Aqueous Solutions Of Sodium Salicylate Research Articles

Enhanced Antimalarial Activity of Extracts of Artemisia annua L. Achieved with Aqueous Solutions of Salicylate Salts and Ionic Liquids.

Artemisinin, a drug used to treat malaria, can be chemically synthesized or extracted from Artemisia annua L. However, the extraction method for artemisinin from biomass needs to be more sustainable while maintaining or enhancing its bioactivity. This work investigates the use of aqueous solutions of salts and ionic liquids with hydrotropic properties as alternative solvents for artemisinin extraction from Artemisia annua L. Among the investigated solvents, aqueous solutions of cholinium salicylate and sodium salicylate were found to be the most promising. To optimize the extraction process, a response surface method was further applied, in which the extraction time, hydrotrope concentration, and temperature were optimized. The optimized conditions resulted in extraction yields of up to 6.50 and 6.44 mg·g-1, obtained with aqueous solutions of sodium salicylate and cholinium salicylate, respectively. The extracts obtained were tested for their antimalarial activity, showing a higher efficacy against the Plasmodium falciparum strain compared with pure (synthetic) artemisinin or extracts obtained with conventional organic solvents. Characterization of the extracts revealed the presence of artemisinin together with other compounds, such as artemitin, chrysosplenol D, arteannuin B, and arteannuin J. These compounds act synergistically with artemisinin and enhance the antimalarial activity of the obtained extracts. Given the growing concern about artemisinin resistance, the results here obtained pave the way for the development of sustainable and biobased antimalarial drugs.

New Zinc Coordination Compound with Simple Salicylato and Pyridine Ligands: Synthesis, Crystal Structure and Hirshfeld Surface Analysis

A novel mononuclear zinc coordination compound with formula [Zn(Hsal)2(Py)2] (H2sal = salicylic acid, Py = pyridine) was prepared by mixing aqueous solutions of sodium salicylate and zinc sulfate in 1:1 molar ratio, and to the resulting solution pyridine was added dropwise. The obtained compound was characterized by elemental analysis, IR spectroscopy, and its crystal structure was determined by single-crystal X-ray diffraction method. X-ray structure analysis has shown that the central zinc ion is four-coordinated by two monodentate salicylato ligands and two pyridine molecules, forming a distorted tetrahedron. Since the asymmetric unit consists of two halves of coordination molecules, orthorhombic Ibca space group symmetry leads to two coordination molecules with slightly different geometry. The comparison between the two is given in terms of interatomic distances and angles, and also in terms of differences in intermolecular interactions obtained as a result of Hirshfeld surface analysis. With the assistance of C-H…O interactions, the adjacent molecules are linked into chains and further connected into three-dimensional network.

Study to reconnoiter solvation consequences of l-arginine/l-histidine and sodium salicylate in aqueous environment probed by physicochemical approach in the temperature range (293.15–318.15) K

Abstract The densities, ρ, ultrasonic speeds, u and viscosities, η of l-arginine and l-histidine in aqueous-sodium salicylate (1% and 2% sodium salicylate in water, w/w) solvents were measured at temperatures (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K and at atmospheric pressure in seven different concentrations. The experimental density data have been used to calculate the apparent molar volume, Vϕ, limiting apparent molar volume, Vϕ° and transfer volume, Vϕ, tr°. Likewise from the ultrasonic speed data, different thermo-acoustical parameters, such as apparent molar compressibility, Ks,ϕ, limiting apparent molar compressibility, Ks, ϕ° and transfer compressibility, Ks, ϕ, tr° have been evaluated. The viscosity data have been used to determine Falkenhagen Coefficient, A, Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δμ1°# and solute, Δμ2°#, entropies, ΔS°# and enthalpies, ΔH°# of activation of viscous flow. These parameters have been discussed in light of solute-solute and solute-solvent interactions prevailing in these solutions and their variations are revealed to get the basic picture of the molecular interactions occurring in the systems studied. The negative values of dB/dT favour structure making behavior of amino acids in aqueous solutions of sodium salicylate. The free energy parameters indicate the formation of transition state in the presence of amino acids.

Coupled mutual diffusion in aqueous sodium (salicylate + sodium chloride) solutions at 25 °C

Taylor dispersion is used to measure the binary mutual diffusion coefficient (D) of aqueous solutions of sodium salicylate (NaSal), a non-steroidal anti-inflammatory drug (NSAID). The D° value estimated by extrapolation to zero NaSal concentration is used to calculate the limiting mobility of the Sal− ion for comparison with the value determined previously from conductivity data. Salt effects on NSAID diffusion are studied by measuring the ternary mutual diffusion coefficients (Dik) of aqueous NaSal(C1) + NaCl(C2) solutions, including results for the diffusion of NaSal in physiological saline solutions with C2 = 0.15 mol dm−3. As the NaCl:NaSal ratio increases, NaSal diffusion coefficient D11 changes from the binary diffusion coefficient of aqueous NaSal (a weighted average of the Na+ and Sal− diffusion coefficients) to the tracer diffusion coefficient of the Sal− ion in NaCl solutions. Coupled diffusion in the solutions is analysed by using Nernst-Planck equations to calculate the fluxes of ions migrating in the electric field (diffusion potential) generated by NaSal and NaCl concentration gradients.

A new interpretation of the mechanism of wormlike micelle formation involving a cationic surfactant and salicylate

HypothesisWhen tetradecyltrimethylammonium bromide, TTAB, is added to aqueous solution of sodium salicylate, NaSal, the threading of the aromatic anion into the micellar palisade leads to the formation of wormlike micelles. Based on the calorimetric titration of NaSal with TTAB, and on the lifetime of fluorescence of salicylate, we propose that the aggregation of the two components directly leads to the formation of wormlike micelles, without any pre-aggregation. ExperimentsBy using an isothermal titration calorimeter, aliquots of TTAB were added to a dilute solution of NaSal. The energy involved in each addition was then integrated and the variation of enthalpy was determined. In the same range of concentrations and molar ratios, the surface tensiometry and time-resolved emission spectroscopy experiments were performed. FindingsA very characteristic calorimetric signal associated with wormlike micelle formation was obtained, being the enthalpy variation of this process, ΔWLMH2980 < 0. When 1.2 mmol L−1 of NaSal is titrated with 11.0 mmol L−1 of TTAB at 298.15 K, ΔfH2980 = −10.31 kJ per mol of injectant. By adding TTAB to NaSal solution, two fluorescence lifetimes of salicylate were observed solely after wormlike micelle being formed. The correspondent lifetime values of 4.0 ns and 7.2 ns are respectively associated with the free and associated species of salicylate. The new results demonstrated that wormlike micelles are the first aggregate formed when TTAB is added to salicylate. This aspect is relevant for understanding the mechanism of wormlike micelles formation.

In-situ odd random phase electrochemical impedance spectroscopy study on the electropolymerization of pyrrole on iron in the presence of sodium salicylate – The influence of the monomer concentration

In this work, the potentiostatic electropolymerization of polypyrrole (PPy) on iron in aqueous solution of sodium salicylate and pyrrole is studied in situ by odd random phase electrochemical impedance spectroscopy (ORP-EIS). The influence of the pyrrole concentration on the electrosynthesis process is investigated. The ORP-EIS technique ensures a reliable analysis of the PPy electrosynthesis on iron by means of an advanced data analysis of the non-linear and non-stationary behaviour and the signal-to-noise ratio of the system. Additionally, the structure and the chemical nature of the PPy film on iron are studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and glow discharge optical emission spectroscopy (GDOES). The results of the characterization confirm the presence of the passivation layer at the PPy/iron interface formed prior to the polymer deposition. The modelling of the impedance evolution over time provides the quantitative analysis of the electropolymerization of PPy on iron. The results show that the electrosynthesis of pyrrole on oxidizable iron in the presence of sodium salicylate is a complex process, which includes not only the pyrrole oxidation reactions but also reactions such as the oxidation/reduction of the iron surface and/or reactions between the iron, formed interlayer and polypyrrole.

Ultrasonic studies on paracetamol in aqueous solutions of sodium salicylate and nicotinamide

Solubility enhancement of poorly soluble drug, paracetamol using hydrotropic agents like sodium salicylate and nicotinamide has been studied. In the present investigation, 1, 2, 3 and 4M of both sodium salicylate and nicotinamide are employed to enhance the solubility of poorly soluble paracetamol to study its different physico-chemical properties at 298.15, 303.15, 308.15 and 313.15K. The values of density (d) and sound velocity (U) have been measured in aqueous paracetamol and paracetamol+aqueous solutions of sodium salicylate and nicotinamide separately in five different concentrations. Densities of these solutions were measured at the above said four temperatures but the ultrasonic velocities (U) have been measured at 298.15K only. Experimental density data have been used to estimate various important parameters, such as apparent molar volume (Vɸ), limiting apparent molar volume (Vɸ0), apparent molar expansibility (Eɸ) and limiting apparent molar expansibility (Eɸ0). Further, from the ultrasonic data, different thermo-acoustical parameters, such as isentropic compressibility (Ks), apparent molar isentropic compressibility (Ks, ɸ), acoustic impedance (Z), molar compressibility (W), free volume (Vf), internal pressure (πi), molar sound velocity (R) and relative association (RA) have been evaluated and discussed in the light of solute-solute and solute-solvent interactions.

Study of the electrochemical stability of polypyrrole coating on iron in sodium salicylate aqueous solution

In this work electrochemical stability of optimized PPy film on iron in aqueous solution of sodium salicylate is studied. The main drawback of conducting polymers is their possibility to undergo an irreversible degradation (overoxidation). The overoxidized polymers lose their properties, for example, conductivity and redox activity, what excludes them from some practical applications. This study demonstrates that lowering the concentration of salicylate in the electrolyte increases the electrode potential, at which overoxidation of PPy begins. It widens the electrode potentials, within which such a polymer can be used. Moreover, it is evidenced that even though the electrolyte concentration is lowered, the redox activity and the electrical properties of the PPy film are retained.

Semibatch reaction crystallization of salicylic acid

Reaction crystallization of salicylic acid has been investigated by experiments and modeling. In the experimental work, dilute hydrochloric acid has been added to an agitated aqueous solution of sodium salicylate in 1L scale, and product crystals have been characterized by image analysis. The results show that the product crystal number mean size at first increases with increasing agitation rate but then gradually decreases again at further increase in stirring rate. At lower stirring rate, larger crystals are obtained when the feeding point is located close to the agitator instead of being located out in the bulk solution. The mean crystal size increases with decreasing feeding rate and with decreasing reactant concentrations. There is a decrease in mean size with increasing feed pipe diameter. These trends in the experimental results show great similarity with previous results on benzoic acid. The experimental results have been examined by a population balance model accounting for meso and micro mixing, and crystal nucleation and growth rate dispersion. It is found that the crystallization kinetic parameter estimation is quite complex, and the objective function hyper surface contains many different minima. Hence, parameter estimation has to rely on a combination of mathematical optimization strategies and a scientific understanding of the physical meaning of the parameters and their relation to current theories. As opposed to our previous work on benzoic acid, it has not been possible to find a set of kinetic parameters that provides for a good description of all experimental data.

Minimum Hydrotrope Concentration Behavior of Aqueous Solution of Sodium Salicylate in Presence of Additives

Hydrotropes are regaining importance in the currently blossoming field of self-organizing molecular systems. Their hydrophile-lipophile balance being on the higher side, their water solubility is significantly more than that of traditional surfactants, and, yet, they provide a sequestered niche or microenvironment for the solubilizate. Hydrotropes start aggregating at a certain concentration known as minimum hydrotrope concentration (MHC). The MHC values fall in the molar range because of which hydrotropes applications are reducing. In this article, the effect of various additives such as alcohols, electrolytes, surfactants, amines, and organic compounds on the behavior of sodium salicylate (NaSal) was investigated using viscosity measurement.

The use of a thermoelectric osmometer to measure the osmotic coefficients of aqueous solutions of sodium salicylate at 25 degrees.

Abstract The use of a thermoelectric osmometer to measure osmotic coefficients for the binary system water-sodium salicylate at low concentrations (0·0 to 0·3 molal) is described. The accuracy and reproducibility of the instrument have been enhanced by employing a microscope to measure sample and reference drop sizes. Activity coefficients, calculated from the osmotic coefficients obtained in these experiments, have been combined with density and diffusional measurements to calculate frictional coefficients for the system.

NMR and neutron scattering studies on spherical and rod-like micelles of dodecyltrimethylammonium bromide in aqueous sodium salicylate solutions

The effect of sodium salicylate (NaSal) additives on micellar structure and dynamics in aqueous solution of dodecyltrimethylammonium bromide (DTAB) has been studied by means of 1H-NMR and quasielastic neutron scattering (QENS) measurements. The molar ratio R (= C NaSal/ C DTAB) dependence on the peak shape of the NMR spectra revealed that a sphere-to-rod-like micellar transition took place around R=0.5. The chemical shift for the 1H atoms of the alkyl group of DTA + ion gave the information for the binding site of Sal − ion in micelles. The R dependence on the chemical shift for the aromatic group of Sal − ion clarified the selective binding feature of Sal − ion in micelles. The dynamic structure factor, S( Q, E), of the micellar molecules exhibited apparent broadening of the elastic scattering peak which was fitted well to a single Lorentzian function. The self-diffusion coefficient D was obtained from the Q-dependence of the HWHM of the Lorentzian function. The slope of D vs. R curve changed around the transition ratio ( R=0.5), reflecting the dynamic slowing down of the local relaxational motion of the micellar molecules in rod-like micelles.

Molecular Complex Formation between Riboflavin and Salicylate in an Aqueous Medium

Abstract Evidence for an intermolecular interaction of riboflavin and sodium salicylate in an aqueous medium was obtained from the presence of isosbestic points in the absorption spectra and an isoemissive point in the emission spectra. The equilibrium constant was estimated from absorption and emission studies, and also from the solubility of riboflavin in an aqueous solution of sodium salicylate, and was found to be in the range of 10–14 mol dm−3. Lifetime measurements indicate a predominantly static mechanism of quenching. The Stern–Volmer constant for the quenching of riboflavin by sodium salicylate was significantly reduced upon the addition of urea. An MD simulation study on the system revealed a stacked conformation, which is probably due to a hydrophobic interaction of the two components.

Industrial polypyrrole electrodeposition on zinc-electroplated steel

Polypyrrole films were electrodeposited on zincated surfaces in a one-step process from aqueous solutions of sodium salicylate and pyrrole. This electrolyte passivates the substrate and makes it possible to obtain strongly adherent PPy films with controlled thickness by electrolysis at constant current. With a view to industrial application for rapid polymerization on common metals, an aqueous solution of 2 M sodium salicylate and 0.5 M pyrrole at pH 5 and room temperature provides optimum conditions. Laboratory studies and deposition with a pilot cell show that 2 μm of polymer can be deposited in 1 s with a current density of 70 A dm−2.

A study of a permanently coated polymeric column for simultaneous separation of inorganic anions and mono-carboxylic acids

A polymeric PRP-1 reversed-phase column was modified by coating it with hexadecyltrimethylammonium bromide and has been used as an analytical column for the separation of inorganic anions and mono-carboxylic acids. An aqueous solution of sodium salicylate was used as the mobile phase and the detection was performed by indirect UV detection. The exchange capacity of the permanently coated column was controlled by changing the concentration of the organic modifier, acetonitrile, in the coating solution. The coated column with a low ion-exchange capacity has a dual retention mechanism of ion-exchange and surface adsorption for carboxylic acids. The contribution of the two mechanisms in the separation was qualitatively evaluated under three chromatographic conditions, by means of equations for ion-exchange chromatography, an adsorption model of the electrical double layer and the separation factor. The extra-column factors that influence the retention of the surface adsorption of the carboxylic acids were discussed. Among the factors studied, the pH of the mobile phase plays a double role, i.e. adjusting the eluting strength and governing the contribution of each mechanism to the separation. Under the chromatographic conditions selected, simultaneous separation of inorganic anions and mono-carboxylic acids was achieved.

Self diffusion and viscoelasticity of elongated micelles from cetyltrimethyl-ammonium bromide in aqueous sodium salicylate solution. II. Temperature effect

Forced Rayleigh scattering and dynamic viscoelastic experiments are performed to study slow global motions of networks formed by elongated micelles from cetyltrimethylammonium bromide (CTAB) in aqueous sodium salicylate (NaSal) solutions at six temperatureT from 25° to 60°C. The CTAB concentrationCD of the solutions is fixed atCD=0.01 M and a ratio of salt concentrationCs toCD is varied from 1 to 41. The self-diffusion coefficientD of the dye-labeled cetyldimethylamine incorporated in the micelles shows a complicatedCs/CD dependence with a maximum that is followed by a minimum at lower temperatures, but these two extremes gradually disappear with increasingT. TheCs/CD dependencies of both the steady-state viscosity η and the terminal relaxation time τ are found consistent with the diffusion behaviour. TheD of all solutions tested monotonically increases withT, but shows different functional dependence onT asCs/CD varies. The applicability of the theory of Brownian motion of a rigid rod in the semidilute regime is examined usingD and τ values.

The cytogenetic effects of sodium salicylate on the root meristem cells of A lium sativum L.

The cytogenetic effects of sodium salicylate were investigated in the root meristem cells of Allium sativum L. Young roots were treated with 0%, 0.05%, 0.1%, 0.25%, 0.5%, 0.75% and 1% aqueous solutions of sodium salicylate for 2, 4, 6 and 8 h periods. Aberrations and dividing cells were determined from the root-tip squashes after a 24h recovery period. Sodium salicylate induced a significant increase in nuclear and chromosomal aberrations. This increase was dependent on both the treatment duration and the concentration of sodium salicylate. The observed aberrations consisted of micronuclei and fragments, nuclear degeneration, chromosome breakage, stickiness of chromosomes, spindle abnormalities, binucleate and polyploid cells. Sodium salicylate was also found to act as a mitodepressant.

Miscibility relationships in systems containing various hydrocarbons, butylcarbitol, and aqueous solutions of sodium salicylate

A study has been made of misciblllty relatlonshlps in systems containing an aqueous solution of sodium salicylate, n-butylcarbitoi, and various hydrocarbons, lncludlng both n-alkanes and aikylbenzenes. At any fixed concentration of sodium salicylate, the minimum amount of n-butyicarbltoi required to produce mlscibillty at 1:l weight percent hydrocarbon-water mixtures increases nearly linearly wlth the number of alkyl carbon atoms in the hydrocarbon. In ail cases a considerably higher welght fraction of n-butyicarbitoi Is requlred to produce misclbillty In the systems containing the alkanes than in those containing aikyibenrenes with the same alkyl carbon number. When the n-butyicarbltoi is replaced by 1-butanol as the cosolvent, this order Is reversed and the misclbliity relationships are simllar to those observed In the hydrocarbon-1-butanol-aqueous sodium p-cymenesulfonate systems, where a higher weight fraction of cosoivent is usually needed to produce misclbllity with the aikylbenzenes than with the alkanes.

Fluorescence of aqueous sodium salicylate under U.-V. excitation

The fluorescence of aqueous solutions of sodium salicylate was investigated in the absence and presence of quenchers (NO–3, I–, Br–, Cl–). The absolute fluorescence yield of salicylate, ϕf= 0.32 ± 0.03, its natural lifetime = 32.3 ns, the Stern-Volmer constants and absolute rate constants for self-quenching and for quenching by the added solutes were obtained. The reversal of self-quenching observed1 in more concentrated solutions is interpreted in terms of ground-state π- bonded dimer formation, as suggested also by n.m.r. results.

N.m.r. study of dimerization in aqueous solutions of sodium salicylate

N.m.r. measurements were carried out on aqueous solutions of ortho, meta and para-hydroxybenzoate ions. Only the ortho isomer, salicylate, gave evidence for specific dimer formation in the ground state. From the concentration dependence of the chemical shifts of particular protons a π-bonded structure is derived for the dimer.