9 research outputs found
Discovery of Covalent Inhibitors of Glyceraldehyde-3-phosphate Dehydrogenase, A Target for the Treatment of Malaria
We developed a new class of covalent
inhibitors of Plasmodium falciparum glyceraldehyde-3-phosphate
dehydrogenase, a validated target for the treatment of malaria, by
screening a small library of 3-bromo-isoxazoline derivatives that
inactivate the enzyme through a covalent, selective bond to the catalytic
cysteine, as demonstrated by mass spectrometry. Substituents on the
isoxazolinic ring modulated the potency up to 20-fold, predominantly
due to an electrostatic effect, as assessed by computational analysis
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
Protein Flexibility in Virtual Screening: The BACE‑1 Case Study
Simulating protein flexibility is a major issue in the
docking-based
drug-design process for which a single methodological solution does
not exist. In our search of new anti-Alzheimer ligands, we were faced
with the challenge of including receptor plasticity in a virtual screening
campaign aimed at finding new β-secretase inhibitors. To this
aim, we incorporated protein flexibility in our simulations by using
an ensemble of static X-ray enzyme structures to screen the National
Cancer Institute database. A unified description of the protein motion
was also generated by computing and combining a set of grid maps using
an energy weighting scheme. Such a description was used in an energy-weighted
virtual screening experiment on the same molecular database. Assessment
of the enrichment factors from these two virtual screening approaches
demonstrated comparable predictive powers, with the energy-weighted
method being faster than the ensemble method. The <i>in vitro</i> evaluation demonstrated that out of the 32 tested ligands, 17 featured
the predicted enzyme inhibiting property. Such an impressive success
rate (53.1%) demonstrates the enhanced power of the two methodologies
and suggests that energy-weighted virtual screening is a more than
valid alternative to ensemble virtual screening given its reduced
computational demands and comparable performance
Selective Arylsulfonamide Inhibitors of ADAM-17: Hit Optimization and Activity in Ovarian Cancer Cell Models
Activated
leukocyte cell adhesion molecule (ALCAM) is expressed
at the surface of epithelial ovarian cancer (EOC) cells and is released
in a soluble form (sALCAM) by ADAM-17-mediated shedding. This process
is relevant to EOC cell motility and invasiveness, which is reduced
by inhibitors of ADAM-17. In addition, ADAM-17 plays a key role in
EGFR signaling and thus may represent a useful target in anticancer
therapy. Herein we report our hit optimization effort to identify
potent and selective ADAM-17 inhibitors, starting with previously
identified inhibitor <b>1</b>. A new series of secondary sulfonamido-based
hydroxamates was designed and synthesized. The biological activity
of the newly synthesized compounds was tested in vitro on isolated
enzymes and human EOC cell lines. The optimization process led to
compound <b>21</b>, which showed an IC<sub>50</sub> of 1.9 nM
on ADAM-17 with greatly increased selectivity. This compound maintained
good inhibitory properties on sALCAM shedding in several in vitro
assays
Structure-Based Lead Optimization and Biological Evaluation of BAX Direct Activators as Novel Potential Anticancer Agents
The
first direct activator of BAX, a pro-apoptotic member of the
BCL-2 family, has been recently identified. Herein, a structure-based
lead optimization turned out into a small series of analogues, where <b>8</b> is the most potent compound published so far. <b>8</b> was used as pharmacological tool to ascertain, for the first time,
the anticancer potential of BAX direct activators and the obtained
results would suggest that BAX direct activators are potential future
anticancer drugs rather than venoms
Structure-Based Optimization of Tyrosine Kinase Inhibitor <b>CLM3</b>. Design, Synthesis, Functional Evaluation, and Molecular Modeling Studies.
Recent
advances in the knowledge of thyroid carcinomas development
identified receptor tyrosine kinases, like VEGFR2 and RET, as viable
and promising targets. Accordingly, their inhibition is emerging as
the major therapeutic strategy to treat these pathologies. In this
study we describe the synthesis and the functional evaluation of three
different series of 4-substituted pyrazolo[3,4-<i>d</i>]pyrimidine
derivatives, <b>8a</b>–<b>g</b>, <b>9a</b>–<b>g</b>, and <b>10a</b>–<b>g</b>, designed exploiting a structure-based optimization of the previously
developed inhibitor <b>CLM3</b>. Compared to the lead, the novel
compounds markedly improved both their inhibitory profile against
the target proteins, VEGFR2 and RET, and their antiproliferative efficacy
against the medullary thyroid cancer cell line TT. Significantly,
compounds <b>8b</b>, <b>9c</b>, and <b>10c</b> proved
to block the kinase activity of the mutant RET<sup>V804L</sup>, which
still lacks effective inhibitors
Identification of Glycogen Synthase Kinase-3 Inhibitors with a Selective Sting for Glycogen Synthase Kinase-3α
The glycogen synthase kinase-3 (GSK-3) has been linked
to the pathogenesis of colorectal cancer, diabetes, cardiovascular
disease, acute myeloid leukemia (AML), and Alzheimer’s disease
(AD). The debate on the respective contributions of GSK-3α and
GSK-3β to AD pathology and AML is ongoing. Thus, the identification
of potent GSK-3α-selective inhibitors, endowed with favorable
pharmacokinetic properties, may elucidate the effect of GSK-3α
inhibition in AD and AML models. The analysis of all available crystallized
GSK-3 structures provided a simplified scheme of the relevant hot
spots responsible for ligand binding and potency. This resulted in
the identification of novel scorpion shaped GSK-3 inhibitors. It is
noteworthy, compounds <b>14d</b> and <b>15b</b> showed
the highest GSK-3α selectivity reported so far. In addition,
compound <b>14d</b> did not display significant inhibition of
48 out of 50 kinases in the test panel. The GSK-3 inhibitors were
further profiled for efficacy and toxicity in the wild-type (wt) zebrafish
embryo assay
Simultaneous Targeting of RGD-Integrins and Dual Murine Double Minute Proteins in Glioblastoma Multiforme
In
the fight against Glioblastoma Multiforme, recent literature data
have highlighted that integrin α5β1 and p53 are part of
convergent pathways in the control of glioma apoptosis. This observation
prompted us to seek a molecule able to simultaneously modulate both
target families. Analyzing the results of a previous virtual screening
against murine double minute 2 protein (MDM2), we envisaged that Arg-Gly-Asp
(RGD)-mimetic molecules could be inhibitors of MDM2/4. Herein, we
present the discovery of compound <b>7</b>, which inhibits both
MDM2/4 and α5β1/αvβ3 integrins. A lead optimization
campaign was carried out on <b>7</b> with the aim to preserve the
activities on integrins while improving those on MDM proteins. Compound <b>9</b> turned out to be a potent MDM2/4 and α5β1/αvβ3
blocker. In p53-wild type glioma cells, <b>9</b> arrested cell
cycle and proliferation and strongly reduced cell invasiveness, emerging
as the first molecule of a novel class of integrin/MDM inhibitors,
which might be especially useful in subpopulations of patients with
glioblastoma expressing a functional p53 concomitantly with a high
level of α5β1 integrin
Simultaneous Targeting of RGD-Integrins and Dual Murine Double Minute Proteins in Glioblastoma Multiforme
In
the fight against Glioblastoma Multiforme, recent literature data
have highlighted that integrin α5β1 and p53 are part of
convergent pathways in the control of glioma apoptosis. This observation
prompted us to seek a molecule able to simultaneously modulate both
target families. Analyzing the results of a previous virtual screening
against murine double minute 2 protein (MDM2), we envisaged that Arg-Gly-Asp
(RGD)-mimetic molecules could be inhibitors of MDM2/4. Herein, we
present the discovery of compound <b>7</b>, which inhibits both
MDM2/4 and α5β1/αvβ3 integrins. A lead optimization
campaign was carried out on <b>7</b> with the aim to preserve the
activities on integrins while improving those on MDM proteins. Compound <b>9</b> turned out to be a potent MDM2/4 and α5β1/αvβ3
blocker. In p53-wild type glioma cells, <b>9</b> arrested cell
cycle and proliferation and strongly reduced cell invasiveness, emerging
as the first molecule of a novel class of integrin/MDM inhibitors,
which might be especially useful in subpopulations of patients with
glioblastoma expressing a functional p53 concomitantly with a high
level of α5β1 integrin