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By the antiviral screening of an in house library of pyrazoline compounds, 4-(3-(4-phenoxyphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl)benzenesulfonamide (5a) was identified as a promising hit compound for the development of anti- Yellow Fever Virus (YFV) agents. Structural optimization studies were focused on the development of 5a analogues which retain the potency as YFV inhibitors and show a reduced cytotoxicity. The synthesized 1-3,5-triphenyl-pyrazolines (4a-j, 5a-j, 6a-j) were evaluated in cell based assays for cytotoxicity and antiviral activity against representative viruses of two of the three genera of the Flaviviridae family, i.e.: Pestivirus (BVDV) and Flavivirus (YFV). These compounds were also tested against a large panel of different pathogenic RNA and DNA viruses. Most of the new 1-3,5-triphenyl-pyrazolines (4a-j, 5a-j, 6a-j) exhibited a specific activity against YFV, showing EC 50 values in the low micromolar range with almost a 10-fold improvement in potency compared to the reference inhibitor 6-azauridine. However, the selectivity indexes of the unsubstituted (4a-j) and the phenoxy (5a-j) analogues were generally modest due to the pronounced cytotoxicity against BHK-21 cells. Otherwise, the benzyloxy derivatives (6a-j) generally coupled high potency and selectivity. On the basis of both anti-YFV activity and selectivity index, pyrazolines 6a and 6b were chosen for time of addition experiments. The selected pyrazolines and the reference inhibitor 6-azauridine displayed maximal inhibition when added in the pretreatment or during the infection., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

A series of (E)-3-heteroarylidenechroman-4-ones (1a-r) was designed, synthesized and investigated in vitro for their ability to inhibit the enzymatic activity of both human monoamine oxidase (hMAO) isoforms, hMAO-A and hMAO-B. All the compounds were found to be selective hMAO-B inhibitors showing IC50 values in the nanomolar or micromolar range. (E)-5,7-Dichloro-3-{[(2-(dimethylamino)pyrimidin-5-yl]methylene}chroman-4-one (1c) was the most interesting compound identified in this study, endowed with higher hMAO-B potency (IC50 = 10.58 nM) and selectivity (SI > 9452) with respect to the reference selective inhibitor selegiline (IC50 = 19.60 nM, IC50 > 3431). Molecular modelling studies were performed for rationalizing at molecular level the target selective inhibition of our compounds, revealing a remarkable contribution of hydrogen bond network and water solvent., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

A series of (2E,4E)-1-(2-hydroxyphenyl)-5-phenylpenta-2,4-dien-1-ones (3a-r) and (2Z,4E)-3-hydroxy-1-(2-hydroxyphenyl)-5-phenylpenta-2,4-dien-1-ones (6a-l) were synthesized and evaluated in vitro as inhibitors of the two human Monoamine oxidase (hMAO) isoforms, MAO-A and MAO-B. Most of the compounds showed a selective MAO-B inhibitory activity in the nanomolar or low micromolar range. (2E,4E)-5-(4-Chlorophenyl)-1-(2-hydroxy-4-methoxyphenyl)penta-2,4-dien-1-one (3g) and (2E,4E)-5-(4-chlorophenyl)-1-(2,4-dihydroxyphenyl)penta-2,4-dien-1-one (3h) were the most potent hMAO-B inhibitors exhibiting IC(50) of 4.51 nM and 11.35 nM, respectively, coupled with high selectivity. Moreover, partial recovery of MAO-B activity was observed after repeated washing in the presence of isatin (reversible inhibitor) and compounds 3g and 3h suggesting a reversible inhibition of the enzyme. Molecular mechanics and quantum chemistry methods were used to elucidate the MAO recognition of the most active inhibitors 3g and 3h., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)