Spectral and HPLC Analyses of Synthesized Butin and Butein.

Butin and butein are significant bioactive flavanones derived from plants, existing as tautomers of each other. However, their physicochemical attributes, such as their spectral profiles under varying experimental conditions in aqueous solutions and established chromatographic methods for distinguishing between them, remain undetermined. In this study, we determined the basic properties of butin and butein using conventional spectroscopic, reversed-phase, and chiral HPLC analyses. The spectra of the synthesized butin and butein were analyzed using a UV-Vis spectrophotometer in several solvents with different polarities as well as in aqueous solutions at various pH values. Furthermore, the behavior of the measured spectra was reproduced by calculations to reveal the effects of the solvent and pH on the spectra of butin and butein in organic and aqueous solutions. Subsequently, we assessed the structural stability of butin and butein using reversed-phase HPLC, which revealed that butein is unstable compared with butin in a general culture medium. The synthesized butin was effectively separated into R- and S-isomers with positive and negative Cotton effects, respectively, via HPLC using a chiral column. These findings will aid in uncovering the individual properties of both butin and butein that may have been concealed by their tautomerism and enable the synthesis of S-butin, which is typically challenging and time-consuming to isolate.

Rapid, Simple and Low-Cost Analytical Method Development for Quantification of Eltrombopag Olamine in Tablet Dosage by UV Spectroscopy Method.

BACKGROUND: Eltrombopag Olamine is a drug used to treat thrombocytopenia, a disorder where blood platelet counts get lower and severe aplastic anemia. It serves as a thrombopoietin receptor agonist, which give rise to platelet production in the bone marrow. OBJECTIVES: The objective of this study is to develop a simple, specific, accurate, precise and economical Ultraviolet spectroscopy method to estimate the amount of Eltrombopag Olamine in bulk and tablet dosage form. METHODS: The developed method was performed using methanol for identification and physicochemical characterization of the drug. The validation parameters like linearity, precision, accuracy, robustness limits of detection and quantitation, and specificity were assessed as per ICH Q2 (R2). RESULTS: The maximum absorbance wavelength (λmax) of the drug was found at 247 nm in methanol. The linearity was found in the concentration range of 2-14 µg/ml with regression equation y = 0.0619x - 0.0123 and r² = 0.999. The standard addition method was used to determine the accuracy of the developed method. The result was found in the % recovery range of 98-99%. The precision was done on λmax with respect to the parameters such as repeatability, intraday, and interday. The method was found to be precise as the % RSD value was found to be <2%. The detection limit value (LOD) and quantitation limit value (LOQ) were 0.0524 µg/ml and 0.1588 µg/ml, respectively. CONCLUSION: The developed method is simple, economical, accurate and selective. The developed method was adaptable for the estimation of Eltrombopag Olamine analysis in pharmaceutical dosage form and routine quality control laboratory.

Determination of Aminoglycosides by Ion-Pair Liquid Chromatography with UV Detection: Application to Pharmaceutical Formulations and Human Serum Samples.

Aminoglycosides (AGs) represent a prominent class of antibiotics widely employed for the treatment of various bacterial infections. Their widespread use has led to the emergence of antibiotic-resistant strains of bacteria, highlighting the need for analytical methods that allow the simple and reliable determination of these drugs in pharmaceutical formulations and biological samples. In this study, a simple, robust and easy-to-use analytical method for the simultaneous determination of five common aminoglycosides was developed with the aim to be widely applicable in routine laboratories. With this purpose, different approaches based on liquid chromatography with direct UV spectrophotometric detection methods were investigated: on the one hand, the use of stationary phases based on hydrophilic interactions (HILIC); on the other hand, the use of reversed-phases in the presence of an ion-pairing reagent (IP-LC). The results obtained by HILIC did not allow for an effective separation of aminoglycosides suitable for subsequent spectrophotometric UV detection. However, the use of IP-LC with a C18 stationary phase and a mobile phase based on tetraborate buffer at pH 9.0 in the presence of octanesulfonate, as an ion-pair reagent, provided adequate separation for all five aminoglycosides while facilitating the use of UV spectrophotometric detection. The method thus developed, IP-LC-UV, was optimized and applied to the quality control of pharmaceutical formulations with two or more aminoglycosides. Furthermore, it is demonstrated here that this methodology is also suitable for more complex matrices, such as serum, which expands its field of application to therapeutic drug monitoring, which is crucial for aminoglycosides, with a therapeutic index ca. 50%.

Applications of Nanozymes in Chiral-Molecule Recognition through Electrochemical and Ultraviolet-Visible Analysis.

Chiral molecules have similar physicochemical properties, which are different in terms of physiological activities and toxicities, rendering their differentiation and recognition highly significant. Nanozymes, which are nanomaterials with inherent enzyme-like activities, have garnered significant interest owing to their high cost-effectiveness, enhanced stability, and straightforward synthesis. However, constructing nanozymes with high activity and enantioselectivity remains a significant challenge. This review briefly introduces the synthesis methods of chiral nanozymes and systematically summarizes the latest research progress in enantioselective recognition of chiral molecules based on electrochemical methods and ultraviolet-visible absorption spectroscopy. Moreover, the challenges and development trends in developing enantioselective nanozymes are discussed. It is expected that this review will provide new ideas for the design of multifunctional chiral nanozymes and broaden the application field of nanozymes.

A (RP)UHPLC/UV analytical method to quantify dsRNA during the mRNA vaccine manufacturing process.

dsRNA is a product related impurity produced during the mRNA manufacturing process. The established immuno-based detection methods lack the flexibility and speed required to be applied throughout the manufacturing process. The RP-HPLC method developed outperforms these in terms of precision, broader detection range, LOD and LOQ, as well as in output variance. Using this method, dsRNA can be quantified in under 30 min for a single sample.

Investigation on molecular and biomolecular spectroscopy of the novel 2BCA molecule to analyse its biological activities and binding interaction with nipah viral protein.

The molecule of 2-Biphenyl Carboxylic Acid (2BCA), which contains peculiar features, was explored making use of density functional theory (DFT) and experimental approaches in the area of quantum computational research. The optimised structure, atomic charges, vibrational frequencies, electrical properties, electrostatic potential surface (ESP), natural bond orbital analysis and potential energy surface (PES) were obtained applying the B3LYP approach with the 6-311++ G (d,p) basis set.. The 2BCA molecule was examined for possible conformers using a PES scan. The methods applied for spectral analyses included FT-IR, FT-RAMAN, NMR, and UV-Vis results. Vibrational frequencies for all typical modes of vibration were found using the Potential Energy Distribution (PED) data. The UV-Vis spectrum was simulated using the TD-DFT technique, which is also seen empirically. The Gauge-Invariant Atomic Orbital (GIAO) approach was employed to model and study the 13C and 1H NMR spectra of the 2BCA molecule in a CDCL3 solution. The spectra were then exploited experimentally to establish their chemical shifts. To predict the donor and acceptor interaction, the NBO analysis was used. The electrostatic potential surface was employed to anticipate the locations of nucleophilic and electrophilic sites. Hirshfeld surfaces and their related fingerprint plots are exploited for the investigation of intermolecular interactions. Reduced Density Gradient (RDG) helps to measure and illustrate electron correlation effects, offering precise insights into chemical bonding, reactivity, and the electronic structure of 2BCA. According to Lipinski and Veber's drug similarity criteria, 2BCA exhibits the typical physicochemical and pharmacokinetic properties that make it a potential oral pharmaceutical candidate. According to the findings of a molecular docking study, the 2BCA molecule has promise as a treatment agent for the Nipah virus (PDB ID: 6 EB9), which causes severe respiratory and neurological symptoms in humans.

Detection of proteins with ascorbic acid-capped gold nanoparticles: a simple and highly sensitive colorimetric assay.

We report a simple and highly sensitive colorimetric method for the detection and quantification of proteins, based on the aggregation of ascorbic acid (AA) capped gold nanoparticles (AuNPs) by proteins. The interactions between our AuNPs and nine different proteins of various sizes and shapes (cytochrome C (12 kDa), lysozyme (14.3 kDa), myoglobin (17 kDa), human serum albumin (66 kDa), bovine serum albumin (66.4 kDa), human transferrin (80 kDa), aldolase (160 kDa), catalase (240 kDa), and human H-ferritin (500 kDa)) generated similar AuNPs-protein absorption spectra in a concentration-dependent manner in the range of 1-15 nM. Upon the addition of a protein, the UV-visible spectra of AuNPs-protein conjugates shifted from 524 nm for the AuNps alone to longer wavelength (600-750 nm) due to the presence of one of these proteins. This bathochromic shift is accompanied by a color change from a cherry red, to dark purple, and then light grey or colorless if excess protein has been added, indicating the formation of AuNPs-protein conjugates followed by protein-induced aggregation of the AuNPs. High-resolution transmission electron microscopy images revealed uniformly distributed spherical nanoparticles with an average size of 27.5 ± 15.2 nm, increasing in size to 39.6 ± 12.9 nm upon the addition of a protein, indicating the formation of AuNPs-protein conjugates in solution. A general mechanism for the protein-induced aggregation of our AuNPs is proposed. The consistent behavior observed with the nine proteins tested in our study suggests that our assay can be universally applied for the quantification of pure proteins in a solution, regardless of size, shape, or molecular weight.

Synthesis, characterisation, and in vitro antiparasitic activity of new flavanoidal tetrazinan-6'-ones and their binding study with calf thymus DNA using molecular modelling and spectroscopic techniques.

With the developing resistance to traditional antiparasitic medications, the purpose of this study was to efficiently develop a series of six noble flavanoidal tetrazinane-6'-one derivatives by a one-pot reaction pathway. FT-IR, 1HNMR, 13CNMR, and Mass spectra were employed for the structural elucidation of the synthesized compounds (7-12). Clinostomum complanatum, a parasite infection model that has been well-established, demonstrated that all the synthesized compounds are potent antiparasitic agents. DNA is the main target for various medicinal compounds. As a result, thestudy of how small molecules attach to DNA has received a lot of attention. In the present study, we have performed various biophysical techniques to determine the mode of binding of synthesized compounds (7-12) with calf thymus DNA (ct-DNA). It was observed from the UV-visible absorbance and fluorescence spectra that all synthesized compounds (7-12) form complexes with the ct-DNA. The value of binding constant (Kb) was obtained to be in the range of 4.36---24.50 × 103 M - 1 at 298 K. Competitive displacement assay with ethidium bromide (EB), CD spectral analysis, viscosity measurements, and in silico molecular docking confirmed that ligands (7-12) incorporate with ct-DNA through groove binding only. Molecular docking studies were performed for all synthesized compounds with the calf thymus DNA and it was found that all the newly synthesized compounds strongly bind with the chain B of DNA in the minor groove with the value of binding energy in the range of -8.54 to -9.04 kcal per mole and several hydrogen bonding interactions.

Efficient trihalomethane quantification in drinking water for minimally-equipped water treatment plants labs.

Chlorine is a common disinfectant used in water treatment. However, its reaction with organic matter can lead to the formation of harmful byproducts, such as trihalomethanes (THMs), which are potentially carcinogenic. To address this issue, the aim of this work was to enhance a colorimetric method capable of quantifying THMs in drinking water through UV/Vis Spectrophotometry, using cost-effective equipment, and validate this methodology for the first time according to established validation protocols. The method's innovation involved replacing the solvent pentane with the more common hexane, along with adjusting the heating ramp, elucidating the mechanisms involved in the process. This method involves the reaction between THMs, pyridine, and NaOH to produce a colored compound, which is then monitored through molecular absorption spectroscopy in the visible region. The method was thoroughly validated, achieving a limit of detection of 13.41 µg L-1 and a limit of quantification of 40.65 µg L-1. Recovery assays ranged from 86.1 % to 90.7 %, demonstrating high accuracy. The quality of the linear fit for the analytical curve exceeded R2 > 0.98. The method was applied to real samples, revealing concentrations ranging from 13.58 to 55.46 µg L-1, all way below the legal limit in Brazil (Maximum Contaminant Levels (MCL) = 100 µg L-1). This cost-effective and straightforward method is suitable for integration into water treatment plant laboratories.

ChlorTox scale assessment, greenness, and whiteness evaluation of selective spectrophotometric analysis of dimenhydrinate and cinnarizine.

Nausea and vomiting are considered common series side effects induced by chemotherapy treatment in cancer patients. This annoying side effect can impair the patient's compliance to cancer treatment and affect their quality of life. Dimenhydrinate and cinnarizine in combined pharmaceutical dosage form is used to control chemotherapy induced nausea and vomiting in cancer patients. For safety, selective spectrophotometric methods based on novel dual resolution strategies were introduced to estimate dimenhydrinate and cinnarizine in presence of their harmful impurities namely benzophenone and 1- (diphenylmethyl)piperazine, respectively. These methods namely, dual ratio difference (DRD), dual ratio extraction (DRE) and dual absorbance extraction coupled with dual ratio extraction (DAE-DRE) were successfully performed to simultaneously analyze the drug of interests dimenhydrinate and cinnarizine in their pure form, synthetic mixtures and in market dosage form. Linearity ranges were 6.0-60.0 µg/mL and 3.0-30.0 µg/mL for dimenhydrinate and cinnarizine, respectively with good recovery% of Mean ± SD for all the proposed methods 99.82 ± 0.48, 99.79 ± 0.40, 100.14 ± 0.82, 100.03 ± 0.69, respectively. ICH guidelines were adhered in accordance with confirming validation of the proposed methods where fulfilling results were accomplished. Various unified greenness and whiteness assessment tools, such as the chlorTox scale, greenness index via spider chart, AGREE (The Analytical Greenness Metric), green certificate, and the RGB12 algorithm were employed in this research to assess the greenness and sustainability of the introduced UV-spectrophotometric methods in comparison to the reported HPLC method. As a result, these methods hold significant potential for utilization in the quality control department of pharmaceutical companies, contributing to enhanced pharmaceutical product analysis and overall sustainability practices.

Validation of a bioanalytical HPLC-UV method to quantify Α-Bisabolol in rat plasma applied to pharmacokinetic pilot study with the drug nanoemulsion.

α-Bisabolol (α-BIS) is a sesquiterpene alcohol present in chamomile essential oil [Chamomilla recutita (L.) Rauschert]. Despite its numerous pharmacological effects, its pharmacokinetics remain understudied. An analytical method capable of quantifying α-BIS in plasma is crucial to enable pharmacokinetic analysis. Presently, only one study has quantified it using mass spectrometry. Administering α-BIS requires a nanoemulsion for intravenous injection. This study aimed to develop and validate a bioanalytical method using high-performance liquid chromatography with an ultraviolet detector to quantify α-BIS in rat plasma. The method employed acetonitrile and ultrapure water (80:20, v/v) as the mobile phase, with a flow rate of 1 ml/min and concentrations ranging from 465 to 29.625 µg/ml. All US Food and Drug Administration-designated assays were successful, indicating the method's precision, accuracy, sensitivity and linearity in determining α-BIS in rat plasma. The developed nanoemulsion, assessed through dynamic light scattering analysis, the ensemble collection of particles and polydispersity index evaluation, proved safe and effective for intravenous administration. The pharmacokinetic parameters such as volume of distribution, clearance and half-life indicated that α-BIS tends to persist in the body. This study provides a foundation for further research to explore α-BIS's potential pharmaceutical applications in the future.

Whitening toothpastes with hydrogen peroxide concentrations vs. at-home bleaching.

OBJECTIVES: To evaluate the effect of whitening toothpastes with different hydrogen peroxide (HP) concentrations on HP permeability, color change, and physicochemical properties, compared to at-home bleaching treatment. MATERIALS AND METHODS: Forty-nine premolars were randomized into seven groups (n = 7): untreated (control); at-home bleaching with 10% carbamide peroxide gel (AH; 10% CP) with 14 and 28 applications of 180 min each (AH [14 × 180 min] and AH [28 × 180 min]); three whitening toothpastes (3% HP; 4% HP and 5% HP) and 10% CP brushed 28 times for 90 s each (TB [28 × 90 s]). HP permeability was measured using a UV-VIS spectrophotometer and color change by a digital spectrophotometer (ΔEab, ΔE00, and ΔWID). Initial concentration, pH, and viscosity were measured through titration, digital pH meter, and rheometer, respectively. Statistical analysis included one-way ANOVA, Tukey's test, and Dunnett's test (α = 0.05). RESULTS: 4% HP group showed acidic pH, the lowest viscosity and the highest HP concentration into the pulp chamber (p < 0.05). The 10% CP groups had lower HP in the pulp chamber and greater color change than other groups (p < 0.05), except the 5% HP group in ΔEab and ΔE00. For ΔWID, the 10% CP AH groups showed greater whitening than other groups (p < 0.05). CONCLUSIONS: Whitening toothpaste with up to 5% HP resulted in higher HP permeability and less color change compared to 10% CP. Higher HP commercial concentrations in toothpaste increased whitening effect; however, acidic pH toothpastes exhibited greater HP permeability. CLINICAL RELEVANCE: Whitening toothpastes with high hydrogen peroxide concentrations were less effective than at-home bleaching, resulting in less color change and greater permeability of hydrogen peroxide, potentially increasing the risk of tooth sensitivity.

The mechanism of interaction between tri-para-cresyl phosphate and human serum protein: A multispectroscopic and in-silico study.

Organophosphate flame retardants (OPFRs) pose the significant risks to the environment and human health and have become a serious public health issue. Tricresyl phosphates (TCPs), a group of aryl OPFRs, exhibit neurotoxicity and endocrine disrupting toxicity. However, the binding mechanisms between TCPs and human serum albumin (HSA) remain unknown. In this study, through fluorescence and ultraviolet-visible (UV-vis) absorption spectroscopy, molecular docking and molecular dynamics (MD), tri-para-cresyl phosphate (TpCP) was selected to explore potential interactions between HSA and TCPs. The results of the fluorescence spectroscopy demonstrated that a decrease in the fluorescence intensity of HSA and a blue shift were observed with the increasing concentrations of TpCP. The binding constant (Ka) was 2.575 × 104 L/mol, 4.701 × 104 L/mol, 5.684 × 104 L/mol and 9.482 × 104 L/mol at 293 K, 298 K, 303 K, and 310 K, respectively. The fluorescence process between HSA and TpCP involved a mix of static and dynamic quenching mechanism. The gibbs free energy (ΔG0) of HSA-TpCP system was -24.452 kJ/mol, -25.907 kJ/mol, -27.363 kJ/mol, and - 29.401 kJ/mol at 293 K, 298 K, 303 K, and 310 K, respectively, suggesting that the HSA-TpCP reaction was spontaneous. The enthalpy change (ΔH0) and thermodynamic entropy change (ΔS0) of the HSA-TpCP system were 60.83 kJ/mol and 291.08 J/(mol·>k), respectively, indicating that hydrophobic force was the major driving force in the HSA-TpCP complex. Furthermore, multispectral analysis also revealed that TpCP could alter the microenvironment of tryptophan residue and the secondary structure of HSA and bind with the active site I of HSA. Molecular docking and MD simulations confirmed that TpCP could spontaneously form a stable complex with HSA, which was consistent with the fluorescence experimental results. This study provides novel insights into the mechanisms of underlying the transportation and distribution of OPFRs in humans.

Formulation and assessment of biological properties of garcinia indica fruit extract mouthrinse as an adjunct to oral hygiene regimen: an in vitro analysis.

The prevalence of gingivitis is substantial within the general population, necessitating rigorous oral hygiene maintenance. OBJECTIVE: This study assessed a Garcinia indica (GI) fruit extract-based mouthrinse, comparing it to a 0.1% turmeric mouthrinse and a 0.2% Chlorhexidine (CHX) mouthrinse. The evaluation encompassed substantivity, staining potential, antimicrobial efficacy and cytocompatibility. METHODOLOGY: The study employed 182 tooth sections. For antimicrobial analysis, 64 extracted human teeth coated with a polymicrobial biofilm were divided into four groups, each receiving an experimental mouthrinse or serving as a control group with distilled water. Microbial reduction was assessed through colony forming units (CFU). Substantivity was evaluated on 54 human tooth sections using a UV spectrophotometer, while staining potential was examined on 64 tooth sections. Cytocompatibility was tested using colorimetric assay to determine non-toxic levels of 0.2% GI fruit extract, 0.1% Turmeric, and 0.2% CHX. RESULTS: Data were analysed with one-way ANOVA (α=0.05). Cell viability was highly significant (p<0.001) in the 0.2% GI group (64.1±0.29) compared to 0.1% Turmeric (40.2±0.34) and 0.2% CHX (10.95±1.40). For antimicrobial activity, both 0.2% GI (20.18±4.81) and 0.2% CHX (28.22±5.41) exhibited no significant difference (P>0.05) at end of 12 hours. However, 0.1% Turmeric showed minimal CFU reduction (P<0.001). Substantivity results at 360 minutes indicated statistically significant higher mean release rate in 0.1%Turmeric (12.47±5.84 ) when compared to 0.2% GI (5.02±3.04) and 0.2% CHX (4.13±2.25) (p<0.001). The overall discoloration changes (∆E) were more prominent in the 0.2% CHX group (18.65±8.3) compared to 0.2% GI (7.61±2.4) and 0.1% Turmeric (7.32±4.9) (P<0.001). CONCLUSION: This study supports 0.2% GI and 0.1% Turmeric mouth rinses as potential natural alternatives to chemical mouth rinses. These findings highlight viability of these natural supplements in oral healthcare.

The investigation of the interaction determination between carbendazim and elastase, using both in vitro and in silico methods.

Pesticides, including fungicides, are one of the important groups of environmental toxins that affect human and animal health. Studies have shown that these compounds are considered chemical pollutants. Carbendazim is a systemic fungicide. Unfortunately, excessive use of carbendazim has caused environmental pollution all over the world. In this study, the effect of carbendazim on the enzyme elastase (secreted from the endocrine gland of the pancreas) has been investigated. In a study, the performance and reaction of carbendazim with elastase were investigated using spectroscopic techniques. The stability and structure of elastase enzymes were studied under the influence of carbendazim. The results of fluorescence emission and UV-visible absorption spectrum showed that in the presence of carbendazim, there is an increase in UV-Vis absorption and a decrease in the intensity of the intrinsic fluorescence emission in the protein spectrum. Additionally, a decrease in the thermal stability of elastase was observed in the presence of carbendazim. The stability and structure of elastase enzyme were investigated in the presence of carbendazim. The results revealed that the UV-Vis absorption increased due to the presence of carbendazim, as indicated by the hyperchromic spectrum at 220 and 280 nm peaks. Additionally, the intrinsic fluorescence emission in the protein spectrum decreased with increasing carbendazim concentration at three different temperatures (298, 303, and 313 K). Moreover, the study demonstrated that the TM decreased from 2.59 to 4.58 with the increase of carbendazim, suggesting a decrease in the stability of the elastase structure in response to the elevated carbendazim concentration. According to the results of the research, the interaction between elastase and carbendazim has occurred, and changes have been made in the enzyme under the influence of carbendazim. The formation of the complex between elastase and carbendazim was consistent with the results obtained from molecular simulation and confirmed the thermodynamic data.

Comparison of DeNovix, NanoDrop and Qubit for DNA quantification and impurity detection of bacterial DNA extracts.

Accurate DNA quantification is key for downstream application including library preparations for whole genome sequencing (WGS) and the quantification of standards for quantitative PCR. Two commonly used technologies for nucleic acid quantification are based on spectrometry, such as NanoDrop, and fluorometry, such as Qubit. The DS-11+ Series spectrophotometer/fluorometer (DeNovix) is a UV spectrophotometry-based instrument and is a relatively new spectrophotometric method but has not yet been compared to established platforms. Here, we compared three DNA quantification platforms, including two UV spectrophotometry-based techniques (DeNovix and NanoDrop) and one fluorometry-based approach (Qubit). We used genomic prokaryotic DNA extracted from Streptococcus pneumoniae using a Roche DNA extraction kit. We also evaluated purity assessment and effect of a single freeze-thaw cycle. Spectrophotometry-based methods reported 3 to 4-fold higher mean DNA concentrations compared to Qubit, both before and after freezing. The ratio of DNA concentrations assessed by spectrophotometry on the one hand, and Qubit on the other hand, was function of the A260/280. In case DNA was pure (A260/280 between 1.7 and 2.0), the ratio DeNovix or Nanodrop vs. Qubit was close or equal to 2, while this ratio showed an incline for DNA with increasing A260/280 values > 2.0. The A260/280 and A260/230 purity ratios exhibited negligible variation across spectrophotometric methods and freezing conditions. The comparison of DNA concentrations from before and after freezing revealed no statistically significant disparities for each technique. DeNovix exhibited the highest Spearman correlation coefficient (0.999), followed by NanoDrop (0.81), and Qubit (0.77). In summary, there is no difference between DeNovix and NanoDrop in estimated gDNA concentrations of S. pneumoniae, and the spectrophotometry methods estimated close or equal to 2 times higher concentrations compared to Qubit for pure DNA.

Insights on multi-spectroscopic approaches for estimating the in vitro binding of favipiravir with adenine nucleotide.

Favipiravir (FVP) is an oral antiviral drug approved in 2021 for the treatment of COVID-19. It is a pyrazine derivative that can be integrated into anti-viral RNA products to inhibit viral replication. While, adenine is a purine nucleobase that is found in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) to generate genetic information. For the first time, the binding mechanism between FVP and adenine was determined using different techniques, including UV-visible spectrophotometry, spectrofluorimetry, synchronous fluorescence (SF) spectroscopy, Fourier transform infrared (FTIR), fluorescence resonance energy transfer (FRET), and metal ion complexation. The fluorescence spectra indicated that FVP is bound to adenine via Van der Waals forces and hydrogen bonding through a spontaneous binding process (ΔGο < 0). The quenching mechanism was found to be static. Various temperature settings were used to investigate thermodynamic characteristics, such as binding forces, binding constants, and the number of binding sites. The reaction parameters, including the enthalpy change (ΔHο) and entropy change (ΔSο), were calculated using Van't Hoff's equation. The findings demonstrated that the adenine-FVP binding was endothermic. Furthermore, the results of the experiments revealed that some metal ions (K+, Ca+2, Co+2, Cu+2, and Al+3) might facilitate the binding interaction between FVP and adenine. Slight changes are observed in the FTIR spectra of adenine, indicating the binding interaction between adenine and FVP. This study may be useful in understanding the pharmacokinetic characteristics of FVP and how the drug binds to adenine to prevent any side effects.

Ceftobiprole quantification in human serum by HPLC-UV to implement routine TDM in clinical practice.

BACKGROUND AND AIMS: Ceftobiprole is a recent 5th generation parenteral cephalosporin with antibacterial activity against a large range Gram+ and Gram- bacteria. Therapeutic drug monitoring (TDM) is an essential tool for maintaining plasma concentrations of antibiotics above the MIC by the end of the dosing interval, thus preventing the resistant strain diffusion. TDM is already recommended for other cephalosporins, and it is a reasonable tool contributing to the safety and efficacy of these drugs. During the treatment of patients in real-life, a number of pharmacokinetic (PK) changes not normally seen in healthy volunteers can occur which can impair the pharmacokinetic/pharmacodynamic target attainment. We aimed to develop simple and rapid HPLC-UV method for determination of ceftobiprole in human serum to implement TDM in clinical practice and support PKs and pharmacokinetic/pharmacodynamic (PK/PD) studies. MATERIALS AND METHODS: Samples preparation of calibration standards, QC, and anonymous patients serum samples was performed by protein precipitation by adding 0.01 ml of sulphosalicylic acid at 30 % to 0.1 ml of each sample. Then samples were vortexed and the centrifuged at 12,000 rpm for 10 min at 4 °C. Fifty microlitres of clear supernatant were diluted 1:1 with mobile phase and transferred into HPLC autosampler held at 8 °C. Chromatographic separation was carried out in a gradient mode at 35 °C on an ultra-Biphenyl column using a Thermo Scientific chromatographic system with a Diode array. Data management was performed with Chromeleon 7.4 software. RESULTS: The HPLC-UV method proved to be linear over wide concentration ranges (0.5-50.0 mg/L) and was accurate and reproducible in the absence of matrix effects, allowing for robust, specific, and rapid quantification of ceftobiprole from a low amount of serum (0.1 mL). The mean steady state Ctrough and Cend values measured in the anonymous patients' samples were 6.26 ± 3.81 mg/L and 22.56 ± 15.69 mg/L, respectively. CONCLUSIONS: We report a broadened simple and fast HPLC with UV detection method for quantification of ceftobiprole in human serum to implement ceftobiprole TDM as clinical routine, and support future (PK/PD) studies in special patients' population.

Exploring a reversible adaptation of conventional HPLC for capillary-scale operation.

This study introduces a feasible approach for utilizing a conventional High-Performance Liquid Chromatography (HPLC) instrument at the capillary scale (1 - 10 µL/min). The development of an active flow splitter and an adapted UV-visible (UV-vis) detection cell are described. The system employs an Arduino Uno board to monitor a flow sensor and control a stepper motor that automates a split valve to achieve capillary-scale flow rates from a conventional pump. A capillary UV-vis cell compatible with conventional detectors, featuring an optical path length with a volume of 14 nL, was developed to address the detection challenges at this scale and minimize extra column band broadening. The system performance was assessed by a lab-packed LC capillary column with 0.25 mm x 15 cm dimensions packed with 3.0 µm C18 particles. Model compounds, particularly polycyclic aromatic hydrocarbons (PAHs), were employed to assess the functionality of all developed components in terms of theoretical plates, resolution, and band broadening. The proposed system is a profitable, reliable, and cost-effective tool for miniaturized liquid chromatography.

Prediction of Vacuum Ultraviolet/Ultraviolet Gas-Phase Absorption Spectra Using Molecular Feature Representations and Machine Learning.

Ultraviolet (UV) absorption spectroscopy is a widely used tool for quantitative and qualitative analyses of chemical compounds. In the gas phase, vacuum UV (VUV) and UV absorption spectra are specific and diagnostic for many small molecules. An accurate prediction of VUV/UV absorption spectra can aid the characterization of new or unknown molecules in areas such as fuels, forensics, and pharmaceutical research. An alternative to quantum chemical spectral prediction is the use of artificial intelligence. Here, different molecular feature representation techniques were used and developed to encode chemical structures for testing three machine learning models to predict gas-phase VUV/UV absorption spectra. Structure data files (.sdf) and VUV/UV absorption spectra for 1397 volatile and semivolatile chemical compounds were used to train and test the models. New molecular features (termed ABOCH) were introduced to better capture pi-bonding, aromaticity, and halogenation. The incorporation of these new features benefited spectral prediction and demonstrated superior performance compared to computationally intensive molecular-based deep learning methods. Of the machine learning methods, the use of a Random Forest regressor returned the best accuracy score with the shortest training time. The developed machine learning prediction model also outperformed spectral predictions based on the time-dependent density functional theory.