Radiosynthesis and Biodistribution of <Superscript>99m</Superscript>Tc-Metronidazole as an <Emphasis Type="Italic">Escherichia coli</Emphasis> Infection Imaging Radiopharmaceutical

Bacterial infection poses life-threatening challenge to humanity and stimulates to the researchers for developing better diagnostic and therapeutic agents complying with existing theranostic techniques. Nuclear medicine technique helps to visualize hard-to-diagnose deep-seated bacterial infections using radionuclide-labeled tracer agents. Metronidazole is an antiprotozoal antibiotic that serves as a preeminent anaerobic chemotherapeutic agent. The aim of this study was to develop technetium-99m-labeled metronidazole radiotracer for the detection of deep-seated bacterial infections. Radiosynthesis of ^99mTc-metronidazole was carried by reacting reduced technetium-99m and metronidazole at neutral pH for 30 min. The stannous chloride dihydrate was used as the reducing agent. At optimum radiolabeling conditions, ~ 94% radiochemical was obtained. Quality control analysis was carried out with a chromatographic paper and instant thin-layer chromatographic analysis. The biodistribution study of radiochemical was performed using Escherichia coli bacterial infection-induced rat model. The scintigraphic study was performed using E. coli bacterial infection-induced rabbit model. The results showed promising accumulation at the site of infection and its rapid clearance from the body. The tracer showed target-to-non-target ratio 5.57 ± 0.04 at 1 h post-injection. The results showed that ^99mTc-MNZ has promising potential to accumulate at E. coli bacterial infection that can be used for E. coli infection imaging.     

Therapeutic potential of pyrrole and pyrrolidine analogs: an update

Molecular Diversity - The chemistry of nitrogen-containing heterocyclic compound pyrrole and pyrrolidine has been a versatile field of study for a long time for its diverse biological and medicinal...     

Recent trends in the chemistry of Sandmeyer reaction: a review

Metal-catalyzed reactions play a vital part to construct a variety of pharmaceutically important scaffolds from past few decades. To carry out these reactions under mild conditions with low-cost easily available precursors, various new methodologies have been reported day by day. Sandmeyer reaction is one of these, first discovered by Sandmeyer in 1884. It is a well-known reaction mainly used for the conversion of an aryl amine to an aryl halide in the presence of Cu(I) halide via formation of diazonium salt intermediate. This reaction can be processed with or without copper catalysts for the formation of C–X (X?=?Cl, Br, I, etc.), C-CF₃/CF₂, C–CN, C–S, etc., linkages. As a result, corresponding aryl halides, trifluoromethylated compounds, aryl nitriles and aryl thioethers can be obtained which are effectively used for the construction of biologically active compounds. This review article discloses various literature reports about Sandmeyer-related transformations developed during 2000–2021 which give different ideas to synthetic chemists about further development of new and efficient protocols for Sandmeyer reaction.

Graphical abstract

An updated compilation of new approaches for Sandmeyer reaction is described in this review to construct a variety of carbon-halogen, carbon-phosphorous, carbon-sulfur, carbon-boron etc. linkages.

     

Cross-coupling reactions towards the synthesis of natural products

Molecular Diversity - Cross-coupling reactions are powerful synthetic tools for the formation of remarkable building blocks of many naturally occurring molecules, polymers and biologically active...     

Extensions of Banach's Contraction Principle

Let A and B be nonempty subsets of a metric space. As a non-self mapping T: A → B does not necessarily have a fixed point, it is of considerable interest to find an element x that is as close to Tx as possible. In other words, if the fixed point equation Tx = x has no exact solution, then it is contemplated to find an approximate solution x such that the error d(x, Tx) is minimum. Indeed, best proximity point theorems investigate the existence of such optimal approximate solutions, called best proximity points, of the fixed point equation Tx = x when there is no exact solution. As d(x, Tx) is at least d(A, B), a best proximity point theorem achieves an absolute minimum of the error d(x, Tx) by stipulating an approximate solution x of the fixed point equation Tx = x to satisfy the condition that d(x, Tx) = d(A, B). This article furnishes extensions of Banach's contraction principle to the case of non-self mappings. On account of the preceding argument, the proposed generalizations are formulated as best proximity point theorems for non-self contractions.     

On the Unital C*-Algebras Generated by Certain Subnormal Tuples

We consider an important class of subnormal operator m-tuples M _p (p = m,m + 1, . . .) that is associated with a class of reproducing kernel Hilbert spaces H_p{{\mathcal H}_p} (with M _m being the multiplication tuple on the Hardy space of the open unit ball \mathbb B^2m{{\mathbb B}^{2m}} in \mathbb C^m{{\mathbb C}^m} and M _m+1 being the multiplication tuple on the Bergman space of \mathbb B^2m{{\mathbb B}^{2m}}). Given any two C*-algebras A{\mathcal A} and B{\mathcal B} from the collection {C^*(M_p), C^*([(M)\tilde]_p): p 3 m}{\{C^*({M}_p), C^*({\tilde M}_p): p \geq m\}} , where C*(M _p ) is the unital C*-algebra generated by M _p and C^*([(M)\tilde]_p){C^*({\tilde M}_p)} the unital C*-algebra generated by the dual [(M)\tilde]_p{{\tilde M}_p} of M _p , we verify that A{\mathcal A} and B{\mathcal B} are either *-isomorphic or that there is no homotopy equivalence between A{\mathcal A} and B{\mathcal B} . For example, while C*(M _m ) and C*(M _m+1) are well-known to be *-isomorphic, we find that C^*([(M)\tilde]_m){C^*({\tilde M}_m)} and C^*([(M)\tilde]_m+1){C^*({\tilde M}_{m+1})} are not even homotopy equivalent; on the other hand, C*(M _m ) and C^*([(M)\tilde]_m){C^*({\tilde M}_{m})} are indeed *-isomorphic. Our arguments rely on the BDF-theory and K-theory.     

Stereoselective synthesis of (S,S)-palythazine from d-mannitol

Exploiting the symmetry element, an asymmetric synthesis of (S,S)-palythazine was accomplished with (R)-glyceraldehyde acetonide as the chiral precursor. The prominent steps involved stereoselective Barbier allylation, ring-closing metathesis, regioselective nucleophilic opening of epoxide, and auto-condensation of aminoketone moiety.     

Spectroscopic studies of atmospheric interest on NO and NO

In recent years, high-resolution photoelectron spectroscopy and ab initio calculations have considerably revised and enlarged the understanding of the electronic structure of the NO and NO⁺ molecules. The experimental potential energy curves for the different electronic states of atmospheric interest molecules like NO and NO⁺ are constructed by using the Rydberg-Klein-Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting technique using the five parameter Hulburt-Hirschfelder (H-H) function. The estimated dissociation energies are 6.381 and 10.693 eV for NO and NO⁺, respectively. These values are in good agreement with the literature values. The r-centroids and Franck-Condon factors (FC Factors) for the band system of B²Π_r-X²Π of NO and a³Σ⁺-X¹Σ⁺, A¹Π-X¹Σ⁺ of NO⁺ molecules have been calculated employing an approximate analytical methods of Jarmain and Fraser, and Nicholls and Jarmain. The absence of the bands in these systems is explained.     

Electrical conduction in copper-poly(vinyl-alcohol) composites

The temperature dependence of d.c. conductivity was investigated in composites of copper (Cu) and poly(vinyl-alcohol) (PVA) prepared by compression of a mixture. A minimum appeared in the conductivity vs reciprocal temperature curves, which is discussed as a result of the competition between hopping and thermally activated modes of conduction. It was also found that the conduction of Cu-PVA composites obeys a percolation model. Dependences of reverse current vs voltage were investigated and discussed in terms of a clean-up effect of charge carriers. Quantitative analysis was carried out to determine the activation energy, drift mobility and carrier concentration.