19F‐NMR Reveals the Role of Mobile Loops in Product and Inhibitor Binding by the São Paulo Metallo‐β‐Lactamase

Resistance to β‐lactam antibiotics mediated by metallo‐β‐lactamases (MBLs) is a growing problem. We describe the use of protein‐observe ¹⁹F‐NMR (PrOF NMR) to study the dynamics of the São Paulo MBL (SPM‐1) from β‐lactam‐resistant Pseudomonas aeruginosa . Cysteinyl variants on the α3 and L3 regions, which flank the di‐Zn^II active site, were selectively ¹⁹F‐labeled using 3‐bromo‐1,1,1‐trifluoroacetone. The PrOF NMR results reveal roles for the mobile α3 and L3 regions in the binding of both inhibitors and hydrolyzed β‐lactam products to SPM‐1. These results have implications for the mechanisms and inhibition of MBLs by β‐lactams and non‐β‐lactams and illustrate the utility of PrOF NMR for efficiently analyzing metal chelation, identifying new binding modes, and studying protein binding from a mixture of equilibrating isomers.     

Synthesis of 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4′′‐hydroxyphenyl)‐thiazoles and their O‐glucosides

In continuation of our work, we synthesized 2‐(sulfamoylphenyl)‐4′‐amino‐4‐(4″‐hydroxyphenyl)‐thiazole ( 3a ), which were reacted with various (aryl/hetroaryl) aldehyde to form 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4″‐hydroxyphenyl)‐thiazoles ( 4a , 4b , 4c , 4d , 4e , 4f ). Glucosylation of compounds ( 4a , 4b , 4c , 4d , 4e , 4f ) have been done by using acetobromoglucose as a glucosyl donor to afford 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(2,3,4,6‐tetra‐O‐acetyl‐4″‐O‐β‐D ‐glucosidoxyphenyl)‐thiazoles ( 5a , 5b , 5c , 5d , 5e , 5f ), further on deacetylation to produce 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4″‐O‐β‐D ‐glucosidoxyphenyl)‐thiazoles ( 6a , 6b , 6c , 6d , 6e , 6f ). The compounds are confirmed by FTIR, ¹H‐NMR, ¹³C‐NMR, and ES‐Mass spectral analysis. J. Heterocyclic Chem., (2011).     

Chiral capillary electrophoresis with cationic pyrrolidinium‐β‐cyclodextrin derivatives as chiral selectors

New single‐isomer, cationic β‐cyclodextrins, including mono‐6‐deoxy‐6‐pyrrolidine‐β‐cyclodextrin chloride (pyCDCl), mono‐6‐deoxy‐6‐(N‐methyl‐pyrrolidine)‐β‐cyclodextrin chloride (N‐CH₃‐pyCDCl), mono‐6‐deoxy‐6‐(N‐(2‐hydroxyethyl)‐pyrrolidine)‐β‐cyclodextrin chloride (N‐EtOH‐pyCDCl), mono‐6‐deoxy‐6‐(2‐hydroxymethyl‐pyrrolidine)‐β‐cyclodextrin chloride (2‐MeOH‐pyCDCl) were synthesized and used as chiral selectors in capillary electrophoresis for the enantioseparation of carboxylic and hydroxycarboxylic acids and dansyl amino acids. The unsubstituted pyCDCl exhibited the greatest resolving ability. Most analytes were resolved over a wide range of pH from 6.0 to 9.0 with this chiral selector. In general, increasing pH led to a decrease in resolution. The effective mobilities of all the analytes were found to decrease with increasing CD concentration. The optimal concentration for most carboxylic acids and dansyl amino acid was in the range 5–7.5 mM and >15 mM for hydroxycarboxylic acids. ¹H NMR experiments provided direct evidence of inclusion in the CD cavity.     

Benzenesulfonamidoquinolino‐β‐cyclodextrin as a Cell‐Impermeable Fluorescent Sensor for Zn2+

A water‐soluble benzenesulfonamidoquinolino‐β‐cyclodextrin has been successfully synthesized in 30 % yield by incorporating a N‐(8‐quinolyl)‐p‐aminobenzenesulfonamide (HQAS) group to β‐cyclodextrin through a flexible linker. This compound exhibits a good fluorescence response in the presence of Zn²⁺ in water but gives poor fluorescence responses with other metal ions commonly present in a physiological environment under similar conditions. Fluorescence microscopic and two‐dimensional NMR experiments showed that benzenesulfonamidoquinolino‐β‐cyclodextrin could bind to the loose bilayer membranes. As a result, benzenesulfonamidoquinolino‐β‐cyclodextrin was found to act as an efficient cell‐impermeable Zn²⁺ probe, showing a specific fluorescent sensing ability to Zn²⁺‐containing damaged cells whilst exhibiting no response in the presence of healthy cells.     

Photoirradiation surface molecularly imprinted polymers for the separation of 6‐O‐α‐d‐maltosyl‐β‐cyclodextrin

Photoirradiation surface molecularly imprinted polymers for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin were synthesized using functionalized silica as a matrix, 4‐(phenyldiazenyl)phenol as a light‐sensitive monomer, and 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin as a template. Fourier transform infrared spectroscopy results indicated that 4‐(phenyldiazenyl)phenol was grafted onto the surface of functionalized silica. The obtained imprinted polymers exhibited specific recognition toward 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin. Equilibrium binding experiments showed that the photoirradiation surface molecularly imprinted polymers obtained the maximum adsorption amount of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin at 20.5 mg/g. In binding kinetic experiments, the adsorption reached saturation within 2 h with binding capacity of 72.8%. The experimental results showed that the adsorption capacity and selectivity of imprinted polymers were effective for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin, indicating that imprinted polymers could be used to isolate 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin from a conversion mixture containing β‐cyclodextrin and maltose. The results showed that the imprinted polymers prepared by this method were very promising for the selective separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin.     

Action of Hydrazines on 2‐(2‐Oxindolin‐3‐ylidene)malononitrile, (E,Z)‐Ethyl 2‐cyano‐2‐(2‐oxindolin‐3‐ylidene)acetate and Isatin‐β‐thiosemicarbazone as a Source of Spiro Indoline‐pyrazole Systems

2‐(2‐Oxindolin‐3‐ylidene)malononitrile ( 1a ) or (E,Z)‐ethyl 2‐cyano‐2‐(2‐oxindolin‐3‐ylidene)acetate ( 1b ) or isatin‐β‐thiosemicarbazone ( 1c ) undergoes reactions with prototype hydrazine hydrate itself and some of its simple congeners to give hydrazone derivatives bearing indoline‐2‐one moiety ( 2 ). The hydrazone derivatives ( 2 ) when heated with acetyl acetone or ethyl acetoacetate in dry pyridine afforded the spiro indoline derivatives ( 3a , 3b ). Also, cinnoline derivative ( 9 ) is obtained by action of hydrazine hydrate on the N‐acetyl derivative of ( 6a ). The structures of the newly synthesized compounds were evaluated by IR, ¹H‐NMR spectroscopy, mass spectra and elemental analyses.     

Efficient Synthesis of Novel 3‐Phenyl‐5‐thioxo‐3,4,5,6‐tetrahydroimidazo[4,5‐c]pyrazole‐2(1H)‐carbothioamide Derivatives Using a CeO2–MgO Catalyst and Evaluation of Antimicrobial Activity

Imidazo[4,5‐c ]pyrazole derivatives ( 3a–f , 4a–f , and 5a–f ) were efficiently synthesized by one‐pot three‐component reactions using CeO₂–MgO as the catalyst. The synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectroscopic analyses. The in vitro antimicrobial activity of the synthesized compounds against various bacterial and fungal strains was screened. Compound 3b was highly active [minimum inhibitory concentration (MIC): 0.5 μg/mL] against Gram‐positive Staphylococcus aureus , and compounds 3b , 3f , 4d , and 4e were highly active (MIC: 0.5, 2, 2, and 0.5 μg/mL, respectively) against Gram‐negative Pseudomonas aeruginosa and Klebsiella pneumoniae , relative to standard ciprofloxacin in the antibacterial activity screening. Compounds 3b and 4f were highly active (MIC: 4 and 0.5 μg/mL, respectively) against Aspergillus fumigatus and Microsporum audouinii in the antifungal activity screening compared with the clotrimazole standard.     

2－脱氧－烟酰胺基－β－D－氨基葡萄糖的合成和表征

A new nicotinic acid derivative,2-deoxy-2-nicotinoylamido-β-D-glucopyranose, was synthesized with β-configuration exclusively. The structure and properties of the product were characterized by ^1H NMR, PT-IR, MS, DSC and polarimeter. The details of ^1H NMR spectrum and the mass spectrum proved that there are a great amount of hydrogen bonds in the product.     

Design,Synthesis, and Evaluation of the Anticancer Properties of a Novel Series of α‐(Benzoylamino)‐β‐substituted Acrylic Amide Derivatives of Pyrazolo[1,5‐a]pyrimidine

A novel series of α‐(benzoylamino)‐β‐substituted acrylic amide derivatives of pyrazolo[1,5‐a]pyrimidine has been synthesized using a convergent multistep synthesis. The synthesized compounds were characterized by ¹H NMR, ¹³C NMR, ESI‐MS, and IR analyses. Those new compounds were screened for their in vitro antiproliferative activity using an MTT assay analysis. Out of nine derivatives synthesized in the current study, compounds 13g , 13d , 13h , and 13i exhibited the greatest anticancer activities in HeLa and HepG₂ cell lines. The in vitro anticancer activity of compound 13g against HeLa, HepG₂, and MCF‐7 cell lines is superior to the marketed drugs paclitaxel and SAHA.     

Phenothiazine‐S,S‐dioxide‐ and fluorene‐based light‐emitting polymers: Introduction of e−‐deficient S,S‐dioxide into e−‐rich phenothiazine

A novel series of poly(10‐hexyl‐phenothiazine‐S,S‐dioxide‐3,7‐diyl) and poly(9,9′‐dioctyl‐fluorene‐2,7‐diyl‐alt‐10‐hexyl‐3,7‐phenothiazine‐S,S‐dioxide) (PFPTZ‐SS) compounds were synthesized through Ni(0)‐mediated Yamamoto polymerization and Pd(II)‐catalyzed Suzuki polymerization. The synthesized polymers were characterized by ¹H NMR spectroscopy and elemental analysis and showed higher glass transition temperatures than that of pristine polyfluorene. In terms of photoluminescence (PL), the PFPTZ‐SS compounds were highly fluorescent with bright blue emissions in the solid state. Light‐emitting devices were fabricated with these polymers in an indium tin oxide/poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate)/polymer/Ca/Al configuration. The electroluminescence (EL) of the copolymers differed from the PL characteristics: the EL device exhibited a redshifted greenish‐blue emission in contrast to the blue emission observed in the PL. Additionally, this unique phenothiazine‐S,S‐dioxide property, triggered by the introduction of an electron‐deficient SO₂ unit into the electron‐rich phenothiazine, gave rise to improvements in the brightness, maximum luminescence intensity, and quantum efficiency of the EL devices fabricated with PFPTZ‐SS. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1236–1246, 2007     

Synthesis of 2‐Hydroxy‐1,4‐oxazin‐3‐ones through Ring Transformation of 3‐Hydroxy‐4‐(1,2‐dihydroxyethyl)‐β‐lactams and a Study of Their Reactivity

The reactivity of 3‐hydroxy‐4‐(1,2‐dihydroxyethyl)‐β‐lactams with regard to the oxidant sodium periodate was evaluated, unexpectedly resulting in the exclusive formation of new 2‐hydroxy‐1,4‐oxazin‐3‐ones through a C3? C4 bond cleavage of the intermediate 4‐formyl‐3‐hydroxy‐β‐lactams followed by a ring expansion. This peculiar transformation stands in sharp contrast with the known NaIO₄‐mediated oxidation of 3‐alkoxy‐ and 3‐phenoxy‐4‐(1,2‐dihydroxyethyl)‐β‐lactams, which exclusively leads to the corresponding 4‐formyl‐β‐lactams without a subsequent ring enlargement. In addition, this new class of functionalized oxazin‐3‐ones was further evaluated for its potential use as building blocks in the synthesis of a variety of differently substituted oxazin‐3‐ones, morpholin‐3‐ones and pyrazinones. Furthermore, additional insights into the mechanism and the factors governing this new ring‐expansion reaction were provided by means of density functional theory calculations.     

Pyrido[1,2‐a]pyrimidin‐4‐ones: Ligand‐based Design,Synthesis, and Evaluation as an Anti‐inflammatory Agent

In the present study, a series of novel pyrido[1,2‐a]pyrimidin‐4‐one derivatives ( 1 – 45 ) were synthesized, characterized, and evaluated for their anti‐inflammatory activity. The structures of all newly synthesized compounds were confirmed by ¹H NMR, ¹³C NMR, mass spectroscopy, and C, H, and N analyses. Preliminary these newly synthesized compounds were evaluated for their in vitro cyclooxygenase (COX)‐2/COX‐1 inhibitory activity. The celecoxib, a COX‐2 inhibitor, was used as a reference standard drug. In this inhibitory study, compounds 42 , 43 , 44 , and 45 were found to have significant in vitro inhibitory profile as compared with the reference drug. These compounds were then subjected to their in vivo anti‐inflammatory assay by using carrageenan‐induced rat paw edema method in next level of screening. Later, these same compounds were tested for their ulcerogenic property. Based on these activity data, the compound 43 (in vitro COX‐2 activity—IC₅₀ = 0.4 μM, SI = 400, in vivo anti‐inflammatory activity—72% inhibition after 3 h, and 0.38%—Ulcer index) was emerged as most promising anti‐inflammatory agent with very low ulcerogenic action.     

Design,synthesis of (Z)‐3‐benzyl‐5‐((1‐phenyl‐3‐(3‐((1‐ substituted phenyl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)‐1H‐pyrazol‐4‐yl)methylene)thiazolidine‐2,4‐dione analogues as potential cytotoxic agents

In an attempt to achieve promising cytotoxic agents, a series of new (Z)‐3‐benzyl‐5‐((1‐phenyl‐3‐(3‐((1‐substituted phenyl‐1H‐1,2,3‐triazol‐4‐yl)methoxy)phenyl)‐1H‐pyrazol‐4‐yl)methylene)thiazolidine‐2,4‐diones 10 a‐n were designed, synthesized, and characterized by ¹H NMR, ¹³C NMR, IR, and ESI‐MS techniques. These compounds synthesized from appropriate reaction procedures with better yields. All the novel synthesized compounds 10a‐n were evaluated for their cytotoxic activity against the MCF‐7 cell line (Human breast cancer cell line) at different concentrations of 0.625, 1.25, 2.5, 5, and 10 μM, respectively. The cytotoxic evaluation assay is presented in terms of IC₅₀ values and percentage cell viability reduction compared against standard drug cisplatin. Among all novel synthesized compounds 10a‐n , some of the representative analogues particularly 10g and 10e exhibit remarkable cytotoxic activity with IC₅₀ values 0.454 and 0.586 μM, comparable to that of the standard drug cisplatin, and some analogues 10d , 10f , 10k, and 10m also have shown significant activity.     

Veronicafolin－β-环糊精的物化表征及Veronicafolin－羟丙基-β-环糊精包合物溶解性的增强

用氢谱、红外光谱、X-射线粉末衍射、热分析、元素分析等测试方法研究了Veronicafolin (3,5,4′-三羟基-6,7,3′-三甲氧基黄酮) 和β-环糊精 (β-CD) 的固体包合物的谱学特征。元素分析结果显示形成Veronicafolin-β-CD·20H2O包合物，其中C：39.58%, H: 5.75%，表明包合物中主客体比为1∶1。该包合类型属于A_L-型。通过紫外-可见分光光度法研究了在羟丙基-β-环糊精（HP-β-CD）的存在下Veronicafolin的相溶解度曲线，测得校正曲线为y = 24148x + 0.0075 (r=0.9999)，相溶解曲线为y=0.4738x-2.0×10^-7 (r=0.9490)，包结平衡常数Ks为4.5×10⁶mol-1。HP-β-CD提高了黄酮醇Veronicafolin的溶解度。     

Chiral separation of rasagiline using sulfobutylether‐β‐cyclodextrin: capillary electrophoresis,NMR and molecular modeling study

Pressure‐assisted stereospecific capillary electrophoresis method was developed for the determination of enantiomeric purity of the antiparkinsonian agent (R)‐rasagiline. The optimized method, 50 mM glycine‐HCl buffer pH 2, supplied with 30 mM sulfobutylether‐β‐cyclodextrin, at 35°C, applying 12 kV in reversed polarity, and –8 mbar pressure (vacuum), short‐end injection with ‐25 mbar × 2 s, was successful for baseline separation of rasagiline enantiomers (R_s = 3.5 ± 0.1) in a short analysis time. The method was validated according to current guidelines and proved to be reliable, linear, precise and accurate for determination of 0.15% S‐enantiomer as chiral impurity in R‐rasagiline sample, as well as quantification of the eutomer. Method application was tested on a commercial tablet formulation. Determination of spatial structure of diastereomeric associates was based on ¹H and 2D ROESY NMR, indicating that the aromatic moiety of the molecule can enter the cyclodextrin cavity. NMR titration and molecular modeling revealed that S‐rasagiline formed a more stable inclusion complex with sulfobutylether‐β‐cyclodextrin, than its antipode, which is in agreement with electrophoretic results.     

Pyrimidine and Pyrazole Linked Azetidin‐2‐ones: Entry to Novel Class of β‐Lactam Heterocycles

A novel series of pyrimidine/pyrazole linked β‐lactams have been synthesized in excellent yields using a simple and efficient methodology involving conjunction of different heterocyclic substrates. All the new products were characterized on the basis of various spectroscopic techniques viz. FT‐IR, ¹H NMR, ¹³C NMR, elemental analysis (CHN), ¹H‐¹H correlation spectroscopy (¹H‐¹H COSY) and mass spectrometry (EIMS) in representative cases. Furthermore, theoretical calculations have also been performed on representative compounds and the results were compared with Cefuroxime axetil (a broad spectrum antibacterial agent). The phenomenon of tautomerism was also observed which was confirmed by different NMR experiments (D₂O exchange study and ¹H‐¹H correlation spectroscopy).     

Synthesis and characterization of a poly(N‐isopropylacrylamide) with β‐cyclodextrin as pendant groups

A novel linear poly(N‐isopropylacrylamide) (PNIPA) with β‐cylodextrin (β‐CD) moiety (PNIPA‐β‐CD) was synthesized by the conjugation of β‐CD carrying amino groups (EDA‐β‐CD) onto PNIPA with epoxy groups (P(NIPA‐co‐GMA), M_n = 3.86 × 10⁴), and the related reaction conditions are investigated. PNIPA‐β‐CD was characterized by means of IR, NMR and UV spectroscopes, element analysis, and differential scanning calorimetry (DSC). The number‐average molecular weight (M_n) and the β‐CD content of the obtained PNIPA‐β‐CD are 4.87 × 10⁴ and 18.8 wt %, respectively. PNIPA‐β‐CD can not only respond to temperature stimuli but also include guest molecules. Lower critical solution temperature (LCST) of aqueous PNIPA‐β‐CD solution is similar to that of PNIPA. The association constant (K_a) for PNIPA‐β‐CD with methyl orange (MO) is 2.4 × 10³ L mol^?1 at pH 1.4, which is comparable to that of EDA‐β‐CD (K_a = 2.9 × 10³ L mol^?1). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3516–3524, 2005     

An Efficient One‐pot Three‐component Method for the Synthesis of 5‐Amino‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐7‐aryl‐7H‐thiazolo[3,2‐a]pyridine‐6,8‐dicarbonitriles

A facile, convenient, and adequate method has been developed for the synthesis of novel 5‐amino‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐7‐aryl‐7H‐thiazolo[3,2‐a]pyridine‐6,8‐dicarbonitriles ( 6 ) by employing 2‐(4‐(2‐oxo‐2H‐chromen‐3‐yl)thiazol‐2‐yl)acetonitrile ( 3 ) as an important precursor. Initially, we have synthesized the target compounds in a stepwise manner and then approached a tandem method to examine the feasibility of one‐pot method. Subsequently, one‐pot three‐component protocol has been established for the synthesis of title compounds by the reaction of 3 with benzaldehyde and malononitrile in refluxing ethanol engender a new six‐membered thiazolo[3,2‐a] pyridine as a hybrid scaffold. Reaction conditions were optimized for this reaction and a broad substrate scope with various aryl and heteroaryl aldehydes make this protocol very practical, attractive, and worthy. Mechanistic aspects for the formation of these compounds were outlined comprehensively. Characterization of these newly synthesized compounds was achieved by means of IR, ¹H NMR, ¹³C NMR, and HRMS.     

Synthesis and Fungicidal Activities of 2,3‐Dimethyl‐4‐(1‐acyloxy)alkoxy‐6‐tert‐butyl‐8‐fluoroquinolines

A series of 2,3‐dimethyl‐4‐(1‐acyloxy)alkoxy‐6‐tert‐butyl‐8‐fluoroquinolines were synthesized by 4‐(tert‐butyl)aniline as the starting material via acylation, substitution, and hydrolysis, and their structures were characterized by ¹H NMR, ¹³C NMR, and HRMS. The fungicidal activity showed that compounds 6c , 6e , and 6f had excellent activity against Sphoaerotheca fuliginea with EC₅₀ values of 38.62, 6.77, and 50.35 mg/L, respectively. The results suggest that this chemotype of compounds warrant further studies as promising fungicide.     

Two new acylated flavonoid glycosides from Morina nepalensis var. alba Hand.‐Mazz.

From the whole plant of Morina nepalensis var. alba Hand.‐Mazz., two new acylated flavonoid glycosides ( 1 and 2 ), together with four known flavonoid glycosides ( 3–6 ), were isolated. Their structures were determined to be quercetin 3‐O‐[2″′‐O‐(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐galactopyranoside (monepalin A, 1 ), quercetin 3‐O‐[2″′‐O‐(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐glucopyranoside (monepalin B, 2 ), quercetin 3‐O‐α‐L ‐arabinopyranosyl‐(1→6)‐β‐D ‐galactopyranoside (rumarin, 3 ), quercetin 3‐O‐β‐D ‐galactopyranoside ( 4 ), quercetin 3‐O‐β‐D ‐glucopyranoside ( 5 ) and apigenin 4^′‐O‐β‐D ‐glucopyranoside ( 6 ). Their structures were determined on the basis of chemical and spectroscopic evidence. Complete assignments of the ¹H and ¹³C NMR spectra of all compounds were achieved from the 2D NMR spectra, including H–H COSY, HMQC, HMBC and 2D HMQC‐TOCSY spectra. Copyright © 2002 John Wiley & Sons, Ltd.