Ammonium Acetate Research Articles

Combination of online hollow fiber liquid phase microextraction with smartphone-based sensing for in situ formaldehyde assay in fabric and wastewater samples.

A miniaturized analytical methodology was introduced based on the combination of a direct and online hollow fiber microextraction method with smartphone color detection. The method was used for the determination of formaldehyde (target analyte) in fabric and wastewater samples. In this regard, two reagents including ammonium acetate buffer and acetylacetone were added to the formaldehyde samples to create a colored compound. The colored compound was extracted from the sample by using the hollow fiber liquid-phase microextraction method, the extracted phase was not taken out of the extraction box and was directly transferred into a specially designed detection cell, and a smartphone was applied forin-situ color sensing and data readout. This combination gathered the advantages of both state-of-the-art microextraction techniques and smartphone sensing. Formaldehyde, as a carcinogenic compound widely used in paint and clothing industries, was selected as a model test. Factors affecting extraction efficiency were investigated and optimized, including the type of organic solvents, reagent concentration, salt, pH, stirring speed, reaction temperature, and extraction time. The linear region of the method under optimal conditions was 40-1500µg L-1 for wastewater samples and 0.3-11.2mg kg-1 for fabrics. The limit of detection and limit of qualification were 13 and 40µg L-1, respectively. The relative standard deviations for concentrations of 100 and 1000µg L-1 were 6% and 4%, respectively. To evaluate the application of the method for real samples, types of fabric and two samples of oil refinery wastewater were selected. The relative recovery in real samples was 84-98%. The results of the analytical parameters of the method show that the developed method can be used as an efficient method to determine formaldehyde in real samples.

Evaluation of diethyl 4-(5-bromo-1H-indol-3-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate: synthesis, anti-corrosion potential, and biomedical applications

The pursuit of advanced multifunctional compounds has gained significant momentum in recent scientific endeavours. This study is dedicated to elucidating the synthesis, rigorous characterization, and multifaceted applications—encompassing anti-corrosion, antimicrobial, and antioxidant properties—of Diethyl 4-(5-bromo-1H-indol-3-yl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate. The 1,4-dihydropyridine derivative was meticulously synthesized through a strategic reaction of ethyl acetoacetate, ammonium acetate, and 5-bromoindole-3-carboxaldehydein the ethanol medium at 60 C. Subsequent spectral validations were conducted using sophisticated techniques, namely FTIR, NMR, and Mass spectrometry, resulting in data that perfectly resonated with the hypothesized chemical structure of the compound. Its anti-corrosive potential was assessed on mild steel subjected to an aggressive acidic environment, employing comprehensive methodologies like gravimetric analysis, Tafel polarization, and EIS. Concurrently, its antimicrobial prowess was ascertained against a spectrum of bacterial and fungal pathogens viz., Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas, Candida albicansandAspergillusniger, leveraging the disc diffusion method and using Gentamicin as a reference standard.The empirical results illustrated a substantial decrement in corrosion rates with ascending concentrations of the organic compound, achieving an apex of anti-corrosive efficacy at 81.89% for a concentration of 2 × 103 M. Furthermore, the compound outperformed Gentamicin in antimicrobial screenings, manifesting superior efficacy against all tested pathogens. The antioxidant potential, quantified using the DPPH free radical scavenging assay against ascorbic acid as a benchmark, was found to have an IC50 value of 113.964 ± 0.076 µg/ml.This comprehensive investigation accentuates the paramount potential of the synthesized dihydropyridine derivative in diverse domains—from industrial applications as a corrosion inhibitor to therapeutic avenues given its pronounced antimicrobial and antioxidant capabilities. The compelling results obtained pave the way for expansive research and development initiatives cantered around this multifaceted compound.Graphical

Innovation of 6-sulfonamide-2H-chromene derivatives as antidiabetic agents targeting α-amylase, α-glycosidase, and PPAR-γ inhibitors with in silico molecular docking simulation.

A new series of 2-imino or 2-oxo-2H-chromene-6-sulfonamide derivatives 2-9 with potential anti-diabetic activity were designed and synthesized. The new 6-sulfonamide chromenes were synthesized by reacting 3-formyl-4-hydroxybenzenesulfonyl chloride with activated methylene derivatives in the presence of ammonium acetate as a catalyst. The structure of the products was confirmed by spectroscopic analysis. All the designed derivatives 2-9 were evaluated for their activity against α-amylase and exhibited inhibitory percentage values higher than 93% at 100 μg mL-1. Additionally, the IC50 values represented a variable degree of activity with two derivatives 2 and 9 exhibiting the most promising derivative results with IC50 values of 1.76 ± 0.01 and 1.08 ± 0.02 μM, respectively, compared to Acarbose (IC50 = 0.43 ± 0.01 μM). Additionally, these derivatives showed potency against the α-glucosidase enzyme with IC50 values of 0.548 ± 0.02 and 2.44 ± 0.09 μg mL-1, compared to Acarbose (0.604 ± 0.02 μg mL-1). Moreover, the in vitro PPAR-γ transactivation assay revealed that chromene-6-sulfonamide derivatives 2 and 9 exhibited potential PPAR-γ activity with IC50 values of 3.152 ± 0.03 and 3.706 ± 0.32 μg mL-1, respectively, compared to Pioglitazone (4.884 ± 0.29 μg mL-1). This indicates that these derivatives have insulin sensitivity and glucose metabolism activity. The in silico ADMET prediction showed that these derivatives have an acceptable range of oral bioavailability, drug-likeness, and a safe toxicity profile, including being non-cytotoxic, non-mutagenic, non-immunotoxic, and non-carcinogenic. Finally, computational docking analysis demonstrated the ability of these derivatives to interact with α-amylase, α-glucosidase, and PPAR-γ enzymes, with confirmed successful placement due to good binding energy values and various interactions within the pocket.

Synthesis of Polysubstituted Pyridines via Nitrogen-doped Graphene Catalyzed One-Pot Multicomponent Reaction under Solvent-Free Conditions

Abstract: Polysubstituted pyridine derivatives were producedwith high to excellent yields in the presence of nitrogen-doped graphene (NDG) as a dual acid–based catalyst. NDG efficiently catalyzes the multicomponent reaction between arylaldehydes, diethyl-acetylene dicarboxylates, malononitrile, and ammonium acetate under solvent-free conditions at 80°C to afford the polysubstituted pyridines in short reaction times. The structures of the synthesized pyridines were established by Ft-IR, 1H, and 13C NMR spectroscopic analysis. The advantages of this method include the in-situ oxidation of prepared 1,4-dihydropyridines, one-pot procedure, solventless system, operational simplicity, and no column chromatography. Additionally, neither toxic solvents nor catalysts are needed, and the procedure can be very reliable among the reported methodologies. The yields and reaction times in the presence of four times recycled catalyst are in comparable to the fresh catalyst. background: Graphene quantum dots have attracted considerable attention of chemists because of their unique properties such as: stability, non-toxicity, good water solubility, biocompatibility. In continuation of our interest in using ionic liquids, water or solvent-free systems as green reaction media in organic reactions for the synthesis of important compounds , we wish to report here efficient synthesis of polysubstituted pyridine derivatives in high to excellent yields using Nitrogen-doped graphene as efficient catalyst.

IDENTIFICATION, SEPARATION, AND CHARACTERIZATION OF DEGRADATION PRODUCTS OF TRIAMCINOLONE HEXACETONIDE USING LC AND LC-MS/MS

Objective: The study aimed to separate the forced degradation products of Triamcinolone hexacetonide using HPLC and characterize the degradation product by LC-MS/MS fragmentation pattern. Methods: Triamcinolone hexacetonide (THA) and its primary degradation products were identified using a liquid chromatography-mass spectrometry/Mass spectrometry (LC-MS/MS) approach. The degradation study was based on in-depth stress testing with acid, base, peroxide, heat, and light. A Zorbax SB C18 column and a greener mobile phase composed of methanol and 10 mmol ammonium acetate buffer in water at pH 3 were employed to accomplish separation and quantitation at a flow rate of 0.7 ml/min in an isocratic mode with a 239 nm detection wavelength. Results: A major degradation product of the drug was obtained in acidic and alkaline stress conditions. The drug was found to be stable for all other stress conditions. The LC-MS/MS analysis results of the active pharmaceutical ingredient and resulting product after degradation were interpreted to identify the novel degradation product and fragments. The developed method was validated as per International Council for Harmonization (ICH) guidelines. The square root of the correlation coefficients, which indicated linearity for THA in 50 to 150 % of the workload, was 0.99. Method Precision assay was performed on six different preparations, percentage relative standard deviation (% RSD) of assay value is 0.17 % and system precision is 0.30 %. In accuracy, overall % RSD of 50 %, 100 %, and 150 % in triplicate is 0.95. Conclusion: It is concluded that the drug is stable to all other stress conditions except for acidic and alkaline stress conditions and generates a novel degradation product. The developed LC (Liquid chromatography) method separates and identifies the degradation product.

Thiamine Hydrochloride: A Highly Efficient Organo-Catalyst for the One-Pot Synthesis of 2, 4, 5-Triaryl Imidazole Derivatives

Abstract: In this study, we have developed an expeditious and efficient method for the synthesis of 2,4,5–triaryl imidazole derivatives using thiamine hydrochloride as a catalyst. The one-pot, solventfree- multicomponent reaction of an aromatic/heterocyclic aldehyde with benzyl and ammonium acetate at reflux conditions leads to the formation of title compounds in extremely good yields. This protocol offers several features, such as safe, simple, atom efficient, economical, mild conditions, minimum waste, easy work-up procedures, shorter reaction time (40-45 min), catalyst recyclability, etc. The developed methodology is operationally simple and eco-friendly.

Simultaneous determination of unecritinib (TQ-B3101) and its active metabolite crizotinib in rat plasma by LC-MS/MS：An application to pharmacokinetic studies

Unecritinib (TQ-B3101) is a selective tyrosine kinase receptor inhibitor. In the study, in vitro metabolic experiments revealed that the hydrolysis of TQ-B3101 was mainly catalyzed by carboxylesterase 2 (CES2), followed by CES1. Next, a sensitive and reliable LC-MS/MS method was established for the simultaneous determination of TQ-B3101 and its metabolite crizotinib in rat plasma. To prevent in vitro hydrolysis of TQ-B3101, sodium fluoride, the CESs inhibitor at a concentration of 2 M, was immediately added after whole blood collection. Plasma samples were extracted by acetonitrile-induced protein precipitation method, and chromatographically separated on a Gemini C18 column (50 mm × 2.0 mm i.d., 5 μm) using gradient elution with a mobile phase of 0.1% formic acid and 5 mmol/L ammonium acetate with 0.1% formic acid. The retention times for TQ-B3101 and crizotinib were 2.61 and 2.38 min, respectively. The analytes were detected with tandem mass spectrometer by positive electrospray ionization, using the ion transitions at m/z 492.3 → 302.3 for TQ-B3101, m/z 450.3 → 260.3 for crizotinib, and m/z 494.0 → 394.3 for imatinib (internal standard). Method validation was conducted in the linear range of 1.00–800 ng/mL for the two analytes. The precision, accuracy and stabilities all met the acceptance criteria. The pharmacokinetic study indicated that TQ-B3101 was rapidly hydrolyzed to crizotinib with the elimination half-life of 1.11 h after a single gavage administration of 27 mg/kg to Sprague-Dawley rats, and the plasma exposure of TQ-B3101 was only 2.98% of that of crizotinib.

Synthesis and in silico inhibitory action studies of azo-anchored imidazo[4,5-b]indole scaffolds against the COVID-19 main protease (Mpro)

The present work elicits a novel approach to combating COVID-19 by synthesizing a series of azo-anchored 3,4-dihydroimidazo[4,5-b]indole derivatives. The envisaged methodology involves the l-proline-catalyzed condensation of para-amino-functionalized azo benzene, indoline-2,3-dione, and ammonium acetate precursors with pertinent aryl aldehyde derivatives under ultrasonic conditions. The structures of synthesized compounds were corroborated through FT-IR, 1H NMR, 13C NMR, and mass analysis data. Molecular docking studies assessed the inhibitory potential of these compounds against the main protease (Mpro) of SARS-CoV-2. Remarkably, in silico investigations revealed significant inhibitory action surpassing standard drugs such as Remdesivir, Paxlovid, Molnupiravir, Chloroquine, Hydroxychloroquine (HCQ), and (N3), an irreversible Michael acceptor inhibitor. Furthermore, the highly active compound was also screened for cytotoxicity activity against HEK-293 cells and exhibited minimal toxicity across a range of concentrations, affirming its favorable safety profile and potential suitability. The pharmacokinetic properties (ADME) of the synthesized compounds have also been deliberated. This study paves the way for in vitro and in vivo testing of these scaffolds in the ongoing battle against SARS-CoV-2.

Utilizing experimental design and desirability function in optimizing RP-HPLC method for simultaneous determination of some skeletal muscle relaxants and analgesics

An experimental design and response surface methodologies using Plackett–Burman and Box-Behnken designs were applied for selecting and optimizing the most appropriate parameters which significantly affect the separation and quantitative estimation of five skeletal muscle relaxants and four analgesic drugs (baclofen, methocarbamol, dantrolene sodium, orphenadrine citrate, cyclobenzaprine hydrochloride, ketoprofen, etoricoxib, ibuprofen, and mefenamic acid) with a relatively short duration of analysis in a single run. For the separation of the nine drugs, an INERTSIL ODS-V3-5 µm C18 column (250 × 4.6 mm I.D.) was used with the optimum mobile phase conditions (45.15 mM ammonium acetate buffer pH 5.56 adjusted with acetic acid, acetonitrile, and methanol in a ratio of 30.5:29.5:40, v/v/v with a flow rate of 1.5 mL/min) and UV-detection at 220 nm. The optimized method was successfully subjected to the validation steps as described in ICH guidelines for linearity, precision, accuracy, robustness, and sensitivity. The optimized and validated method was effectively applied to determine the content of the studied drugs in their pharmaceutical preparations and to expand its applicability to the counterfeit estimation of etoricoxib in different brands of tablet dosage forms.

Solvatochromism and halochromism in nitro lophine derivatives: Photophysical study, computational calculations and applications as pH sensing material

Nitro Lophines were readily synthesized via multicomponent reaction of benzil, nitro benzaldehyde and ammonium acetate. All three nitro Lophines were isolated in good yields and were also characterized by various analytical and spectroscopic techniques. A distinctive solvatochromism was observed in case of ortho and para nitro containing Lophines in their absorbance spectra. In particular, naked eye solvatochromism was observed, in case of para nitro Lophine, in the form of yellow and red coloured solution in methanol and DMSO respectively. Halochromism studies revealed the hypsochromic shift under acidic pH while bathochromic shift under alkaline pH for both nitro Lophines. Again the para nitro Lophine demonstrated wonderful distinctive colour change under acidic and alkaline pH in both methanol and DMSO as solvents. The measurement of absorbance at different pH values was carried out and the data obtained were used for calculation of dissociation constants employing several graphical methods. Computational calculations were carried out using TD-DFT for UV–Vis absorption calculation while graph-convolutional neural network model was utilized for calculation of dissociation constants. Ultimately, a reusable naked eye pH detection paper could be developed using para nitro Lophine as a sole indicator.

Development and validation of an HILIC/MS/MS method for determination of nusinersen in rabbit plasma

A hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC/MS/MS) method was developed and validated for the quantitative analysis of the fully phosphorothioate modified oligonucleotide nusinersen. HILIC/MS/MS method is more robust and compatible with mass spectrometry than ion pair reversed-phase liquid chromatography-tandem mass spectrometry (IP-RP-LC/MS/MS). Various types and concentrations of additives and different pH of mobile phase affected the mass spectrometry response, chromatographic peak shape and retention of nusinersen. The optimized extraction method of nusinersen employs hydrophilic-lipophilic balance solid phase extraction, with a recovery of up to 80%. Chromatographic quantification was performed using a gradient system on an amide column and the mobile phase consisted of ammonium acetate, acetonitrile and water in a certain proportion. The fully phosphorothioate modified nusinersen can obtain a high mass spectrometry response by providing greater peak symmetry and high ionization efficiency in a high-pH mobile phase. Moreover, the significant carry over interference was observed at the pH 6.3 of the mobile phase. Adjusting the pH value up to 10, and the carry over interference disappeared. The lower limit of quantitation of this developed HILIC/MS/MS assay was 30.0 ng/mL and the method was systematic methodology validated. This HILIC/MS/MS method provides an attractive and robust alternative for the quantitative analysis of nusinersen and was applied in the pharmacokinetic study of nusinersen in rabbits.

Solvent free green synthesis of tri-substituted imidazoles catalyzed by multi-doped ZnO-GCN nanocomposites

Applying the method of grinding, a series of 2,4,5-tri-substituted imidazole derivatives have been synthesised in highly satisfactory yields without the need for a solvent. In which grinding a mixture of benzoin or benzil and verities of the aldehydes in the existence of ammonium acetate, as a nitrogen source is successfully synthesized by using the efficient multi-doped ZnO- graphitic carbon nitride (g-C3N4) nanocomposite catalyst (Bi (4 %), Cr(1 %)-doped ZnO-GCN). In this protocol, comparative studies of the single-pot synthesis of 2,4,5-trisubstituted imidazole compounds are performed by using conventional and mechanochemical grinding methods with and without Bi-Cr-doped ZnO-GCN nanocomposite catalyst. All synthesised compoundswere characterised by their melting points, 1HNMR, and 13CMR spectra. In these studies, we found that grinding methodology with Bi-Cr-doped ZnO-GCN nanocomposite catalyst enhanced the reaction efficiencies with a short reaction time, excellent products, a cleaner reaction, and an easy workup. Additionally, the reaction follows green chemistry guidelines because it just requires the grinding of the substrates and catalyst in the absence of a solvent. Furthermore, the final product is simply purified by recrystallization as well as whenever needed using the column chromatography process.

A Green and Convenient Approach for the Synthesis of Indole-acrylonitrile and Indole-coumarin Hybrids in Aqueous Media

Abstract: Indole–acrylonitrile hybrids were synthesized via a catalyst-free reaction of aromatic aldehydes and 3-(cyanoacetyl)indole in aqueous media. Also, indole-coumarin hybrids were synthesized via a domino reaction of salicylaldehyde derivatives and 3-(cyanoacetyl)indole in the presence of ammonium acetate in aqueous media. The advantages of the present protocol are high yields, short reaction times, mild reaction conditions, operational simplicity, and environmentally benign, and also there is no need to purification of products.

A green analytical method for the simultaneous determination of 17 perfluoroalkyl substances (PFAS) in human serum and semen by ultra-performance liquid chromatography-tandem mass spectrometry (UPCL-MS/MS)

The ubiquity of perfluoroalkyl substances has raised concerns about the unintended consequences of PFAS exposure on human health. In the present study, an eco-friendly ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination of 17 PFAS in human serum and semen samples. QuEChERS salts MgSO4:NaCl 4:1 (w/w) were used for the extraction. The separation of analytes was performed on an ACQUITY BEH C18 column (100 ×2.1mm, 1.7 μm), using water:methanol 95:5 and methanol as mobile phases A and B, respectively, both containing 2mM ammonium acetate. Multiple reaction monitoring (MRM) in negative ion mode was used, selecting two transitions for each analyte, except for perfluorobutanoic acid (PFBA) and perfluorobutane sulfonic acid (PFBS). The analytical method was validated according to the Organization of Scientific Area Committees (OSAC) for Forensic Sciences guidelines and AGREE approach software was used to evaluate the greenness of the method. The developed procedure was applied to the analysis of 10 paired human serum and semen samples, proving the suitability in high throughput laboratories due to the easy preparation and the reduced volume of toxic solvents. Moreover, it allows to perform further investigation on the correlation between serum and semen PFAS concentration, focusing on male reproductive system correlated pathologies, such as male infertility.

Preparing N defect modified g-C3N4 for enhanced photocatalytic degradation of methylene blue by constructing a urea–ammonium acetate system

Preparing N defect modified g-C3N4 for enhanced photocatalytic degradation of methylene blue by constructing a urea–ammonium acetate system

Stability-Indicating UPLC-PDA-QDa Methodology for Carvedilol and Felodipine in Fixed-Dose Combinations Using AQbD Principles

The development of analytical procedures, in line with the recent regulatory requirements ICH Q2 (R2) and ICH Q14, is progressing, and it must be able to manage the entire life cycle of the methodology. This is also applicable to and especially challenging for combinations of drug substances and dosage form. A reliable and efficient, stability-indicating, MS-compatible, reverse-phase ultra-performance liquid chromatographic (UPLC®) method was developed for the determination of carvedilol and felodipine in a combination oral dosage form. The development of the method, performed using analytical quality by design (AQbD) principles, was in line with the future regulatory requirements. Furthermore, the fixed-dose combination dosage forms are a clear solution to the polypharmacy phenomenon in the elderly population. The main factors evaluated were the mobile phase buffer, organic modifier, column, flow, and column temperature. The optimum conditions were achieved with a Waters Acquity HSS T3 (100 × 2.1 mm i.d., 1.8 µm) column at 38 °C, using ammonium acetate buffer (5 mM, pH 4.5) (Solution A) and MeOH (Solution B) as mobile phases in gradient elution (t = 0 min, 10% B; t = 1.5 min, 10% B; t = 12.0 min, 90% B; t = 13.0 min, 10% B; t = 15.5 min, 10% B) at a flow rate of 0.2 mL/min and UV Detection of 240 and 362 nm for carvedilol (CAV) and felodipine (FLP), respectively. The linearity was demonstrated over concentration ranges of 30–650 µg/mL (R2 = 0.9984) (CAV) and 32–260 µg/mL (R2 = 0.9996) (FLP). Forced degradation studies were performed by subjecting the samples to hydrolytic (acid and base), oxidative, and thermal stress conditions. Standard solution stability was also performed. The proposed validated method was successfully used for the quantitative analysis of bulk, stability, and fixed-dose combination dosage form samples of the desired drug product. Using the AQbD principles, it is possible to generate methodologies with improved knowledge, leading to high-quality data, lower operation costs, and minimum regulatory risk. Furthermore, this work paves the way for providing a platform of robust analytical methods for the simultaneous quantification of innovative on-demand new dose combinations.

Synthesis of 2‐Trifluoromethyl Pyridines through Multicomponent Kröhnke Reaction

A multicomponent Kröhnke reaction route toward 2‐trifluoromethyl pyridines from reaction of chalcones with easily available and stable 1‐(3,3,3‐trifluoro‐2‐oxopropyl)pyridin‐1‐ium bromide and ammonium acetate is reported. The reaction is found to be general with a range of substituted chalcones, and the applicability of the methodology in gram scale is demonstrated. Preliminary results suggest that this transformation is initiated by 1,4‐Michael addition, followed by inter‐ and intramolecular nucleophilic addition, and elimination.

Development and validation of the chromatography-mass spectrometry technique for polyprenols quantitative assessment

Introduction. Polyprenols are known as a class of natural long-chain isoprenoid alcohols, which are natural bioregulators that directly participate in the synthesis of cell membrane glycoproteins. Their hepatoprotective activity is proven, as well other types of their pharmacological effects are known, which is the reason of significant interest in these substances as a promising medicinal product. It is non-trivial task to determine the sum of polyprenols in extracts as include design and implementation of accurate reproducible analytical methods, which will subsequently be used in standardization.Aim. Development and validation of the chromatographic-mass spectrometric technique for polyprenols identification and their quantitative assessment.Materials and methods. Chromatographic separation of polyprenols was performed by using an HPLC Agilent 1260 Infinity II (Agilent Technologies, США); with the mixture of methanol, n-hexane, propanol-2, and aqueous ammonium acetate solution as eluent in gradient mode. An AB Sciex QTrap® 3200MD (AB Sciex Pte. Ltd., Singapore) triple quadrupole mass spectrometer was used as a detector, with the registration of polyprenols adducts.Results and discussion. The conditions for chromatographic separation and detection of polyprenols were identified. The developed technique was validated for the following characteristics: specificity, limit of detection, limit of quantification, linearity, accuracy, precision, range of application, and stability.Conclusion. It was determined the content of polyprenols in the substance recieved from Ginkgo biloba L. and Picea abies L. The developed technique can be used in the future to assess the content of polyprenols in drug products or pharmaceutical substances.

Novel Biopolymer-Based Catalyst for the Multicomponent Synthesis of N-aryl-4-aryl-Substituted Dihydropyridines Derived from Simple and Complex Anilines.

Although Hantzsch synthesis has been an established multicomponent reaction method for more than a decade, its derivative, whereby an aniline replaces ammonium acetate as the nitrogen source, has not been explored at great length. Recent studies have shown that the products of such a reaction, N-aryl-4-aryldihydropyridines (DHPs), have significant anticancer activity. In this study, we successfully managed to synthesize a wide range of DHPs (18 examples, 8 of which were novel) using a metal-free, mild, inexpensive, recoverable, and biopolymer-based heterogeneous catalyst, known as piperazine, which was supported in agar-agar gel. In addition, 8 further examples (3 novel) of such dihydropyridines were synthesized using isatin instead of aldehyde as a reactant, producing spiro-linked structures. Lastly, this catalyst managed to afford an unprecedented product that was derived using an innovative technique-a combination of multicomponent reactions. Essentially, the product of our previously reported aza-Friedel-Crafts multicomponent reaction could itself be used as a reactant instead of aniline in the synthesis of more complex dihydropyridines.

An Improved HPLC Separation Method for TSPO Radioligand [11C]ER176 Clinical Production.

Mitochondrial membrane translocator protein 18 kDa (TSPO) expression is increased in activated microglia, established as a plausible target of neuroinflammation imaging. [11C]ER176, specifically binding to TSPO, has been developed as the third generation of radioligand for PET imaging of TSPO, which showed the potential in better quantifying neuroinflammation than its predecessors. In the current study, we developed an automated radiosynthesis with an improved HPLC purification method for [11C]ER176 clinical production. The improved HPLC separation was integrated into the automated production of [11C]ER176 using a reverse phase semi-preparative HPLC column with an isocratic pump and the mixture of methanol and 50 mM ammonium acetate as the mobile phase. The fraction corresponding to [11C]ER176 was collected around 8.5-9.0 min without the risk of getting contaminations from nearby impurities. The automated production process took about 30 min after end of bombardment (EOB) and the quality of the final product [11C]ER176 met all specifications for clinical use based on current US Pharmacopeia and FDA CGMP requirements.