Cu(II)-Catalyzed Hydroboration Reactions of 1,1-Disubstituted α,β-Unsaturated Ketones, Esters, and Amides in Pure Water

Here, a Cu2(OH)2CO3-catalyzed hydroboration reaction of 1,1-disubstituted α,β-unsaturated compounds has been developed. The reaction was carried out using water as a solvent at room temperature except for N-monosubstituted α,β-unsaturated amides. This method is applicable to diverse 1,1-disubstituted α,β-unsaturated ketones, esters, and amides, showing excellent reactivity (up to 98% yield). Gram-scale experiments and functional group transformations further demonstrated the practicality of this method.

Unlocking InhA: Novel approaches to inhibit Mycobacterium tuberculosis

Multidrug-resistant tuberculosis continues to pose a health security risk and remains a public health emergency. Antimicrobial resistance result from treatment regimens that are both insufficient and incomplete leading to the emergence of multidrug-resistant tuberculosis, extensively drug-resistant tuberculosis and totally drug-resistant tuberculosis. The impact of tuberculosis on the people suffering from HIV (Human immunodeficiency virus infection) have resulted in the increased research efforts in designing and discovery of novel antitubercular drugs that may result in decreasing treatment duration, minimising the need for multiple drug intake, minimising cytotoxicity and enhancing the mechanism of action of drug. While many drugs are available to treat tuberculosis, a precise and timely cure is still absent. Consequently, further investigation is needed to identify more recent molecular equivalents that have the potential to swiftly remove this disease. Isoniazid (INH), a treatment for tuberculosis (TB), targets the enzyme InhA (mycobacterium enoyl acyl carrier protein reductase), the Mycobacterium tuberculosis enoyl-acyl carrier protein (ACP) reductase, most common INH resistance is circumvented by InhA inhibitors that do not require KatG (catalase-peroxidase) activation, as a result, researchers are trying to work in the area of development of InhA inhibitors which could help in eradicating the era of tuberculosis from the world.

Discovery of new diaryl ether inhibitors against Mycobacterium tuberculosis targeting the minor portal of InhA

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) affects 10 million people each year and the emergence of resistant TB augurs for a growing incidence. In the last 60 years, only three new drugs were approved for TB treatment, for which resistances are already emerging. Therefore, there is a crucial need for new chemotherapeutic agents capable of eradicating TB. Enzymes belonging to the type II fatty acid synthase system (FAS-II) are involved in the biosynthesis of mycolic acids, cell envelope components essential for mycobacterial survival. Among them, InhA is the primary target of isoniazid (INH), one of the most effective compounds to treat TB. INH acts as a prodrug requiring activation by the catalase-peroxidase KatG, whose mutations are the major cause for INH resistance. Herein, a new series of direct InhA inhibitors were designed based on a molecular hybridization approach. They exhibit potent inhibitory activities of InhA and, for some of them, good antitubercular activities. Moreover, they display a low toxicity on human cells. A study of the mechanism of action of the most effective molecules shows that they inhibit the biosynthesis of mycolic acids. The X-ray structures of two InhA/NAD+/inhibitor complexes have been obtained showing a binding mode of a part of the molecule in the minor portal, rarely seen in the InhA structures reported so far.

Synthesis, Biological Evaluation and Molecular Dynamics Simulation Studies of Novel Diphenyl Ethers

Background:

The well-known antibacterial agent Triclosan (TCL) that targets bacterial enoylacyl protein reductase has been described to inhibit human fatty acid synthase (FASN) via the enoylacyl reductase domain. A Literature survey indicates that TCL is selectively toxic to cancer cells and furthermore might indeed reduce cancer incidence in vivo. A recent study found that TCL inhibits FASN by acting as an allosteric protein-protein interface (PPI) inhibitor. It induces dimer orientation changes that effect in a downstream reorientation of catalytic residues in the NADPH binding site proposing TCL as a viable scaffold to design a superior molecule that might have more inhibitory potential. This unveils tons of potential interaction space to take advantage of future inhibitor design.

Objective:

Synthesis of TCL mimicking novel diphenyl ether derivatives, biological evaluation as potential antiproliferative agents and molecular docking and molecular dynamics simulation studies.

Methods:

A series of novel N-(1-(3-hydroxy-4-phenoxyphenyl)-3-oxo-3-phenylpropyl)acetamides (3a-n) and N-(3(3-hydroxy-4phenoxyphenyl)-3-oxo-1-phenylpropyl) acetamides (6a-n) were designed, synthesized, characterized and evaluated against HepG2, A-549, MCF-7 and Vero cell lines. The induction of antiproliferative activity of selected compounds (3d and 6c) was done by AO/EB (acridine orange/ethidium bromide) nuclear staining method, DNA fragmentation study, and cell cycle analysis was performed by flow cytometry. Molecular docking and dynamics simulation study was also performed.

Results:

Among the tested compounds, compound 3d was most active (IC50 13.76 ± 0.43 µM) against A-549 cell line. Compounds 3d and 3g were found to be moderately active with IC50 30.56 ± 1.1 µM and 25.05 ± 0.8 µM respectively against MCF-7 cell line. Morphological analysis of A-549 cells treated with 3d and 6c clearly demonstrated the reduction of cell viability and induction of apoptosis. DNA fragmentation was observed as a characteristic of apoptosis in treated cells. Further, cell cycle analysis by flow cytometry confirmed that compounds 3d and 6c significantly arrested the cell cycle at the G0/G1 phase. Molecular docking study demonstrated that these compounds exhibit high affinity for the human fatty acid synthase (hFASN) target. Molecular dynamics simulation study of the most active compound 3d was performed for calculating binding free energies using Molecular Mechanics–Generalized Born Surface Area (MM/GBSA).

Conclusion:

Compound 3d (IC50 13.76 ± 0.43 µM) has been identified as a potential lead molecule for anticancer activity against A-549 cells followed by 3l, 6c, and 3g. Thus, the design of diphenyl ether derivatives with enhanced affinity to the binding site of hER may lead to the discovery of potential anticancer agents.

Predictive Power of In Silico Approach to Evaluate Chemicals against M. tuberculosis: A Systematic Review

Mycobacterium tuberculosis (Mtb) is an endemic bacterium worldwide that causes tuberculosis (TB) and involves long-term treatment that is not always effective. In this context, several studies are trying to develop and evaluate new substances active against Mtb. In silico techniques are often used to predict the effects on some known target. We used a systematic approach to find and evaluate manuscripts that applied an in silico technique to find antimycobacterial molecules and tried to prove its predictive potential by testing them in vitro or in vivo. After searching three different databases and applying exclusion criteria, we were able to retrieve 46 documents. We found that they all follow a similar screening procedure, but few studies exploited equal targets, exploring the interaction of multiple ligands to 29 distinct enzymes. The following in vitro/vivo analysis showed that, although the virtual assays were able to decrease the number of molecules tested, saving time and money, virtual screening procedures still need to develop the correlation to more favorable in vitro outcomes. We find that the in silico approach has a good predictive power for in vitro results, but call for more studies to evaluate its clinical predictive possibilities.