Dimethyl Sulfoxide-methanol Research Articles

Green solvent-based extraction of three Fabaceae species: A potential antioxidant, anti-diabetic, and anti-leishmanial agents

The Fabaceae is renowned for its diverse range of chemical compounds with significant biological activities, making it a valuable subject for pharmacological studies. The chemical composition and biological activities of three Fabaceae species were investigated using methanol separately and in combination with dimethyl sulfoxide (DMSO) and glycerol for extraction. The results revealed the highest phenolic (49.59 ± 0.38 mg gallic acid equivalent/g), flavonoid (29.16 ± 0.39 mg rutin equivalent/g), and alkaloid (14.23 ± 0.54 mg atropine equivalent/g) contents in the Caesalpinia decapetala methanol extracts. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and DNA protection activity were the highest (0.88 ± 0.43 μg/mL IC50 and 2149.26 band intensity) in Albizia julibrissin methanol extracts. The α-amylase activity was highest in all methanol extracts (<15 μg/mL IC50 values), while the α-glucosidase inhibition potential was highest (<1 μg/mL IC50 value) in the methanol–glycerol and methanol–DMSO extracts. Pearson coefficient analysis showed a strong positive correlation between the DPPH and α-amylase assays and phytochemicals. Anti-leishmanial activity was observed in decreasing order: A. julibrissin (74.75 %) > C. decapetala (70.86 %) > Indigofera atropurpurea (65.34 %). Gas chromatography-mass spectrometry revealed 33 volatile compounds and, aamong these (Z)-9-octadecenamide was detected in the highest concentration ranging from 21.85 to 38.61 %. Only the methanol extracts of the examined species could be assessed for in vivo studies for immediate applications.

The investigation of the ultrafast excited state deactivation mechanisms for coumarin 307 in different solvents.

The intramolecular charge transfer (ICT) and twisted intramolecular charge transfer (TICT) processes of coumarin 307 (C307) in different solvents were investigated by performing steady-state/time-resolved transient absorption spectroscopic and steady-state photoluminescence spectroscopic characterizations in combination with time-dependent density functional theoretical calculation (TDDFT). The study unveiled the remarkable influence of solvent polarity and the strength of intermolecular hydrogen bonds formed between the solutes and solvents on the relaxation dynamics of the electronic excited state. Significantly, the emergence of the TICT state was observed in polar solvents, specifically dimethylformamide (DMF) and dimethyl sulfoxidemethanol (DMSO), owing to their inherent polarity as well as the enhanced intermolecular hydrogen bonding interactions. Interestingly, even in a weak polar solvent such as methanol (MeOH), the TICT state was also observed due to the intensified hydrogen bonding effects. Conversely, nonpolar solvents, exemplified by 1,4-dioxane (Diox), resulted in the stabilization of the ICT state due to the augmented N-H⋯O hydrogen bonding interactions. The experimental findings were corroborated by the computational calculations, thus ensuring the reliability of the conclusions drawn. Furthermore, schematic diagrams were presented to illustrate the mechanisms underlying the excited-state deactivation. Overall, this investigation contributes valuable mechanistic insights and provides a comprehensive understanding of the photochemical and photophysical properties exhibited by coumarin dyes.

Preparation and structural characterization of regioselective 4-O/6-O-desulfated chondroitin sulfate

The sulfation pattern plays a crucial role in chondroitin sulfate (CS) biological activity, and preparation of CS with defined structure is essential for accurate pharmacological study. In this study, we focused on the preparation of regioselective 4-O/6-O-desulfated CS derived from porcine, employing a dimethyl sulfoxide-methanol (DMSO-MeOH) method and an N-methyl-N-(trimethylsilyl) -trifluoroacetamide (MTSTFA) method CS, respectively. Results showed that the sulfate at C4 position (4-O-S) of N-acetylgalactosamine (GalNAc) was selectively removed by the DMSO-MeOH method, and the sulfate at C6 position (6-O-S) of GalNAc was selectively removed by the MTSTFA method. Structures of desulfated CS were characterized by means of FT-IR, NMR and disaccharide composition analysis. The preparations of regioselective 4-O/6-O-desulfated CS are powerful for the study of structure-activity relationship of CS.

Investigations of preferential solvation on some poly(siloxane-azomethine)s containing dihydroxyanthraquinone units

UV/VIS absorption and emission spectra of some polyazomethines containing dihydroxyanthraquinone units and siloxane moieties have been investigated in solvents of different polarities. The Catalan solvent scale was used for describing the solvatochromic shifts of the absorption and emission bands. The influence of the solvent and composition of binary solvent mixtures on the solvation of the absorption and emission maxima have been studied. The following binary solvent mixtures were utilized: methanol-dimethyl sulfoxide (MeOH-DMSO), chloroform-DMSO (CHCl3-DMSO) and chloroform-methanol (CHCl3-MeOH). The preferential solvation parameters local mole fraction (X2), excess function (δs2) and preferential solvation constant (KPS) were determined.

Chromatographic analysis of ivabradine on polar, nonpolar and chemically modified adsorbents by HPTLC

Thin-layer chromatography (TLC) was used to evaluate the behavior of ivabradine in various chromatographic systems. The mobile phases used were aqueous (methanol–water and acetonitrile–water) and non-aqueous (methanol–acetonitrile and methanol–dimethyl sulfoxide) in a wide range of concentrations (0–100%, v/v). The stationary phases used were high-performance TLC plates: Kieselgel 60 F254 S, RP-2 F254 S, RP-8 F254 S, RP-18 F254 S, RP-18 WF254 S, Kieselgel 60 CN F254 S, Kieselgel 60 Diol F254 S, and Kieselgel 60 NH2 F254 s; and TLC plates: aluminum oxide 150 F254, cellulose F, and polyamide 11 F254. The usefulness of various mobile and stationary phases in the separation of ivabradine was demonstrated. Retention mechanisms as well as the Soczewiński-Snyder equation are discussed.

Potentials of mean force of sodium chloride ion pair in dimethyl sulfoxide–methanol mixtures

The constrained molecular dynamics technique has been used to simulate solutions of sodium chloride ion pair in pure methanol (MeOH), pure dimethyl sulfoxide (DMSO) and DMSO–MeOH mixtures with MeOH mole fractions (xMeOH) of 0.25, 0.50 and 0.75. The potentials of mean force (PMFs) of the sodium chloride ion pair have been computed for all the above compositions. The PMFs for the pure solvents indicate that contact ion pairs (CIPs) are more stable than the solvent separated ion pairs (SSIPs). In the mixtures, contact ion pairs (CIPs) dominate the PMF and solvent assisted ion pairs (SAIPs) persist in all the compositions. As the mole fraction of DMSO increases, the stability of CIP increases. In all three solvent mixtures, the Na+Cl− ion pair is preferentially solvated by MeOH molecules. These results have been confirmed by dynamical ion pair trajectories for long times. A study of the running coordination numbers in the CIP and SAIP/SSIP configurations shows that the number of DMSO and methanol molecules around the ion pair does not change significantly with composition beyond xMeOH=0.50.

Use of Catalytic Fluoride under Neutral Conditions for Cleaving Silicon–Oxygen Bonds

This Article describes the development of conditions for cleaving silicon-oxygen bonds using catalytic quantities of fluoride at neutral pH in mixed organic-aqueous solutions that contain buffer. A variety of silicon protecting groups can be removed under these conditions, which show tolerance for acid- and base-sensitive groups. A modified procedure also is presented using catalytic fluoride in anhydrous dimethyl sulfoxide-methanol, which generates primarily volatile silicon byproducts.

Simple thin-layer chromatographic method for analysis of ranitidine in its pharmaceutical formulations: Application to the analysis of photolytic degradation products

Thin-layer chromatography and high-performance thin-layer chromatography have been used for analysis of ranitidine hydrochloride standard, the components of ranitidine medications (Ranic, Ranisan, Ranitin, Ranigast, and Zantac), and the products from photolytic degradation of these medications. Chromatograms were developed with methanol-water, methanol-acetonitrile, methanol-dimethyl sulfoxide (DMSO), methanol-aqueous ammonia solution, methanol-ethyl acetate, and acetonitrile-DMSO mobile phases. Retention and separation were compared and the applicability of particular mobile phases for analysis of ranitidine standard and the products obtained from photolysis of ranitidine generic drugs was studied.

Purification of high-throughput organic synthesis libraries by counter-current chromatography

Experiments were performed to evaluate whether counter-current chromatography (CCC) could function as an alternative purification method to reversed-phase high-performance liquid chromatography (RP-HPLC) and normal-phase supercritical fluid chromatography (SFC). RP-HPLC and SFC are the routine methods currently used in our high-throughput purification (HTP) facility for the purification of high-throughput organic synthesis (HTOS) libraries and medicinal chemistry reaction mixtures. Pre-equilibration of the solvent mixture layers was not mandatory for effective chromatography when hexanes–ethyl acetate–methanol–water (HEMW) solvent mixtures were used. Key to the use of CCC for high-throughput applications is the ability to effectively select a solvent system appropriate to each library member. Pilot-scale CCC elution time was used to estimate a starting solvent ratio and RP-HPLC retention time was then used to adjust solvent ratios within a particular library. It was also found that dimethyl sulfoxide (DMSO) and DMSO–methanol were suitable as sample injection solvents when using the HEMW solvent systems.

Structure and tribological properties of amorphous carbon films deposited by electrochemical method on GCr15 steel substrate

Amorphous carbon films were deposited on GCr15 steel substrates by electrolysis of methanol, dimethylsulfoxide (DMSO) and the methanol–DMSO intermixture electrolytes, respectively, under high voltage and low temperature conditions. The microstructure and wear morphology of the deposited films were analyzed using X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) combined with energy dispersive X-ray fluorescence spectrometer (EDX), respectively. The tribological properties of the films were evaluated using a ball-on-disk rotating friction tester under dry friction condition. The results show that the films deposited by electrodeposition technique on GCr15 steel substrates are amorphous carbon films. It is also found that the electrolytes have an obvious influence on the tribological properties of the deposited films with the electrodeposition method. The tribological properties of the films deposited with the intermixture electrolyte are better than those of the films deposited by other pure electrolytes. The related growth mechanism of the films in the liquid-phase electrodeposition is discussed as well in this study. Via the reaction of the CH 3 groups with each other to form carbon network and reaction of the CH 3 and SO 2+ groups to achieve the doping of sulfur atom in the carbon network, respectively, in other words, amorphous carbon films can be obtained on GCr15 steel substrates by electrodeposition technique.

Excess molar enthalpies and heat capacities of dimethyl sulfoxide + seven normal alkanols at 303.15 K and atmospheric pressure

Excess molar enthalpies and heat capacities of binary mixtures containing dimethyl sulfoxide (DMSO) + seven normal alkanols, namely methanol, ethanol, propan-1-ol, butan-1-ol, hexan-1-ol, octan-1-ol, and decan-1-ol, have been determined at 303.15 K and atmospheric pressure. With the exception of the DMSO–methanol system, which shows negative values, all mixtures show positive values of excess molar enthalpies over the whole range of mole fraction, increasing as the number of carbon atoms increases. Heat capacities of pure components have been determined in the range 288.15 < T (K) < 325.15. Molar heat capacities of the mixtures are always positive and decrease as the number of carbon atoms decreases. The results were fitted to the Redlich–Kister polynomial equation. Molecular interactions in the mixtures are interpreted on the basis of the results obtained.

Guest-induced chain folding in amphiphilic calixarene structures

Amphiphilic calixarenes represent a promising class of derivatives, potentially useful for transporting molecules because of their ability to self-organize as Solid Lipid Nanoparticles in water. The current study shows that after derivatization of the para-H-calix[4]arene with hexanoyl chains, the resultant amphiphilic calixarenes retain their properties to complex small organic molecules. The solid structures of the complexes of para-hexanoyl-calix[4]arene with methanol, dimethylformamide–methanol, dimethyl sulfoxide–methanol and nitrobenzene are reported. As for the p-tert-butyl calix[4]arene, aliphatic guests are stabilized by a variety of short-range interactions including C–H⋯π or π−π interactions. Moreover, the presence of the grafted hydrophobic chains generates an extension of the hydrophobic calixarene cavity and thus provides another site where complexation can take place. The structures show that the geometry of the hexanoyl chains is modified by the presence of the guest molecules and that the chains fold over to aid encapsulation of the guest.

σ-Complexes as biochemical and biophysical probes. Part 6. The interaction of N-2,4,6-trinitrophenyl-L-lysine with methoxide ion in dimethylsulfoxide-methanol (95%-5% v/v) mixture: proton transfer and σ-complex formation

The interaction of N-2,4,6-trinitrophenyl-L-lysine as the hydrochloride salt, 1, with methoxide ion in dimethyl sulfoxide-methanol (DMSO-MeOH, 95/5, v/v) mixture has been investigated using UV-visible spectrophotometry at 25 o C. An initial 1:1 interaction between MeO - and 1 results in the rapid and reversible deprotonation of N(1)-H while a 2:1 interaction involves the rapid transfer of a proton from NH3 + to the base. Deprotonation of N(1)-H in 1 is thus the kinetically and thermodynamically preferred process. At mole ratios MeO - :1 being > 3, addition of the MeO - nucleophile to the C-3 position of the doubly deprotonated substrate generates a σadduct. The order of acidity: N(1)-H > NH3 + > COOH which emerges in 1 is attributed to characteristic solute-solvent interactions involving delocalized anions in the DMSO-MeOH solvent mixture. The significance of the inversion of acid strengths observed in this study, in relation to general acid-base catalysis by protein residues in the non-aqueous environment of enzyme active sites in biological systems, is highlighted.

NMR Study of the Stoichiometry, Stability, and Ligand Interchange of Silver Ion-Hexathia-18-crown-6 Complex in Binary Dimethyl Sulfoxide Solvent Mixtures at 300 K

Proton NMR was used to study the complexation reaction between silver ion and hexathia-18-crown-6 in a number of binary mixed solvents of dimethyl sulfoxide with acetonitrile and methanol. Formation constants for the resulting 1:1 complexes in different solvent mixtures were determined by computer fitting of the chemical shift-mole ratio data. The influence of solvent composition on the stability of the resulting complex is discussed. The exchange kinetics of Ag+-hexathia-18-crown-6 in 70-30 wt.% dimethyl sulfoxide-acetonitrile and 75-25 wt.% dimethyl sulfoxide-methanol were studied by proton NMR line-shape analysis. In both solvent mixtures, the exchange of thiacrown ether between the free and complexed sites was found to proceed via a dissociative pathway. The exchange rates and the activation parameters Ea, Δ H‡, Δ S‡, and Δ G‡ for the ligand exchange were determined and the influence of solvent properties on these parameters discussed.

Substituent Effect on Acidity of Substituted 2-(4-Nitrobenzoylamino)alkanamides in Methanol-Dimethyl Sulfoxide Mixtures

The dissociation constants of substituted 2-(4-nitrobenzoylamino)alkanamides, N-[2-(4-nitrobenzoylamino)alkanoyl]pyrrolidines, and N-alkyl-4-nitrobenzamides have been measured spectrophotometrically in 60 and 80% v/v DMSO. The pKA values of these N-acids are discussed from the point of view of substituents at the acetamide α-carbon atom.

Kinetics and Mechanism of Cyclization of Substituted 2-(Benzoylamino)alkanamides in Strongly Basic Medium

The cyclization reaction of substituted 2-(benzoylamino)alkanamides 1a-1i giving the corresponding substituted 2-phenylimidazol-4(5H)-ones 2a-2i has been studied. The equilibrium constants of reactions of compounds 1d-1f and 2-[(4-nitrobenzoyl)amino]-2,3-dimethylbutanenitrile (3) with methoxide have been determined in methanol-dimethyl sulfoxide media. For compound 1d and N-methyl derivatives 1a-1c, the cyclization rate constants have been measured in dependence on methoxide concentration in media of varying contents of dimethyl sulfoxide. The cyclization reaction mechanism involves formation of anion in a rapid pre-equilibrium and subsequent rate-limiting step: either formation of a cyclic intermediate or splitting off of OH- ion from this intermediate. The product formed in the given medium is immediately transformed into its conjugate base. A change in reaction medium affects the reactions of all the compounds in the same way. The ratio of concentration of substrate to that of its anion at low methoxide concentrations is affected by the solvent composition (MeOH-DMSO). At higher methoxide and DMSO concentrations the reaction rate distinctly decreases, which can be interpreted by the transformation of reactive anion into non-reactive dianion. The corresponding N-methylbenzoylamino compounds are cyclized faster by a factor of 400 as compared with compounds having no methyl group at the benzamide group.

Dissociation of Amides in Strongly Basic Medium of Sodium Methoxide in Dimethyl Sulfoxide-Methanol Mixtures

The dissociation constants of eleven amides have been measured in methanol and its mixtures with dimethyl sulfoxide (10 to 80% v/v) using sodium methoxide as the base. The experimental dissociation constants have been used to construct the H- acidity function as a function of methoxide concentration and composition of the DMSO-MeOH mixture as well as function of methoxide concentration in methanol. Moreover, with the help of construction of acidity function, the functions have been devised for constant sodium methoxide concentrations (0.025, 0.1, and 0.2 mol l-1) and changing composition of the DMSO-MeOH mixture.

Stopped-Flow Kinetics of the Formation and Decomposition of 2,4- and 4,4-Disubstituted Meisenheimer Complexes in the Reaction of 4-Piperidino-1,3-dinitrophenanthrene with Potassium Methoxide in Dimethyl Sulfoxide–Methanol

Abstract The formation of 2,4-disubstituted anionic σ complex, followed by the formation of 4,4-disubstituted one was confirmed by means of absorption and NMR spectra in the reaction of 4-piperidino-1,3-dinitrophenanthrene with potassium methoxide in DMSO–CH3OH. The rates and activation parameters were determined by kinetic studies using stopped-flow and conventional spectrophotometers. It was found, compared with the previous results on the naphthalene system that the presence of H5 of the title compound affects the rates differently.

Formation of spiro adduct from N-methyl-N-(2,4,6-trinitrophenyl)glycine anion

The intramolecular nucleophilic addition of N-methyl-N-(2,4,6-trinitrophenyl)glycine anion in methanol-dimethyl sulfoxide mixtures produces spiro[(3-methyl-5-oxazolidinone)-2,1'-(2',4',6'-trinitrobenzenide)]. The spiro adduct has been identified by means of 1H and 13C NMR spectroscopy. This is the first case when the formation of a Meisenheimer adduct with carboxylate ion is observed. Logarithm of the equilibrium constant of adduct formation increases linearly with the mole fraction of dimethyl sulfoxide in its mixture with methanol.

ChemInform Abstract: Reactions in Strongly Basic Media. Part 9. Correlation of the Rates of Methoxide‐Catalyzed Methanolysis of 1‐Substituted 2,4‐Dinitrobenzenes and 2‐Substituted 5‐Nitropyridines in Methanolic Dimethyl Sulfoxide with an Acidity Function. Details of the Mechanistic Pathway.

ChemInform Abstract: Reactions in Strongly Basic Media. Part 9. Correlation of the Rates of Methoxide‐Catalyzed Methanolysis of 1‐Substituted 2,4‐Dinitrobenzenes and 2‐Substituted 5‐Nitropyridines in Methanolic Dimethyl Sulfoxide with an Acidity Function. Details of the Mechanistic Pathway.