Monoamine Oxidase Inhibitory Activity: Methyl- versus Chlorochalcone Derivatives.

Numerous studies have shown that chalcones are promising scaffolds for the development of new monoamine oxidase-B (MAO-B) inhibitors. As a continuation of our ongoing research into the development of reversible human MAO-B (hMAO-B) inhibitors, two series of twenty chalcones containing electron-donating and electron-withdrawing substituents were synthesized. All compounds were found to be competitive, selective, and reversible inhibitors of hMAO-B except (2E)-1-(4-methylphenyl)-3-(4-nitrophenyl)prop-2-en-1-one (P7) and (2E)-1-(4-chlorophenyl)-3-(4-nitrophenyl)prop-2-en-1-one (P17), which were found to be selective inhibitors of hMAO-A. The most potent hMAO-B inhibitor, (2E)-1-(4-chlorophenyl)-3-(4-ethylphenyl)prop-2-en-1-one (P16), showed a Ki value of 0.11±0.01 µm. Molecular docking simulations were carried out to identify the hypothetical binding mode for the most potent compounds in the active sites of hMAO-A and B. The ability of the compounds to cross the blood-brain barrier was assessed by parallel artificial membrane permeability assay (PAMPA). Additionally, the most potent hMAO-B inhibitor P16 showed no toxicity in cultured hepatic cells at concentrations of 5 and 25 µm.

Potent and Selective Monoamine Oxidase-B Inhibitory Activity: Fluoro- vs. Trifluoromethyl-4-hydroxylated Chalcone Derivatives.

For various neurodegenerative disorders like Alzheimer's and Parkinson's diseases, selective and reversible MAO-B inhibitors have a great therapeutic value. In our previous study, we have shown that a series of methoxylated chalcones with F functional group exhibited high binding affinity toward human monoamine oxidase-B (hMAO-B). In continuation of our earlier study and to extend the understanding of the structure-activity relationships, a series of five new chalcones were studied for their inhibition of hMAO. The results demonstrated that these compounds are reversible and selective hMAO-B inhibitors with a competitive mode of inhibition. The most active compound, (2E)-1-(4-hydroxyphenyl)-3-[4-(trifluoromethyl)phenyl]prop-2-en-1-one, exhibited a Ki value of 0.33 ± 0.01 µm toward hMAO-B with a selectivity index of 26.36. A molecular docking study revealed that the presence of a H-bond network in hydroxylated chalcone with the N(5) atom of FAD is crucial for MAO-B selectivity and potency.

Design, Synthesis, and Characterization of Some Hybridized Pyrazolone Pharmacophore Analogs against Mycobacterium tuberculosis.

Twenty-seven hybridized pyrazolone analogs were designed, docked, synthesized in two series and evaluated for their in vitro antimycobacterial properties. In the first series, four Schiff base derivatives, 6b, 7b, 7h, and 7i, show good antitubercular activity with minimum inhibition concentration (MIC) values in the range of 32.56-42.55 µM. In the second series, two compounds, 8b and 8c, possessed significant antitubercular activity with MIC <0.37 and <0.44 µM, respectively; they were even more potent than the standards pyrazinamide (12.99 µM), ciprofloxacin (4.82 µM), and streptomycin (5.36 µM), with a selectivity index of >630. Compounds 8b and 8c showed shikimate kinase inhibition activity at 5.84 and 6.93 µM, respectively. The activity and docking results lead to the conclusion that the compounds without double bond in the imine side chain and hydrophobic clashes at the pyrazolone end are necessary for good accommodation in the binding pocket and for imparting flexibility. All the compounds were also tested for antimicrobial activity (antibacterial and antifungal) and show highly significant activities against all the microorganisms tested.