Deformylation of indole and azaindole-3-carboxaldehydes using anthranilamide and solid acid heterogeneous catalyst via quinazolinone intermediate

The Synthesis and Biological Evaluation of 2-(1H-Indol-3-yl)quinazolin-4(3H)-One Derivatives

The treatment of many bacterial diseases remains a significant problem due to the increasing antibiotic resistance of their infectious agents. Among others, this is related to Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) and Mycobacterium tuberculosis. In the present article, we report on antibacterial compounds with activity against both S. aureus and MRSA. A straightforward approach to 2-(1H-indol-3-yl)quinazolin-4(3H)-one and their analogues was developed. Their structural and functional relationships were also considered. The antimicrobial activity of the synthesized compounds against Mycobacterium tuberculosis H₃₇Rv, S. aureus ATCC 25923, MRSA ATCC 43300, Candida albicans ATCC 10231, and their role in the inhibition of the biofilm formation of S. aureus were reported. 2-(5-Iodo-1H-indol-3-yl)quinazolin-4(3H)-one (3k) showed a low minimum inhibitory concentration (MIC) of 0.98 μg/mL against MRSA. The synthesized compounds were assessed via molecular docking for their ability to bind long RSH (RelA/SpoT homolog) proteins using mycobacterial and streptococcal (p)ppGpp synthetase structures as models. The cytotoxic activity of some synthesized compounds was studied. Compounds 3c, f, g, k, r, and 3z displayed significant antiproliferative activities against all the cancer cell lines tested. Indolylquinazolinones 3b, 3e, and 3g showed a preferential suppression of the growth of rapidly dividing A549 cells compared to slower growing fibroblasts of non-tumor etiology.

A comprehensive insight into aldehyde deformylation: mechanistic implications from biology and chemistry

Aldehyde deformylation is an important reaction in biology, organic chemistry and inorganic chemistry and the process has been widely applied and utilized. For instance, in biology, the aldehyde deformylation reaction has wide differences in biological function, whereby cyanobacteria convert aldehydes into alkanes or alkenes, which are used as natural products for, e.g., defense mechanisms. By contrast, the cytochromes P450 catalyse the biosynthesis of hormones, such as estrogen, through an aldehyde deformylation reaction step. In organic chemistry, the aldehyde deformylation reaction is a common process for replacing functional groups on a molecule, and as such, many different synthetic methods and procedures have been reported that involve an aldehyde deformylation step. In bioinorganic chemistry, a variety of metal(iii)-peroxo complexes have been synthesized as biomimetic models and shown to react efficiently with aldehydes through deformylation reactions. This review paper provides an overview of the various aldehyde deformylation reactions in organic chemistry, biology and biomimetic model systems, and shows a broad range of different chemical reaction mechanisms for this process. Although a nucleophilic attack at the carbonyl centre is the consensus reaction mechanism, several examples of an alternative electrophilic reaction mechanism starting with hydrogen atom abstraction have been reported as well. There is still much to learn and to discover on aldehyde deformylation reactions, as deciphered in this review paper.

Radiosynthesis and evaluation of 18F-labeled dopamine D4-receptor ligands

INTRODUCTION

The dopamine D4 receptor (D4R) has attracted considerable attention as potential target for the treatment of a broad range of central nervous system disorders. Although many efforts have been made to improve the performance of putative radioligand candidates, there is still a lack of D4R selective tracers suitable for in vivo PET imaging. Thus, the objective of this work was to develop a D4-selective PET ligand for clinical applications.

METHODS

Four compounds based on previous and new lead structures were prepared and characterized with regard to their D4R subtype selectivity and predicted lipophilicity. From these, 3-((4-(2-fluorophenyl)piperazin-1-yl)methyl)-1H-pyrrolo[2,3-b]pyridine I and (S)-4-(3-fluoro-4-methoxybenzyl)-2-(phenoxymethyl)morpholine II were selected for labeling with fluorine-18 and subsequent evaluation by in vitro autoradiography to assess their suitability as D4 radioligand candidates for in vivo imaging.

RESULTS

The radiosynthesis of [18F]I and [18F]II was successfully achieved by copper-mediated radiofluorination with radiochemical yields of 7% and 66%, respectively. The radioligand [18F]II showed specific binding in areas where D4 expression is expected, whereas [18F]I did not show any uptake in distinct brain regions and exhibited an unacceptable degree of non-specific binding.

CONCLUSIONS

The compounds studied exhibited high D4R subtype selectivity and logP values compatible with high brain uptake, but only ligand [18F]II showed low non-specific binding and is therefore a good candidate for further evaluation.

ADVANCES IN KNOWLEDGE

The discovery of new lead structures for high-affinity D4 ligands opens up new possibilities for the development of suitable PET-radioligands.

IMPLICATIONS FOR PATIENT

PET-imaging of dopamine D4-receptors could facilitate understanding, diagnosis and treatment of neuropsychiatric and neurodegenerative diseases.

Discovery of 3,3'-diindolylmethanes as potent antileishmanial agents

An efficient protocol for synthesis of 3,3'-diindolylmethanes using recyclable Fe-pillared interlayered clay (Fe-PILC) catalyst under aqueous medium has been developed. All synthesized 3,3'-diindolylmethanes showed promising antileishmanial activity against Leishmania donovani promastigotes as well as axenic amastigotes. Structure-activity relationship analysis revealed that nitroaryl substituted diindolylmethanes showed potent antileishmanial activity. The 4-nitrophenyl linked 3,3'-diindolylmethane 8g was found to be the most potent antileishmanial analog showing IC50 values of 7.88 and 8.37 μM against both L. donovani promastigotes and amastigotes, respectively. Further, a pharmacophore based QSAR model was established to understand the crucial molecular features of 3,3'-diindolylmethanes essential for potent antileishmanial activity. These compounds also exhibited promising antifungal activity against Cryptococcus neoformans, wherein fluorophenyl substituted 3,3'-diindolylmethanes were found to be most potent antifungal agents. Developed synthetic protocol will be useful for economical and eco-friendly synthesis of potent antileishmanial and antifungal 3,3'-diindolylmethane class of compounds.