ABCB1 Structural Models, Molecular Docking, and Synthesis of New Oxadiazolothiazin-3-one Inhibitors

Docking methods are powerful tools for in silico screening and drug lead generation and optimization. Here, we describe the synthesis of new inhibitors of ABCB1 whose design was based on construction and preliminary confirmation of a model for this membrane transporter of the ATP-binding cassette family. We chose the strategy to build our three-dimensional model of the ABCB1 transporter by homology. Atomic coordinates were then assayed for their reliability using the measured activity of some oxadiazolothiazin-3-one compounds. Once established their performance by docking analysis, we synthesized new compounds whose forecasted activity was tested by MTT and cytofluorimetric assays. Our docking model of MDR1, MONBD1, seems to reliably satisfy our need to design and forecast, on the basis of their LTCC blockers ability, the inhibitory activity of new molecules on the ABCB1 transporter

p53 Functional Inhibitors Behaving Like Pifithrin‑β Counteract the Alzheimer Peptide Non-β-amyloid Component Effects in Human SH-SY5Y Cells

Alzheimer’s disease (AD) develops from a complex setting of genetic and biochemical alterations, including an increased level of p53 in the brain. Here, the robust and specific activation of p53 by the fibrillar non-β-amyloid component (NAC) of AD was demonstrated in human neuroblastoma SH-SY5Y cells. For the first time, the increase in the level of p53 target gene transcription, the cell cycle arrest, and the induction of apoptosis elicited by NAC were evidenced. These effects were counterbalanced by pifithrin-β, a small molecule interfering with the p53 functions. Using the structure of a pifithrin-β analogue as a reference, a pharmacophore-based virtual screening of the ZINC database was performed. Among the resulting hits, 20 druglike heterocyclic compounds were selected and evaluated for their neuroprotective activity against fibrillar NAC in the human SH-SY5Y cellular model. Three compounds exhibited neuroprotective effects. In particular, 2-(4-methoxyphenyl)-7-methyl-7<i>H</i>-pyrazolo­[4,3-<i>e</i>]­[1,2,4]­triazolo­[1,5-<i>c</i>]­pyrimidine resulted in a promising lead compound for further development of anti-AD agents in terms of neuroprotection, reducing the rate of NAC-induced cell death with an activity higher than that of pifithrin-β, as a result of a more effective functional inhibition of p53 target gene transcription

Deepening the Topology of the Translocator Protein Binding Site by Novel <i>N</i>,<i>N</i>‑Dialkyl-2-arylindol-3-ylglyoxylamides

As a continuation of our studies on 2-phenylindol-3-ylglyoxylamides as potent and selective translocator protein (TSPO) ligands, two subsets of novel derivatives, featuring hydrophilic group (OH, NH₂, COOH) at the para-position of the pendent 2-phenyl ring (<b>8</b>–<b>16</b>) or different 2-aryl moieties, namely, 3-thienyl, <i>p</i>-biphenyl, 2-naphthyl (<b>23</b>–<b>35</b>), were synthesized and biologically evaluated, some of them showing <i>K</i>_i values in the subnanomolar range and the 2-naphthyl group performance being the best. The resulting SARs confirmed the key role played by interactions taking place between ligands and the lipophilic L1 pocket of the TSPO binding site. Docking simulations were performed on the most potent compound of the present series (<b>29</b>) exploiting the recently available 3D structures of TSPO bound to its standard ligand (PK11195). Our theoretical model was fully consistent with SARs of the newly investigated as well of the previously reported 2-phenylindol-3-ylglyoxylamide derivatives

Deepening the Topology of the Translocator Protein Binding Site by Novel <i>N</i>,<i>N</i>‑Dialkyl-2-arylindol-3-ylglyoxylamides

As a continuation of our studies on 2-phenylindol-3-ylglyoxylamides as potent and selective translocator protein (TSPO) ligands, two subsets of novel derivatives, featuring hydrophilic group (OH, NH₂, COOH) at the para-position of the pendent 2-phenyl ring (<b>8</b>–<b>16</b>) or different 2-aryl moieties, namely, 3-thienyl, <i>p</i>-biphenyl, 2-naphthyl (<b>23</b>–<b>35</b>), were synthesized and biologically evaluated, some of them showing <i>K</i>_i values in the subnanomolar range and the 2-naphthyl group performance being the best. The resulting SARs confirmed the key role played by interactions taking place between ligands and the lipophilic L1 pocket of the TSPO binding site. Docking simulations were performed on the most potent compound of the present series (<b>29</b>) exploiting the recently available 3D structures of TSPO bound to its standard ligand (PK11195). Our theoretical model was fully consistent with SARs of the newly investigated as well of the previously reported 2-phenylindol-3-ylglyoxylamide derivatives

3-Aryl-[1,2,4]triazino[4,3-<i>a</i>]benzimidazol-4(10<i>H</i>)-one: A Novel Template for the Design of Highly Selective A_2B Adenosine Receptor Antagonists

In an effort to identify novel ligands possessing high affinity and selectivity for the A_2B AR subtype, we further investigated the class of 3-aryl­[1,2,4]­triazino­[4,3-<i>a</i>]­benzimidazol-4­(10<i>H</i>)-ones <b>V</b>, previously disclosed by us as selective A₁ AR antagonists. Preliminary assays on a number of triazinobenzimidazoles derived from our “in-house” collection revealed that all the derivatives selected showed significant affinity at A_2B AR, no affinity at A₃ AR, and various degrees of selectivity toward A₁ and A_2A ARs. Investigation of a new series featuring modified substituents at the 10-position (4′-chlorophenyl or phenylethyl groups), and a chlorine atom at the 7-position (X) of the triazinobenzimidazole nucleus, yielded highly potent and selective A_2B AR antagonists. The presence of a pendant 3-phenyl ring appears to hamper the interaction with A_2A AR, conferring high A_2B/A_2A AR selectivity. Derivative <b>13</b> (X = Cl, R = C₆H₅) is the most potent and selective compound, with an IC₅₀ of 3.10 nM at A_2B AR and no affinity at A₁, A_2A, and A₃ ARs