Development of Ecofriendly Derivative Spectrophotometric Methods for the Simultaneous Quantitative Analysis of Remogliflozin and Vildagliptin from Formulation.

Three rapid, accurate, and ecofriendly processed spectrophotometric methods were validated for the concurrent quantification of remogliflozin (RGE) and vildagliptin (VGN) from formulations using water as dilution solvent. The three methods developed were based on the calculation of the peak height of the first derivative absorption spectra at zero-crossing points, the peak amplitude difference at selected wavelengths of the peak and valley of the ratio spectra, and the peak height of the ratio first derivative spectra. All three methods were validated adapting the ICH regulations. Both the analytes showed a worthy linearity in the concentration of 1 to 60 µg/mL and 2 to 90 µg/mL for VGN and RGE, respectively, with an exceptional regression coefficient (r2 ≥ 0.999). The developed methods demonstrated an excellent recovery (98.00% to 102%), a lower percent relative standard deviation, and a relative error (less than ±2%), confirming the specificity, precision, and accuracy of the proposed methods. In addition, validated spectrophotometric methods were commendably employed for the simultaneous determination of VGN and RGE from solutions prepared in the laboratory and the formulation. Hence, these methods can be utilized for the routine quality control study of the pharmaceutical preparations of VGN and RGE in pharmaceutical industries and laboratories. The ecofriendly nature of the anticipated spectrophotometric procedures was confirmed by the evaluation of the greenness profile by a semi-quantitative method and the quantitative and qualitative green analytical procedure index (GAPI) method.

Sensitive CE-MS method for monitoring of riociguat and desmethylriociguat levels in human serum.

Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10-1000 ng/mL), with adequate accuracy (90.1-114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR.

Enantioselective separation and dissipation of pydiflumetofen enantiomers in grape and soil by supercritical fluid chromatography-tandem mass spectrometry.

Pydiflumetofen is registered in many countries and is widely used in crop production in the racemate form. However, the environmental behavior of the enantiomers has not been studied. An effective and sensitive chiral analytical method was first established for analyzing the pydiflumetofen enantiomers by supercritical fluid chromatography with tandem triple quadrupole mass spectrometry. The enantiomers could be separated and detected using the Chiralcel OD-3 column in less than 3 min. The separation conditions were as follows: mobile phase, CO2 /methanol (80:20); flow rate, 1.0 mL/min; column temperature, 30°C, auto back-pressure regulator pressure, 2000 psi with modified quick, easy, cheap, effective, rugged, and safe sample treatment method. The average recoveries of analytes from both matrices at three spiking levels were in the range of 84.1-103.0%. The limit of quantitation for each enantiomer was 0.005 mg/kg with a baseline resolution of approximately 1.64. The method was applied to monitor the enantioselective dissipation of pydiflumetofen in grape and soil. In grapes, (-)-pydiflumetofen was degraded more rapidly than (+)-pydiflumetofen. In soil, (+)-pydiflumetofen was preferentially degraded. The data provided useful references for the risk assessment and rational use of pydiflumetofen in agriculture.

One-step cold-induced aqueous two-phase system for the simultaneous determination of fipronil and its metabolites in dietary samples by liquid chromatography-high resolution mass spectrometry and the application in Total Diet Study.

Herein, a cold-induced aqueous two-phase system (CI-ATPS)-based concurrent sample enrichment and cleanup strategy was developed for the analysis of fipronil and its metabolites in dietary samples by liquid chromatography-high resolution mass spectrometry. By optimizing the conditions in CI-ATPS, the analytes were extracted to a small volume acetonitrile-rich phase with the enrichment factor of three-folds. Additionally, the lipids could be efficiently precipitated between the lower and upper layer to complete the removal of lipids. In detection analysis, a target single ion monitoring mode was employed to enhance the detection capability of fipronil and its metabolites. Generally, this established method could detect the target analytes in dietary samples at ng/kg level. Finally, this method was validated and certificated by a proficiency test, then was also successfully applied to dietary samples in the Total Diet Study, and the results showed that 56.3% of samples were detected with fipronil or its metabolites.

Isolation, functional characterization, and biological properties of MCh-AMP1, a novel antifungal peptide from Matricaria chamomilla L.

The antimicrobial activities of natural products have attracted much attention due to the increasing incidence of pathogens that have become resistant to drugs. Thus, it has been attempted to promisingly manage infectious diseases via a new group of therapeutic agents called antimicrobial peptides. In this study, a novel antifungal peptide, MCh-AMP1, was purified by reverse phase HPLC and sequenced by de novo sequencing and Edman degradation. The antifungal activity, safety, thermal, and pH stability of MCh-AMP1 were determined. This peptide demonstrated an antifungal activity against the tested Candida and Aspergillus species with MIC values in the range of 3.33-6.66 µM and 6.66-13.32 µM, respectively. Further, physicochemical properties and molecular modeling of MCh-AMP1 were evaluated. MCh-AMP1 demonstrated 3.65% hemolytic activity at the concentration of 13.32 µM on human red blood cells and 10% toxicity after 48 hr at the same concentration on HEK293 cell lines. The antifungal activity of MCh-AMP1 against Candida albicans was stable at a temperature range of 30-50°C and at the pH level of 7-11. The present study indicates that MCh-AMP1 may be considered as a new antifungal agent with therapeutic potential against major human pathogenic fungi.

Antineoplastic Constituents from the Chemical Diversified Extract of Radix puerariae.

To enhance the structural diversity of isoflavonoids and provide more derivatives for the biological screening, a semisynthetic mixture was generated by diversification of the crude extract of Radix puerariae (Pueraria montana var. lobata) through the chemical reaction with hydrazine hydrate. Eleven 3,4-diarylpyrazoles (1-11) and two 5-phenyl-6-benzyldihydropyridazinones (12 and 13) were isolated from the semisynthetic mixture, and their structures were identified by spectroscopic methods in combination with X-ray crystallographic analysis. Among them, nine compounds (5-13) were new derivatives. All the compounds were evaluated on the inhibitory activities against the prostate cancer cell lines LNCaP and PC3. Compounds 12 and 13 were found to exhibit much more potent inhibitory activities against the androgen dependent LNCaP cells than the androgen independent PC3 cells. Rapid synthesis of new 3,4-diarylpyrazoles and two 5-phenyl-6-benzyldihydropyridazinones with significant biological activity highlights the great potential of one-pot combinatorial modification for the diversification of natural products.

RP-HPLC-UV Method for Simultaneous Quantification of Second Generation Non-Steroidal Antiandrogens Along with their Active Metabolites in Mice Plasma: Application to a Pharmacokinetic Study.

A simple, specific and reproducible high-performance liquid chromatography (HPLC) assay method has been developed and validated for the quantitation of second generation antiandrogens and their active metabolites namely apalutamide, enzalutamide, N-desmethylenzalutamide (active metabolite of enzalutamide), darolutamide and ORM-15341 (active metabolite of darolutamide) in mice plasma. The method involves extraction of apalutamide, enzalutamide, N-desmethylenzalutamide, darolutamide and ORM-15341 along with internal standard (IS) from 100 µL mice plasma through a simple protein precipitation process. The chromatographic analysis was performed on a Waters Alliance HPLC system using a gradient mobile phase (comprising 10 mM ammonium acetate and acetonitrile in a flow-gradient) and X-Terra Phenyl column. The UV detection wave length was set at λmax 250 nm. Apalutamide, enzalutamide, N-desmethylenzalutamide, darolutamide and ORM-15341 and the IS eluted at 13.6, 11.4, 9.68, 6.11, 6.93 and 4.69 min, respectively with a total run time of 15 min. Method validation was performed as per regulatory guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 209 - 5215 ng/mL (r 2=0.998). The intra- and inter-day precisions were in the range of 0.56-13.5 and 1.04-13.9%, respectively. The validated HPLC method was successfully applied to a pharmacokinetic study in mice.

In Vitro Selection of a Single-Stranded DNA Molecular Recognition Element against the Pesticide Fipronil and Sensitive Detection in River Water.

Fipronil is a commonly used insecticide that has been shown to have environmental and human health risks. The current standard methods of detection for fipronil and its metabolites, such as GC-MS, are time consuming and labor intensive. In this study, a variant of systematic evolution of ligands by exponential enrichment (SELEX), was utilized to identify the first single-stranded DNA (ssDNA) molecular recognition element (MRE) that binds to fipronil with high affinity (Kd = 48 ± 8 nM). The selected MRE displayed low cross binding activity on various environmentally relevant, structurally unrelated herbicides and pesticides, in addition to broad-spectrum binding activity on major metabolites of fipronil and a structurally similar pesticide in prepared river samples. Additionally, a proof-of-principle fluorescent detection assay was developed by using the selected ssDNA MRE as a signal-reporting element, with a limit of detection of 105 nM in a prepared river water sample.

Enantiomeric-Enriched Ferrocenes: Synthesis, Chiral Resolution, and Mathematic Evaluation of CD-chiral Selector Energies with Ferrocene-Conjugates.

Enantiomeric-enriched ferrocene-modified pyrazoles were synthesized via the reaction of the ferrocene alcohol, (S)-FcCH(OH)CH3 (Fc = ferrocenyl), with various pyrazoles in acidic conditions at room temperature within several minutes. X-ray structural data for racemic (R,S)-1N-(3,5-dimethyl pyrazolyl)ethyl ferrocene (1) and its (S)-enantiomer (S)-1 were determined. A series of racemic pyrazolylalkyl ferrocenes was separated into enantiomers by analytical HPLC on ß- and γ-cyclodextrins (CD) chiral stationary phases. The quantum chemical calculations of interaction energies of ß-CD were carried out for both (R)- and (S)-enantiomers. A high correlation between experimental HPLC data and calculated interaction energies values was obtained.

Simple dialkyl pyrazole-3,5-dicarboxylates show in vitro and in vivo activity against disease-causing trypanosomatids.

The synthesis and antiprotozoal activity of some simple dialkyl pyrazole-3,5-dicarboxylates (compounds 2-6) and their sodium salts (pyrazolates) (compounds 7-9) against Trypanosoma cruzi, Leishmania infantum and Leishmania braziliensis are reported. In most cases the studied compounds showed, especially against the clinically significant amastigote forms, in vitro activities higher than those of the reference drugs (benznidazole for T. cruzi and glucantime for Leishmania spp.); furthermore, the low non-specific cytotoxicities against Vero cells and macrophages shown by these compounds led to good selectivity indexes, which are 8-72 times higher for T. cruzi amastigotes and 15-113 times higher for Leishmania spp. amastigotes than those of the respective reference drugs. The high efficiency of diethyl ester 3 and its sodium salt 8 against the mentioned protozoa was confirmed by further in vitro assays on infection rates and by an additional in vivo study in a murine model of acute and chronic Chagas disease. The inhibitory capacity of compounds 3 and 8 on the essential iron superoxide dismutase of the aforementioned parasites may be related to the observed anti-trypanosomatid activity. The low acute toxicity of compounds 3 and 8 in mice is also reported in this article.

Acyl dihydropyrazolo[1,5-a]pyrimidinones as metabotropic glutamate receptor 5 positive allosteric modulators.

We report the optimization of a series of metabotropic glutamate receptor 5 (mGlu5) positive allosteric modulators (PAMs) from an acyl dihydropyrazolo[1,5-a]pyrimidinone class. Investigation of exocyclic amide transpositions with this unique 5,6-bicyclic core were conducted in attempt to modulate physicochemical properties and identify a suitable backup candidate with a reduced half-life. A potent and selective PAM, 1-(2-(phenoxymethyl)-6,7-dihydropyrazolo[1,5-a]pyrimidin-4(5H)-yl)ethanone (9a, VU0462807), was identified with superior solubility and efficacy in the acute amphetamine-induced hyperlocomotion (AHL) rat model with a minimum effective dose of 3mg/kg. Attempts to mitigate oxidative metabolism of the western phenoxy of 9a through extensive modification and profiling are described.

3,5-Diarylpyrazole Derivatives Obtained by Ammonolysis of the Total Flavonoids from Chrysanthemum indicum Extract Show Potential for the Treatment of Alzheimer's Disease.

Four new 3,5-diarylpyrazole analogues (1-4) were isolated from an extract of the flowers of Chrysanthemun indicum using a combination of ammonolysis of the total flavonoid extract and an Aß aggregation inhibitory activity guided purification procedure. All four compounds (1-4) showed moderate to potent activity against Aß aggregation with EC50 values of 4.3, 15.8, 1.3, and 2.9 µM, respectively. Moreover, compound 3 showed low cytotoxicity and significant neuroprotective activity against Aß-induced cytotoxicity in the SH-SY5Y cell line. This report is the first to show that 3,5-diarylpyrazole analogues can inhibit Aß aggregation and exhibit neuroprotective activity with potential for the treatment of Alzheimer's disease. Taken together, the method presented here offers an alternative approach to yield bioactive compounds.

Novel antibacterial targets and compounds revealed by a high-throughput cell wall reporter assay.

UNLABELLED: A high-throughput phenotypic screen based on a Citrobacter freundii AmpC reporter expressed in Escherichia coli was executed to discover novel inhibitors of bacterial cell wall synthesis, an attractive, well-validated target for antibiotic intervention. Here we describe the discovery and characterization of sulfonyl piperazine and pyrazole compounds, each with novel mechanisms of action. E. coli mutants resistant to these compounds display no cross-resistance to antibiotics of other classes. Resistance to the sulfonyl piperazine maps to LpxH, which catalyzes the fourth step in the synthesis of lipid A, the outer membrane anchor of lipopolysaccharide (LPS). To our knowledge, this compound is the first reported inhibitor of LpxH. Resistance to the pyrazole compound mapped to mutations in either LolC or LolE, components of the essential LolCDE transporter complex, which is required for trafficking of lipoproteins to the outer membrane. Biochemical experiments with E. coli spheroplasts showed that the pyrazole compound is capable of inhibiting the release of lipoproteins from the inner membrane. Both of these compounds have significant promise as chemical probes to further interrogate the potential of these novel cell wall components for antimicrobial therapy. IMPORTANCE: The prevalence of antibacterial resistance, particularly among Gram-negative organisms, signals a need for novel antibacterial agents. A phenotypic screen using AmpC as a sensor for compounds that inhibit processes involved in Gram-negative envelope biogenesis led to the identification of two novel inhibitors with unique mechanisms of action targeting Escherichia coli outer membrane biogenesis. One compound inhibits the transport system for lipoprotein transport to the outer membrane, while the other compound inhibits synthesis of lipopolysaccharide. These results indicate that it is still possible to uncover new compounds with intrinsic antibacterial activity that inhibit novel targets related to the cell envelope, suggesting that the Gram-negative cell envelope still has untapped potential for therapeutic intervention.

Determination and dissipation of fipronil and its metabolites in peanut and soil.

In this study, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was established for the extraction and cleanup of fipronil and its three metabolites (fipronil solfone, sulfide, and desulfinyl) in peanut kernel, shell, straw, seedling, and soil samples, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for analysis. The average recoveries were 66-116% at the level of 0.001-0.1 mg/kg with the RSD <19%, and the limit of detection was 0.3 ng/g for all matrices. The dissipation experiment results demonstrated that fipronil dissipated more rapidly in peanut seedling than in soil, with half-lives of <1 day in peanut seedling and 32-57 days in soil depending on the soil pH. The final residues at harvest of peanut kernels were all below 0.02 mg/kg, whereas in peanut shell and straw, the total highest residues were 0.99 and 0.30 mg/kg, respectively. Fipronil-desulfinyl and fipronil-sulfone were the highest residue metabolites in peanut plant (seedling and straw) and soil samples, respectively.

Rapid residue analysis of oxathiapiprolin and its metabolites in typical Chinese soil, water, and sediments by a modified quick, easy, cheap, effective, rugged, and safe method with ultra high performance liquid chromatography and tandem mass spectrometry.

A sensitive and effective method for the simultaneous determination of residues from a new fungicide, oxathiapiprolin, and its metabolites (IN-E8S72 and IN-WR791) in soil, water, and sediment, was developed using ultra high performance liquid chromatography with tandem mass spectrometry. Three compounds were extracted from water, soil, and sediment by using acetonitrile and different proportions of formic acid aqueous solution (1% v/v for water; 2% v/v for soil; and sediment), and were cleaned with octadecylsilane. The target compounds were determined within 5 min using an electrospray ionization source in the positive mode for oxathiapiprolin and in the negative mode for the two metabolites. The limits of quantification for all the three compounds were 0.1 µg/kg in water and 1 µg/kg in soil and sediment. Recovery studies were performed using three spiked levels (0.1, 1, and 10 µg/kg for water; 1, 10, and 50 µg/kg for soil and sediment). The overall average recoveries ranged from 64.8 to 112.7% with all intra- and interday relative standard deviation values below 19.4 and 19.1%, respectively. The method validation confirmed that the proposed method was convenient and reliable for determining residual oxathiapiprolin and its metabolites in soil, water, and sediments.

Pyrazolopyrimidines in 'all-natural' products for erectile dysfunction treatment: the unreliable quality of dietary supplements.

A herbal food supplement advertised as a potency pill was screened for the presence of PDE5 inhibitors. The resulting signals were characterised by UV, LC-MS in ESI-negative mode, and NMR spectroscopy using 1D and 2D experiments. Several substances were identified, bearing the basic chemical structure of sildenafil, but were not supposed to exhibit PDE5 inhibition. These compounds may be process-related impurities or by-products of different reaction steps in the synthesis of PDE5 analogues. As they were found to be present in different capsules at different concentrations, this is an example of the unreliable quality of dietary supplements.

Determination of pyrazole and pyrrole pesticides in environmental water samples by solid-phase extraction using multi-walled carbon nanotubes as adsorbent coupled with high-performance liquid chromatography.

A solid-phase extraction (SPE) method using multi-walled carbon nanotubes as adsorbent coupled with high-performance liquid chromatography was developed for the determination of four pyrazole and pyrrole pesticides (fenpyroximate, chlorfenapyr, fipronil and flusilazole) in environmental water samples. Several parameters, such as extraction adsorbent, elution solvent and volume and sample loading flow rate were optimized to obtain high SPE recoveries and extraction efficiency. The calibration curves for the pesticides extracted were linear in the range of 0.05-10 µg L(-1) for chlorfenapyr and fenpyroximate and 0.05-20 µg L(-1) for fipronil and flusilazole, with the correlation coefficients (r(2)) between 0.9966 and 0.9990. The method gave good precisions (relative standard deviation %) from 2.9 to 10.1% for real spiked samples from reservoir water and seawater; method recoveries ranged 92.2-105.9 and 98.5-103.9% for real spiked samples from reservoir water and seawater, respectively. Limits of detection (S/N = 3) for the method were determined to be 8-19 ng L(-1). The optimized method was successfully applied to the determination of four pesticides of pyrazoles and pyrroles in real environmental water samples.

Computational study of antimalarial pyrazole alkaloids from Newbouldia laevis.

Six pyrazole alkaloids of natural origin (isolated from Newbouldia laevis in DR Congo) that exhibit antimalarial activity-namely withasomnine, newbouldine, and their para-hydroxy and -methoxy derivatives-were investigated theoretically. The nitro derivatives of withasomnine and para-hydroxywithasomnine, which show enhanced antimalarial activity, were also studied in this manner. A thorough conformational study was performed in vacuo and in three solvents (chloroform, acetonitrile, and water) at different levels of theory (HF, DFT/B3LYP, and MP2) using different basis sets. Adducts with explicit water molecules were calculated at the HF level. Due to the rigidity of the pyrazole system and the benzene ring, the only factor that influences the energies of withasomnine and newbouldine is the relative orientation of the two ring systems; two orientations are equally preferred. The para-hydroxy and -methoxy derivatives show a preference for a planar orientation of the OH and OC bonds. The main stabilizing influence on the nitro derivative of para-hydroxywithasomnine is the intramolecular hydrogen bond between the two consecutive functional groups. The calculated adducts show the preferred arrangements of water molecules in the vicinity of the N atoms of the pyrazole system and, for the derivatives, also in the vicinity of the substituents on the benzene ring.

Identification of new synthetic PDE-5 inhibitors analogues found as minor components in a dietary supplement.

A dietary supplement sold in erotic shops was analysed. It contains dithiodesmethylcarbodenafil as the major component, which was already reported as an adulterant in dietary supplements. Additionally three more compounds were found and their structures were elucidated after isolation using NMR and mass spectroscopy. They were designated as isonitrosoprodenafil, dithiodesethylcarbodenafil and norcarbodenafil.

A chromatographic and computational study on the driving force operating in the exceptionally large enantioseparation of N-thiocarbamoyl-3-(4'-biphenyl)-5-phenyl-4,5-dihydro-(1H) pyrazole on a 4-methylbenzoate cellulose-based chiral stationary phase.

This paper describes the results obtained in the HPLC enantioseparation of N-thiocarbamoyl-3-(4'-biphenyl)-5-phenyl-4,5-dihydro-(1H) pyrazole on a cellulose tris(4-methylbenzoate) chiral stationary phase (OJ-3 CSP) using normal-phase and polar organic conditions. The enantioseparation factor (α=207) observed using the mixture n-hexane-2-propanol 70:30 as a mobile phase is among the highest values ever reported in enantioselective HPLC. The enantioseparation process was investigated by means of molecular modelling techniques. Chromatographic and theoretical investigations addressed the extreme affinity of the most CSP retained (S)-enantiomer to the intermolecular H bond network between the ligand thioamide group and the stationary phase O atoms.