Synthesis and Biological Evaluation of Some 1,2‐Disubstituted Benzimidazole Derivatives as New Potential Anticancer Agents

The synthesis of some new 1‐(2‐aryl‐2‐oxoethyl)‐2‐[(morpholine‐4‐yl)thioxomethyl]benzimidazole derivatives and investigation of their anticancer activities were the aims of this work. 2‐(Chloromethyl)benzimidazole compound was reacted with sulfur and morpholine via Willgerodt–Kindler reaction to give 2‐[(morpholine‐4‐yl)thioxomethyl]benzimidazole. Then, the obtained compound was reacted with appropriate α‐bromoacetophenone derivatives in the presence of potassium carbonate to give the final products. Structure elucidation of the final compounds was achieved by FT‐IR, ¹H NMR spectroscopy and MS spectrometry. The anticancer activities of the final compounds were evaluated by MTT assay, BrdU method, and flow cytometric analysis on C6, MCF‐7, and A549 tumor cells. Most of the synthesized compounds exhibited considerable selectivity against the MCF‐7 and C6 cell lines.     

Analytical characterization of “etonitazepyne,” a new pyrrolidinyl-containing 2-benzylbenzimidazole opioid sold online

This paper reports on the identification and full chemical characterization of the substance colloquially called “etonitazepyne” or “N-pyrrolidino etonitazene” (2-(4-ethoxybenzyl)-5-nitro-1-(2-(pyrrolidin-1-yl)ethyl)-1H-benzo[d]imidazole), a potent NPS opioid of the 5-nitrobenzimidazole class. Identification of etonitazepyne was performed, on a sample purchased during routine monitoring of the drug market, using GC-MS, HRAM LC-MS/MS, ¹H NMR, and FTIR. The chromatographic data, together with the FTIR data, indicated the presence of a highly pure compound and already indicated a benzimidazole structure. The specific benzimidazole regio-isomer was confirmed using ¹H NMR spectroscopy, resulting in the unambiguous identification of etonitazepyne.     

Structural characterization and pharmacological evaluation of the new synthetic cannabinoid CUMYL‐PEGACLONE

The number of new psychoactive substances (NPS) that have emerged on the European market has been rapidly growing in recent years, with a particularly high number of new compounds from the group of synthetic cannabinoid receptor agonists. There have been various political efforts to control the trade and the use of NPS worldwide. In Germany, the Act to control the distribution of new psychoactive substances (NpSG) came into force in November 2016. In this new act, two groups of substances were defined, the group “cannabimimetics/synthetic cannabinoids” covering indole, indazole, and benzimidazole core structures, and a second group named “compounds derived from 2‐phenethylamine.” Shortly after, the first retailers of “herbal blends” promoted new products allegedly not violating the German NpSG. We describe the identification and structural elucidation of one of the first synthetic cannabinoids not being covered by the NpSG, 5‐pentyl‐2‐(2‐phenylpropan‐2‐yl)‐2,5‐dihydro‐1H‐pyrido[4,3‐b]indol‐1‐one. For isolation of the substance a flash chromatography separation was applied. The structure elucidation was performed using gas chromatography–mass spectrometry (GC–MS), gas chromatography‐solid state infrared spectroscopy (GC–sIR), liquid chromatography–electrospray ionization–quadrupole time of flight–mass spectrometry (LC–ESI–qToF–MS) and nuclear magnetic resonance (NMR) analysis. Additionally, binding affinity towards the cannabinoid receptors CB₁ and CB₂ and efficacy in a cAMP accumulation assay were measured, showing full agonistic activity and high potency at both receptors. The new compound bears a γ‐carboline core structure circumventing the German NpSG and the generic definitions in other national laws. As a semi‐systematic name for 2‐cumyl‐5‐pe ntyl‐ga mma‐c arbol in‐1‐one CUMYL‐PEGACLONE is suggested.     

Synthesis and characterization of tritium labeled N‐((R)‐1‐((S)‐4‐(4‐chlorophenyl)‐4‐hydroxy‐3,3‐dimethylpiperidin‐1‐yl)‐3‐methyl‐1‐oxobutan‐2‐yl)‐3‐sulfamoylbenzamide

N‐((R)‐1‐((S)‐4‐(4‐chlorophenyl)‐4‐hydroxy‐3,3‐dimethylpiperidin‐1‐yl)‐3‐methyl‐1‐oxobutan‐2‐yl)‐3‐sulfamoylbenzamide is a potent C‐C chemokine receptor 1 (CCR1) antagonist. The compound, possessing benzamide functionality, successfully underwent tritium/hydrogen (T/H) exchange with an organoiridium catalyst (Crabtree's catalyst). The labeling pattern in the product was studied with liquid chromatography–mass spectrometry, time‐of‐flight mass spectrometry, and ³H‐NMR. Overall, multiple labeled species were identified. In addition to the anticipated incorporation of tritium in the benzamide moiety, tritium labeling was observed in the valine portion of the molecule including substitution at its chiral carbon. Using authentic standards, liquid chromatography analysis of the labeled compound showed complete retention of stereochemical configuration.     

Syntheses,calcium channel modulation effects,and nitric oxide release studies of O2‐alkyl‐1‐(pyrrolidin‐1‐yl) diazen‐1‐ium‐1,2‐diolate 4‐aryl(heteroaryl)‐1,4‐dihydro‐2,6‐dimethyl‐3‐nitropyridine‐5‐carboxylates

A group of racemic 4‐aryl(heteroary)‐1,4‐dihydro‐2,6‐dimethyl‐3‐nitropyridine‐5‐carboxy‐lates possessing a potential nitric oxide donor C‐5 O²‐alkyl‐1‐(pyrrolidin‐1‐yl)diazen‐1‐ium‐1,2‐diolate ester [alkyl=(CH₂)_n, n=1–4] substituent were synthesized using a modified Hantzsch reaction. Compounds having a C‐4 2‐trifluoromethylphenyl ( 16 ), 2‐pyridyl ( 17 ), or benzofurazan‐4‐yl ( 20 ) substituent generally exhibited more potent smooth‐muscle calcium channel antagonist activity (IC₅₀ values in the 0.55 to 38.6 μM range) than related analogs having a C‐4 3‐pyridyl ( 18 ), or 4‐pyridyl ( 19 ) substituent with IC₅₀ values > 29.91 μM, relative to the reference drug nifedipine (IC₅₀=0.0143 μM). The point of attachment of C‐4 isomeric pyridyl substituents was a determinant of antagonist activity where the relative potency profile was 2‐pyridyl > 3‐pyridyl and 4‐pyridyl. Subgroups of compounds 16a–d , 17a–d , and 20a–d having alkyl spacer groups of variable chain length [–CO₂(CH₂)_nO–, n=1–4] exhibited small differences in calcium channel antagonist potency. Replacement of the ester “methyl” moiety of Bay K 8644 by an O²‐alkyl‐1‐(pyrrolidin‐1‐yl)diazen‐1‐ium‐1,2‐diolate group provided the Bay K 8644 group of analogs 16a‐d that retained the desired cardiac positive inotropic effect. The most potent compound in this group, O²‐ethyl‐1‐(pyrrolidin‐1‐yl)diazen‐1‐ium‐1,2‐diolate 1,4‐dihydro‐2,6‐dimethyl‐3‐nitro‐4‐(2‐trifluoromethylphenyl)pyridine‐5‐carboxylate ( 16b , EC₅₀=0.096 μM) is about eightfold more potent positive inotrope (cardiac calcium channel agonist) than the reference compound Bay K 8644 (EC₅₀=0.77 μM). A similar replacement of the ester “isopropyl” group in the C‐4 benzofurazan‐4‐yl group of compounds by an O²‐alkyl‐1‐(pyrrolidin‐1‐yl)diazen‐1‐ium‐1,2‐diolate ester substituent provided compounds 20 (n=1 and 4) that were approximately equipotent cardiac positive inotropes with the parent reference compound PN 202‐791 ( 3 , EC₅₀=9.40 μM). The O²‐alkyl‐1‐(pyrrolidin‐1‐yl)diazen‐1‐ium‐1,2‐diolate ester moiety present in 1,4‐dihydropyridine calcium channel modulating compounds 16–20 is not a suitable ?NO donor moiety because the percent nitric oxide released upon in vitro incubation with either l ‐cysteine, rat serum, or pig liver esterase was less than 1%. Drug Dev. Res. 60:204–216, 2003. © 2003 Wiley‐Liss, Inc.     

Characterization and analysis of biphalin: an opioid peptide with a palindromic sequence

Abstract: Among the many opioid peptides developed to date as nonaddictive analgesics, biphalin has exhibited extraordinary high potency and many other desirable characteristics. Biphalin is an octapeptide consisting of two monomers of a modified enkephalin, attached via a hydrazine bridge, and with the amino acids assembled in a palindromic sequence. Its structure is (Tyr‐d ‐Ala‐Gly‐Phe‐NH‐)‐₂. However, this unique peptide, like any other synthetic peptide, needs strict quality control because of certain drawbacks associated with peptide synthesis. This paper discusses our approaches to characterizing and analyzing biphalin. Many techniques were used, including elemental analysis, amino acid analysis, amino acid sequence analysis (AASA), mass spectrometry (MS), ¹H‐NMR, ¹H‐correlated spectroscopy (COSY)‐NMR, high‐performance liquid chromatography (HPLC) and capillary electrophoresis (CE). Electrospray ionization (ESI) mass spectrometry, which included both ESI‐MS and ESI‐MS/MS, was performed to confirm the full sequence because AASA results alone verified only the monomer sequence, and not the full sequence. Although the ¹H‐NMR results led to a preliminary assignment of many protons, the ¹H COSY‐NMR results allowed for unequivocal assignment of almost all protons. Peptide purity was determined using two techniques, reversed‐phase HPLC and CE. The counter‐ion of the peptide, trifluoroacetic acid, was determined by CE, using an indirect detection method developed previously in our laboratory. This paper illustrates successful application of nonconventional techniques to characterize and analyze a structurally modified peptide, biphalin, when standard techniques for peptide analysis are inadequate.     

The identification and analytical characterization of 2,2′‐difluorofentanyl

New psychoactive substances (NPS) have expanded their distribution and become widely available in the global market in recent years. The illicit use of fentanyl and its analogs has become an important worldwide concern linked to their high potency and risk of fatal overdose. This study describes the analytical characterization of a new fentanyl derivative N‐(1‐(2‐fluorophenethyl)‐4‐piperidinyl)‐N‐(2‐fluorophenyl)propionamide (2,2′‐difluorofentanyl). Identification was based on ultra‐high‐performance liquid chromatography–quadrupole time‐of‐flight–mass spectrometry (UHPLC–QTOF–MS), gas chromatography–mass spectrometry (GC–MS), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. To our knowledge, this study is the first to report on analytical data for this compound. The most abundant fragment ion in the electrospray ionization (ESI) mass spectrum under collision‐induced dissociation (CID) mode was formed by the cleavage between the piperidine ring and the N‐phenyl‐amide moiety of the protonated molecule. Two diagnostic ions in the electron ionization (EI) mass spectrum were formed by the loss of a tropylium ion (M‐91), and by the degradation of the piperidine ring and dissociate of the COC₂H₅ moiety altogether, respectively.     

Identification and analytical characterization of four synthetic cannabinoids ADB‐BICA,NNL‐1, NNL‐2, and PPA(N)‐2201

Since the first appearance as psychotropic drugs in illegal markets in 2008, the spread of synthetic cannabinoids is becoming a serious problem in many countries. This paper reports on the analytical properties and structure elucidation of four cannabimimetic derivatives in seized material: 1‐benzyl‐N ‐(1‐carbamoyl‐2,2‐dimethylpropan‐1‐yl)‐1H ‐indole‐3‐carboxamide (ADB‐BICA, 1 ), N ‐(1‐carbamoylpropan‐1‐yl)‐1‐(5‐fluoropentyl)‐1H ‐pyrrolo[2,3‐b]pyridine‐3‐carboxamide (NNL‐1, 2 ), (4‐benzylpiperazin‐1‐yl)(1‐(5‐fluoropentyl)‐1H ‐indol‐3‐yl)methanone (NNL‐2, 3 ), and N ‐(1‐carbamoyl‐2‐phenylethyl)‐1‐(5‐fluoropentyl)‐1H ‐indazole‐3‐carboxamide (PPA(N)‐2201, 4) . The identifications were based on liquid chromatography‐quadrupole‐time‐of‐flight‐mass spectrometry (LC‐QTOF‐MS), gas chromatography‐mass spectrometry (GC‐MS), Fourier transform infrared spectroscopy (FT‐IR), and nuclear magnetic resonance (NMR) spectroscopy. No chemical or pharmacological data about compounds 1–3 have appeared until now, making this the first report on these compounds. The GC‐MS data of 4 has been reported, but this study added the LC‐MS, FT‐IR, and NMR data for additional characterization. Copyright © 2016 John Wiley & Sons, Ltd.     

Design,synthesis, and biological evaluation of 5‐(4‐(pyridin‐4‐yl)‐1H‐1,2,3‐triazol‐1‐yl)benzonitrile derivatives as xanthine oxidase inhibitors

A series of 5‐(4‐(pyridin‐4‐yl)‐1H‐1,2,3‐triazol‐1‐yl)benzonitrile derivatives ( 1a–p ) was designed, synthesized, and identified as xanthine oxidase inhibitors with micromolar level potencies. Among them, the most promising compounds 1j and 1k were obtained with IC₅₀ values of 8.1 and 6.7 μm , respectively. The Lineweaver–Burk plot revealed that compound 1k acted as a mixed‐type xanthine oxidase inhibitor. SAR analysis revealed that a carbon atom occupying the X³ position is not as effective as a nitrogen atom, and an iso‐pentyloxy or a cyclopentyloxy at the 2‐position of benzonitrile moiety will benefit the inhibitory potency. The basis of xanthine oxidase inhibition by 1k was rationalized by molecular modeling studies.     

Synthesis,In Vitro Protoporphyrinogen Oxidase Inhibition,and Herbicidal Activity of N‐(Benzothiazol‐5‐yl)hexahydro‐1H‐isoindole‐1,3‐diones and N‐(Benzothiazol‐5‐yl)hexahydro‐1H‐isoindol‐1‐ones

Protoporphyrinogen oxidase ( EC 1.3.3.4 ) is one of the most significant targets for a large family of herbicides. As part of our continuous efforts to search for novel protoporphyrinogen oxidase‐inhibiting herbicides, N‐(benzothiazol‐5‐yl)tetrahydroisoindole‐1,3‐dione was selected as a lead compound for structural optimization, leading to the syntheses of a series of novel N‐(benzothiazol‐5‐yl)hexahydro‐1H‐isoindole‐1,3‐diones ( 1a – o ) and N‐(benzothiazol‐5‐yl)hexahydro‐1H‐isoindol‐1‐ones ( 2a – i ). These newly prepared compounds were characterized by elemental analyses, ¹H NMR, and ESI‐MS, and the structures of 1h and 2h were further confirmed by X‐ray diffraction analyses. The bioassays indicated that some compounds displayed comparable or higher protoporphyrinogen oxidase inhibition activities in comparison with the commercial control. Very promising, compound 2a , ethyl 2‐((6‐fluoro‐5‐(4,5,6,7‐tetrahydro‐1‐oxo‐1H‐isoindol‐2(3H)‐yl)benzo[d]thiazol‐2‐yl)‐sulfanyl)acetate, was recognized as the most potent candidate with K_i value of 0.0091 μm . Further greenhouse screening results demonstrated that some compounds exhibited good herbicidal activity against Chenopodium album at the dosage of 150 g/ha.     

Roflumilast analogs with improved metabolic stability,plasma protein binding,and pharmacokinetic profile

With the aim of studying their in vitro and in vivo pharmacokinetics, new chromatographic methods were developed for the determination of three new roflumilast synthetic analogs ( I?III ) as PDE‐4B inhibitors in rat liver S9 fraction, phosphate buffered saline, pH 7.4, and human and rat plasma. The developed high performance liquid chromatography?ultra violet (HPLC?UV) methods were performed on a Zorbax Eclipse C8 column and UV detection was carried out at 215 nm. The three compounds were tested for their metabolic stability and were found to be metabolically more stable than roflumilast especially the 2‐mercaptobenzothiazol‐6‐yl analog ( III ) which displayed an in vitro half‐life time (247.55 minutes) higher than that of roflumilast (12.29 minutes) and a low in vitro clearance of 5.67 mL/min./kg. Possible phase I metabolites were investigated using ultra‐performance liquid chromatography?tandem mass spectrometry (UPLC–MS/MS) showing hydroxylation of the unsubstituted benzothiazol‐2‐yl ( I ) and benzothiazole‐6‐yl ( II ) analogs and a cleaved benzothiazole metabolite of the 2‐mercaptobenzothiazol‐6‐yl analog ( III ). Plasma protein binding affinity was tested using equilibrium membrane dialysis method showing a very high percentage (more than 95%) of plasma protein binding of compounds I and II where compound III exhibited lower percentage (53.71%) demonstrating its accessibility for tissue distribution. Also, a UPLC–MS/MS method was developed using an Acquity UPLC BEH shield RP C18 column to be applied to an in vivo pharmacokinetic study in rats following a subcutaneous dose (1 mg/kg). Compounds I?III showed improved in vivo pharmacokinetic parameters especially compound III which displayed a half‐life 3‐fold greater than roflumilast (21 hours) and a C_max value of 113.958 ng/mL. Accordingly, this new chemical entity should be subjected to further investigation as it can be a good drug candidate for treating chronic obstructive pulmonary disease.     

Phase I metabolism of the carbazole‐derived synthetic cannabinoids EG‐018, EG‐2201, and MDMB‐CHMCZCA and detection in human urine samples

Synthetic cannabinoids (SCs) are a structurally diverse class of new psychoactive substances. Most SCs used for recreational purposes are based on indole or indazole core structures. EG‐018 (naphthalen‐1‐yl(9‐pentyl‐9H‐carbazol‐3‐yl)methanone), EG‐2201 ((9‐(5‐fluoropentyl)‐9H‐carbazol‐3‐yl)(naphthalen‐1‐yl)methanone), and MDMB‐CHMCZCA (methyl 2‐(9‐(cyclohexylmethyl)‐9H‐carbazole‐3‐carboxamido)‐3,3‐dimethylbutanoate) are 3 representatives of a structural subclass of SCs, characterized by a carbazole core system. In vitro and in vivo phase I metabolism studies were conducted to identify the most suitable metabolites for the detection of these substances in urine screening. Detection and characterization of metabolites were performed by liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS) and liquid chromatography–electrospray ionization–quadrupole time‐of‐flight–mass spectrometry (LC–ESI–QToF–MS). Eleven in vivo metabolites were detected in urine samples positive for metabolites of EG‐018 (n = 8). A hydroxypentyl metabolite, most probably the 4‐hydroxypentyl isomer, and an N‐dealkylated metabolite mono‐hydroxylated at the carbazole core system were most abundant. In vitro studies of EG‐018 and EG‐2201 indicated that oxidative defluorination of the 5‐fluoropentyl side chain of EG‐2201 as well as dealkylation led to common metabolites with EG‐018. This has to be taken into account for interpretation of analytical findings. A differentiation between EG‐018 and EG‐2201 (n = 1) uptake is possible by the detection of compound‐specific in vivo phase I metabolites evaluated in this study. Out of 30 metabolites detected in urine samples of MDMB‐CHMCZCA users (n = 20), a metabolite mono‐hydroxylated at the cyclohexyl methyl tail is considered the most suitable compound‐specific consumption marker while a biotransformation product of mono‐hydroxylation in combination with hydrolysis of the terminal methyl ester function provides best sensitivity due to its high abundance.     

The in vivo and in vitro phase I metabolism of FYL‐67, a novel oxazolidinone antibacterial drug,studied by LC‐MS/MS

In our previous study, FYL‐67, a novel linezolid analogue with the morpholinyl ring replaced by a 4‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl group, was demonstrated to own an excellent activity against Gram‐positive organisms,such as methicillin‐resistant Staphylococcus aureus (MRSA). However, metabolic biotransformation was not investigated. This study was performed to identify the phase I metabolites of FYL‐67 using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). The chemical structures were confirmed by comparison with corresponding chemical standards obtained internal. Primary elucidation of the metabolic pathway of FYL‐67 in vitro was performed using liver preparations (microsomes and hepatocytes) from rats and humans, and SD (Sprague Dawley, rat, rattus norvegicus) rats were used for the study of in vivo approach. To the end, two metabolites (M₁ and M₂) were detected after in vitro as well as in vivo experiments. Based on LC‐MS/MS analyses, the metabolites were demonstrated to be 5‐(aminomethyl)‐3‐(3‐fluoro‐4‐(4‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl)phenyl)oxazolidin‐2‐one (M₁) and 3‐(3‐fluoro‐4‐(4‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl)phenyl)‐5‐(hydroxymethyl)oxazolidin‐2‐one (M₂). Amide hydrolysis at acetyl group of FYL‐67 leading to the formation of M₁ was observed and suggested to play a major role in both in vivo and in vitro phase I metabolism of FYL‐67. M₁ was demonstrated to undergo a further oxidation to form M₂. In addition, the results indicated no species difference existing between rats and humans. The outcomes of our research can be utilized for the development and validation of the analytical method for the quantification of FYL‐67 as well as its metabolites in biological samples. Furthermore, it is helpful to conduct studies of pharmacodynamics and toxicodynamics. Copyright © 2015 John Wiley & Sons, Ltd.     

Identification and characterization of 2,5‐dimethoxy‐3,4‐dimethyl‐β‐phenethylamine (2C‐G) – A new designer drug

This study presents and discusses the mass spectrometric, infrared spectroscopic and nuclear magnetic resonance spectroscopic data of 2,5‐dimethoxy‐3,4‐dimethyl‐β‐phenethylamine (2C‐G), a new designer drug. A powder sample containing 2C‐G was seized in Poland in 2011. The paper focuses on a comparison of the analytical features of 2C‐G and other members of the 2C‐series, in order to assess the possibility of unequivocal identification. The occurrence of intense peak at m/z = 178 and different intensities of the ions at m/z = 165 and 180 in the gas chromatography‐electron impact‐mass spectrometry (GC‐EI/MS) spectrum of 2C‐G made it possible to distinguish it from 2C‐E. Differences in relative intensities of the ions at m/z = 192, 179 and 177 were observed for GC‐EI/MS spectra of TFAA derivatives of 2C‐G and 2C‐E. An identical set of ions was recorded for these substances using the liquid chromatography‐electrospray ionization/quadrupole time of flight mass spectrometry (LC‐ESI/QTOFMS) method in both MS and tandem mass spectrometry (MS/MS) mode, but the distinction was possible based on differences in the ion intensities at m/z = 193.1223 and 178.0988. The Fourier transform infrared (FTIR) spectrum of 2C‐G was significantly different from other members of the 2C‐series, with a characteristic doublets at 993–1014 cm^‐1 and 1099–1124 cm^‐1, and the ratio of bands at higher wavenumbers. Final elucidation of the structure of 2C‐G was carried out by ¹H and ¹³C NMR spectroscopy. The study indicated that the marketing of analogues of controlled substances poses a real analytical challenge for forensic laboratories, and the application of sophisticated methods is often required for unequivocal identification of a new substance. Copyright © 2012 John Wiley & Sons, Ltd.     

Identification of the designer steroid Androsta‐3,5‐diene‐7,17‐dione in a dietary supplement

A liquid chromatography‐mass spectrometry (LC–MS) screen for known anabolic‐androgenic steroids in a dietary supplement product marketed for “performance enhancement” detected an unknown compound having steroid‐like spectral characteristics. The compound was isolated using high performance liquid chromatography with ultraviolet detection (HPLC–UV) coupled with an analytical scale fraction collector. After the compound was isolated, it was then characterized using gas chromatography with simultaneous Fourier Transform infrared detection and mass spectrometry (GC–FT–IR–MS), liquid chromatography–high resolution accurate mass–mass spectrometry (LC–HRAM–MS) and nuclear magnetic resonance (NMR). The steroid had an accurate mass of m/z 285.1847 (error?0.57 ppm) for the protonated species [M + H]⁺, corresponding to a molecular formula of C₁₉H₂₄O₂. Based on the GC–FT–IR–MS data, NMR data, and accurate mass, the compound was identified as androsta‐3,5‐diene‐7,17‐dione. Although this is not the first reported identification of this designer steroid in a dietary supplement, the data provided adds information for identification of this compound not previously reported. This compound was subsequently detected in another dietary supplement product, which contained three additional active ingredients.     

Anticonvulsant and Neurotoxicity Evaluation of Some Novel Kojic Acids and Allomaltol Derivatives

A series of new 3‐hydroxy‐6‐hydroxymethyl/methyl‐2‐substituted 4H‐pyran‐4‐ones were synthesized and prepared by the reaction of kojic acid or allomaltol with piperidine derivatives and formaline as potential anticonvulsant compounds. The structure of the synthesized compounds was confirmed using the elemental analysis results and the spectroscopic techniques such as IR, ¹H‐NMR, and ESI‐MS. Anticonvulsant activities were examined by maximal electroshock (MES) and subcutaneous Metrazol (scMet)‐induced seizure tests. Neurotoxicity was determined by the rotorod toxicity test. All these tests were performed in accordance with the procedures of the Antiepileptic Drug Development (ADD) program. According to the activity studies and at all doses, 3‐hydroxy‐2‐[(4‐hydroxy‐4‐phenylpiperidin‐1‐yl)methyl]‐6‐methyl‐4H‐pyran‐4‐one (compound 1 ), 2‐{[4‐(4‐chlorophenyl)‐3,6‐dihydropyridin‐1(2H)‐yl]methyl}‐3‐hydroxy‐6‐methyl‐4H‐pyran‐4‐one (compound 6 ), 2‐[(4‐acetyl‐4‐phenylpiperidin‐1‐yl)methyl]‐3‐hydroxy‐6‐(hydroxymethyl)‐4H‐pyran‐4‐one (compound 11 ), and 2‐{[4‐(4‐chlorophenyl)‐3,6‐dihydropyridin‐1(2H)‐yl] methyl}‐3‐hydroxy‐6‐hydroxymethyl‐4H‐pyran‐4‐one (compound 12 ) were found to have anticonvulsant activity against MES‐induced seizures at 4 h. Also, 2‐{[4‐(4‐bromophenyl)‐4‐hydroxypiperidin‐1‐yl]methyl}‐3‐hydroxy‐6‐(hydroxymethyl)‐4H‐pyran‐4‐one (compound 8 ) was determined to be the most active compound against scMet‐induced seizures at all doses at 0.5 and 4 h. In the rotorod neurotoxicity screening, all compounds showed no toxicity at all doses.     

Synthesis and Pharmacological Evaluation of Some Novel Thebaine Derivatives: N‐(Tetrazol‐1H‐5‐yl)‐6,14‐endoethenotetrahydrothebaine Incorporating the 1,3,4‐Oxadiazole or the 1,3,4‐Thiadiazole Moiety

In this study, we synthesized some novel N‐(tetrazol‐1H‐5‐yl)‐6,14‐endoethenotetrahydrothebaine 7α‐substituted 1,3,4‐oxadiazole and 1,3,4‐thiadiazole derivatives as potential analgesic agents. The structures of the compounds were established on the basis of their IR, ¹H NMR, ¹³C NMR, 2D NMR, and high‐resolution mass spectral data. The analgesic activity was evaluated by a rat‐hot plate test model and a rat tail‐flick model. Compound 12 showed analgesic activity higher than that of morphine. In addition to a histopathological and biochemical evaluation, the LD₅₀ dose for the most active compound 12 was determined.     

Identification of five pyrrolidinyl substituted cathinones and the collision‐induced dissociation of electrospray‐generated pyrrolidinyl substituted cathinones

This article reports on the analytical properties of five pyrrolidinyl substituted cathinones: α ‐pyrrolidinononaphenone (α ‐PNP, 1 ), 4‐chloro‐α ‐pyrrolidinopropiophenone (4‐Cl‐α ‐PPP, 2 ), 4‐chloro‐α ‐pyrrolidinovalerophenone (4‐Cl‐α ‐PVP, 3 ), 5‐dihydrobenzofuranpyrovalerone (5‐DBFPV, 4 ), and 2‐(pyrrolidin‐1‐yl)‐1‐(5,6,7,8‐tetrahydronaphthalen‐2‐yl)hexan‐1‐one (β ‐THNPH, 5 ). These identifications were based on liquid chromatography–quadrupole time‐of‐flight‐mass spectrometry (LC–QTOF–MS), gas chromatography–mass spectrometry (GC–MS) and nuclear magnetic resonance spectroscopy (NMR). To our knowledge, no analytical data about α ‐PNP, 4‐Cl‐α ‐PPP, 4‐Cl‐α ‐PVP, and β ‐THNPH have appeared until now, making this the first report on these compounds. Moreover, in order to study the collision‐induced dissociation (CID) characteristic fragmentation routes of pyrrolidinyl substituted cathinones, a total number of 13 pyrrolidinyl substituted cathinones were selected and discussed. The major fragmentation pathways under CID mode are produced, leading to the formation of characteristic ions. Product ions of [M‐C₄H₉N]⁺ and C_nH_2nN⁺ indicate the presence of pyrrolidinyl substitution. Characteristic fragments are also produced via the cleavages of the CH–N(CH₂)₄ bond and the CO‐CHN bond. Copyright © 2016 John Wiley & Sons, Ltd.     

Identification,isolation, and synthesis of seven novel impurities of anti‐diabetic drug Repaglinide

Seven unknown impurities in Repaglinide bulk drug batches at below 0.1% (ranging from 0.05 to 0.10%) were detected by an ultra‐performance liquid chromatographic (UPLC) method. These impurities were isolated from the crude sample of Repaglinide using preparative high performance liquid chromatography (prep‐HPLC). Based on liquid chromatography‐electrospray ionization‐mass spectrometry (LC‐ESI/MS) study, the chemical structures of seven new impurities ( 8 , 9 , 10 , 11 , 13 , 14, and 16 ) were presumed and characterized as 4‐(cyanomethyl)‐2‐ethoxybenzoic acid ( 8) , 4‐(cyanomethyl)‐2‐ethoxy‐N‐(3‐methyl‐1‐(2‐(piperidin‐1‐yl)phenyl)butyl)benzamide ( 9 ), 4‐(2‐amino‐2‐oxoethyl)‐2‐ethoxy‐N‐(3‐methyl‐1‐(2‐(piperidin‐1‐yl)phenyl)butyl) benzamide ( 10 ) and 2‐(3‐ethoxy‐4‐((3‐methyl‐1‐(2‐(piperidin‐1‐yl)phenyl)butyl) carbamoyl) phenyl) acetic acid ( 11) and 4‐(cyanomethyl)‐N‐cyclohexyl‐2‐ethoxybenzamide ( 13) , 2‐(4‐(cyclohexylcarbamoyl)‐3‐ethoxyphenyl) acetic acid ( 14) and N‐cyclohexyl‐4‐(2‐(cyclohexylamino)‐2‐oxoethyl)‐2‐ethoxybenzamide ( 16) . The complete spectral analysis, proton nuclear magnetic resonance (¹H NMR), ¹³C NMR, MS, and infrared (IR) confirmed the proposed chemical structures of impurities. Identification, structural characterization, formation, and their synthesis was first reported in this study. The impurity 11 was crystallized and structure was solved by single crystal X‐ray diffraction. Copyright © 2017 John Wiley & Sons, Ltd.     

Cyclic enkephalin analogs containing various para‐substituted phenylalanine derivatives in place of Tyr1 are potent opioid agonists*

Abstract: The cyclic enkephalin analog H‐Tyr‐c[d ‐Cys‐Gly‐Phe(pNO₂)‐d ‐Cys]NH₂ is a highly potent opioid agonist with IC₅₀s of 35 pm and 19 pm in the guinea‐pig ileum (GPI) and mouse vas deferens (MVD) assays, respectively. The Phe¹‐analog of this peptide showed 370‐fold and 6790‐fold lower agonist potency in the GPI and MVD assays, respectively, indicating the importance of the Tyr¹ hydroxyl‐group in the interaction with μ and δ opioid receptors. In the present study, the effect of various substituents (‐NH₂, ‐NO₂, ‐CN, ‐CH₃, ‐COOH, ‐COCH₃, ‐CONH₂) introduced in the para‐position of the Phe¹‐residue of H‐Phe‐c[d ‐Cys‐Gly‐Phe(pNO₂)‐d ‐Cys]NH₂ on the in vitro opioid activity profile was examined. Most analogs showed enhanced μ and δ agonist potencies in the two bioassays, except for the Phe(pCOOH)¹‐analog, which was weakly active, probably as a consequence of the negative charge. The most potent compounds were the Phe(pCOH₃)¹‐ and the Phe(pCONH₂)¹‐analogs. The latter compound showed subnanomolar μ and δ agonist potencies and represents the most potent enkephalin analog lacking the Tyr¹ hydroxyl‐group reported to date. Taken together, these results indicate that various substituents introduced in the para‐position of Phe¹ enhance opioid activity via hydrogen bonding or hydrophobic interactions with the receptor. Comparison with existing structure‐activity relationship on phenolic hydroxyl replacements in morphinans indicates that these nonpeptide opiates and some of the cyclic enkephalin analogs described here may have different modes of binding to the receptor.