through a fitting process, were used to examine their dependence on concentration and temperature. Thermodynamic parameters, such as Gibbs free energy (ΔG), molar enthalpy of activation (ΔH), and molar entropy of activation (ΔS), were evaluated using the temperature dependence of the dipolar relaxation time. The study provided valuable insights into the molecular interactions and dynamic behavior of the components in the binary mixture system. Additionally, a molecular dynamics (MD) simulation study was conducted on the binary mixture of BZ and MeOH to determine the Radial Distribution Function (RDF) and coordination number for different pairs of molecules and atoms, which revealed information about the binding and arrangement of the local structure.

Determination of ursolic acid in ethanolic extract of Rotheca serrata (L.) Steane & Mabb. by HPLC method

Rotheca serrata (L.) Steane & Mabb. a plant having significant medicinal value is used in treating a fever, rheumatism, inflammation, pain, and malarial fever. Ursolic acid has a five-ringed pentacyclic structure belongs to the family of triterpenoids. It has antioxidant, antitumor, and hepato-protective properties. The method in HPLC was developed on a SHIMADZU, Shimpack ODS (25 cm × 4.6 mm, 5 µm) column. The mobile phase consisted of a 70:25:5 (v/v/v) mixture of methanol, acetonitrile, and 0.02 M ammonium acetate buffer (pH 3.5). A flow rate of 1.2 mL/min and λmax of 215 nm. Ursolic acid from the extract and standard was eluted at the same retention time of 4.1 min. 20–120 µg/mL was the linearity range chosen and was found to be linear (R 2=0.996). The value of LOD was 0.85 µg/mL and LOQ was 1.96 µg/mL. The method for analysis of ursolic was found to be accurate with good repeatability.

Extraction of anthocyanins from purple sweet potato using supercritical carbon dioxide and conventional approaches

This research investigates the potential of supercritical carbon dioxide (SCCO2) technology as a green and sustainable approach to improve anthocyanin extraction from purple sweet potatoes (PSP). The study explored different extraction parameters (i.e., temperatures of 35–55 °C, cosolvent concentrations of 10–30 % (w/w), ethanol ratios of 30–70 % (v/v), pressures of 30–40 MPa, extraction times of 120–180 min, and solvent: sample ratios of 25:1–45:1(v/w)), to optimize the total phenolic content (TPC), anthocyanin content (ANC), and antioxidant activity (AA). Additionally, conventional extraction methods using different solvent (ethanol and methanol) mixtures, solvent: sample ratios (15:1; 45:1; 6:1 (v/w)), temperatures (35–50 °C), and extraction times (50–60 min) were performed for the extraction of phenolic compounds from PSP. The highest TPC (340 mg GAE/g dry PSP), ANC (136 mg C3G/100 g dry PSP), and AA (ABTS (7.3 mg TEV/g dry PSP), DPPH (18.2 mg TEV/g dry PSP), and FRAP (1399 mg GAE/100 g)) were achieved with 30 MPa, 35 °C and 20 % cosolvent concentration operated for 180 min. These findings underscore the use of SCCO2 extraction to obtain anthocyanin extracts that can potentially be used as a coloring agent in the food industry. The proposed SCCO2 extraction method provides an eco-friendly alternative to conventional methods for extracting phenolic compounds.

Influence of Solid Alkaline Photocatalysts Irradiated with UV Light on Fuel Properties of Palm Oil Biodiesel.

TiO2 nanoparticles are full of porosity that can be impregnated with a strong alkaline catalyst CH3ONa to form a TiO2/CH3ONa catalyst. TiO2 of the anatase phase, which is a semiconductor material, has been a prominent photocatalyst due to its excited photocatalyst activity, chemical and biological stability, and nontoxicity. The CH3ONa compound has been widely used as a catalyst for transesterification. Although the synthesized photocatalyst TiO2 powder with CH3ONa is anticipated to greatly enhance the transesterification efficiency, leading to improving biodiesel properties, relevant studies have not been found. After the photocatalyst was prepared, a reactant mixture of palm oil, methanol, and heterogeneous catalyst TiO2/CH3ONa was illuminated by ultraviolet (UV) light from light-emitting diode (LED) lamps. The experimental results revealed that the formation of fatty acid methyl esters was significantly increased to 98.4% with ultraviolet-light illumination for the molar ratio of methanol/palm oil equal to 6 and 3 wt % catalyst addition. The decrease of the catalyst amount to 2 wt % resulted in a slight decrease of the fatty acid methyl esters to 97.06 wt %. The lowest kinematic viscosity and acid value and the highest distillation temperature, heating value, and cetane index were observed under the above reaction conditions. The distillation temperature and cetane index were increased while the acid value was decreased under ultraviolet illumination on the reactant mixture. Consequently, the optimum preparing conditions for biodiesel production were 6 and 3 wt % for the molar ratio of methanol/palm oil and catalyst addition under UV-light irradiation.

The Effect of Pro- and Eukaryotic Inductors on the Synthesis and Antimicrobial Activity of Acinetobacter calcoaceticus IMV B-7241 Surfactants

By now, the mixed cultivation ("co-cultivation") of antimicrobial compound producers with other microorganisms or the introduction of biological inductors in different physiological states (live and inactivated cells, as well as the corresponding supernatants) into the culture medium is a simple, cheap, and effective way to increase the synthesis of practically important microbial metabolites and regulate their biological activity. In most studies, researchers use bacterial strains of various species as inductors, however, in recent years, there have been an increasing number of publications reporting the use of eukaryotic inductors, in response to which there's observed an increase in the synthesis of antimicrobial compounds by the bacterial producers. In addition, the effectiveness of biological inductors depends on the conditions of their cultivation and physiological state. Aim. To study the effect of the methods of preparation and physiological state of biological inductors (gram-negative bacteria Enterobacter cloacae C-8 and yeast Saccharomyces cerevisiae BTM-1) on the activity of biosynthetic enzymes and antimicrobial activity of Acinetobacter calcoaceticus IMV B-7241 surfactants. Methods. Purified glycerol and crude glycerol in equimolar carbon concentration were used as a substrate for cultivation of A. calcoaceticus IMV B-7241. The microbial inductors were grown on both agar and liquid media with glucose as a carbon source. Live or inactivated cells of S. cerevisiae BTM-1 or E. cloacae C-8, as well as the corresponding supernatant, were added to the medium in an amount of 2.5–10 % (v/v). The extracellular surfactants were obtained from the supernatant of the culture liquid by extraction with a mixture of chloroform and methanol (2:1). The antimicrobial activity of surfactants against bacterial (Bacillus subtilis BT-2, Escherichia coli IEM-1, Staphylococcus aureus BMS-1, Pseudomonas sp. MI-2) and yeast (Candida albicans D-6 and Candida tropicalis PE-2) test cultures was determined by the indicator of the minimum inhibitory concentration. The activity of enzymes for the biosynthesis of surface-active glyco- (phosphoenolpyruvate carboxylase, phosphoenolpyruvate synthetase, phosphoenolpyruvate carboxykinase, trehalose phosphate synthase) and aminolipids (NADP+-dependent glutamate dehydrogenase) was analyzed in cell-free extracts obtained after sonication of cells. Results. The introduction into the culture medium of A. calcoaceticus of IMV B-7241 with glycerol of various purification degrees, both pro- and eukaryotic inductors in different physiological states was accompanied by the synthesis of surfactants, the antimicrobial activity of which against the test cultures was higher by one to two orders of magnitude compared to preparations obtained without inductors. It was found that E. cloacae C-8 cells grown in liquid medium were slightly more effective as inductors than those grown in agar medium: the minimum inhibitory concentrations against bacterial and yeast cultures of surfactants synthesised in their presence were 1–6 and 2.5–8 μg/mL, respectively. When live S. cerevisiae BTM-1 or E. cloacae C-8 cells were used as inductors, the production of microbial surfactants with higher antimicrobial activity than those synthesized in the presence of inactivated cells or supernatants was observed: the minimum inhibitory concentrations against the test cultures were in the range of 0.85–16, 2–20 and 1.5–22 μg/mL, respectively. The higher antimicrobial activity of surfactants synthesized in the presence of a pro- or eukaryotic inductor in the medium with purified glycerol may be caused by an increase of aminolipids in their composition, as evidenced by a 1.6–2.1-fold increase in NADP+-dependent glutamate dehydrogenase activity in A. calcoaceticus IMV B-7241 cells compared to the values of cultivation without inductors. The same level of activity of this enzyme during the cultivation of the IMV B-7241 strain in the medium with crude glycerol in the presence of inductors and without them may indicate the synthesis under such conditions of other, than aminolipids, metabolites with antimicrobial activity. Conclusions. As a result of this study, it was established that the antimicrobial activity of A. calcoaceticus IMV B-7241 surfactants can be increased by introducing pro- and eukaryotic inductors in the form of live or inactivated cells, as well as the corresponding supernatants into the medium with glycerol of different degrees of purification.

A stationary phase of tetraethylene glycol-modified silica for separation of phenolic acids

AbstractSilica, as a stationary phase, has low separation efficiency accompanied by overlapping, broadened, and tailed peaks, so it needs to be modified to improve its efficiency. This study aims to develop a silica-based stationary phase modified by tetraethylene glycol (TEG) to separate phenolic compounds. Silica was modified by a chemical bond between silanol groups on the silica surface and TEG through a 3-glycidyloxypropylmethoxysilane reaction. The modified silica was packed into a capillary column and used to separate simple phenolic compounds consisting of phenol, pyrocatechol, and pyrogallol. A sample of 0.2 µL was injected into the capillary liquid chromatography and the mobile phase employed was acetonitrile 98% with a flow rate of 3 μL min−1. Elution was also done isocratically in this process and detection was carried out at a wavelength of 254 nm. The mixture of simple phenolic compounds was successfully separated in less than 7 min. The asymmetry factor and resolution were 1.43–2.12 and 1.72–5.43 respectively. The number of the theoretical plates ranged from 213 to 7,857. Columns containing Si-TEG stationary phase also separate phenolic compounds, which consist of gallic acid, syringic acid, ferulic acid, and caffeic acid. A sample of 0.2 µL was injected into the capillary liquid chromatography and successfully separated the mixture in less than 12 min. The samples were eluted isocratically using a mixture of methanol and 50 mM phosphate buffer pH 2.5 (8:92) with a flow rate of 3 μL min−1. The phenolic acids compounds were detected at a wavelength of 280 nm. The chromatogram showed four separate peaks. The asymmetry factor and resolution were 1.53–1.63 and 1.14–1.74, respectively, but the number of the theoretical plates was low, ranging from 190 to 796.

Spectroscopic, anti-cancer, anti-bacterial and theoretical studies of new bivalent Schiff base complexes derived from 4-bromo-2,6-dichloroaniline

In this paper, four new mono-nuclear Ni(II), Pd(II), Pt(II) and Zn(II) complexes were prepared by using a bi-dentate Schiff base ligand, (E)-2-(((4-bromo-2,6-dichlorophenyl)imino)methyl)-5-chlorophenol (BrcOH), with bivalent ions in a methanol and distil water mixture as solvent in presence of NaOH as base. The structures of the prepared compounds were characterized by spectroscopic techniques (IR and 1H NMR), CHN analysis, and molar conductivity. The M(II) (Ni, Pd and Pt) ions are four-coordinated by a bi-dentate N2O2 donor ligand, forming square planar geometry, whereas the Zn(II) is coordinated as a tetrahedral geometry. The newly synthesized compounds, which include the Schiff base ligand and its complexes, underwent antibacterial screening against E. coli and S. aureus. The results demonstrated a remarkable and noteworthy biological activity of these compounds against these pathogenic bacterial strains. Different binding energies showed good correlation, with Pd showing the strongest binding. Small energy differences indicated high reactivity, with Ni and Pd complexes being the most reactive. Electrophilicity index exhibited electron-accepting properties, with Zn showing the highest reactivity. The dipole moments showed polarity and charge separation, with Pt having the highest polarity. We evaluated the pharmacokinetic properties (ADME) of a ligand and its metal complexes using the Swiss ADME website. The results of the in-silico prediction of physicochemical properties revealed that ten compounds in total adhered to Lipinski's rule.