Exploring Azatidinone Moiety: An Insight into its Anti-tubercular Potency

TB is becoming a worldwide problem and it was declared since 1993 by the World Health Organization (WHO), a global health emergency. The current problem of tuberculosis therapy is the emergence of multi-drug resistant (MDR) strains, caused by the improper use of antibiotics in chemotherapy of TB patients. Azatidinones, a β-lactam cyclic amide with four atoms in a ring, has been considered as a magic moiety (wonder nucleus) which possesses almost all types of biological activities. This diversity in the biological response profile has attracted the attention of many researchers to explore this skeleton to its multiple potential against several activities. Present article is sincere attempt to review chemistry, method of synthesis of azatidinones and to study azatidinones synthesized in last few years which have shown potent antitubercular activity.

Controlling the ambipolarity of thieno-benzo-isoindigo polymer-based transistors: the balance of face-on and edge-on populations

The asymmetric cyclic amide structure of thieno-benzo-isoindigo (TBIG) is introduced for the series of TBIG-based polymers, and their fundamental characteristics in terms of the organic field-effect transistor mobilities are investigated.

Atmospheric Oxidation of Piperazine Initiated by OH: A Theoretical Kinetics Investigation

Piperazine (Pz) mixed with other amines is a proposed carbon capture solvent, but there is concern about the impact of Pz on air quality, including the potential to produce toxic products. Here, the •OH initiated oxidation of Pz has been studied by ab initio modelling and RRKM / master equation kinetic simulations. The Pz + •OH reaction is found to proceed at around the capture rate, consistent with experiment, with abstraction predominantly from C—H sites. The subsequent reaction kinetics of carbon centred Pz radicals with O2 are also studied, so as to determine the first-generation oxidation products. We find that the Pz radical predominantly reacts with O2 to produce a cyclic imine product + HO2• under tropospheric conditions, with the stabilized peroxyl radical formed as a minor product. Subsequent reaction of the peroxyl radical with NO produces an alkoxyl radical that can react with O2 to yield a cyclic amide or undergo unimolecular ring opening followed by a second O2 addition / HO2• elimination step to produce CH2=NCH2CH2NHCHO.<br>

Atmospheric Oxidation of Piperazine Initiated by OH: A Theoretical Kinetics Investigation

Piperazine (Pz) mixed with other amines is a proposed carbon capture solvent, but there is concern about the impact of Pz on air quality, including the potential to produce toxic products. Here, the •OH initiated oxidation of Pz has been studied by ab initio modelling and RRKM / master equation kinetic simulations. The Pz + •OH reaction is found to proceed at around the capture rate, consistent with experiment, with abstraction predominantly from C—H sites. The subsequent reaction kinetics of carbon centred Pz radicals with O2 are also studied, so as to determine the first-generation oxidation products. We find that the Pz radical predominantly reacts with O2 to produce a cyclic imine product + HO2• under tropospheric conditions, with the stabilized peroxyl radical formed as a minor product. Subsequent reaction of the peroxyl radical with NO produces an alkoxyl radical that can react with O2 to yield a cyclic amide or undergo unimolecular ring opening followed by a second O2 addition / HO2• elimination step to produce CH2=NCH2CH2NHCHO.<br>

Vinylpyrroles: solid-state structures and aggregation-induced emission properties

A cyclic ester and a cyclic amide functionalized monopyrroles show aggregation-induced emission (AIE) by the restriction of intramolecular rotation (RIR) mechanism.

High-Resolution X-Ray Structures of Two Functionally Distinct Members of the Cyclic Amide Hydrolase Family of Toblerone Fold Enzymes

ABSTRACTThe Toblerone fold was discovered recently when the first structure of the cyclic amide hydrolase, AtzD (a cyanuric acid hydrolase), was elucidated. We surveyed the cyclic amide hydrolase family, finding a strong correlation between phylogenetic distribution and specificity for either cyanuric acid or barbituric acid. One of six classes (IV) could not be tested due to a lack of expression of the proteins from it, and another class (V) had neither cyanuric acid nor barbituric acid hydrolase activity. High-resolution X-ray structures were obtained for a class VI barbituric acid hydrolase (1.7 Å) from aRhodococcusspecies and a class V cyclic amide hydrolase (2.4 Å) from aFrankiaspecies for which we were unable to identify a substrate. Both structures were homologous with the tetrameric Toblerone fold enzyme AtzD, demonstrating a high degree of structural conservation within the cyclic amide hydrolase family. The barbituric acid hydrolase structure did not contain zinc, in contrast with early reports of zinc-dependent activity for this enzyme. Instead, each barbituric acid hydrolase monomer contained either Na+or Mg2+, analogous to the structural metal found in cyanuric acid hydrolase. TheFrankiacyclic amide hydrolase contained no metal but instead formed unusual, reversible, intermolecular vicinal disulfide bonds that contributed to the thermal stability of the protein. The active sites were largely conserved between the three enzymes, differing at six positions, which likely determine substrate specificity.IMPORTANCEThe Toblerone fold enzymes catalyze an unusual ring-opening hydrolysis with cyclic amide substrates. A survey of these enzymes shows that there is a good correlation between physiological function and phylogenetic distribution within this family of enzymes and provide insights into the evolutionary relationships between the cyanuric acid and barbituric acid hydrolases. This family of enzymes is structurally and mechanistically distinct from other enzyme families; however, to date the structure of just two, physiologically identical, enzymes from this family has been described. We present two new structures: a barbituric acid hydrolase and an enzyme of unknown function. These structures confirm that members of the CyAH family have the unusual Toblerone fold, albeit with some significant differences.