Identification of mutaprodenafil in a dietary supplement and its subsequent synthesis

We isolated a new illegal sildenafil analogue named mutaprodenafil from a dietary supplement for erectile dysfunction (ED) and proposed that it is an aildenafil derivative containing an imidazole moiety. We subsequently synthesized mutaprodenafil from a thioaildenafil and authenticated its structure.     

Combined use of liquid chromatography with mass spectrometry and nuclear magnetic resonance for the identification of degradation compounds in an erythromycin formulation

A commercial erythromycin formulation containing erythromycin A (EA) as the major compound showed the presence of an unknown degradation compound that was co-eluted with erythromycin E (EE) in the European Pharmacopoeia (Ph. Eur.) liquid chromatographic (LC) method. The amount of the degradation compound increased with respect to time. To separate this unknown (UNK1), investigation was performed with different LC methods coupled to ultraviolet detection (LC-UV). With the present Ph. Eur. method, the degradation compound could not be well separated. However, with the most selective LC-UV method (XTerra method), two more degradation products (UNK2 and UNK3) were found in the formulation which could not be observed using other methods because of their poor separation. By combining the results obtained with LC-UV, LC/MS and LC/NMR, the degradation products were identified as pseudoerythromycin A hemiketal (PsEAHK), erythromycin A enol ether carboxylic acid and erythromycin C enol ether carboxylic acid. PsEAHK is known to be a base-catalysed degradation product of EA, whereas the other two degradation products were newly identified.     

Syntheses and Biological Activities of Novel Benzotriazole Compounds Containing a Thioamide Group

IntroductionTriazoles(including benzotriazole)and their deri-vatives represent one of the most active classes of com-pounds possessing a wide spectrum of biological activi-ties.During the past several years,considerable evi-dence has been accumulated to d…     

Synthesis, Dimeric Crystal Structure, and Biological Activities of N-(4-Methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl)-N-(2-trifluoromethyl-phenyl)-guanidine

The title compound, N-(4-methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl)-N′-(2-trifluoromethyl-phenyl)-guanidine, was synthesized and its structure was confirmed by using IR, MS, 1H NMR, and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound has a weak herbicidal activity.     

Positive ion electrospray ionization tandem mass spectrometry coupled to ion-pairing high-performance liquid chromatography with a phosphate buffer for the quantitative analysis of intracellular nucleotides

A novel analytical procedure has been developed for the analysis of intracellular nucleotide triphosphates. Positive ion electrospray ionization tandem mass spectrometry (MS/MS) was interfaced to ion-pairing high-performance liquid chromatography (HPLC) utilizing a mobile phase containing 10 mM ammonium phosphate, pH 6.4, with 2 mM tetrabutylammonium hydroxide and 15% acetonitrile. The methodology was developed to support the analysis of the 5'-triphosphate anabolite of the antiviral agent (-)-FTC ((2R, 5S)-5-fluoro-1-[2-(hydroxymethyl-1,3-oxathiolan-5-yl]cytosine) in human peripheral blood mononuclear cells (PBMCs). In this procedure, all nucleotides were extracted from PBMCs with aqueous methanol, isolated with high recovery using a novel ion-pairing solid phase extraction procedure, and then analyzed directly with LC/MS/MS with a 10-min analysis time. A calibration curve was generated representing (-)-FTC 5'-triphosphate ((-)-FTCTP) concentration over the range of 0.083 to 83 picomol/10(6) cells (approximately 0.08 to 80 picomoles on-column). Linear regression analysis with 1/x(2) weighting yielded a coefficient of determination (r(2)) of greater than 0.999. The back-calculated concentrations of all calibration standards had relative errors within the range of +5 to -3%. A preliminary assessment of intra-assay precision and accuracy, analyte stability, and LC/MS system stability indicated a robust method capable of being validated with a limit of quantitation estimated conservatively at 0.08 picomol/10(6) cells (approximately 0.08 picomoles on-column; signal-to-noise (S/N) = 5). The general method developed here should be adaptable to all purine- and pyrimidine-based nucleotide applications. This report provides a detailed discussion on the key HPLC, MS, and sample preparation procedures that hold the potential for even greater nucleotide sensitivity.     

Synthesis, Structure and Biological Activities of 2- （4-Met hoxybenzoyl ）-N-phenyl- 2- （ 1,2,4-triazol- 1-yl ） thioacetamide

The title compound, 2-(methoxybenzoyl)-N-phenyl-2-(1,2,4-triazol-l-yl) thioacetamide was synthesized by several reactions from 4-methoxyacetophenone, triazole and phenyl isothiocyanate. The structure was identified by elemental analysis, ^1H NMR, MS and IR. The single crystal structure of 2-(methoxybenzoyl)-N-phenyl-2-(1,2,4-triazol-l-yl)thioacetamide was determined withX-ray diffraction. The preliminary bioassays show that the title compound exhibits weak antifungal activities and plant-growth regulatory activity.     

Synthesis, Crystal Structure and Biological Activities of N＇ - （ 4-Methoxybenzylidene ） -2- （ 1H-1, 2,4- triazol-1-yl） acetohydrazide

The title compound, N‘-( 4-methoxybenzylidene ) -2-( IH-1, 2,4-triazol-1-yl ) acetohydrazide, was synthesized and its structure was confirmed by means of IR, MS,^1H NMR and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test shows that the synthesized compound has a low antifungal activity.     

2-{[(2'-氰基联苯基-4-基)甲基]氨基}-3-硝基苯甲酸甲酯的合成

以3-硝基-2-氨基苯甲酸甲酯为原料,经三氟乙酰化、N-烷基化和脱保护反应制得坎地沙坦中间体2-{[(2'-氰基联苯基-4-基)甲基]氨基}-3-硝基苯甲酸甲酯,其结构经~1H NMR,~(13)C NMR和MS(ESI)确证。     

Synthesis,characterization, and antimicrobial and catalytic activity of a new Schiff base and its metal(II) complexes

We presented the synthesis of a new Schiff base and its complexes properties with some transition metal ions in this study. (1-amino-2-thioxo-4-p-tolyl-1,2-dihydropyrimidin-5-yl)(p-tolyl)methanone was synthesized as the starting material, and (1-((2-hydroxynaphthalen-1-yl)methyleneamino)-2-thioxo-4-p-tolyl-1,2-dihydropyrimidin-5-yl)(p-tolyl)methanone (Hnafmmp) (1) and its Ni(II) (2), Pd(II) (3), Pt(II) (4), Cu(II) (5), Co(II) (6) complexes were prepared using above-mentioned starting material. The structures of these new compounds (ligand and its complexes) were characterized with UV–Vis, FTIR, LC–MS, ¹H NMR, ¹³C NMR, magnetic susceptibility, conductivity measurement, X-ray powder diffraction method, and thermal analyses techniques. The ¹H NMR chemical shifts of all complexes were calculated by using the gauge-invariant atomic orbital HF (3.21G) method in DMSO phases. All measured results were compared with the experimental data. The ligand and its complexes were also evaluated as antimicrobial agents against representative strains bacteria. Furthermore, we studied the catalytic activity of these compounds in Suzuki–Miyaura cross-coupling reaction in aqueous media.     

Synthesis, Crystal Structure and Biological Activities of N′-(4-Methoxybenzylidene)-2-(1H-1,2,4-triazol-1-yl)acetohydrazide

The title compound, N′-(4-methoxybenzylidene)-2-(1 H -1,2,4-triazol-1-yl)acetohydrazide, was synthesized and its structure was confirmed by means of IR, MS, 1H NMR and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test shows that the synthesized compound has a low antifungal activity.     

Synthesis, Crystal Structure and Biological Activities of 2- （4-Fluorophenyl） -2-oxo-1-（1H-1,2,4-triazol-1-yl） ethyl morpholine-4-carbodithioate

The title compound, 2-（ 4-fluorophenyl ） -2-oxo-1-（ 1H-1, 2,4-triazol-1-yl ） ethyl morpholine-4-carbodithioate, was synthesized and its structure was confirmed by means of IR, MS, 1 H NMR and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound possesses some biological activities.     

Synthesis, Dimeric Crystal Structure, and Biological Activities of N- （ 4-Methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl ） -N＇- （ 2-trifluoromethyl-phenyl ） -guanidine

The title compound, N-（4-methyl-6-oxo-1,6-dihydro-pyrimidin-2-yl）-N＇-（2-tritluoromethyl-phenyl）-guanidine, was synthesized and its structure was confirmed by using IR, MS,^1H NMR, and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound has a weak herbicidal activity.     

Differentiation between sulfoaildenafil and its analogs

An analog of aildenafil, which is a potent and highly selective inhibitor of phosphodiesterase 5, was found in a dietary supplement marketed for enhancement of sexual function. The compound was isolated by silica gel column chromatography, and its structure was identified by means of 13C-NMR spectrometry, 1H-NMR spectrometry, high-resolution MS, and X-ray structure determination. The compound was identified to be sulfoaildenafil (other names: thioaildenafil, dimethyl sildenafil thione, and thiomethisosildenafil). Sulfoaildenafil is very similar to the compound thiohomosildenafil. As it is difficult to distinguish between them by LC-photodiode array detector analysis, ultra-performance LC (UPLC)/MS, ion trap LC/MS/MS (LC/IT-MS/MS), and GC/MS were performed. The mass spectra of thiohomosildenafil by UPLC/MS and LC/IT-MS/MS showed mass fragments of m/z 58, 72, and 355, and the mass spectrum by GC/MS showed mass fragments of m/z 56, 72, and 420. Some of these fragments had low intensities, but they were useful for distinguishing between the two compounds. The relationship between aildenafil (other names: dimethylsildenafil and methisosildenafil) and homosildenafil is similar to that between sulfoaildenafil and thiohomosildenafil. Therefore, these compounds were also examined.     

Analysis of oxidized epigallocatechin gallate by liquid chromatography/mass spectrometry

(-)-Epigallocatechin gallate (EGCG) of catechins changes from non-colored at around neutral pH to yellow at higher pH region in aqueous solution. The pH-dependent oxidation of EGCG was analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). LC/MS/MS analysis of EGCG and its related compounds, (-)-epicatechin gallate (ECG) and (-)-epigallocatechin (EGC), successfully elucidated the structure relationship of EGCG solution involving the color change reaction at different pH conditions. The oxidation species produced at alkaline pH was detected at a different retention time from EGCG in the chromatograms of the EGCG sample. The oxidation species was found to correspond to M+14 (where M is the molecular weight of EGCG), which has two hydrogen atoms removed and addition of one oxygen atom to the gallyl moiety in the B-ring of EGCG.     

Determination of selected non-authorized insecticides in peppers by liquid chromatography time-of-flight mass spectrometry and tandem mass spectrometry

In this work, two analytical methods based on liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC/ESI-TOFMS) and tandem mass spectrometry (LC/ESI-MS/MS) are described for the identification, confirmation and quantitation of three insecticides non-authorized in the European Union (nitenpyram, isocarbophos and isofenphos-methyl) but detected in recent monitoring programmes in pepper samples. The proposed methodologies involved a sample extraction procedure using liquid-liquid partition with acetonitrile followed by a cleanup step based on dispersive solid-phase extraction. Recovery studies performed on peppers spiked at different fortification levels (10 and 50 microg kg(-1)) yielded average recoveries in the range 76-100% with relative standard deviation (RSD) (%) values below 10%. Identification, confirmation and quantitation were carried out by LC/TOFMS and LC/MS/MS using a hybrid triple quadrupole linear ion trap (QqLIT) instrument in multiple-reaction monitoring (MRM) mode. The obtained limits of quantitation (LOQs) were in the range 0.1-5 microg kg(-1), depending on each individual technique. Finally, the proposed methods were successfully applied to the analysis of suspected pepper samples.     

Liquid chromatographic determination of St. John's wort components in functional foods

A method was developed for determination of St. John's wort marker compounds hypericin, pseudohypericin, hyperforin, and adhyperforin in functional foods. Solid-phase extraction provided analyte extraction and significant sample cleanup prior to analysis using liquid chromatography (LC) with UV and fluorescence detection. In addition to quantification using LC-UV, confirmation was made with electrospray ionization LC mass spectrometry (LC/MS). Several commercially available tea and drink products claiming to contain St. John's wort were tested. Recoveries ranged from 51 to 98% for the liquid samples. Comparison of the concentrations in 4 St. John's wort teas showed a variation in analyte concentration (1044-10 ng/mL marker compounds in brewed tea) and composition. No marker compounds were found in the beverages, indicating possible decomposition of the marker compounds caused by low pH and/or exposure to light. A solvent extraction procedure was developed for analysis of the marker compounds from solid samples. Analytes were detected at low parts per million, with an average recovery of 75%. No St. John's wort components were found in the 2 solid functional food samples analyzed.     

Synthesis of highly fluorescent and water soluble perylene bisimide

Designed and synthesized a new highly water soluble N,N¹-bis（2-（（5-（（dimethylamino）methyl）furan-2-yl）methylthio）ethyl）-perylene -3,4,9,10-tetracarboxylic diimide from 2-（（5-（（dimethylamino）methyl）furan-2-yl）methylthio）ethanamine and perylene-3,4,9,10- tetracarboxylic dianhydride.The compound was characterized by ¹H,¹³C,2D NMR,mass and IR techniques.The compound is highly fluorescent with good solubility in water and other polar solvents.     

Investigation of amodiaquine bulk drug impurities by liquid chromatography/ion trap mass spectrometry

Three unknown impurities in an amodiaquine bulk drug sample were detected by reversed-phase high-performance liquid chromatography with ultraviolet detection (HPLC/UV). A liquid chromatography/tandem mass spectrometry (LC/MS(n)) method is described for the investigation of these impurities. Mass spectral data were acquired on an LCQ ion trap mass analyzer equipped with an electrospray ionization (ESI) source operated in positive ion mode. The fragmentation behavior of amodiaquine and its impurities has been studied. Based on the mass spectral data and the specifics of the synthetic route, the possible structures of these impurities were elucidated as 4-[(5-chloroquinolin-4-yl)amino]-2-(diethylaminomethyl)phenol (impurity I), 4-[(7-chloroquinolin-4-yl)-amino]phenol (impurity II) and 4-[(7-chloroquinolin-4-yl)amino]-2-(diethylaminomethyl)-N(1)-oxy]phenol (impurity III). The structures were confirmed by their independent synthesis and NMR spectral assignment.     

Synthesis,Crystal Structure and Anti-breast Cancer Activity of ((3S,5R)-5-((1H-1,2,4-triazol-1-yl)methyl)-5-(2,4-difluorophenyl)tetrahydrofuran-3-yl)methyl 4-Methylbenzenesulfonate

The new heterocycle compound ((3S,5R)-5-((1H-1,2,4-triazol-1-yl)methyl)-5-(2,4-difluorophenyl)tetrahydrofuran-3-yl)methyl 4-methylbenzenesulfonate (1), designed using((3R,5S)-5-(2,4-difluorophenyl)-5-iodotetrahydrofuran-3-yl)methyl isobutyrate(2) as the start material, was successfully obtained via multiple synthesis route and finally characterized by IR, ~1H NMR, and single-crystal X-ray crystallography. In addition, the in vitro anticancer activities of the newly synthesized complex 1 have been emulated against three human breast cancer cell lines BT474, MCF7 and MB.     

A New Chromone Derivative from Stellera chamaejasme L.

A new chromone derivative,3-[1-(2,4,6-trihydroxyphenyl)3-di-(4-hydroxyphenyl) 1-propanone-2-yl]5,7-dihydroxy-8-di(4-hydroxyphenyl)methyl-4H-1-benzopyran-4-one,named as isomohsenone was isolated from the roots of Stellera chamaejasme L.together with known chamaechromone. Its structure was determined by the analysis of MS and NMR data,especially 2D NMR spectra.