Study on the interaction between erythrosine B and the cardiac drug amiodarone using fluorescence, scattering, and absorbance spectra and their analytical application.

In an acidic buffered solution, erythrosine B can react with amiodarone to form an association complex, which not only generates great enhancement in resonance Rayleigh scattering (RRS) spectrum of erythrosine B at 346.5 nm but also results in quenching of fluorescence spectra of erythrosine B at λemission = 550.4 nm/λexcitation = 528.5 nm. In addition, the formed erythrosine B-amiodarone complex produces a new absorbance peak at 555 nm. The spectral characteristics of the RRS, absorbance, and fluorescence spectra, as well as the optimum analytical conditions, were studied and investigated. As a result, new spectroscopic methods were developed to determine amiodarone by utilizing erythrosine B as a probe. Moreover, the ICH guidelines were used to validate the developed RRS, photometric, and fluorimetric methods. The enhancements in the absorbance and the RRS intensity and the decrease in the fluorescence intensity of the used probe were proportional to the concentration of amiodarone in ranges of 2.5-20.0, 0.2-2.5, and 0.25-1.75 µg/mL, respectively. Furthermore, limit of detection values were 0.52 ng/mL for the spectrophotometric method, 0.051 µg/mL for the RRS method, and 0.075 µg/mL for the fluorimetric method. Moreover, with good recoveries, the developed spectroscopic procedures were applied to analyze amiodarone in its commercial tablets.

Isolation and biochemical characterization of novel acid phosphatase and zinc-dependent acid phosphatase from the chicken's brain.

The AcPase exhibits a specific activity of 31.32 U/mg of protein with a 728-fold purification, and the yield of the enzyme is raised to 3.15 %. The Zn2+-dependent AcPase showed a purification factor of 1.34 specific activity of 14 U/mg of proteins and a total recovery of 5.14. The SDS-PAGE showed a single band corresponding to a molecular weight of 18 kDa of AcPase and 29 kDa of Zn2+-dependent AcPase. The AcPase enzyme has shown a wide range of substrate specificity for p-NPP, phenyl phosphate and FMN, while in the case of ZnAcPase α and ß-Naphthyl phosphate and p-NPP were proved to be superior substrates. The divalent metal ions like Mg2+, Mn2+, and Ca2+ increased the activity, while other substrates decreased the enzyme activity. The Km (0.14 mM) and Vmax (21 µmol/min/mg) values of AcPase were higher than those of Zn2+-AcPase (Km = 0.5 mM; Vmax = 9.7 µmol/min/mg). The Zn2+ ions activate the Zn2+-AcPase while Fe3+, Al3+, Pb2+, and Hg2+ showed inhibition on enzyme activity. Molybdate, vanadate and phosphate were found to be competitive inhibitors of AcPase with Ki values 316 µM, 185 µM, and 1.6 mM, while in Zn2+-AcPase tartrate and phosphate also showed competitive inhibition with Ki values 3 mM and 0.5 mM respectively.

Validated spectrofluorimetric and resonance Rayleigh scattering methods for determining naftidrofuryl in varied pharmaceutical samples based on its interaction with erythrosin B.

Naftidrofuryl is a vasodilator medication used for treating cerebral and peripheral vascular diseases. In this study, two spectroscopical techniques, spectrofluorimetric and resonance Rayleigh scattering (RRS), were utilized to quantify naftidrofuryl in its pharmaceutical samples. The developed methodologies in this study rely on a facile process of forming an association complex between erythrosine B reagent and naftidrofuryl under acidic conditions. The fluorimetric assay is based on the ability of naftidrofuryl to quench and decrease the native fluorescence intensity of the reagent when measured at λ emis . = 550 nm ( λ excit . = 526 nm). Under similar reaction conditions, the RRS method relies on the observed amplification in the RRS spectrum of the reagent at a wavelength of 577 nm following its interaction with naftidrofuryl. The methods exhibited linearity within the ranges 0.2-1.6 µg/ml (r2  = 0.999) and 0.1-1.4 µg/ml (r2  = 0.9994), with limit of quantitation values of 0.146 and 0.099 µg/ml, and limit of detection values of 0.048 and 0.032 µg/ml, for the fluorometric and the RRS methods, respectively. Moreover, the quenching between the dye and naftidrofuryl was studied using Stern-Volmer analysis, and the methodologies were experimentally optimized and validated. Additionally, acceptable recoveries were achieved when the procedures were applied to determine naftidrofuryl in pharmaceutical samples.

Adsorption and Removal of Tetrabromobisphenol A by Adsorption on Functionalized Mesoporous Silica Nanotubes: Isotherms, Kinetics, Thermodynamics, and Optimization via Box-Behnken Design.

In pursuit of environmental safety, a novel and efficient method-dispersive solid-phase extraction based on functionalized mesoporous silica nanotubes (FMSNT nanoadsorbent)-was developed to remove tetrabromobisphenol A (TBBPA) from water samples. Characterization and comprehensive analysis of the FMSNT nanoadsorbent, including maximum adsorption capacity of 815.85 mg g-1 for TBBPA and its water stability, confirmed its potential. Subsequent analysis revealed the impact of multiple factors, for instance pH, concentration, dose, ionic strength, time, and temperature, on the adsorption process. The findings revealed that the adsorption of TBBPA followed the Langmuir and pseudo-second-order kinetics models while primarily driven by hydrogen bond interactions between bromine ions or hydroxyl groups of TBBPA and amino protons around the cavity. The novel FMSNT nanoadsorbent showed high stability and efficiency even after five times of recycling. Moreover, the overall process was identified as chemisorption, endothermic, and spontaneous. Finally, the Box-Behnken design was applied to optimize the results, confirming good reusability even after five cycles.

Development of Sٍٍensitive Spectrofluorimetric Methods for Determining Netilmicin Based on Selective Condensation Reactions of its Amine Moiety with each Acetylacetone/Formaldehyde and Ninhydrin/Phenylacetaldehyde Reagents.

Netilmicin is an aminoglycoside antibiotic used to treat infections caused by a broad spectrum of Gram-negative and Gram-positive bacteria and is pharmaceutically formulated in ophthalmic dosage forms. In this study, two spectrofluorimetric approaches were designed and developed to switch-on the fluorescence activity of NTC. The first method, or Hantzsch (HNZ) method, was relied on measuring the generated fluorescence intensity upon the condensation of NTC with acetylacetone and formaldehyde (Hantzsch reaction) at λemis=483 nm/λexcit=425.5 nm. While the second fluorometric method (NHD method) was relied on measuring the generated fluorescence intensity upon the condensation of NTC with ninhydrin/phenylacetaldehyde at λemis=482.2 nm/λexcit=385.8 nm. The reaction conditions for the two approaches were well investigated and optimized. The selectivity study for the methods was investigated by determining NTC in the presence of the co-formulated drug (dexamethasone) and pharmaceutical excipients. The validation for two approaches was performed based on ICH guidelines, and ranges of linearity were 0.1-1.2 and 1.5-6.0 µg/mL, while LOD values were 0.039 and 0.207 µg/mL for the HNZ method and the NHD method, respectively. Finally, NTC has been determined in different ophthalmic preparations by the proposed approaches with adequate recovery values.

Crystal Structure, Topology, DFT and Hirshfeld Surface Analysis of a Novel Charge Transfer Complex (L3) of Anthraquinone and 4-{[(anthracen-9-yl)meth-yl] amino}-benzoic Acid (L2) Exhibiting Photocatalytic Properties: An Experimental and Theoretical Approach.

Here, we report a facile route to the synthesizing of a new donor-acceptor complex, L3, using 4-{[(anthracen-9-yl)meth-yl] amino}-benzoic acid, L2, as donor moiety with anthraquinone as an acceptor moiety. The formation of donor-acceptor complex L3 was facilitated via H-bonding and characterized by single-crystal X-ray diffraction. The X-ray diffraction results confirmed the synthesized donor-acceptor complex L3 crystal belongs to the triclinic system possessing the P-1 space group. The complex L3 was also characterized by other spectral techniques, viz., FTIR and UV absorption spectroscopy, which confirmed the formation of new bonds between donor L2 moiety and acceptor anthraquinone molecule. The crystallinity and thermal stability of the newly synthesized complex L3 was confirmed by powdered XRD and TGA analysis and theoretical studies; Hirshfeld surface analysis was performed to define the type of interactions occurring in the complex L3. Interestingly, theoretical results were successfully corroborated with experimental results of FTIR and UV absorption. The density functional theory (DFT) calculations were employed for HOMO to LUMO; the energy gap (∆E) was calculated to be 3.6463 eV. The complex L3 was employed as a photocatalyst for the degradation of MB dye and was found to be quite efficient. The results showed MB dye degraded about 90% in 200 min and followed the pseudo-first-order kinetic with rate constant k = 0.0111 min-1 and R2 = 0.9596. Additionally, molecular docking reveals that the lowest binding energy was -10.8 Kcal/mol which indicates that the L3 complex may be further studied for its biological applications.