Measurement of atmospheric amines and aminoamides by column adsorption/extraction and hydrophilic liquid chromatography-electrospray-tandem mass spectrometry.

Sampling and chromatography-mass spectrometry methods were investigated to measure atmospheric amines and aminoamides. Amines and their amide derivatives play significant roles in new particle formation (NPF) in the atmosphere, especially diamines and aminoamides have higher NPF potentials compared to monoamines. For amine sampling, silica gel tube collection and formic acid extraction gave good overall recoveries (>93 ± 8%) for mono-, di-, tri-, tetramines, and aminoamides. Two chromatography methods were subjected to analyze the extracted amines. One involved direct analysis using hydrophilic interaction liquid chromatography with carboxyl or diol group functioned separation column (carboxyl-HILIC or diol-HILIC), and the other utilized derivatization with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) and subsequent reversed-phase chromatography (HPLC). Separated amines were detected by electrospray ionization and tandem mass spectrometry in both cases. DBD-F-HPLC method provided good sensitivity for mono- and all polyamines (limit of detection (LOD) < 4.6 nM, relative standard deviation (RSD) for 100 nM < 9.2%). However, aminoamides could not be detected by DBD-F-HPLC. Carboxyl-HILIC provided good sensitivities for mono- and diamines and aminoamides (LOD < 1.6 nM, RSD < 4.8%). Forest air measurement was performed and data obtained by carboxyl-HILIC and DBD-F-HPLC showed good agreement for 1,3-diaminopropane, 1,4-diaminobutane (putrescine) and 1,5-diaminopentane (cadaverine) (R2 = 0.9215-0.9739, n = 7-14). Carboxyl-HILIC method was the best for the amine analysis, and combination with silica gel tube sampling provides atmospheric monitoring available. The developed method can be used not only to study atmospheric chemistry of diamines and aminoamides but also to analyze flavor/odor of foods, flowers and wastes.

The investigation of selected bioactive compounds and antioxidant properties of Crataegus monogyna L.

This work presents investigation of chemical composition and antioxidant activity of ethanolic extracts of leaves with flowers and berries prepared by ultrasound and Soxhlet extractions of Crataegus monogyna from Bosnia and Herzegovina. Total phenolic, flavonoid, and anthocyanin contents were measured by spectrophotometric methods. The sample of leaves with flowers extracted by Soxhlet extraction was the richest in the content of total phenolic compounds (14.43 mg GAE/g DW) and total flavonoids (2.22 mg QE/g DW). Same extract showed the best antioxidant activity with an IC50 value of 0.71 mg/mL for DPPH and 0.38 mg/mL for ABTS assay, as well as the highest content of gallic acid, caffeic acid, and hyperoside 0.04 mg GAE/g DW, 0.60 mg CA/g DW and 2.61 mg HYP/g DW, respectively, determined by HPLC-ED. Vitexin was not detected. The extract of berries obtained by ultrasound extraction had the highest amount of total anthocyanins (1.69 mg/100 g DW).

Validation of LC-MS/MS method for opioid monitoring in Valencia City wastewater: Assessment of synthetic wastewater as potential aid.

In this study, a comprehensive and sensitive method for the simultaneous detection of 17 opioids (OPs) and their human metabolites in wastewater using high-performance liquid chromatography coupled to tandem mass spectrometry was validated. The chromatographic separations of opioids were carried out on a Kinetex® Biphenyl column (1.7 µm, 100 Å, 50 × 2.1 mm). A synthetic wastewater approach was used for recovery studies to mimic a contaminant-free matrix. Two solid-phase extraction (SPE) sorbents (hydrophilic-lipophilic balance and mixed mode with the previous phase and a weak cationic exchange) were studied to optimize sample treatment and obtain higher recoveries. The mixed mode was chosen because the recoveries of 17 target analytes at three spiked concentrations (25, 50, and 100 ng mL-1) were > 80 % for 75 % of the analytes in a simulated wastewater. The intra- and inter-day relative standard deviations (RSDs) were between ±1 % and ±20 %. The method limits of quantification ranged from 5 to 25 ng L-1, the only exceptions being heroin (275 ng L-1) and morphine-3ß-glucuronide (250 ng L-1). Suppression/enhancement is comparable between the synthetic and the influent wastewater. The analytical method was applied to the OPs analysis in twenty-one influent samples collected from the treatment plants treating the wastewater of Valencia City (Spain). Twelve OPs were detected with total daily concentrations ranging from 1 ng L-1 to 2135 ng L-1. The widespread presence of these compounds in water suggests potential widespread exposure, highlighting the need for increased environmental awareness. Furthermore, the estimated daily intake results raise concerns about opioid use as a potential future health and social issue.

Challenges encountered in the enantioselective analysis of new psychoactive substances exemplified by clephedrone (4-CMC).

In this study we report on efforts to develop an enantioselective method for the detection of the drug of abuse clephedrone (1-(4-chlorophenyl)-2-(methylamino)-1-propanone (4-chloromethcathinone, also known as 4-CMC or para-chloro-methcathinone)) and its phase-1 metabolites in human biological fluids. The major goal is not to only report results, but primarily to emphasize the various challenges encountered when developing a reliable analytical method for the detection and quantification of novel psychoactive substances (NPS) and their metabolites in the matrix of interest. Such challenges start with the lack of chemical stability of some NPS in biological matrices. Additionally, most often metabolites are unavailable in pure form to serve as analytical standards, just as deuterated standards for native drugs and metabolites are frequently not commercially available. Furthermore, if the NPS is chiral, enantiomerically pure standards with known absolute stereochemistry are required, as well as a stereochemical stability of a drug and its metabolites becomes an issue. In addition, the chirality of a NPS significantly increases the number of species to be detected in the sample and thus challenges the development of an adequate separation method. These issues are shortly addressed, and some solutions offered in this manuscript.

Identification of an endonuclease and N6-adenine methyltransferase from Ureaplasma parvum SV3F4 strain.

Here, we report a novel endonuclease and N6-adenine DNA methyltransferase (m6A methyltransferase) in the Ureaplasma parvum SV3F4 strain. Our previous study found that the SV3F4 strain carries 17 unique genes, which are not encoded in the two previously reported U. parvum serovar 3 strain, OMC-P162 and ATCC 700970. Of these 17 unique genes, UP3_c0261 and UP3_c0262, were originally annotated as encoding hypothetical proteins. Comparative genomics analyses more recently indicated they encode a Type II restriction endonuclease and an m6A methyltransferase, respectively. The UP3_c0261 and UP3_c0262 genes were individually expressed and purified in Escherichia coli. The UP3_c0261 recombinant protein showed endonuclease activity on the pT7Blue vector, recognizing and cleaving a GTNAC motif, resulting in a 5 base 5' extension. The UP3_c0261 protein digested a polymerase chain reaction (PCR) product harboring the GTNAC motif. The endonuclease UP3_c0261 was designated as UpaF4I. Treatment of the PCR product with the recombinant protein UP3_c0262 completely blocked the restriction enzyme activity of UpaF4I. Analysis of the treated PCR product harboring a modified nucleotide by UP3_c0262 with HPLC-MS/MS and MS/MS showed that UP3_c0262 was an m6A methyltransferase containing a methylated A residue in both DNA strands of the GTNAC motif. Whole genome methylation analysis of SV3F4 showed that 99.9 % of the GTNAC motif was m6A modified. These results suggest the UP3_c0261 and UP3_c0262 genes may act as a novel Type II restriction-modification system in the Ureaplasma SV3F4 strain.

Experimental design optimisation and validation by accuracy profile of a novel method for Hg speciation analysis by HPLC-ICP-MS and application to Total Diet Studies.

This study addresses the development and validation of an analytical method for speciation analysis of mercury (inorganic/Hg2+ and methylmercury/CH3Hg+) in fishery products. The Hg species are separated by reversed-phase (RP) high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). The effective separation of Hg2+ and CH3Hg+ was achieved in <8 min using a peptide mapping RP column and a mobile phase containing 2-mercaptoethanol at 0.25% (v/v) and methanol at 1% (v/v). The optimization was carried out using an experimental design through response surface methodology (RSM) with central composite design (CCD), addressing both the HPLC separation and the sample extraction. The method validation was carried out based on the accuracy profile approach. For this purpose, six series of measurements were carried out in duplicate over a time span of 2 months. The limits of quantification (LOQ) were 2.5 µg/kg (wet weight, ww) for CH3Hg+ and 1.2 µg/kg (ww) for Hg2+. The intermediate reproducibility in terms of coefficient of variation (CVR) was <6%. The bias (%) obtained for the analysis of four certified reference materials (CRMs), namely TORT-3 (lobster hepatopancreas), SRM 1566-b (oyster tissue), SQID-1 (cuttlefish) and NMIJ CRM 7402-a (cod fish tissue) was <7%. This demonstrates the method robustness and suitability for routine speciation analysis of CH3Hg+ and Hg2+ in fishery products. The method is intended to be applied for the analysis of the panel of fishery products and fish-based foods in the framework of the (ongoing) third French Total Diet Study.

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.

Asymmetric catalytic synthesis of chiral covalent organic framework composite (S)-DTP-COF@SiO2 for HPLC enantioseparations by normal-phase and reversed-phase chromatographic modes.

A novel CCOF core-shell composite material (S)-DTP-COF@SiO2 was prepared via asymmetric catalytic and in situ growth strategy. The prepared (S)-DTP-COF@SiO2 was utilized as separation medium for HPLC enantioseparation using normal-phase and reversed-phase chromatographic modes, which displays excellent chiral separation performance for alcohols, esters, ketones, and epoxides, etc. Compared with chiral commercial chromatographic columns (Chiralpak AD-H and Chiralcel OD-H columns) and some previously reported chiral CCOF@SiO2 (CC-MP CCTF@SiO2 and MDI-ß-CD-modified COF@SiO2)-packed columns, there are 4, 3, 13, and 15 tested racemic compounds that could not be resolved on the Chiralpak AD-H column, Chiralcel OD-H column, CC-MP CCTF@SiO2 column, and MDI-ß-CD-modified COF@SiO2 column, respectively, which indicates that the resolution effect of (S)-DTP-COF@SiO2-packed column can be complementary to the other ones. The effects of the analyte mass, column temperature, and mobile phase composition on the enantiomeric separation were investigated. The chiral column exhibits good reproducibility after multiple consecutive injections. The RSDs (n = 5) of the peak area and retention time were less than 1.5% for repetitive separation of 2-methoxy-2-phenylethanol and 1-phenyl-1-pentanol. The chiral core-shell composite (S)-DTP-COF@SiO2 exhibited good enantiomeric separation performance, which not only demonstrates its potential as a novel CSP material in HPLC but also expands the range of applications for chiral COFs.

Phytochemical-mediated regulation of aflatoxigenic fungi contamination in a shifting climate and environment.

Mycotoxin contamination poses a significant problem in developing countries, particularly in northern Pakistan's fluctuating climate. This study aimed to assess aflatoxin contamination in medicinal and condiment plants in Upper Dir (dry-temperate) and Upper Swat (moist-temperate) districts. Plant samples were collected and screened for mycotoxins (Aflatoxin-B1 and Aflatoxin-B-2). Results showed high levels of AFB-1 (11,505.42 ± 188.82) as compared to AFB-2 (846 ± 241.56). The maximum contamination of AFB-1 in Coriandrum sativum (1154.5 ± 13.43 ng to 3328 ± 9.9 ng) followed by F. vulgare (883 ± 9.89 ng to 2483 ± 8.4 ng), T. ammi (815 ± 11.31 ng to 2316 ± 7.1 ng), and C. longa (935.5 ± 2.12 ng to 2009 ± 4.2 ng) while the minimum was reported in C. cyminum (671 ± 9.91 ng to 1995 ± 5.7 ng). Antifungal tests indicated potential resistance in certain plant species (C. cyminum) while A. flavus as the most toxins contributing species due to high resistance below 80% (54.2 ± 0.55 to 79.5 ± 2.02). HPLC analysis revealed hydroxyl benzoic acid (5136 amu) as the dominant average phytochemical followed by phloroglucinol (4144.31 amu) with individual contribution of 8542.08 amu and 12,181.5 amu from C. cyaminum. The comparison of average phytochemicals revealed the maximum concentration in C. cyminum (2885.95) followed by C. longa (1892.73). The findings revealed a statistically significant and robust negative correlation (y = - 2.7239 × + 5141.9; r = - 0.8136; p < 0.05) between average mycotoxins and phytochemical concentrations. Temperature positively correlated with aflatoxin levels (p < 0.01), while humidity had a weaker correlation. Elevation showed a negative correlation (p < 0.05), while geographical factors (latitude and longitude) had mixed correlations (p < 0.05). Specific regions exhibited increasing aflatoxin trends due to climatic and geographic factors.

Evaluation of the Antioxidant Activity and Phenolic Composition of Different Monofloral and Polyfloral Brazilian Honey Extracts.

This study aimed to evaluate the chemical composition and antioxidant activity of phenolic extracts from monofloral and polyfloral honey samples obtained from different Brazilian regions. The chemical composition (total content of phenolic compounds and flavonoids) of extracts were measured by using colorimetric assays and analyzed by high performance liquid chromatographic (HPLC-DAD). The antioxidant activity was evaluated by chemical and biochemical assays (reducing power assay, 1,1-diphenyl-2-picrylhydrazyl (DPPH•) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic) acid (ABTS•+) scavenger assays. It was also investigated the ability of extracts in attenuate lipid peroxidation induced by Fe2+ in phospholipids. The obtained results clearly demonstrated that the botanical origin and geographical region of honey collection influenced the chemical composition and antioxidant activity of extracts. Furthermore, the samples were constituted by phenolic acids and flavonoids, which p-coumaric acid was predominant among the compounds identified. All samples were able to scavenge free radicals and inhibit lipid peroxidation, and good correlations were obtained between the flavonoid content and honey color. In conclusion, the obtained extracts were constituted by antioxidant compounds, which reinforce the usage of honey in human diets, and demonstrated that the region of honey collection strong influenced in the chemical composition and, consequently, its biological effect.

[Applications of high performance liquid chromatography-mass spectrometry in proteomics].

Proteomics profiling plays an important role in biomedical studies. Proteomics studies are much more complicated than genome research, mainly because of the complexity and diversity of proteomic samples. High performance liquid chromatography-mass spectrometry (HPLC-MS) is a fundamental tool in proteomics research owing to its high speed, resolution, and sensitivity. Proteomics research targets from the peptides and individual proteins to larger protein complexes, the molecular weight of which gradually increases, leading to sustained increases in structural and compositional complexity and alterations in molecular properties. Therefore, the selection of various separation strategies and stationary-phase parameters is crucial when dealing with the different targets in proteomics research for in-depth proteomics analysis. This article provides an overview of commonly used chromatographic-separation strategies in the laboratory, including reversed-phase liquid chromatography (RPLC), hydrophilic interaction liquid chromatography (HILIC), hydrophobic interaction chromatography (HIC), ion-exchange chromatography (IEC), and size-exclusion chromatography (SEC), as well as their applications and selectivity in the context of various biomacromolecules. At present, no single chromatographic or electrophoretic technology features the peak capacity required to resolve such complex mixtures into individual components. Multidimensional liquid chromatography (MDLC), which combines different orthogonal separation modes with MS, plays an important role in proteomics research. In the MDLC strategy, IEC, together with RPLC, remains the most widely used separation mode in proteomics analysis; other chromatographic methods are also frequently used for peptide/protein fractionation. MDLC technologies and their applications in a variety of proteomics analyses have undergone great development. Two strategies in MDLC separation systems are mainly used in proteomics profiling: the "bottom-up" approach and the "top-down" approach. The "shotgun" method is a typical "bottom-up" strategy that is based on the RPLC or MDLC separation of whole-protein-sample digests coupled with MS; it is an excellent technique for identifying a large number of proteins. "Top-down" analysis is based on the separation of intact proteins and provides their detailed molecular information; thus, this technique may be advantageous for analyzing the post-translational modifications (PTMs) of proteins. In this paper, the "bottom-up" "top-down" and protein-protein interaction (PPI) analyses of proteome samples are briefly reviewed. The diverse combinations of different chromatographic modes used to set up MDLC systems are described, and compatibility issues between mobile phases and analytes, between mobile phases and MS, and between mobile phases in different separation modes in multidimensional chromatography are analyzed. Novel developments in MDLC techniques, such as high-abundance protein depletion and chromatography arrays, are further discussed. In this review, the solutions proposed by researchers when encountering compatibility issues are emphasized. Moreover, the applications of HPLC-MS combined with various sample pretreatment methods in the study of exosomal and single-cell proteomics are examined. During exosome isolation, the combined use of ultracentrifugation and SEC can yield exosomes of higher purity. The use of SEC with ultra-large-pore-size packing materials (200 nm) enables the isolation of exosomal subgroups, and proteomics studies have revealed significant differences in protein composition and function between these subgroups. In the field of single-cell proteomics, researchers have addressed challenges related to reducing sample processing volumes, preventing sample loss, and avoiding contamination during sample preparation. Innovative methods and improvements, such as the utilization of capillaries for sample processing and microchips as platforms to minimize the contact area of the droplets, have been proposed. The integration of these techniques with HPLC-MS shows some progress. In summary, this article focuses on the recent advances in HPLC-MS technology for proteomics analysis and provides a comprehensive reference for future research in the field of proteomics.

Exploring the Clinical and Hematological Characteristics of Beta-Thalassemia Trait: A Comprehensive Analysis in a Tertiary Care Hospital Setting.

Beta-thalassemia is one of the most common inherited hematological diseases caused by more than 350 mutations in the ß-globin gene (HBB). Beta-thalassemia carrier or trait is associated with defects in one allele of the HBB gene. The majority of beta-thalassemia trait cases remain concealed in society and remain unnoticed as they are mostly asymptomatic or present with mild symptoms of anemia. There is a 25% chance of having children with beta-thalassemia major and a 50% chance of having carrier babies when two people with beta-thalassemia trait are married. Hence, it is important to identify the individuals with beta-thalassemia trait and provide counseling to understand the risks of pregnancy and its outcome. Aim To study the identification of beta-thalassemia trait cases along with their clinical findings and hematological correlation. Materials and methods Study Design This was a retrospective study conducted at Saveetha Medical College and Hospital for a period of four years from January 2020 to December 2023. Inclusion Criteria Age group more than 18 years, antenatal mother, cases of anemia who were refractory to iron treatment, and screening of family members in the positive cases of beta-thalassemia trait. Exclusion Criteria History of blood transfusion within three months was excluded. Data Collection  A total number of 837 cases were screened to rule out the presence of beta-thalassemia trait/hemoglobin (Hb) variants. A 2 mL of intravenous blood samples were collected in an ethylene diamine tetraacetic acid (EDTA) vacutainer tube and processed in a Sysmex XN 1000 (Hyogo, Japan: Sysmex Corporation) automated hematology analyzer. The hematological parameters were analyzed. Statistical Analysis The study included both descriptive and analytical characteristics. Mean and standard deviation (SD) were calculated for all the hematological parameters. Beta-thalassemia trait was diagnosed with an HbA2 level of more than 4.0% through high-performance liquid chromatography (HPLC) analysis. Results  Among the 837 samples studied for HPLC screening, 74 (8.8%) cases were found to have beta-thalassemia trait. The age group included was from 18 years to 56 years. Of 74 cases studied, 32(43%) were females and 42(57%) were males. Among the 74 cases studied, the Mentzer index <13 was seen in 58 (78%) cases and the Mentzer index >13 was seen in 16 cases (22%). Thirty-four cases (46%) of beta-thalassemia traits presented to the hospital with a history of fever for evaluation and antenatal screening accounted for 19 cases (26%). The mean red blood cell (RBC) count was 5.5 million/cu.mm; mean corpuscular volume (MCV) was 63.8 fL; mean corpuscular hemoglobin (MCH) was 19.6 pg; red cell distribution width coefficient of variation (RDW-CV) was 17.8%. Among the 74 cases studied, 37(46%) cases had an Hb of more than 11 g/dL, 22 cases had mild anemia, 12 cases had moderate anemia, and three cases had severe anemia. Conclusion This study concluded that regular monitoring of the Mentzer index along with HPLC analysis is an effective approach in identifying beta-thalassemia trait cases and further providing genetic counseling among the couples that will help in reducing high-risk pregnancy and the birth of a child with thalassemia major.

A promoter polymorphism defines distinct roles in anther development for Col-0 and Ler-0 alleles of Arabidopsis ACYL-COA BINDING PROTEIN3.

Acyl-CoA-Binding Proteins (ACBPs) bind acyl-CoA esters and function in lipid metabolism. Although acbp3-1, the ACBP3 mutant in Arabidopsis thaliana ecotype Col-0, displays normal floral development, the acbp3-2 mutant from ecotype Ler-0 characterized herein exhibits defective adaxial anther lobes and improper sporocyte formation. To understand these differences and identify the role of ERECTA in ACBP3 function, the acbp3 mutants and acbp3-erecta (er) lines were analyzed by microscopy for anther morphology and high-performance liquid chromatography for lipid composition. Defects in Landsberg anther development were related to the ERECTA-mediated pathway because the progenies of acbp3-2 × La-0 and acbp3-1 × er-1 in Col-0 showed normal anthers, contrasting to that of acbp3-2 in Ler-0. Polymorphism in the regulatory region of ACBP3 enabled its function in anther development in Ler-0 but not Col-0 which harbored an AT-repeat insertion. ACBP3 expression and anther development in acbp3-2 were restored using ACBP3pro (Ler)::ACBP3 not ACBP3pro (Col)::ACBP3. SPOROCYTELESS (SPL), a sporocyte formation regulator activated ACBP3 transcription in Ler-0 but not Col-0. For anther development, the ERECTA-related role of ACBP3 is required in Ler-0, but not Col-0. The disrupted promoter regulatory region for SPL binding in Col-0 eliminates the role of ACBP3 in anther development.

Analytical method development and validation for simultaneous estimation of Bempedoic acid and Ezetimibe in pure and its pharmaceutical dosage form by RP-HPLC.

A simple, accurate and precise method was developed for the simultaneous estimation of the bempedoic acid and ezetimibe in pure and tablet dosage form. The developed method was validated as per International Conference on Harmonization guidelines. The chromatographic separation was achieved isocratically on a Waters- C18, 250 × 4.6 mm, 5 µm column. Mobile phase containing K2HPO4-methanol in the ratio 60:40 in buffer at pH 4.3 was pumped through column at a flow rate of 1.0 ml/min. The temperature was maintained at 25°C. The optimized wavelength selected was 242 nm. The separation of bempedoic acid and ezetimibe showed retention times of 3.090 and 4.268 min respectively. The RSD values of the bempedoic acid and ezetimibe were 0.34 and 0.08 respectively. The accuracy of method was determined at three levels (50,100 and 150%). The percentage recovery was obtained as 100.0 and 100.0% for bempedoic acid and ezetimibe, respectively. The limits of determination and quantitation obtained from regression equations of bempedoic acid and ezetimibe were 1.065, 3.550 and 0.203, 0.677, respectively. The regression equation of bempedoic acid is y = 20,795x + 24,168, and it is y = 6,885.7x + 11,000 for ezetimibe. The retention times were decreased and the run time was decreased, so that the method developed is simple and economical that can be adopted for regular quality control tests in industry.

Assessment of drug-drug interaction of dapagliflozin with LCZ696 based on an LC-MS/MS method.

The co-administration of dapagliflozin (DPF) and sacubitril/valsartan (LCZ696) has emerged as a promising therapeutic approach for managing heart failure. Given that DPF and LCZ696 are substrates for P-glycoprotein, there is a plausible potential for drug-drug interactions when administered concomitantly. To investigate the pharmacokinetic changes when these drugs are co-administered, we have established and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method capable of simultaneously detecting DPF, LBQ657 (the active metabolite of sacubitril) and valsartan in rat plasma. This method has demonstrated selectivity, sensitivity, and accuracy. Drug-drug interactions were examined by the LC-MS/MS method. The mechanisms were investigated using everted intestinal sac models and Caco-2 cells. The results showed that DPF significantly increased the area under the curve (AUC(0-t)) (3,563.3 ± 651.7 vs. 7,146.5 ± 1,714.9 h µg/L) of LBQ657 (the active metabolite of sacubitril) and the AUC(0-t) (24,022.4 ± 6,774.3 vs. 55,728.3 ± 32,446.3 h µg/L) of valsartan after oral co-administration. Dapagliflozin significantly increased the amount of LBQ657 and valsartan in intestinal sacs by 1- and 1.25-fold at 2.25 h. Caco-2 cell uptake studies confirmed that P-glycoprotein is the transporter involved in this interaction. This finding enhances the understanding of drug-drug interactions in the treatment of heart failure and provides a guidence for clinical therapy.

Cellular metabolomics study of the antitumor mechanism of Sijunzi decoction combined with mitomycin C.

Mitomycin C (MMC) has an antitumor effect and is considered as a broad-spectrum antibiotic. Sijunzi Decoction (SJZD), a well-known ancient Chinese prescription, is widely used in the treatment of cancer when combined with chemotherapy drugs. Studies have shown that SJZD can be combined with other drugs to enhance the therapeutic effect against cancer and inhibit the toxicity of chemotherapy drugs, but the specific mechanism is not clear. Thus, we hope to further explore the antitumor mechanism of combined SJZD and MMC. 3-(4,5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide assay, flow cytometry, western blot, 1H NMR and HPLC-MS were used to study the mechanism at the cellular level. The results show that the combined administration can have a more significant effect on inhibiting the proliferation of cancer cells, promoting their apoptosis. Based on metabolomics, 38 biomarkers were found in the MMC group and 43 biomarkers were found in the combined administration group. Among them, 18 unique biomarkers were discovered in the combined administration group. Studies have shown that the antitumor mechanism of combined administration is related to amino acid metabolism, energy metabolism, lipid metabolism and nucleotide metabolism, among which amino acid metabolism is the most important. In addition, SJZD achieves the effect of toxin reduction and efficiency enhancement by improving the body's immunity and improving the oxidative stress environment.

Binding characteristics of the doxepin E/Z-isomers to the histamine H1 receptor revealed by receptor-bound ligand analysis and molecular dynamics study.

Doxepin is an antihistamine and tricyclic antidepressant that binds to the histamine H1 receptor (H1R) with high affinity. Doxepin is an 85:15 mixture of the E- and Z-isomers. The Z-isomer is well known to be more effective than the E-isomer, whereas based on the crystal structure of the H1R/doxepin complex, the hydroxyl group of Thr1123.37 is close enough to form a hydrogen bond with the oxygen atom of the E-isomer. The detailed binding characteristics and reasons for the differences remain unclear. In this study, we analyzed doxepin isomers bound to the receptor following extraction from a purified H1R protein complexed with doxepin. The ratio of the E- and Z-isomers bound to wild-type (WT) H1R was 55:45, indicating that the Z-isomer was bound to WT H1R with an approximately 5.2-fold higher affinity than the E-isomer. For the T1123.37V mutant, the E/Z ratio was 89:11, indicating that both isomers have similar affinities. Free energy calculations using molecular dynamics (MD) simulations also reproduced the experimental results of the relative binding free energy differences between the isomers for WT and T1123.37V. Furthermore, MD simulations revealed that the hydroxyl group of T1123.37 did not form hydrogen bonds with the E-isomer, but with the adjacent residues in the binding pocket. Analysis of the receptor-bound doxepin and MD simulations suggested that the hydroxyl group of T1123.37 contributes to the formation of a chemical environment in the binding pocket, which is slightly more favorable for the Z-isomer without hydrogen bonding with doxepin.

Green method by National Environmental Methods Index and Eco-Scale Assessment for evaluation of gatifloxacin-based product by HPLC.

The literature reveals gaps in the availability of green analytical methods for assessing products containing gatifloxacin (GFX), a fluoroquinolone. Presently, method development is supported by tools such as the National Environmental Methods Index (NEMI) and Eco-Scale Assessment (ESA), which offer objective insights into the environmental friendliness of analytical procedures. The objective of this work was to develop and validate a green method by the NEMI and ESA to quantify GFX in eye drops using HPLC. The method utilized a C8 column (4.6 × 150 mm, 5 µm), with a mobile phase of purified water containing 2% acetic acid and ethanol (70:30, v/v). The injection volume was 10 µL and the flow rate was 0.7 mL/min in isocratic mode at 25°C, with detection performed at 292 nm. The method demonstrated linearity in the range of 2-20 µg/mL, and precision at intra-day (relative standard deviation [RSD] 1.44%), inter-day (RSD 3.45%), and inter-analyst (RSD 2.04%) levels. It was selective regarding the adjuvants of the final product (eye drops) and under forced degradation conditions. The method was accurate (recovery 101.07%) and robust. The retention time for GFX was approximately 3.5 min. The greenness of the method, as evaluated by the NEMI, showed four green quadrants, and by ESA, it achieved a score of 88.

A comprehensive measure of Golgi sphingolipid flux using NBD C6-Ceramide: evaluation of sphingolipid inhibitors.

Measurements of sphingolipid metabolism are most accurately performed by liquid chromatography-mass spectrometry. However, this technique is expensive, not widely accessible, and without the use of specific probes, it does not provide insight into metabolic flux through the pathway. Employing the fluorescent ceramide analogue NBD-C6-ceramide as a tracer in intact cells, we developed a comprehensive HPLC-based method that simultaneously measures the main nodes of ceramide metabolism in the Golgi. Hence, by quantifying the conversion of NBD-C6-Ceramide to NBD-C6-sphingomyelin, NBD-C6-Hexosylceramides, and NBD-C6-ceramide-1-phosphate (NBD-C1P), the activities of Golgi resident enzymes sphingomyelin synthase 1, glucosylceramide synthase, and ceramide kinase (CERK) could be measured simultaneously. Importantly, the detection of NBD-C1P allowed us to quantify CERK activity in cells, a usually difficult task. By applying this method, we evaluated the specificity of commonly used sphingolipid inhibitors and discovered that PDMP, which targets glucosylceramide synthase, and fenretinide (4HPR), an inhibitor for dihydroceramide desaturase, also suppress CERK activity. This study demonstrates the benefit of an expanded analysis of ceramide metabolism in the Golgi, and it provides a qualitative and easy-to-implement method.

Chiral Hydroxy Metabolite of Mebendazole: Analytical and Semi-Preparative High-Performance Liquid Chromatography Resolution and Chiroptical Properties.

Mebendazole (MBZ) is a benzimidazole carbamate anthelmintic used worldwide for the treatment and prevention of parasitic disorders in animals and humans. A large number of in vivo and in vitro studies have demonstrated that MBZ also has anticancer activity in multiple types of cancers. After oral administration, the phenylketone moiety of MBZ is rapidly reduced to the hydroxyl group to form the chiral hydroxy metabolite (MBZ-OH). To the best of our knowledge, there is no information in the literature on the stereochemical course of transformation and the anthelmintic and antitumor activity of individual enantiomers of MBZ-OH. In the present study, we describe in detail the direct HPLC resolution of MBZ-OH on a 100 mm × 4.6 mm Chirapak IG-3 column packed with 3 µm silica particles containing amylose (3-chloro-5-methylphenylcarbamate) as a selector. At 25 °C and using pure methanol as the mobile phase, the enantioseparation and resolution factors were 2.38 and 6.13, respectively. These conditions were scaled up at a semi-preparative scale using a 250 mm × 10 mm Chiralpak IG column to isolate multi-milligram amounts of both enantiomeric forms of the chiral metabolite. The chiroptical properties of the collected enantiomers were determined and, through a theoretical study, were related to the more stable conformations of MBZ-OH. The first and second eluted enantiomers were dextrorotatory and levorotatory, respectively, in dimethylformamide solution. Finally, by recording the retention factors of the enantiomers as the water content in the water-acetonitrile mobile phases was progressively varied, U-shaped retention maps were generated, indicating a dual and competitive hydrophilic interaction liquid chromatography and reversed-phase liquid chromatography retention mechanism on the Chirapak IG-3 chiral stationary phase.