14 research outputs found
Development of Macrocyclic Peptidomimetics Containing Constrained α,α-Dialkylated Amino Acids with Potent and Selective Activity at Human Melanocortin Receptors
We
report the development of macrocyclic melanocortin derivatives
of MT-II and SHU-9119, achieved by modifying the cycle dimension and
incorporating constrained amino acids in ring-closing. This study
culminated in the discovery of novel agonists/antagonists with an
unprecedented activity profile by adding pieces to the puzzle of the
melanocortin receptor selectivity. Finally, the resulting 19- and
20-membered rings represent a suitable frame for the design of further
therapeutic ligands as selective modulators of the melanocortin system
Development of Macrocyclic Peptidomimetics Containing Constrained α,α-Dialkylated Amino Acids with Potent and Selective Activity at Human Melanocortin Receptors
We
report the development of macrocyclic melanocortin derivatives
of MT-II and SHU-9119, achieved by modifying the cycle dimension and
incorporating constrained amino acids in ring-closing. This study
culminated in the discovery of novel agonists/antagonists with an
unprecedented activity profile by adding pieces to the puzzle of the
melanocortin receptor selectivity. Finally, the resulting 19- and
20-membered rings represent a suitable frame for the design of further
therapeutic ligands as selective modulators of the melanocortin system
Ligand-Based NMR Study of C‑X‑C Chemokine Receptor Type 4 (CXCR4)–Ligand Interactions on Living Cancer Cells
Peptide-binding
G protein-coupled receptors (GPCRs) are key effectors
in numerous pathological and physiological pathways. The assessment
of the receptor-bound conformation of a peptidic ligand within a membrane
receptor such as a GPCR is of great impact for a rational drug design
of more potent analogues. In this work, we applied multiple ligand-based
nuclear magnetic resonance (NMR) methods to study the interaction
of peptide heptamers, derived from the C-X-C Motif Chemokine 12 (CXCL12),
and the C-X-C Chemokine Receptor Type 4 (CXCR4) on membranes of human
T-Leukemia cells (CCRF-CEM cells). This study represents the first
structural investigation reporting the receptor-bound conformation
of a peptide to a GPCR directly on a living cell. The results obtained
in the field of CXCL12/CXCR4 are proofs of concept, although important
information for researchers dealing with the CXCR4 field arises. General
application of the presented NMR methodologies is possible and surely
may help to boost the development of new therapeutic agents targeting
GPCRs
Development of Macrocyclic Peptidomimetics Containing Constrained α,α-Dialkylated Amino Acids with Potent and Selective Activity at Human Melanocortin Receptors
We
report the development of macrocyclic melanocortin derivatives
of MT-II and SHU-9119, achieved by modifying the cycle dimension and
incorporating constrained amino acids in ring-closing. This study
culminated in the discovery of novel agonists/antagonists with an
unprecedented activity profile by adding pieces to the puzzle of the
melanocortin receptor selectivity. Finally, the resulting 19- and
20-membered rings represent a suitable frame for the design of further
therapeutic ligands as selective modulators of the melanocortin system
Designed Glucopeptides Mimetics of Myelin Protein Epitopes As Synthetic Probes for the Detection of Autoantibodies, Biomarkers of Multiple Sclerosis
We previously reported that CSF114Â(Glc) detects diagnostic
autoantibodies in multiple sclerosis sera. We report herein a bioinformatic
analysis of myelin proteins and CSF114Â(Glc), which led to the identification
of five sequences. These glucopeptides were synthesized and tested
in enzymatic assays, showing a common minimal epitope. Starting from
that, we designed an optimized sequence, SP077, showing a higher homology
with both CSF114Â(Glc) and the five sequences selected using the bioinformatic
approach. SP077 was synthesized and tested on 50 multiple sclerosis
patients’ sera, and was able to detect higher antibody titers
as compared to CSF114Â(Glc). Finally, the conformational properties
of SP077 were studied by NMR spectroscopy and structure calculations.
Thus, the immunological activity of SP077 in the recognition of specific
autoantibodies in multiple sclerosis patients’ sera may be
ascribed to both the optimized design of its epitopic region and the
superior surface interacting properties of its C-terminal region
New Anticancer Agents Mimicking Protein Recognition Motifs
The
novel tetrasubstituted pyrrole derivatives <b>8g</b>, <b>8h</b>, and <b>8i</b> showed selective cytotoxicity against
M14 melanoma cells at low micromolar concentration. Structure–activity
relationships (SARs) indicated the presence of three aromatic substituents
on the pyrrole core as necessary for biological activity. Computational
studies strongly suggest that the peculiar 3D orientation of these
substituents is able to reproduce the hydrophobic side chains in LxxLL-like
protein recognition motifs. Biological results showed altered p53
expression and nuclear translocation in cells sensitive to the compounds,
suggesting p53 involvement in their anticancer mechanism of action.
Unfortunately, because of poor solubility of the active analogues,
it was not possible to perform further investigation by NMR techniques.
Pharmacophore models were generated and used to perform 3D searches
in molecular databases. Results indicated that two compounds share
the same pharmacological profile and the same pharmacophoric features
with our new derivatives, and one of them inhibited MDM2–MDM4
heterodimer formation
Structure–Activity Relationships and Biological Characterization of a Novel, Potent, and Serum Stable C‑X‑C Chemokine Receptor Type 4 (CXCR4) Antagonist
In
our ongoing pursuit of CXCR4 antagonists as potential anticancer
agents, we recently developed a potent, selective, and plasma stable
peptide, Ac-Arg-Ala-[d-Cys-Arg-Phe-Phe-Cys]-COOH (<b>3</b>). Nevertheless, this compound was still not potent enough (IC<sub>50</sub> ≈ 53 nM) to enter preclinical studies. Thus, a lead-optimization
campaign was here undertaken to further improve the binding affinity
of <b>3</b> while preserving its selectivity and proteolytic
stability. Specifically, extensive structure–activity relationships
(SARs) investigations were carried out on both its aromatic and disulfide
forming amino acids. One among the synthesized analogue, Ac-Arg-Ala-[d-Cys-Arg-Phe-His-Pen]-COOH (<b>19</b>), displayed subnanomolar
affinity toward CXCR4, with a marked selectivity over CXCR3 and CXCR7.
NMR and molecular modeling studies disclosed the molecular bases for
the binding of <b>19</b> to CXCR4 and for its improved potency
compared to the lead <b>3</b>. Finally, biological assays on
specific cancer cell lines showed that <b>19</b> can impair
CXCL12-mediated cell migration and CXCR4 internalization more efficiently
than the clinically approved CXCR4 antagonist plerixafor
Ligand-Based NMR Study of C‑X‑C Chemokine Receptor Type 4 (CXCR4)–Ligand Interactions on Living Cancer Cells
Peptide-binding
G protein-coupled receptors (GPCRs) are key effectors
in numerous pathological and physiological pathways. The assessment
of the receptor-bound conformation of a peptidic ligand within a membrane
receptor such as a GPCR is of great impact for a rational drug design
of more potent analogues. In this work, we applied multiple ligand-based
nuclear magnetic resonance (NMR) methods to study the interaction
of peptide heptamers, derived from the C-X-C Motif Chemokine 12 (CXCL12),
and the C-X-C Chemokine Receptor Type 4 (CXCR4) on membranes of human
T-Leukemia cells (CCRF-CEM cells). This study represents the first
structural investigation reporting the receptor-bound conformation
of a peptide to a GPCR directly on a living cell. The results obtained
in the field of CXCL12/CXCR4 are proofs of concept, although important
information for researchers dealing with the CXCR4 field arises. General
application of the presented NMR methodologies is possible and surely
may help to boost the development of new therapeutic agents targeting
GPCRs
Anti-Candida activity of <i>DNal</i> and Gly10 substituted peptides expressed as MIC 90 (µM) at 48 h.
<p>Each MIC value is the average of at least three independent experiments.</p
Antibacterial activity of selected peptides expressed as MIC 100 (µM) at 18 h.
<p>Each MIC value is the average of at least three independent experiments.</p