Design and synthesis of novel N-benzylidenesulfonohydrazide inhibitors of MurC and MurD as potential antibacterial agents

A series of novel N-benzylidenesulfonohydrazide compounds were designed and synthesized as inhibitors of UDP-N-acetylmuramic acid: L-alanine ligase (MurC) and UDP-N-acetylmuramoyl-L-alanine: D-glutamate ligase (MurD) from E. coli, involved in the biosynthesis of bacterial cell-walls. Some compounds possessed inhibitory activity against both enzymes with IC(50) values as low as 30 microM. In addition, a new, one-pot synthesis of amidobenzaldehydes is reported.     

NaBH4 reduction of ortho and para-nitroaniline catalyzed by silver nanoparticles synthesized using Tamarindus indica seed coat extract

Research on Chemical Intermediates - This study deals with reduction of ortho and para-nitroaniline by NaBH4 with silver nanoparticles (AgNPs), synthesized by use of a green method, as catalyst. In...     

Investigation of tyrosine nitration and nitrosylation of angiotensin II and bovine serum albumin with electrospray ionization mass spectrometry

Protein tyrosine nitration is one of the important regulatory mechanisms in various cellular phenomena such as cell adhesion, endo/exo-cytosis of cellular materials, and signal transduction. In the present study, electrospray ionization tandem mass spectrometry (ESI-MS/MS) with a linear ion-trap mass spectrometer was applied for identification of nitrated proteins and localization of the modified tyrosine residues. When angiotensin II(DRVYIHPF) was nitrated in vitro with tetranitromethane (TNM), the mass spectrum showed a shift of +45 Da which corresponded to tyrosine nitration. An additional +29 Da mass shift was also detected by ESI-MS. This differed from nitrated peptide analysis with matrix-associated laser desorption/ionization mass spectrometry (MALDI-MS), which showed oxygen neutral loss from the nitrated tyrosine residues upon laser irradiation. Hence the +29 Da mass shift of the nitrated peptide observed by ESI-MS suggested the introduction of an NO group for nitrosylation of tyrosine residues. To confirm this in vitro nitrosylation on the protein level, bovine serum albumin was in vitro nitrated with TNM and analyzed by ESI-MS/MS. As expected, +29 as well as +45 Da mass shifts were detected, and the +29 Da mass shift was found to correspond to the modification on tyrosine residues by NO. Although the chemical mechanism by which this occurs in ESI-MS is not clear, the +29 Da mass shift could be a new potential marker of nitrosylated peptides.     

A Simple Synthesis of 5‐(2‐Aminophenyl)‐1H‐pyrazoles

A four‐step synthesis of 1‐substituted 5‐(2‐aminophenyl)‐1H‐pyrazoles 5 as a novel type of histamine analogs and versatile building blocks for further transformations was developed. The synthesis starts from commercially available 2‐nitroacetophenone ( 12 ), which is converted into the enamino ketone 13 as the key intermediate. Cyclization of the key intermediate 13 with monosubstituted hydrazines 14a – 14l afforded the 5‐(2‐nitrophenyl)‐1H‐pyrazoles 17a – 17l . Finally, catalytic hydrogenation of the nitro compounds 17a, 17c – 17e , and 17g – 17j furnished the title compounds 5a, 5c – 5e , and 5g – 5j , respectively, in good yields. As demonstrated by some further transformations, additional functionalization of compounds 17 and 5 is feasible, either by electrophilic substitution at C(4) of the pyrazole ring, or at the NH₂ group.     

Efficient synthesis of polycycles bearing prenylated, geranylated, and farnesylated citrans: application to 3′-prenylrubranine and petiolin D regioisomer

Efficient synthetic routes for biologically interesting polycycles with prenylated, geranylated, and farnesylated citrans were developed from several trihydroxybenzenes with prenyl, geranyl, and farnesyl groups on the benzene rings. Ethylenediamine diacetate-catalyzed cyclization by a domino aldol-type/electrocyclization/H-shift/hetero Diels-Alder reaction of prenylated, geranylated, and farnesylated trihydroxybenzenes with citral or trans,trans-farnesal provided a variety of tetracycles bearing prenylated, geranylated, and farnesylated citrans. The mechanistic pathway for regio- and stereochemistry of synthesized polycycles was described. As an application of this methodology, 3′-prenylrubranine and petiolin D regioisomer were first synthesized.     

Efficient synthesis of tetrahydroquinolinones by acetic acid-mediated formal [3+3] cycloaddition

Abstract  

A simple and efficient method to synthesize a variety of tetrahydroquinolinones was successfully achieved by reacting various β-enaminones with several α,β-unsaturated aldehydes. This strategy can be viewed as a Br?nsted acid-mediated formal [3+3] cycloaddition.     

Continuous Production of Functionalized Polymer Particles Employing the Phase Separation in Polymer Blend Films

This study reports a continuous prepartion of spherical or hemispherical polymer particles simply utilizing the phase separation in polymer blend films during the coating process. We took an advantage of the strong phase separation between a water‐soluble crystalline polymer as a matrix and hydrophobic polymers as minor components. We demonstrated the prepartion of water‐soluble polystyrene (PS) particles, nitrilotriacetic acid (NTA)‐functionalized PS particles for protein separation, and semiconducting poly(3‐hexylthiophene) (P3HT) particles. The sizes of the particles could be controlled by adjusting the film thickness and weight fraction of the minor component polymers in the blend film. It provides a simple facile way to prepare polymer particles in a continous process.