2-Phenyloxazole-4-carboxamide as a Scaffold for Selective Inhibition of Human Monoamine Oxidase B

Quantitative live cell imaging of a tauopathy model enables the identification of a polypharmacological drug candidate that restores physiological microtubule interaction

Tauopathies such as Alzheimer's disease are characterized by aggregation and increased phosphorylation of the microtubule-associated protein tau. Tau's pathological changes are closely linked to neurodegeneration, making tau a prime candidate for intervention. We developed an approach to monitor pathological changes of aggregation-prone human tau in living neurons. We identified 2-phenyloxazole (PHOX) derivatives as putative polypharmacological small molecules that interact with tau and modulate tau kinases. We found that PHOX15 inhibits tau aggregation, restores tau's physiological microtubule interaction, and reduces tau phosphorylation at disease-relevant sites. Molecular dynamics simulations highlight cryptic channel-like pockets crossing tau protofilaments and suggest that PHOX15 binding reduces the protofilament's ability to adopt a PHF-like conformation by modifying a key glycine triad. Our data demonstrate that live-cell imaging of a tauopathy model enables screening of compounds that modulate tau-microtubule interaction and allows identification of a promising polypharmacological drug candidate that simultaneously inhibits tau aggregation and reduces tau phosphorylation.

Computational Chemistry and Molecular Modeling of Reversible MAO Inhibitors

Proper elucidation of drug-target interaction is one of the most significant steps at the early stages of the drug development research. Computer-aided drug design tools have substantial contribution to this stage. In this chapter, we specifically concentrate on the computational methods widely used to develop reversible inhibitors for monoamine oxidase (MAO) isozymes. In this context, current computational techniques in identifying the best drug candidates showing high potency are discussed. The protocols of structure-based drug design methodologies, namely, molecular docking, in silico screening, and molecular dynamics simulations, are presented. Employing case studies of safinamide binding to MAO B, we demonstrate how to use AutoDock 4.2.6 and NAMD software packages.

Promising Non-cytotoxic Monosubstituted Chalcones to Target Monoamine Oxidase-B

A library of monosubstituted chalcones (1-17) bearing electron-donating and electron-withdrawing groups on both aromatic rings were selected. The cell viability on human tumor cell lines was evaluated first. The compounds unable to induce detectable cytotoxicity (1, 13, and 14) were tested using the monoamine oxidase (MAO) activity assay. Interestingly, they inhibit MAO-B, acting as competitive inhibitors, with 13 and 14 showing the best profiles. In particular, 13 exhibited a potency higher than that of safinamide, taken as a reference. Docking studies and crystallographic analysis showed that in human MAO-B 13 binds with the halogen-substituted aromatic ring in the entrance cavity, similar to safinamide, whereas 14 is accommodated in the opposite way. The main conclusion of this cell biology, biochemistry, and structural study is to highlights 13 as a chalcone derivative that is worth consideration for the development of novel MAO-B-selective inhibitors for the treatment of neurodegenerative diseases.

Novel 1,3,4-thiadiazole compounds as potential MAO-A inhibitors - design, synthesis, biological evaluation and molecular modelling

Monoamine oxidases (MAOs) are important drug targets for the management of neurological disorders. Herein, a series of new 1,3,4-thiadiazole derivatives bearing various alkyl/arylamine moieties as MAO inhibitors were designed and synthesized. All of the compounds were more selective against hMAO-A than hMAO-B. The half maximal inhibitory concentration (IC₅₀) values of most of the compounds were lower than that of the common drug moclobemide (IC₅₀ = 4.664 μM) and compound 6b was proven to be the most active compound (IC₅₀ = 0.060 μM). Moreover, it was seen that compound 6b showed a similar inhibition profile to that of clorgyline (IC₅₀ = 0.048 μM). The inhibition profile was found to be reversible and competitive for compound 6b with MAO-A selectivity. Molecular modelling studies aided in the understanding of the interaction modes between compound 6b and MAO-A. Furthermore, this compound was predicted to have a good pharmacokinetic profile and high BBB penetration. Therefore, such compounds are of interest towards developing new MAO inhibitors.

Coumarin-Rasagiline Hybrids as Potent and Selective hMAO-B Inhibitors, Antioxidants, and Neuroprotective Agents

The frequency, complexity and morbidity of neurodegenerative diseases make them a great challenge for nowadays medicine. Most of the treatments currently used for Parkinson's disease - the second most prevalent - are only symptomatic. Therefore, it is urgent to develop drugs that are able to act simultaneously on different targets, being able to stop neuronal death and promote the recovery of neuronal populations already affected. In this work, we studied the activity of a series of hybrid molecules, which combine the structure of both coumarin and an alkynylamine group inspired on rasagiline, as MAO inhibitors, antioxidants and neuroprotective agents. Half of the studied hybrids turned out to be selective monoamine oxidase B (hMAO-B) inhibitors in the low micro/nanomolar range, demonstrating that positions 3 (compounds 1-3) and 7 (compounds 8 and 10) of the coumarin scaffold are the most suitable for the incorporation of the alkynylamine chain. All the studied compounds proved to be capable of neutralizing free radicals (DPPH). Finally, the 4-(but-2-yn-1-ylamino)coumarin (5) showed neuroprotective effects on glial cells and the 4-methyl-7-(pent-2-yn-1-ylamino)coumarin (8) inhibited intraneuronal ROS production as well.