Glutamate Elicits Therapeutic Responses in Light-Induced Sleep-Deprived Zebrafish, Danio rerio

Sleep deprivation disrupts most neurotransmitters, which can lead to adverse behavioural changes and other psychiatric illnesses. Many neurotransmitter systems, including dopamine (DA), serotonin (5-HT), norepinephrine (N.E.) and GABA, have been implicated in the pathophysiology of mood disorders. The precise significance of sleep deprivation (S.D.) changes in the neurotransmitter levels and the mechanism underlying behavioural alterations is unknown. According to research, sleep deprivation (S.D.) has a major effect on an individual’s quality of life and ability to perform essential physiological functions. As a result, we wanted to confirm the levels of neurotransmitters and behavioural modifications in zebrafish after 24, 48, and 72 hours of sleep deprivation and glutamate treatment on the sleep-deprived groups. The T-maze test was used to assess learning and memory alterations in zebrafish. We used the Novel Tank Test (NTT) and Light and Dark Test (LDT) to examine the anxiety-like behaviour. The spectrofluorimetric method was used to determine the quantities of DA, 5-HT, N.E. and GABA. From this study, it is evident that 72h sleep-deprived fish had a loss of learning and memory via T-maze test and also the anxiety levels were very high in the sleep-deprived group than the other groups. The groups that received glutamate after sleep deprivation showed betterment in the behavioural response. Also, the levels of neurotransmitters were increased in the glutamate treated groups than the sleep-deprived groups. Our findings indicate that sleep loss dramatically impairs behavioural responses and disrupts most neurotransmitter concentrations. When sleep-deprived fish were given glutamate, their behaviour and neurotransmitter levels were nearly identical to those of the control group. This study will have a greater impact on sleep deprivation therapy and pave the way for using the neurotransmitters as external therapeutic agents in treating sleep deprivation and other behavioural changes related to sleep deprivation.It has been suggested that zebrafish is an excellent testing subject for loss of sleep on cognition and that it may also be an efficient model for unravelling the pathways that underpin learning and memory formation.

Spectrofluorimetric Determination of Some N. Containing Medicines Using Rhodamine 6G as a Chromogenic Reagent

A sensitive spectrofluorimetric method has been developed for the analysis of some medicines containing primary, secondary, and tertiary amino groups, namely Diclofenac (DIC), Domperidone (DOM), Famotidine (FAM), and Propranolol (PRO), in their pure and medicinal forms. The method is based on the quenching of the fluorescence intensity of rhodamine 6G (R6G) through the formation of ion-pair complexes between the above medicines and the R-6G reagent, which is measured at 552 nm after excitation at 402 nm. The calibration graphs were rectilinear in the concentration ranges of 0.10- 9.00, 0.05-15.00, 0.10-14.0 and 0.05-5.00 µg mL-1 for above medicines respectively. The recovery (%) values were ranged between 99.45%- 100.97%. The detection limits ranged in the concentration of 0.243-0.754 µg/mL, and the limits of quantitation were 0.806- 2.420 µgmL-1 for all drugs. The method was successfully applied for the determination of these drugs in their pharmaceutical preparations.

Micellar-Enhanced Spectrofluorimetric Method for Quantification of Diclofenac Potassium in Pure Form, in Pharmaceutical Preparations and Human Plasma

A rapid, simple and economical spectrofluorimetric method for the determination of diclofenac potassium in pure form, in pharmaceutical preparations and in human plasma has been developed. The method is based on the enhancement of the fluorescence signal of diclofenac potassium by the addition of sodium dodecyl sulphate in McIvaine buffer with a pH of 5. Different experimental conditions such as buffer type, pH, type and concentration of surfactants were investigated. The fluorescence intensity of the solution was recorded at 361 nm after excitation at 243 nm. The method shows linearity in the concentration range of 0.2 μg mL–1–10 μg mL–1 with a good correlation coefficient of 0.997. The relative standard deviation value was 3.62 (n = 7). The limit of detection and limit of quantification were calculated to be 2.84 × 10–3 μg mL–1 and 9.47 × 10–3 μg mL-1, respectively. The effect of excipients and co-administrated drugs was investigated and no interference was observed. The method was successfully applied for the determination of diclofenac potassium in pure form, in pharmaceutical products and in human plasma. The percentage recoveries obtained ranged from 100.25% to 102.16% for pure form and 97.50% to 102.00% for pharmaceutical products and from 98.50% to 101.67% for human plasma.

A new spectrofluorimetric method for the determination of ascorbic acid with bromocresol purple in pharmaceutical samples

Based on the interaction between ascorbic acid and bromocresol purple, a new simple, straightforward, and quick method for the quantification of ascorbic acid is proposed. The procedure is based on the determined quenching effect of ascorbic acid on the natural fluorescence signal of bromocresol purple in the reaction between ascorbic acid and bromocresol purple in phosphate buffer solution (pH 6). The reduction of bromocresol purple fluorescence intensity is detected at 641 nm, while excitation occurs at 318 nm. The linear relationship between the reduced fluorescence intensity of bromocresol purple and the concentration of ascorbic acid is in the range 4.65 × 10–5 to 4.65 × 10–6 mol L−1 (R2 = 0.9964), with the detection limit of 8.77 × 10–7 mol L−1 and quantification limit of 2.35 × 10–5 mol L−1. The findings in this study further show that the new method provides good precision and repeatability, as well as satisfactory recovery values in terms of accuracy. The new method is tested on fifteen samples with different amounts of ascorbic acid and additional components. The effects of interfering components such as citrus bioflavonoids, citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The effects of interfering components such as citrus bioflavonoids (routine and hesperidin), citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The results of iodometric titration point out that the new method is effective for the determination of ascorbic acid in pharmaceutical samples. Article Highlights A new spectrofluorimetric method for determination of ascorbic acid in pharmaceutical samples using bromocresol purple. Determination of optimal parameters for ascorbic acid determination in a variety of pharmaceutical samples. Examination of the influence of additional substances in the pharmaceutical samples on the analysis.

Two facile approaches based on association complex with erythrosine-B for nano-level analysis of duloxetine: application to content uniformity

Duloxetine is an antidepressant that exhibits its action by preventing the reuptake of serotonin and norepinephrine by neurons. In this analytical study, we developed two facile, sensitive methods for duloxetine analysis. Both methods rely on the formation of binary association complex between erythrosine-B and duloxetine in an acidic medium using spectrofluorimetric and resonance Rayleigh scattering (RRS) techniques. Spectrofluorimetric method simply uses the quenching property of the formed complex on the native fluorescence of erythrosine-B at an emission wavelength of 557.2 nm ( λ ex = 528.6), while RRS is based on detecting the enhancement in the RRS signal at 357.2 nm. The proposed methods have been validated according to the International Conference on Harmonization guidelines. The approaches provide linear assay of duloxetine hydrochloride over 0.1–2.4 µg ml −1 and 0.2–2.0 µg ml −1 for spectrofluorimetric and RRS methods, respectively. Variables affecting methods and complex formation were studied and optimized. The limit of detection values were 0.03 and 0.056 µg ml −1 for spectrofluorimetric and RRS methods, respectively. Both approaches were applied with acceptable results for formulation analysis and evaluation of cymbatex capsule content uniformity.

Green and sensitive spectrofluorimetric method for the determination of two cephalosporins in dosage forms

Using two green and sensitive spectrofluorimetric methods, we quantified two cephalosporins, cefepime (CFM) and cefazolin (CFZ), in raw and pharmaceutical formulations. The first method is based on the reaction between CFM and fluorescamine (borate buffer, pH 8), which yields a highly fluorescent product. After excitation at 384 nm, the fluorescent product emits light at 484 nm. At concentration ranges from 12.0 to 120.0 ng ml −1 , the relative fluorescence intensity/concentration curve was linear with a limit of quantification (LOQ) of 2.46 ng ml −1 . The second method relied on measuring the CFZ quenching action on acriflavine fluorescence through formation of an ion-associate complex using Britton–Robinson buffer at pH 8. We measured acriflavine fluorescence at 505 nm after excitation at 265 nm. The decrease in acriflavine fluorescence intensity was CFZ concentration-dependent. Using this method, we quantified CFZ in concentrations ranging from 1 to 10 µg ml −1 with a LOQ of 0.48 µg ml −1 . We studied and optimized the factors influencing reaction product formation. Moreover, we adapted our methods to the investigation of the mentioned drugs in raw and pharmaceutical formulations with greatly satisfying results. We statistically validated our methods according to International Council on Harmonisation Guidelines. The obtained results were consistent with those obtained with the official high-performance liquid chromatography methods.

Label-Free Electrochemical Test of Protease Interaction with a Peptide Substrate Modified Gold Electrode

Efficient deposition of biomolecules on the surface, maintaining their full activity and stability, is a most significant factor in biosensor construction. For this reason, more and more research is focused on the development of electrochemical biosensors that have the ability to electrically detect adsorbed molecules on electrode surface with high selectivity and sensitivity. The presented research aims to develop an efficient methodology that allows quantification of processes related to the evaluation of enzyme activity (proprotein convertase) using electrochemical methods. In this study we used impedance spectroscopy to investigate the immobilization of peptide substrate (Arg-Val-Arg-Arg) modified with 11-mercaptoundecanoic acid on the surface of gold electrode. Both the synthesis of the peptide substrate as well as the full electrochemical characteristics of the obtained electrode materials have been described. Experimental conditions, including concentration of peptide substrate immobilization, modification time, linker, and the presence of additional blocking groups have been optimized. The main advantages of the described method is that it makes it possible to observe the peptide substrate–enzyme interaction without the need to use fluorescent labels. This also allows observation of this interaction at a very low concentration. Both of these factors make this new technique competitive with the standard spectrofluorimetric method.